Research Article Adsorption of Organic Dyes by TiO @Yeast …downloads.hindawi.com/journals/jnm/2015/498304.pdf · 2019-07-31 · Research Article Adsorption of Organic Dyes by TiO

Research ArticleAdsorption of Organic Dyes by TiO2Yeast-Carbon CompositeMicrospheres and Their In Situ Regeneration Evaluation

Zheng Pei1 Zhang Kaiqiang1 Dang Yu1 Bai Bo2 Guan Weisheng1 and Suo Yourui2

1College of Environmental Science and Engineering Changrsquoan University Xirsquoan 710054 China2Northwest Plateau Institute of Biology Chinese Academy of Sciences Xining 810001 China

Correspondence should be addressed to Bai Bo baibochina163com

Received 21 July 2014 Revised 9 September 2014 Accepted 1 October 2014

Academic Editor Jinmei He

Copyright copy 2015 Zheng Pei et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

TiO2yeast-carbon microspheres with raspberry-like morphology were fabricated based on the pyrolysis method The obtained

products were characterized by field emission scanning electron microscopy (FE-SEM) energy dispersive spectrometry (EDS)and X-ray diffraction (XRD) Effects of initial dye concentration and contact time on adsorption capacity of TiO

2yeast-carbon

for cationic dye methylene blue (MB) and anionic dye congo red (CR) were investigated Experimental data were described byLangmuir Freundlich Temkin and Koble-Corrigan isotherm models respectively It was found that the equilibrium data ofMB adsorption were best represented by Koble-Corrigan and CR adsorption was best described by both Freundlich and Koble-Corrigan isotherm models The kinetic data of MB and CR adsorption fitted pseudo-second-order kinetic model well The resultsdemonstrated that TiO

2yeast-carbon microspheres achieved favorable removal for the cationic MB in comparison with that

for the anionic CR In addition regeneration experimental results showed that TiO2yeast-carbon exhibited good recycling

stability reusability and in situ renewability suggesting that the as-prepared TiO2yeast-carbon might be used as the potential

low cost alternative for recalcitrant dye removal from industrial wastewater One possible mechanism for regenerating dye-loadedTiO2yeast in situ was also proposed

1 Introduction

Organic dyes are widely and frequently used in variousindustries as textile printing petroleum paper and rubber[1 2] During the manufacturing and dyeing process asubstantial amount of dyestuff is lost into water which posesa great threat to the environment Typically the presenceof these toxic organic compounds reduces light penetrationinto water affects photosynthesis of aquatic lives impedesthe growth of microbes creates toxicity to fish accumulatesin the food chain and even travels long distance causingharm not only to the place where they are produced andused but also globally [3] Moreover most of the organicdyes are recalcitrant and difficult to degrade because oftheir complex and stable aromatic molecular structure [4]Hence the removal or degradation of organic dyes fromwater bodies has become a major environmental problemTill now some physical or chemical strategies have been

attempted to remove dye contaminants from water includ-ing adsorption [5] advanced oxidation process (AOP) [6]membrane filtration [7] ozonation [8] and coagulation-flocculation [9] Among the above-mentioned technologiesadsorption has been proven to be one of themost efficient andreliable methods for removing dyes from aqueous solutionbecause of its flexibility high efficiency ease of operationsimplicity of design and insensitivity to toxic pollutants [10]A wide variety of low cost and easily available materials suchas bentonite [11] fly ash [12] clay [13] active carbon [14]and agriculture wastes [15 16] have been exploited for theremoval of dyes from aqueous solutions

Yeast-carbon is a porous and amorphous solid carbonmaterial which is derived mainly from bakerrsquos yeast Forexample Nacco and Aquarone [17] firstly reported the fab-rication of yeast-carbon by carbonizing yeast cells in gas-heated muffle The prepared yeast-carbon exhibited largersurface area Guan et al [18] synthesized amphiphilic porous

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2015 Article ID 498304 13 pageshttpdxdoiorg1011552015498304

2 Journal of Nanomaterials

S

N

(H3C)2N N+(CH3)2

Clminus

(a)

S

SN

N

N

N

NH2

NH2

O O

O

O

OminusNa+

OminusNa+

(b)

Figure 1 The structures of dyes (a) MB and (b) CR

hollow carbonaceous spheres via mild hydrothermal treat-ment of yeast cells and further pyrolyzing The obtainedcarbon spheres displayed effective sorption of phenol fromwater In comparison with the great successes in the yeast-carbon synthesis the practical application of yeast-carbonas adsorbent in wastewater treatment has still been limitedbecause the adsorbent could get saturated easily in theadsorption process which requires extra regeneration orcomplete replacement [4] More recently TiO

2has become a

hot topic mainly for its excellent photocatalytic performance[19] The integration of adsorption and TiO

2photocatalysis

seems to offer a good solution to overcome the shortcomingof extra regeneration or complete replacement from thetraditional adsorption process In such a synergetic processthe rich pore structure of adsorbents might promote thetransfer and adsorption of organic dyes while the TiO

2could

destroy dyes by photocatalytic oxidation thus regeneratingthe adsorbent in situ [20]

In the previous work we fabricated the novelTiO2yeast-carbon microsphere with raspberry-like mor-

phology based on the pyrolysis method [21] In the presentwork as a continual job the prepared hybrid raspberry-likeTiO2yeast-carbon microspheres were further used as ad-

sorbents for removal of two typical organic dyes (Methyleneblue and Congo red) from aqueous solution The adsorptionequilibrium isotherms and kinetics was fully conductedMoreover in situ regeneration of the adsorbents wasinvestigated and one possible mechanism for regeneratingdye-loaded TiO

2yeast in situ was also proposed

2 Materials and Methods

21 Materials The powdered yeast was provided by AngelYeast Co TiO

2with the primary particle size at 20ndash30 nm

was from Degussa and was used without further purifi-cation Absolute ethanol and double-distilled water wereused throughout all the experimental procedures Methyleneblue (MB) and Congo red (CR) were purchased from XirsquoanChemical Agent Company and were used as pollutants in thepresent work Analytic grade sodium hydroxide (NaOH) andsulfuric acid (H

2SO4) were purchased from Xirsquoan Chemical

Agent Company

22 Synthesis of TiO2Yeast-Carbon Microspheres In a typi-

cal synthesis procedure 01 g of TiO2was dissolved in 200mL

of distilled water using ultrasonic vibration for 10min andthe pH value was adjusted to approximately 9-10 by addingdropwise sodium hydroxide (10molL)Then the dispersionwas stirred inmagnetic stirrers for 30min to facilitate particledeaggregation In a separate vessel 125 g yeast powder waswashed with distilled water and absolute ethanol for threetimes respectively Subsequently the yeast was dispersed in200mL of distilled water and magnetically stirred vigorouslyfor 30min and the pH value was adjusted to approximately3 with sulfuric acid (10molL) After that the above TiO

2

and yeast cells were gathered by centrifugation from theirown suspensions and redispersed in 200mLof distilledwaterrespectively Thereafter TiO

2and yeast suspensions were

slowly mixed with continuously magnetic stirring for 15 h atroom temperature and left for 30 h without further stirringin order to ensure the formation of TiO

2yeast particlesThe

mixturewas collected by centrifugationwashedwith distilledwater and absolute ethanol for three times and then desic-cated at 353K for 10 h Finally the dried TiO

2yeast particles

were calcined at 573K in a nitrogen pipe furnace for 10 hand cooled to room temperature After that TiO

2yeast-

carbon hybrid microspheres were obtained For comparisonthe yeast-carbon was prepared by similar method withoutadding TiO

2

23 Characterization Surface structure and morphology ofsamples were observed by using Philip XL-30 field emissionscanning electron microscope (FE-SEM) Detailed composi-tion characterization was carried out with energy-dispersivespectroscopy (EDS) analysis X-ray diffraction (XRD) pat-terns were conducted on X Pert Pro diffractometer using CuK120572 radiation (120582 = 015418 nm) at a scanning rate of 10∘min

24 Dye Solution Preparation Methylene blue and Congored were cationic and anionic dyes respectively and wereused as model pollutants to study the adsorption propertiesof TiO

2yeast-carbon microspheres The structures of both

dyes are shown in Figure 1 Stock MB and CR solutions(10 gL) were prepared by dissolving 1 g of MB or CR in 1 L ofdouble distilled water respectively Experimental solutions ofdesired concentration were obtained by further dilution

25 Analysis of Organic Dyes The samples were separatedfrom the solution at set intervals with centrifugation at3000 rpm for 5min and were returned to the reaction system

Journal of Nanomaterials 3

immediately after each analysis The concentrations of MBand CR in the supernatant solution were determined using adouble beamUVvisible spectrophotometer (UV-752 Shang-hai) at 6664 nm and 4990 nm respectively Calibrationcurve was found to be very reproducible and linear over theconcentration range used in this work

26 Batch Adsorption Experiments Adsorption studies werecarried by adding 025 g TiO

2yeast-carbon microspheres

and 100mL MB or CR solution of certain concentration intoa set of flasks followed by stirring inmagnetic stirrers at roomtemperature without adjusting the solution pH The flaskswere wrapped in aluminum foil to prevent photolysis Afterdesired adsorption time 5mL sample supernatant was takenout to analyze the residual concentration of MB or CR In allsets of experiments each test was conducted in duplicatesand the mean value was recorded The amount of adsorbeddye per gram TiO

2yeast-carbon hybrid microspheres at

equilibrium (119902119890 mgg) and at time 119905 (119902

119905 mgg) was calculated

by the following equation

119902119890=

(1198620minus 119862119890) 119881

119898

119902119905=

(1198620minus 119862119905) 119881

119898

(1)

where 1198620 119862119890 and 119862

119905(mgg) are concentrations of dye at

initial equilibrium and time 119905 respectively 119881 (L) is thevolumeof the dye solution and119898 (g) is themass of adsorbent

27 In Situ Regeneration of TiO2Yeast-Carbon Microspheres

In order to evaluate the reusability and renewability of theTiO2yeast-carbon MB was chosen as the model pollutant

The procedure is as follows an amount of 014 g of pre-pared TiO

2yeast-carbon was suspended in a MB solution

(100mL) with an initial concentration of 2mgL in a beakerThe solution was magnetically stirred in dark for about 25 hto ensure the establishment of an adsorption-desorptionequilibrium Then the mixed suspensions were irradiatedunder aUV lamp (Philips TL 8W08F8T5BLB 00155mbulbdiameter 026m bulb length and 12WUVA output) locateddirectly above the flasks at a distance of 6 cm from the surfaceof the solution The aqueous samples were taken out at aregular interval time and analyzed until a second equilibriumwas achieved whichmeant that a cycle was over At the end ofeach run the dye-loaded TiO


were collected by centrifugation washed thoroughly anddried to be reused in the next cycle Another cycle ofsorption-regeneration was repeated in the same manner asmentioned above All of the experiments were performed intriplicate at room temperatureThe removal rate (120578) ofMBwas calculated by the following equation

120578 =

(1198620minus 119862119890)

1198620

times 100 (2)

3 Results and Discussion

31 Characterization Figure 2(a) is the SEM images of yeast-carbon It reveals that the yeast-carbon had smooth surfacemorphology and uniform size (length = 35plusmn04 120583m width =23plusmn05 120583m) Figure 2(b) depicts an image of the TiO

2yeast

which is the precursor of TiO2yeast-carbon The size of

TiO2yeast (length = 37 plusmn 04 120583m width = 26 plusmn 05 120583m)

increased compared with the yeast-carbon in Figure 2(a)which may be assigned to the attachment of TiO

2particles

Figure 2(c) presents an overall image of the TiO2yeast-

carbon hybrid microspheres The micrograph in Figure 2(c)indicates that the particles inherited the general shape andgood dispersity of the precursor in Figure 2(b) Figures 2(d)and 2(e) expresses the TiO

2yeast-carbon spheres in differ-

ent magnifications The TiO2yeast-carbon in Figure 2(d)

exhibits a typical raspberry-like structure since the TiO2

nanoparticles were randomly decorated on the surface ofcarbon microspheres Figure 2(f) displays the detailed infor-mation of the outer appearance of the TiO

2yeast-carbon

microspheres under a higher magnification It can be clearlyseen that the surfaces of the microspheres were coated withsmall TiO

2particles whereas some residual bare areas still

remainedThese residual bare regions were of great benefit tothe adsorption of dye molecules in aqueous solution

Additionally the unique raspberry-like structure ofTiO2yeast-carbon is further confirmed from the EDS anal-

ysis In the insert image in Figure 2(a) C O Zn P and Ptelements can be observed C O and P result from the yeastcells Zn element comes from the yeast cells activation agentZnCl2 and Pt is assumed to be due to the metal spraying

before SEM studies C O P and Ti elements are observedin the insert image in Figure 2(d) C O and P elements alsoderive from the yeast and the Ti element detected indicatesthat TiO

2has been already successfully coated on the yeast

carbonXRD patterns of TiO

2 yeast yeast-carbon and

TiO2yeast-carbon are shown in Figure 3 Diffraction

peaks at around 20∘ in Figures 3(a) and 3(b) indicate theformation of amorphous species Figure 3(c) illustratesan XRD pattern of TiO

2yeast-carbon The broad peak

at 20∘ is mainly caused by the amorphous structure ofyeast-carbon Moreover the remaining diffraction peaks arein good agreement with TiO

2in Figure 3(d) and no other

diffraction peaks can be detected within the investigatedrange Figure 3(d) exhibits the XRD pattern of the originalcomponents of TiO

2nanoparticles (P25 TiO

2 78 anatase-

type TiO2and 22 rutile-type TiO

2) The observed sharper

diffraction peaks at 25∘ 379∘ 482∘ 548∘ and 630∘ areconsistent with diffraction peaks of anatase-type TiO

2

(JCPDS number 21-1272) [22] and the other diffractionpeaks centering at 690∘ 703∘ and 750∘ correspond wellwith the reflections of rutile-type TiO

2(JCPDS number

21-1276) [23]

32 Adsorption Capacity of MB and CR on TiO2Yeast-

Carbon Figure 4 describes the measured isotherms for MBand CR on the TiO

2yeast-carbon samples at the same

initial dye concentration From Figure 4 119876119905for MB and CR


05 1 15 2 25 3 35

C

Zn PPtO

(a) (b)

(c)

0 1 2 3 4 5

C

O P Ti

(d)

(e) (f)

Figure 2 FE-SEM images of (a) the yeast-carbon (b) general observation of the raspberry-like TiO2yeast precursor (c) the overall view

of the raspberry-like TiO2yeast-carbon microspheres (d-e) the selected raspberry-like TiO

2yeast-carbon microspheres and (f) typical

raspberry-like TiO2yeast-carbon microspheres observed under high magnifications

increased dramatically during the initial time Then MB andCR adsorption reached equilibrium at the time of about 80and 130min respectively which was similar to observationsof Hameed et al [24] As shown in Figure 4 two adsorptionstages existed obviously a very rapid initial adsorption overa few minutes followed by a longer period of much sloweruptake The rapid uptake at the initial contact time couldbe ascribed to the fact that there were plenty of availableadsorption active sites on the surface of TiO

2yeast-carbon

while the slow rate of dye adsorption was probably due to therepulsive forces between the dye molecules in the solution

and on the surface of the TiO2yeast-carbon [25] It can

also be seen from Figure 4 that the adsorption capacityof cationic dye MB by TiO

2yeast-carbon was significantly

higher than that of anionic dye CR as manifested by theapproximately 3-fold higher adsorption capacity of the CRwhich could be assigned to the negatively charged surface ofthe adsorbent [21 26] Moreover because the CR possessesmore polar atoms (N and S) the interaction between CRand TiO

2yeast-carbon may be stronger than that between

MB and TiO2yeast-carbon This may induce a collapse in

the pore structure of TiO2yeast-carbon and then create a


Anatase-TiO2

Rutile-TiO2

0

1000

2000

3000

4000

5000

6000

7000

8000

Inte

nsity

(au

)

10 20 30 40 50 60 70

2120579 (deg)

∘

∘

∘∘

∘

+

+

+

+

+++

110110

004 200

105 211 204301

101

(d)

(c)

(b)

(a)

Figure 3 XRD patterns for (a) the premier yeast (b) the preparedyeast-carbon (c) TiO

2yeast-carbon (d) the pure TiO

2

Methylene blueCongo red

(b)

(a)

0 20 40 60 80 100 120 140 160 180Time (min)

00

01

02

03

04

05

06

07

08

09

Qt

(mg

g)

Figure 4 Adsorption isotherms for MB (a) and CR (b) onTiO2yeast-carbon

sharp decrease in the adsorption capacity It is noteworthythat the adsorption capacity of MB on TiO

2yeast-carbon

is similar to that of Basic Green 5 measured by Juang etal [27] According to the adsorption results above it isexperimentally demonstrated that TiO

2yeast-carbon may

be a good adsorbent for the removal of MB even if nochemical modification is taken

The favorable removal of cationicMB in comparisonwiththe anionic CR by TiO

2yeast-carbon adsorbent can be fur-

ther verified by changing of initial dye concentration Figure 5illustrates the influence of dye concentration on adsorptioncapacity of TiO

2yeast-carbon nanocomposite for MB and

CRAs shown in Figure 5 the adsorption capacity forMB andCR augmented with the increase of dye concentration which

2 4 6 8 10 1200

05

10

15

20

C0 (mgg)

C0 (mgg)

Adso

rptio

n ca

paci

tyQe

(mg

g)

Congo red

Adso

rptio

n ca

paci

tyQe

(mg

g)

0 1 2 3 4 5 6

00

05

10

15

20

25

Methylene blue

Figure 5 Influence of adsorbate concentration on adsorptioncapacity of TiO

2yeast-carbon nanocomposite for MB and CR

could be explained by the elevated concentration gradientbetween the bulk solution and the surface of the TiO

2yeast-

carbon [25] As presented in Figure 5 the adsorption ofMB on TiO

2yeast-carbon showed higher capacity than

CR within the investigated concentration However theadsorption capacity forMBorCR is sure to reach a constant ifthe dye concentration exceeds continuously because a certainamount of TiO

2yeast-carbon could only provide limited

active adsorption sites

33 Adsorption Isotherms Adsorption isotherm models areimportant to investigate how adsorbates interact with adsor-bents [28] and are widely used to describe the adsorptionprogress [10] Langmuir Freundlich Temkin and Koble-Corrigan isotherm models were used to fit the equilibriumdata obtained from the study of MB and CR adsorption ontoTiO2yeast-carbon at initial concentrations of 10sim50mgL

and 30sim110mgL respectivelyLangmuir isotherm assumes monolayer adsorption onto

a surface containing a finite number of adsorption sites ofuniform strategies of adsorption with no transmigration ofthe adsorbate in the plane of surface [10 29] The nonlinearLangmuir equation is given as

119876119890=

119876119898119870119871119862119890

1 + 119870119871119862119890

(3)

where 119876119890is the amount of dye adsorbed per unit mass of

the hybrid microspheres at equilibrium (mgg) 119862119890is the

equilibrium concentration of the adsorbate (mgL)119876119898is the

theoretical maximum adsorption capacity (mgg) and 119870119871is

the Langmuir adsorption constant reflecting the tendency ofadsorption (Lmg)


To predict whether the adsorption process is favorable orunfavorable equilibrium parameter119877

119871 a dimensionless con-

stant separation factor is defined by Weber and Chakravortias the following equation [30]

119877119871=

1

1 + 1198701198711198620119898

(4)

where 1198620119898

is the highest initial dye concentration (mgL)the value of 119877

119871indicates the type of isotherm to be either

favorable (0 lt 119877119871

lt 1) unfavorable (119877119871

gt 1) irreversible(119877119871= 0) or linear (119877

119871= 1)

The Freundlich model is an empirical theory basedon adsorption on heterogeneous surface with nonuniformdistribution of adsorption energy and affinities through amultilayer adsorption [31] The nonlinear Freundlich equa-tion is expressed as follows [32]

119876119890= 119870119865119862119890

1119899 (5)

where 119870119865is the Freundlich isotherm constant related to

the sorption capacity and represents the strength of theadsorptive bond (mgsdotgminus1 (Lsdotmgminus1)1n)The constant 1119899 givesan indication of how favorable the adsorption process is anda value between 01 and 10 represents a favorable adsorption[33]

Moreover Temkin isotherm takes the adsorbate-adsorb-ent interactions into account based on the assumptions thatthe heat of adsorption of all the molecules in the layerdecreases linearly with coverage due to adsorbent-adsorbateinteractions and that the adsorption is characterized bya uniform distribution of binding energies up to somemaximum binding energy [34 35]The Temkin isotherm hasgenerally been applied as

119876119890= 119860 sdot ln (119861 sdot 119862

119890) (6)

where 119860 = 119877119879119887 and 119887 is Jmol 119879 (K) is the absolute tem-perature 119877 (8314 JmolsdotK) is the universal gas constant and119861 (Lmol) is the equilibrium binding constant correspondingto the maximum binding energy respectively

Koble-Corrigen (K-C) isotherm model is an empiricalthree-parameter model which combines both Langmuir andFreundlich isotherm models for representing equilibriumadsorption data and is given by (7) as follows [36]

119876119890=

119860KC sdot 119862120573

119890

1 + 119861KC119862120573

119890

(7)

where 119860KC 119861KC and 120573 are Koble-Corrigen isotherm con-stants When 120573 = 1 the equation reduces to Langmuirequation if 119861KC sdot 119862

120573

119890≪ 1 the equation becomes Freundlich

equation If 119861KC sdot 119862120573

119890≫ 1 the adsorbate quantity per unit

weight of adsorbent at equilibrium remains to be a constantof 119860KC119861KC [37]

A comparison of the adsorption experimental isothermsof MB onto the TiO

2yeast-carbon and theoretical plots

of the Langmuir Freundlich Temkin and Koble-Corriganisotherm models was shown in Figure 6 Correlation coeffi-cients and constants of the models were given in Table 1

Ce (mgL)04 06 08 10 12 14 16 18 20

02

22

04

06

08

10

12

Methylene blueLangmuirFreundlich

TemkinKoble-Corrigan

qe

(mg

g)

Figure 6 Comparison of Langmuir Freundlich Temkin andKoble-Corrigan isotherm models for MB adsorption ontoTiO2yeast-carbon composites (adsorbent = 0014 g solution

volume = 100mL pH = 6 contact time = 15 h temperature = 298Kand concentration of MB = 10 20 30 40 and 50mgL resp)

Table 1 Isotherm constants for the adsorption of MB and CR ontoTiO2yeast-carbon

Adsorption isothermmodels Constants MB CR

Langmuir isotherm

119876119898(mgg) 220 162

119870119871(lmg) 065 0571198772 06745 09128

119877119871 02346 02597

Freundlich isotherm1n 0630 0655

119870119865[(mgg)(mgminus1)1119899] 0840 0033

1198772 05832 09920

Temkin isothermA 0607 0500B 4314 05101198772 07517 09134

Koble-Corriganisotherm

119860KC 863 003119861KC 708 522120573 420 1541198772 09745 09883

As can be seen from Figure 6 Koble-Corrigan isothermplot was very close to the experimental data plot Besides itwas observed in Table 1 that the value of1198772 of Koble-Corriganmodel (1198772 gt 097) was higher than those of Temkin Lang-muir and Freundlich isotherm models showing that Koble-Corrigan model was most suitable for the MB adsorptionthan the other models This indicated that a combination ofheterogeneous and homogeneous uptakes occurred in MBuptake by the synthesized TiO

2yeast-carbon Meanwhile


Table 2 Isotherm models for adsorption of MB and CR on various adsorbents

Adsorbent Dyes Adsorption isotherm ReferenceActivated carboncobalt ferritealginate MB Langmuir Freundlich Ai et al [40]Bamboo-based activated carbon MB Langmuir Hameed et al [24]TiO2yeast MB Langmuir Chen and Bai [33]Graphene MB Langmuir Liu et al [41]Perlite MB Langmuir Dogan et al [42]Garlic peel MB Freundlich Hameed and Ahmad [43]TiO2yeast-carbon MB Koble-Corrigan This studyBagasse fly ash and activated carbon CR Redlich-Peterson Mall et al [34]Kaolin CR Langmuir Vimonses et al [2]Bentonite zeolite CR Freundlich Vimonses et al [2]Activated carbon prepared from coir pith CR Langmuir Freundlich Namasivayam and Kavitha [44]Chitosanmontmorillonite nanocomposite CR Langmuir L Wang and A Wang [45]TiO2yeast-carbon CR Freundlich Koble-Corrigan This study

comparing the coefficients of determination of the Langmuirand Freundlich models we could infer that homogeneousuptake was the main mechanism of the MB adsorptionprocess [38] Moreover the value of 119877

119871from the Langmuir

isotherm was between 0 and 1 the Freundlich constant1119899 was smaller than 1 and the value 120573 in Koble-Corriganmodel is over 1 indicating that the adsorption of MB ontoTiO2yeast-carbon was a favorable adsorption process

Figure 7 typically showed the adsorption isotherms of CRonto the TiO

2yeast-carbonThe parameters of the isotherm

equations were summarized in Table 1 It was shown inFigure 7 that bothKoble-Corrigan and Freundlichmodels aresuitable for CR adsorption process From Figure 7 the lowdeviation between the calculated behavior and experimentalplot had been observed This fitting result can be explainedby the presence of competition between adsorbate moleculesfor the adsorption sites on the surface [36] The higher valueof 1198772 in Table 1 from Freundlich model than Koble-Corriganmodel implied that Freundlich model fitted the most exactlyIn contrast the 119877

119871value obtained from the Langmuir model

the Freundlich constant (1119899) and the value 120573 from Koble-Corriganmodel exhibited the same tendency as those forMBadsorption above representing that the adsorption of CR onthe TiO

2yeast-carbon was favorable

The above analyses showed that the Koble-Corriganmodel yields a better fit of MB than the other models CRadsorption on the TiO

2yeast-carbon microspheres con-

forms well to Freundlich and Koble-Corrigan modelsNamely the Koble-Corrigan model fitted both MB and CRadsorption well In addition constants of 119860KC and 119861KC fromKoble-Corrigan model are indicators of adsorption capacityand affinity of the adsorbent [36] The values of Kolbe-Corrigan constant 119860KC were 863 and 003 and those of 119861KCwere 708 and 522 for MB and CR respectively The greater119860KC and 119861KC values for MB indicated higher MB adsorptioncapacity affinity and intensity compared to CR adsorptiononto TiO

2yeast-carbon microspheres This phenomenon

was in accordance with the result illustrated in Figure 4which may be attributed to the different active functionalgroups in MB and CR molecules [39] revealing that the

2 3 4 5 6 7 8

01

02

03

04

05

06

07

Congo redLangmuirFreundlich


Ce (mgL)

08

qe

(mg

g)

Figure 7 Comparison of Langmuir Freundlich Temkin and K-C isotherm models for CR adsorption onto TiO

2yeast-carbon

composites (adsorbent = 0014 g solution volume = 100mL pH =6 contact time = 15 h temperature = 298K and concentration ofCR = 30 50 70 90 and 110mgL resp)

TiO2yeast-carbon microspheres can be served as a promis-

ing adsorptive material for MBSince adsorption isotherm is basically important to

describe how adsorbates interact with adsorbents someresearchers had also investigated the best fitted isothermmodels for the adsorption of MB and CR onto several adsor-bents in aqueous solutions [2 24 33 34 40ndash45] The resultswere listed in Table 2 and the TiO

2yeast-carbon studied in

this work represented different adsorption behaviors

34 Adsorption Kinetics To investigate the adsorptionmech-anism such as mass transfer and chemical reaction the MBandCR adsorption datawere analyzed using the pseudo-first-order and pseudo-second-order models respectively The


10 mgL 20 mgL 30 mgL

40 mgL 50 mgL

5 10 15 20 25

000

025

050

075

Time (min)

ln(qeminusqt)

(a)


40 mgL 50 mgL

5 10 15 20 250

30

60

90

120

150

Time (min)

tqt

(minmiddotg

mg)

(b)

Figure 8 Pseudo-first-order (a) and pseudo-second-order (b) adsorption kinetics for adsorption ofMB onto TiO2yeast-carbon at different

initial concentrations (TiO2yeast-carbon dosage = 014 gL pH = 60 temperature = 298K and concentration of MB = 10 20 30 40 and

50mgL resp)

pseudo-first-order kinetic model was described by Lagergrenand the pseudo-second-order kinetic model was based onthe assumption that the rate limiting step of the adsorptionprocess was chemical sorption [25] The pseudo-first-orderequation can be expressed as [46]

ln (119876119890minus 119876119905) = ln119876

119890minus 1198961sdot 119905 (8)

where 119876119890(mgg) and 119876

119905(mgg) are the amounts of dye

adsorbed onto the composites at equilibrium and at time 119905respectivelyThe rate constant 119896

1(minminus1) of the pseudo-first-

order model was calculated from the plots of ln(119876119890minus 119876119905)

versus 119905The pseudo-second-order equation can be described in

the following equation [28]

119905

119876119905

=

1

(1198962sdot 1198762

119890)

+

119905

119876119890

(9)

where 1198962(gsdotmgminus1sdotminminus1) is the adsorption rate constant of

the pseudo-second-order equation and can be obtained fromthe linear plots of 119905119876

119905against 119905

Besides the applicability of both kinetic models wastested through the sum of error squares (SSE) which wasgiven as follows [47]

SSE () =radic

sum(119876119890exp minus 119876

119890cal)2

119873

(10)

where 119873 is the number of data points The higher thecorrelation coefficient (1198772) and the lower the values of SSE

the better the goodness of fit will be Table 3 also listedthe calculated SSE results for MB and CR adsorption ontoTiO2yeast-carbon at different initial concentrations

Figure 8 exhibits the plots of the pseudo-first-orderand pseudo-second-order kinetics of MB adsorption onTiO2yeast-carbon at different initial concentrations The

adsorption rate constants correlation coefficient and SSEvalues were calculated and summarized in Table 2 It wasobserved from Table 2 that the experimental 119876

119890values

(119876119890exp) did not agree with the calculated ones (119876

119890cal)although the correlation coefficient values for the pseudo-first-order at some concentrations were higher than 085 Asa result the sorption of MB on the TiO

2yeast-carbon did

not follow pseudo-first-order in all cases It was also obviousthat the correlation coefficient 1198772 was found to range from0936 to 0994 for the pseudo-second-order kinetic modelwhich were higher than those for the pseudo-second-ordermodel and the experimental 119876

119890values (119876

119890exp) were closerwith the theoretical calculated values (119876

119890cal) compared to thepseudo-first-order model Furthermore SSE values for thepseudo-second-order model were lower than those for thepseudo-second-order model All the illustrations mentionedabove indicated that the adsorption of MB onto TiO

2yeast-

carbon followed the pseudo-second-order kineticmodel andthe chemical sorption might be involved in the adsorptionprocess Moreover the rate constant (119896

2) decreased with the

increase of the initial MB concentrations which was due tothe striking hindrance of higher concentrations of MB [40]

Figure 9 presents the plots of the pseudo-first-orderand pseudo-second-order kinetics of CR adsorption on


Table 3 Kinetic adsorption parameters of different initial concentration of MB and CR

1198620(mgL) 119876

119890exp (mgg) Pseudo-first-order Pseudo-second-order1198961(minminus1) 119876

119890cal (mgg) 1198772 SSE () 119896

2(gmgsdotmin) 119876

119890cal (mgg) 1198772 SSE ()

MB10 043 34 times 10minus3 216 0868 087 0426 039 0961 01020 060 49 times 10minus3 165 0912 101 0404 063 0989 00830 081 10 times 10minus2 182 0683 042 0260 101 0994 00240 106 24 times 10minus2 179 0953 038 0055 116 0976 02450 215 20 times 10minus2 184 0767 018 0049 214 0936 032

CR30 029 96 times 10minus2 167 0960 069 0270 030 0981 00490 062 85 times 10minus2 125 0903 032 0052 064 0989 011110 124 110 times 10minus2 375 0941 125 0040 133 0994 001

5 10 15 20 25

minus4

minus3

minus2

minus1

0

Time (min)

30mgL90 mgL110 mgL

ln(qeminusqt)

(a)

5 10 15 20 25

20

40

60

80

100

Time (min)

30mgL90 mgL110 mgL

tQt

(minmiddotg

mg)

(b)

Figure 9 Pseudo-first-order (a) and pseudo-second-order (b) adsorption kinetics for adsorption of CR onto TiO2yeast-carbon at different

initial concentrations (TiO2yeast-carbondosage= 014 gL pH=60 temperature = 298K and concentration ofMB=30 90 and 110mgL

resp)

TiO2yeast-carbon at different initial concentrations The

adsorption rate constants correlation coefficient and SSEvalues are also given in Table 3The results presented an idealfit to the pseudo-second-order kinetics for all concentrationswith the higher correlation coefficient (1198772 gt 098) andlower SSE values A good agreement with this model wasconfirmed by the similar values of calculated adsorptioncapacity at equilibrium (119876

119890cal) and experimental ones (119876119890exp)

for all concentrations The best fit to the pseudo-second-order kinetics model indicates that the adsorption mecha-nism depends on the adsorbate and adsorbent and the ratecontrolling stepmight be chemical sorption involving valenceforces through exchange or sharing of electrons [2] The rate

constant (1198962) also decreased with the increase of the initial

CR concentrations owing to that the higher probability ofcollisions among CR molecules would decrease the sorptionrate [28] Similar kinetic results have also been reported forthe CR adsorption onto bagasse fly ash [34] activated carbonfrom coir [44] and chitosanmontmorillonite [45]

35 Regeneration of Dye Loaded TiO2Yeast-Carbon Micro-

spheres No matter if adsorption is carried out in statical ordynamical forms it will gradually reach equilibrium if morecontaminated water was treated or more adsorption cycleswere conducted without regeneration [48] So the removal of


2 4 6 8 10 12 14 16 18

08

06

04

02

00

h

h

Rem

oval

rate

Time (h)

1 2 3

In dark

In dark

In dark Light on

Light on

Light on

(a) Yeast-carbon(b) TiO2yeast-carbon

(a)

(a)(a)

(b)(b)

(b)

Figure 10 The circulation experiment of TiO2yeast-carbon com-

posite microspheres

adsorbed pollutants and the regeneration study of saturatedcomposite were completely necessary Hence experimentswere performed to evaluate the lifetime and reusing efficiencyof prepared composite in removing MB (Figure 10)

For the dark adsorption section in the first cycle nearabsorption-desorption equilibrium was established duringthe 30 h dark phase before the irradiation of the dyes solu-tions It can also be seen from Figure 10 that strengtheningtrend occurs for the adsorption capacities of TiO

2yeast-

carbon microsphere when TiO2nanoparticles were attached

onto the yeast-carbon This enhanced effect of absorptionmight be ascribed to the integration of yeast-carbon andTiO2nanoparticles which creates more adsorption sites for

MB The dark adsorption results show that TiO2yeast-

carbon microsphere have faster adsorption kinetics due totheir larger vacant surface area compared to the naked yeast-carbon This phenomenon can be further affirmed by thepseudo-first-order kinetic data in Table 4 As can be seenthe kinetic rate constant in dark (119896dark) for TiO

2yeast-

carbon is 55 times 10minus3 which is almost 42 times of that forthe yeast-carbon The higher 119896dark gave clear evidence thatTiO2yeast-carbon exhibited higher adsorption rate than

yeast-carbon Thereafter the experiments for the removal ofMB compound from aqueous solution were continued forabout 3 h under UV light irradiation Figure 10 shows thatin the first cycle approximately 30 of MB was removedfrom the aqueous solution by adsorption on the naked yeast-carbon In the presence of the raspberry-like TiO

2yeast-

carbon microspheres and under UV irradiation nearly 85of MB molecule disappearance was accomplished

These results suggest that the prepared TiO2yeast-

carbon composites are effective for the removal of MB fromaqueous solutions The integration of adsorption by theyeast-carbon with photocatalysis by the TiO

2nanoparticles

attached on the yeast-carbon surface showed a combinedfunction in the removal of the MB molecule Specifically

yeast-carbon can increase the photodegradation rate byprogressively allowing an increased concentration of MB tocome in contact with the TiO

2nanoparticles through means

of adsorption TiO2nanoparticles on the surface of yeast-

carbon can be activated to generate hydroxyl free radicalswhich can decompose most of the MB molecules and keepthe adsorption sites unsaturated In return the simultaneousadsorption of theMBmolecules onto the renewed areas of theyeast-carbon provides a continuous supply of substrate to theTiO2nanoparticles [49] Thus the adsorption performance

of the yeast-carbon and the photocatalytic property of theattached TiO

2have been integrated as a novel property for

the raspberry-like TiO2yeast-carbon composites

It was also observed in Figure 10 that after three timesreuses the MB removal by yeast-carbon apparently droppedfrom 306 to 70 It could be attributed to the fact that theremoval of MB in aqueous solution by yeast-carbon mostlyrelied on adsorption which fully depended on the absorptionsites Hereby the bare active sites on yeast-carbon werecovered by MB molecules adsorbed in the last cycle whichgave explanation for the rapid loss of MB removal How-ever the TiO

2yeast-carbon still achieved desired removal

efficiency for MB with slight decrease from 844 to 593even though it had been reused for three times that is after3 successive cycles under UV light irradiation the removalrate of MB by TiO

2yeast-carbon was still 70 of that

for the first cycling run These phenomena give evidencethat TiO

2yeast-carbon nanocomposites exhibited excellent

photocatalytic stability and regeneration efficiencyThe outstanding regeneration ability of TiO

2yeast-

carbon in comparison with the yeast-carbon could be furtheraffirmed by contrasting the pseudo-first-order kinetic rateconstants 119896dark (in dark) and 119896light (light on) in Table 4As can be seen the 119896dark for TiO

2yeast-carbon during

three cycle times are 55 times 10minus3 42 times 10minus3 and 90 times 10minus3respectively which were almost 42 150 and 101 timesthose for the yeast-carbon The higher 119896dark means thatTiO2yeast-carbon regenerated by UV light illumination

exhibited higher adsorption rate than yeast-carbon Besidesirradiation of yeast-carbon after dark adsorption equilibriumhad resulted in smaller 119896light (122 times 10minus3 57 times 10minus4 and17 times 10minus5) compared to TiO

2yeast-carbon under UV light

showing that the attachment of TiO2nanoparticles on the

surface of yeast-carbon had a great significant influence onthe removal rate of MB and implied that in situ regenerationof the MB-loaded TiO

2yeast-carbon had already occurred

36 In Situ Regenerating Mechanism for TiO2Yeast-Carbon

Based on the results above a synergistic effect might beone possible mechanism for in situ regenerating dye-loadedTiO2yeast-carbonThe synergistic effect works by integrat-

ing the adsorption of the yeast-carbonwith the photocatalysisof the TiO

2nanoparticles attached on the yeast-carbon sur-

face More specifically based on the bare areas on the surfaceof yeast-carbon and TiO

2 dye molecules were adsorbed onto

the TiO2yeast-carbon through means of adsorption Then

the adsorption sites are keeping unsaturated by illuminatingthe whole system Because the irradiation of TiO

2particles


Table 4 Kinetic constant (gmgsdotmin) 119896dark (in dark) 119896light (light on) and Adj 119877-Square 1198772 for removing MB

Cycle 1 Cycle 2 Cycle 3Yeast-carbon TiO2yeast-carbon Yeast-carbon TiO2yeast-carbon yeast-carbon TiO2yeast-carbon

119896dark 13 times 10minus3 55 times 10minus3 28 times 10minus4 42 times 10minus3 89 times 10minus5 90 times 10minus4

1198772 0980 0838 0834 0870 0866 0904

119896light 122 times 10minus3 603 times 10minus3 57 times 10minus4 557 times 10minus3 17 times 10minus5 544 times 10minus3

1198772 0992 0917 0946 0968 0894 0946

on the yeast-carbon with photons of energy (hv) equal toor higher than those of band gap results in the excitation ofelectrons from the valence band (vb) to the conduction band(cb) of the particle which can produce the electrons (119890cb

minus)in the conduction band and the holes (ℎvb

+) at the valenceband edge of the TiO

2(11) [50] The electrons and holes can

migrate to the particle surface of TiO2 where the ℎvb

+ canreact with the adsorbed O

2 surrounded water molecules

and surface hydroxide group respectively to generate thehighly reactive hydroxyl radicals (∙OH) ((12) and (13)) andsuperoxide ions O

2

minus (14) The resulted ∙OH and O2

minus areknown to be very powerful and indiscriminately oxidizingagents and can oxidize the organic compounds adsorbed ontoor very close to the TiO

2surface during the photocatalytic

process resulting in degradation of dye into small units likecarbon dioxide and water (15)

TiO2+ ℎV 997888rarr TiO

2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)

OHminus + TiO2(ℎ+) 997888rarr

∙OH (13)

TiO2(119890minus) +O2997888rarr TiO

2+O2

∙minus (14)

O2

∙minus or ∙OH + dye 997888rarr CO2+H2O (15)

Simultaneously the renewed adsorption sites provide adurative supply of MB molecule for TiO

2particle Then

the activity of TiO2yeast-carbon was successfully recovered

after in situ regeneration The recovered adsorbent could beused for the next adsorption and catalytic reaction cycle Allin all the combination of both adsorption and heterogeneouscatalysis could be regarded as cleaner greener favored andpromising technology for removing dye from water Anoptimal amount of TiO

2coverage should exist since the

coverage rate of the attached TiO2nanoparticles onto the

yeast-carbon surface in the TiO2yeast-carbon composite is

an important factor for the control of removing dyes Thisaspect is currently under investigation

4 Conclusions

In conclusion TiO2yeast-carbon with raspberry-like struc-

turewas successfully prepared based on pyrolysismethod andwas characterized by FE-SEM EDS and XRD The syntheticTiO2yeast-carbon was used as adsorbent to remove MB

andCR from aqueous solutions respectively FE-SEM imagesdisplayed that TiO

2yeast-carbon microspheres have rough

surface morphology and uniform diameter with good dis-persity EDS showed that TiO

2has been already successfully

coated on the yeast carbon The adsorption results showedthat TiO

2yeast-carbon microspheres achieved favorable

removal of cationic MB in comparison with the anionic CREquilibrium data for MB adsorption were best describedby the Koble-Corrigan isotherm model The adsorption ofCR onto TiO

2yeast-carbon showed best agreement with

both Freundlich and Koble-Corrigan models Kinetic dataindicated that the adsorption of both MB and CR ontoTiO2yeast-carbon microspheres obeyed pseudo-second-

order kinetic model well Moreover regeneration experi-ments showed that TiO

2yeast-carbon composites exhib-

ited excellent recycling stability reusability and renewableability One possible mechanism for regenerating dye-loadedTiO2yeast in situ was also proposed This paper may be

useful for further research and practical applications of thenovel TiO

2yeast composite in dye wastewater treatment

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was financially supported by the National Nat-ural Science Foundation of China (no 21176031) Funda-mental Research Funds for the Central Universities (no2013G2291015) and National Undergraduate Training Pro-grams for Innovation and Entrepreneurship of ChangrsquoanUniversity (no 201410710059)

References

[1] M Saquib M Abu Tariq M M Haque and M Muneer ldquoPho-tocatalytic degradation of disperse blue 1 using UVTiO

2H2O2

processrdquo Journal of Environmental Management vol 88 no 2pp 300ndash306 2008

[2] V Vimonses S Lei B Jin C W K Chow and C SaintldquoKinetic study and equilibrium isotherm analysis of Congo Redadsorption by claymaterialsrdquoChemical Engineering Journal vol148 no 2-3 pp 354ndash364 2009

[3] A Roy S Chakraborty S P Kundu B Adhikari and S BMajumder ldquoAdsorption of anionic-azo dye from aqueous solu-tion by lignocellulose-biomass jute fiber equilibrium kineticsand thermodynamics studyrdquo Industrial and Engineering Chem-istry Research vol 51 no 37 pp 12095ndash12106 2012


[4] N M Mahmoodi ldquoBinary catalyst system dye degradationusing photocatalysisrdquo Fibers and Polymers vol 15 no 2 pp273ndash280 2014

[5] V S Mane and P V V Babu ldquoStudies on the adsorption ofBrilliant Green dye from aqueous solution onto low-cost NaOHtreated saw dustrdquo Desalination vol 273 no 2-3 pp 321ndash3292011

[6] S Hisaindee M A Meetani and M A Rauf ldquoApplication ofLC-MS to the analysis of advanced oxidation process (AOP)degradation of dye products and reaction mechanismsrdquo TrACTrends in Analytical Chemistry vol 49 pp 31ndash44 2013

[7] J Wu M A Eiteman and S E Law ldquoEvaluation of membranefiltration and ozonation processes for treatment of reactive-dyewastewaterrdquo Journal of Environmental Engineering vol 124 no3 pp 272ndash277 1998

[8] K Turhan I Durukan S A Ozturkcan and Z TurgutldquoDecolorization of textile basic dye in aqueous solution byozonerdquo Dyes and Pigments vol 92 no 3 pp 897ndash901 2012

[9] S S Moghaddam M R A Moghaddam and M AramildquoCoagulationflocculation process for dye removal using sludgefrom water treatment plant optimization through responsesurface methodologyrdquo Journal of Hazardous Materials vol 175no 1ndash3 pp 651ndash657 2010

[10] L Wang J Zhang R Zhao C Li Y Li and C ZhangldquoAdsorption of basic dyes on activated carbon prepared fromPolygonum orientale Linn equilibrium kinetic and thermody-namic studiesrdquo Desalination vol 254 no 1ndash3 pp 68ndash74 2010

[11] QHHu S ZQiao FHaghsereshtMAWilson andGQ LuldquoAdsorption study for removal of basic red dye using bentoniterdquoIndustrial amp Engineering Chemistry Research vol 45 no 2 pp733ndash738 2006

[12] D Sun X Zhang Y Wu and X Liu ldquoAdsorption of anionicdyes from aqueous solution on fly ashrdquo Journal of HazardousMaterials vol 181 no 1ndash3 pp 335ndash342 2010

[13] G K Sarma S SenGupta and K G Bhattacharyya ldquoMethyleneblue adsorption on natural and modified claysrdquo SeparationScience and Technology vol 46 no 10 pp 1602ndash1614 2011

[14] A A Ahmad A Idris and B H Hameed ldquoOrganic dyeadsorption on activated carbon derived from solid wasterdquoDesalination and Water Treatment vol 51 no 13ndash15 pp 2554ndash2563 2013

[15] M Jayarajan R Arunachalam and G Annadurai ldquoAgriculturalwastes of Jackfruit peel nano-porous adsorbent for removal ofRhodamine dyerdquo Asian Journal of Applied Sciences vol 4 no 3pp 263ndash270 2011

[16] D Ucar and B Armagan ldquoThe removal of reactive black 5 fromaqueous solutions by cotton seed shellrdquo Water EnvironmentResearch vol 84 no 4 pp 323ndash327 2012

[17] R Nacco and E Aquarone ldquoPreparation of active carbon fromyeastrdquo Carbon vol 16 no 1 pp 31ndash34 1978

[18] Z Guan L Liu L He and S Yang ldquoAmphiphilic hollowcarbonaceous microspheres for the sorption of phenol fromwaterrdquo Journal of Hazardous Materials vol 196 pp 270ndash2772011

[19] W Jiang J A Joens D D Dionysiou and K E OrsquoShealdquoOptimization of photocatalytic performance of TiO

2coated

glassmicrospheres using response surfacemethodology and theapplication for degradation of dimethyl phthalaterdquo Journal ofPhotochemistry and Photobiology A Chemistry vol 262 pp 7ndash13 2013

[20] J Matos A Garcia T Cordero J-M Chovelon and C Fer-ronato ldquoEco-friendly TiO

2-AC photocatalyst for the selective

photooxidation of 4-chlorophenolrdquo Catalysis Letters vol 130no 3-4 pp 568ndash574 2009

[21] D Yu B Bo and H Yunhua ldquoFabrication of TiO2yeast-

carbon hybrid composites with the raspberry-like structureand their synergistic adsorption-photocatalysis performancerdquoJournal of Nanomaterials vol 2013 Article ID 851417 8 pages2013

[22] M Liu L Piao W Lu et al ldquoFlower-like TiO2nanostructures

with exposed 001 facets facile synthesis and enhanced photo-catalysisrdquo Nanoscale vol 2 no 7 pp 1115ndash1117 2010

[23] S Feng J Yang M Liu et al ldquoHydrothermal growth of double-layer TiO

2nanostructure film for quantum dot sensitized solar

cellsrdquoThin Solid Films vol 520 no 7 pp 2745ndash2749 2012[24] B H Hameed A T M Din and A L Ahmad ldquoAdsorption of

methylene blue onto bamboo-based activated carbon kineticsand equilibrium studiesrdquo Journal of Hazardous Materials vol141 no 3 pp 819ndash825 2007

[25] Y-P Chang C-L Ren J-C Qu and X-G Chen ldquoPreparationand characterization of Fe

3O4graphene nanocomposite and

investigation of its adsorption performance for aniline and p-chloroanilinerdquo Applied Surface Science vol 261 pp 504ndash5092012

[26] J Rivera-Utrilla I Bautista-Toledo M A Ferro-Garca andC Moreno-Castilla ldquoActivated carbon surface modificationsby adsorption of bacteria and their effect on aqueous leadadsorptionrdquo Journal of Chemical Technology and Biotechnologyvol 76 no 12 pp 1209ndash1215 2001

[27] L C Juang C C Wang and C K Lee ldquoAdsorption of basicdyes ontoMCM-41rdquoChemosphere vol 64 no 11 pp 1920ndash19282006

[28] H-X Ou Y-J Song Q Wang et al ldquoAdsorption of lead(II)by silicacell composites from aqueous solution kinetic equi-librium and thermodynamics studiesrdquo Water EnvironmentResearch vol 85 no 2 pp 184ndash191 2013

[29] I Langmuir ldquoThe adsorption of gases on plane surfaces ofglassmica and platinumrdquoThe Journal of the AmericanChemicalSociety vol 40 no 9 pp 1361ndash1403 1918

[30] T W Weber and R K Chakravorti ldquoPore and solid diffusionmodels for fixed-bed adsorbersrdquo AIChE Journal vol 20 no 2pp 228ndash238 1974

[31] L Huang Y Sun W Wang Q Yue and T Yang ldquoComparativestudy on characterization of activated carbons prepared bymicrowave and conventional heating methods and applicationin removal of oxytetracycline (OTC)rdquo Chemical EngineeringJournal vol 171 no 3 pp 1446ndash1453 2011

[32] H M F Freundlich ldquoUber die adsorption in losungenrdquoZeitschrift Fur Physikalische Chemie International Journal ofResearch in Physical Chemistry and Chemical Physics A vol 57pp 385ndash470 1906

[33] L Chen and B Bai ldquoEquilibrium kinetic thermodynamic andin situ regeneration studies about methylene blue adsorptionby the raspberry-like TiO

2yeast microspheresrdquo Industrial and

Engineering Chemistry Research vol 52 no 44 pp 15568ndash155772013

[34] I D Mall V C Srivastava N K Agarwal and I M MishraldquoRemoval of congo red from aqueous solution by bagasse fly ashand activated carbon kinetic study and equilibrium isothermanalysesrdquo Chemosphere vol 61 no 4 pp 492ndash501 2005


[35] M I Tempkin and V Pyzhev ldquoKinetics of ammonia synthesison promoted iron catalystsrdquo Acta Physiochim (URSS) vol 12no 3 pp 217ndash222 1940

[36] P Wu W Wu S Li et al ldquoRemoval of Cd2+ from aqueoussolution by adsorption using Fe-montmorilloniterdquo Journal ofHazardous Materials vol 169 no 1ndash3 pp 824ndash830 2009

[37] W Jiang M Pelaez D D Dionysiou M H Entezari D Tsout-sou and K OrsquoShea ldquoChromium(VI) removal by maghemitenanoparticlesrdquo Chemical Engineering Journal vol 222 pp 527ndash533 2013

[38] M Zhang H Zhang D Xu et al ldquoRemoval of ammonium fromaqueous solutions using zeolite synthesized from fly ash by afusion methodrdquo Desalination vol 271 no 1ndash3 pp 111ndash121 2011

[39] M Hamidpour M Kalbasi M Afyuni and H ShariatmadarildquoKinetic and isothermal studies of cadmium sorption ontobentonite and zeoliterdquo International Agrophysics vol 24 no 3pp 253ndash259 2010

[40] L Ai M Li and L Li ldquoAdsorption of methylene blue fromaqueous solution with activated carboncobalt ferritealginatecomposite beads kinetics isotherms and thermodynamicsrdquoJournal of Chemical amp Engineering Data vol 56 no 8 pp 3475ndash3483 2011

[41] T Liu Y Li Q Du et al ldquoAdsorption of methylene bluefrom aqueous solution by graphenerdquo Colloids and Surfaces BBiointerfaces vol 90 no 1 pp 197ndash203 2012

[42] MDoganMAlkan andYOnganer ldquoAdsorption ofmethyleneblue from aqueous solution onto perliterdquo Water Air and SoilPollution vol 120 no 3-4 pp 229ndash248 2000

[43] B H Hameed and A A Ahmad ldquoBatch adsorption of methy-lene blue from aqueous solution by garlic peel an agriculturalwaste biomassrdquo Journal ofHazardousMaterials vol 164 no 2-3pp 870ndash875 2009

[44] C Namasivayam and D Kavitha ldquoRemoval of Congo Red fromwater by adsorption onto activated carbon prepared from coirpith an agricultural solid wasterdquoDyes and Pigments vol 54 no1 pp 47ndash58 2002

[45] LWang andAWang ldquoAdsorption characteristics of Congo redonto the chitosanmontmorillonite nanocompositerdquo Journal ofHazardous Materials vol 147 no 3 pp 979ndash985 2007

[46] S A Idris K M Alotaibi T A Peshkur P Anderson MMorris and L T Gibson ldquoAdsorption kinetic study effect ofadsorbent pore size distribution on the rate of Cr (VI) uptakerdquoMicroporous and Mesoporous Materials vol 165 pp 99ndash1052013

[47] W Guan J Pan H Ou et al ldquoRemoval of strontium(II) ions bypotassium tetratitanate whisker and sodium trititanate whiskerfrom aqueous solution equilibrium kinetics and thermody-namicsrdquo Chemical Engineering Journal vol 167 no 1 pp 215ndash222 2011

[48] L F Liu P H Zhang and F L Yang ldquoAdsorptive removal of 24-DCP from water by fresh or regenerated chitosanACFTiO

2

membranerdquo Separation and Purification Technology vol 70 no3 pp 354ndash361 2010

[49] B Bai N Quici Z Li and G L Puma ldquoNovel one stepfabrication of raspberry-like TiO

2yeast hybrid microspheres

via electrostatic-interaction-driven self-assembled heterocoag-ulation for environmental applicationsrdquo Chemical EngineeringJournal vol 170 no 2-3 pp 451ndash456 2011

[50] V K Gupta R Jain A Mittal M Mathur and S SikarwarldquoPhotochemical degradation of the hazardous dye Safranin-TusingTiO2 catalystrdquo Journal of Colloid and Interface Science vol309 no 2 pp 464ndash469 2007

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


S

N

(H3C)2N N+(CH3)2

Clminus

(a)

S

SN

N

N

N

NH2

NH2

O O

O

O

OminusNa+

OminusNa+

(b)

Figure 1 The structures of dyes (a) MB and (b) CR

hollow carbonaceous spheres via mild hydrothermal treat-ment of yeast cells and further pyrolyzing The obtainedcarbon spheres displayed effective sorption of phenol fromwater In comparison with the great successes in the yeast-carbon synthesis the practical application of yeast-carbonas adsorbent in wastewater treatment has still been limitedbecause the adsorbent could get saturated easily in theadsorption process which requires extra regeneration orcomplete replacement [4] More recently TiO

2has become a

hot topic mainly for its excellent photocatalytic performance[19] The integration of adsorption and TiO

2photocatalysis

seems to offer a good solution to overcome the shortcomingof extra regeneration or complete replacement from thetraditional adsorption process In such a synergetic processthe rich pore structure of adsorbents might promote thetransfer and adsorption of organic dyes while the TiO

2could

destroy dyes by photocatalytic oxidation thus regeneratingthe adsorbent in situ [20]

In the previous work we fabricated the novelTiO2yeast-carbon microsphere with raspberry-like mor-

phology based on the pyrolysis method [21] In the presentwork as a continual job the prepared hybrid raspberry-likeTiO2yeast-carbon microspheres were further used as ad-

sorbents for removal of two typical organic dyes (Methyleneblue and Congo red) from aqueous solution The adsorptionequilibrium isotherms and kinetics was fully conductedMoreover in situ regeneration of the adsorbents wasinvestigated and one possible mechanism for regeneratingdye-loaded TiO

2yeast in situ was also proposed

2 Materials and Methods

21 Materials The powdered yeast was provided by AngelYeast Co TiO

2with the primary particle size at 20ndash30 nm

was from Degussa and was used without further purifi-cation Absolute ethanol and double-distilled water wereused throughout all the experimental procedures Methyleneblue (MB) and Congo red (CR) were purchased from XirsquoanChemical Agent Company and were used as pollutants in thepresent work Analytic grade sodium hydroxide (NaOH) andsulfuric acid (H

2SO4) were purchased from Xirsquoan Chemical

Agent Company

22 Synthesis of TiO2Yeast-Carbon Microspheres In a typi-

cal synthesis procedure 01 g of TiO2was dissolved in 200mL

of distilled water using ultrasonic vibration for 10min andthe pH value was adjusted to approximately 9-10 by addingdropwise sodium hydroxide (10molL)Then the dispersionwas stirred inmagnetic stirrers for 30min to facilitate particledeaggregation In a separate vessel 125 g yeast powder waswashed with distilled water and absolute ethanol for threetimes respectively Subsequently the yeast was dispersed in200mL of distilled water and magnetically stirred vigorouslyfor 30min and the pH value was adjusted to approximately3 with sulfuric acid (10molL) After that the above TiO

2

and yeast cells were gathered by centrifugation from theirown suspensions and redispersed in 200mLof distilledwaterrespectively Thereafter TiO

2and yeast suspensions were

slowly mixed with continuously magnetic stirring for 15 h atroom temperature and left for 30 h without further stirringin order to ensure the formation of TiO

2yeast particlesThe

mixturewas collected by centrifugationwashedwith distilledwater and absolute ethanol for three times and then desic-cated at 353K for 10 h Finally the dried TiO

2yeast particles

were calcined at 573K in a nitrogen pipe furnace for 10 hand cooled to room temperature After that TiO

2yeast-

carbon hybrid microspheres were obtained For comparisonthe yeast-carbon was prepared by similar method withoutadding TiO

2

23 Characterization Surface structure and morphology ofsamples were observed by using Philip XL-30 field emissionscanning electron microscope (FE-SEM) Detailed composi-tion characterization was carried out with energy-dispersivespectroscopy (EDS) analysis X-ray diffraction (XRD) pat-terns were conducted on X Pert Pro diffractometer using CuK120572 radiation (120582 = 015418 nm) at a scanning rate of 10∘min

24 Dye Solution Preparation Methylene blue and Congored were cationic and anionic dyes respectively and wereused as model pollutants to study the adsorption propertiesof TiO

2yeast-carbon microspheres The structures of both

dyes are shown in Figure 1 Stock MB and CR solutions(10 gL) were prepared by dissolving 1 g of MB or CR in 1 L ofdouble distilled water respectively Experimental solutions ofdesired concentration were obtained by further dilution

25 Analysis of Organic Dyes The samples were separatedfrom the solution at set intervals with centrifugation at3000 rpm for 5min and were returned to the reaction system










119902119890=

(1198620minus 119862119890) 119881

119898

119902119905=

(1198620minus 119862119905) 119881

119898

(1)

where 1198620 119862119890 and 119862










120578 =

(1198620minus 119862119890)

1198620

times 100 (2)



2yeast




2particles







2yeast-carbon

















2 78 anatase-




2


2(JCPDS number

21-1276) [23]






05 1 15 2 25 3 35

C

Zn PPtO

(a) (b)

(c)

0 1 2 3 4 5

C

O P Ti

(d)

(e) (f)






2yeast-carbon










Anatase-TiO2

Rutile-TiO2

0

1000

2000

3000

4000

5000

6000

7000

8000

Inte

nsity

(au

)

10 20 30 40 50 60 70

2120579 (deg)

∘

∘

∘∘

∘

+

+

+

+

+++

110110

004 200

105 211 204301

101

(d)

(c)

(b)

(a)



2


(b)

(a)

0 20 40 60 80 100 120 140 160 180Time (min)

00

01

02

03

04

05

06

07

08

09

Qt

(mg

g)



2yeast-carbon


2yeast-carbon may







2 4 6 8 10 1200

05

10

15

20

C0 (mgg)

C0 (mgg)

Adso

rptio

n ca

paci

tyQe

(mg

g)

Congo red

Adso

rptio

n ca

paci

tyQe

(mg

g)

0 1 2 3 4 5 6

00

05

10

15

20

25

Methylene blue




2yeast-









119876119890=

119876119898119870119871119862119890

1 + 119870119871119862119890

(3)










119877119871=

1

1 + 1198701198711198620119898

(4)

where 1198620119898



favorable (0 lt 119877119871



119871= 1)


119876119890= 119870119865119862119890

1119899 (5)




119876119890= 119860 sdot ln (119861 sdot 119862

119890) (6)



119876119890=

119860KC sdot 119862120573

119890

1 + 119861KC119862120573

119890

(7)


120573








Ce (mgL)04 06 08 10 12 14 16 18 20

02

22

04

06

08

10

12



qe

(mg

g)





Langmuir isotherm

119876119898(mgg) 220 162

119870119871(lmg) 065 0571198772 06745 09128

119877119871 02346 02597


119870119865[(mgg)(mgminus1)1119899] 0840 0033

1198772 05832 09920



119860KC 863 003119861KC 708 522120573 420 1541198772 09745 09883




















2 3 4 5 6 7 8

01

02

03

04

05

06

07



Ce (mgL)

08

qe

(mg

g)


2yeast-carbon










40 mgL 50 mgL

5 10 15 20 25

000

025

050

075

Time (min)

ln(qeminusqt)

(a)


40 mgL 50 mgL

5 10 15 20 250

30

60

90

120

150

Time (min)

tqt

(minmiddotg

mg)

(b)



50mgL resp)


ln (119876119890minus 119876119905) = ln119876

119890minus 1198961sdot 119905 (8)

where 119876119890(mgg) and 119876







119905

119876119905

=

1

(1198962sdot 1198762

119890)

+

119905

119876119890

(9)



119905against 119905


SSE () =radic

sum(119876119890exp minus 119876

119890cal)2

119873

(10)





119890values



2yeast-carbon did


119890values (119876



2yeast-







1198620(mgL) 119876


119890cal (mgg) 1198772 SSE () 119896


119890cal (mgg) 1198772 SSE ()



5 10 15 20 25

minus4

minus3

minus2

minus1

0

Time (min)

30mgL90 mgL110 mgL

ln(qeminusqt)

(a)

5 10 15 20 25

20

40

60

80

100

Time (min)

30mgL90 mgL110 mgL

tQt

(minmiddotg

mg)

(b)



resp)










2 4 6 8 10 12 14 16 18

08

06

04

02

00

h

h

Rem

oval

rate

Time (h)

1 2 3

In dark

In dark

In dark Light on

Light on

Light on


(a)

(a)(a)

(b)(b)

(b)


posite microspheres



2yeast-





2yeast-



2yeast-




2nanoparticles
















2yeast-

















2particles





1198772 0980 0838 0834 0870 0866 0904


1198772 0992 0917 0946 0968 0894 0946









2






2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)


∙OH (13)


2+O2

∙minus (14)

O2



2particle Then







4 Conclusions



















Acknowledgments


References


2H2O2





















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials












119902119890=

(1198620minus 119862119890) 119881

119898

119902119905=

(1198620minus 119862119905) 119881

119898

(1)

where 1198620 119862119890 and 119862










120578 =

(1198620minus 119862119890)

1198620

times 100 (2)



2yeast




2particles







2yeast-carbon

















2 78 anatase-




2


2(JCPDS number

21-1276) [23]






05 1 15 2 25 3 35

C

Zn PPtO

(a) (b)

(c)

0 1 2 3 4 5

C

O P Ti

(d)

(e) (f)






2yeast-carbon










Anatase-TiO2

Rutile-TiO2

0

1000

2000

3000

4000

5000

6000

7000

8000

Inte

nsity

(au

)

10 20 30 40 50 60 70

2120579 (deg)

∘

∘

∘∘

∘

+

+

+

+

+++

110110

004 200

105 211 204301

101

(d)

(c)

(b)

(a)



2


(b)

(a)

0 20 40 60 80 100 120 140 160 180Time (min)

00

01

02

03

04

05

06

07

08

09

Qt

(mg

g)



2yeast-carbon


2yeast-carbon may







2 4 6 8 10 1200

05

10

15

20

C0 (mgg)

C0 (mgg)

Adso

rptio

n ca

paci

tyQe

(mg

g)

Congo red

Adso

rptio

n ca

paci

tyQe

(mg

g)

0 1 2 3 4 5 6

00

05

10

15

20

25

Methylene blue




2yeast-









119876119890=

119876119898119870119871119862119890

1 + 119870119871119862119890

(3)










119877119871=

1

1 + 1198701198711198620119898

(4)

where 1198620119898



favorable (0 lt 119877119871



119871= 1)


119876119890= 119870119865119862119890

1119899 (5)




119876119890= 119860 sdot ln (119861 sdot 119862

119890) (6)



119876119890=

119860KC sdot 119862120573

119890

1 + 119861KC119862120573

119890

(7)


120573








Ce (mgL)04 06 08 10 12 14 16 18 20

02

22

04

06

08

10

12



qe

(mg

g)





Langmuir isotherm

119876119898(mgg) 220 162

119870119871(lmg) 065 0571198772 06745 09128

119877119871 02346 02597


119870119865[(mgg)(mgminus1)1119899] 0840 0033

1198772 05832 09920



119860KC 863 003119861KC 708 522120573 420 1541198772 09745 09883




















2 3 4 5 6 7 8

01

02

03

04

05

06

07



Ce (mgL)

08

qe

(mg

g)


2yeast-carbon










40 mgL 50 mgL

5 10 15 20 25

000

025

050

075

Time (min)

ln(qeminusqt)

(a)


40 mgL 50 mgL

5 10 15 20 250

30

60

90

120

150

Time (min)

tqt

(minmiddotg

mg)

(b)



50mgL resp)


ln (119876119890minus 119876119905) = ln119876

119890minus 1198961sdot 119905 (8)

where 119876119890(mgg) and 119876







119905

119876119905

=

1

(1198962sdot 1198762

119890)

+

119905

119876119890

(9)



119905against 119905


SSE () =radic

sum(119876119890exp minus 119876

119890cal)2

119873

(10)





119890values



2yeast-carbon did


119890values (119876



2yeast-







1198620(mgL) 119876


119890cal (mgg) 1198772 SSE () 119896


119890cal (mgg) 1198772 SSE ()



5 10 15 20 25

minus4

minus3

minus2

minus1

0

Time (min)

30mgL90 mgL110 mgL

ln(qeminusqt)

(a)

5 10 15 20 25

20

40

60

80

100

Time (min)

30mgL90 mgL110 mgL

tQt

(minmiddotg

mg)

(b)



resp)










2 4 6 8 10 12 14 16 18

08

06

04

02

00

h

h

Rem

oval

rate

Time (h)

1 2 3

In dark

In dark

In dark Light on

Light on

Light on


(a)

(a)(a)

(b)(b)

(b)


posite microspheres



2yeast-





2yeast-



2yeast-




2nanoparticles
















2yeast-

















2particles





1198772 0980 0838 0834 0870 0866 0904


1198772 0992 0917 0946 0968 0894 0946









2






2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)


∙OH (13)


2+O2

∙minus (14)

O2



2particle Then







4 Conclusions



















Acknowledgments


References


2H2O2





















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




05 1 15 2 25 3 35

C

Zn PPtO

(a) (b)

(c)

0 1 2 3 4 5

C

O P Ti

(d)

(e) (f)






2yeast-carbon










Anatase-TiO2

Rutile-TiO2

0

1000

2000

3000

4000

5000

6000

7000

8000

Inte

nsity

(au

)

10 20 30 40 50 60 70

2120579 (deg)

∘

∘

∘∘

∘

+

+

+

+

+++

110110

004 200

105 211 204301

101

(d)

(c)

(b)

(a)



2


(b)

(a)

0 20 40 60 80 100 120 140 160 180Time (min)

00

01

02

03

04

05

06

07

08

09

Qt

(mg

g)



2yeast-carbon


2yeast-carbon may







2 4 6 8 10 1200

05

10

15

20

C0 (mgg)

C0 (mgg)

Adso

rptio

n ca

paci

tyQe

(mg

g)

Congo red

Adso

rptio

n ca

paci

tyQe

(mg

g)

0 1 2 3 4 5 6

00

05

10

15

20

25

Methylene blue




2yeast-









119876119890=

119876119898119870119871119862119890

1 + 119870119871119862119890

(3)










119877119871=

1

1 + 1198701198711198620119898

(4)

where 1198620119898



favorable (0 lt 119877119871



119871= 1)


119876119890= 119870119865119862119890

1119899 (5)




119876119890= 119860 sdot ln (119861 sdot 119862

119890) (6)



119876119890=

119860KC sdot 119862120573

119890

1 + 119861KC119862120573

119890

(7)


120573








Ce (mgL)04 06 08 10 12 14 16 18 20

02

22

04

06

08

10

12



qe

(mg

g)





Langmuir isotherm

119876119898(mgg) 220 162

119870119871(lmg) 065 0571198772 06745 09128

119877119871 02346 02597


119870119865[(mgg)(mgminus1)1119899] 0840 0033

1198772 05832 09920



119860KC 863 003119861KC 708 522120573 420 1541198772 09745 09883




















2 3 4 5 6 7 8

01

02

03

04

05

06

07



Ce (mgL)

08

qe

(mg

g)


2yeast-carbon










40 mgL 50 mgL

5 10 15 20 25

000

025

050

075

Time (min)

ln(qeminusqt)

(a)


40 mgL 50 mgL

5 10 15 20 250

30

60

90

120

150

Time (min)

tqt

(minmiddotg

mg)

(b)



50mgL resp)


ln (119876119890minus 119876119905) = ln119876

119890minus 1198961sdot 119905 (8)

where 119876119890(mgg) and 119876







119905

119876119905

=

1

(1198962sdot 1198762

119890)

+

119905

119876119890

(9)



119905against 119905


SSE () =radic

sum(119876119890exp minus 119876

119890cal)2

119873

(10)





119890values



2yeast-carbon did


119890values (119876



2yeast-







1198620(mgL) 119876


119890cal (mgg) 1198772 SSE () 119896


119890cal (mgg) 1198772 SSE ()



5 10 15 20 25

minus4

minus3

minus2

minus1

0

Time (min)

30mgL90 mgL110 mgL

ln(qeminusqt)

(a)

5 10 15 20 25

20

40

60

80

100

Time (min)

30mgL90 mgL110 mgL

tQt

(minmiddotg

mg)

(b)



resp)










2 4 6 8 10 12 14 16 18

08

06

04

02

00

h

h

Rem

oval

rate

Time (h)

1 2 3

In dark

In dark

In dark Light on

Light on

Light on


(a)

(a)(a)

(b)(b)

(b)


posite microspheres



2yeast-





2yeast-



2yeast-




2nanoparticles
















2yeast-

















2particles





1198772 0980 0838 0834 0870 0866 0904


1198772 0992 0917 0946 0968 0894 0946









2






2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)


∙OH (13)


2+O2

∙minus (14)

O2



2particle Then







4 Conclusions



















Acknowledgments


References


2H2O2





















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Anatase-TiO2

Rutile-TiO2

0

1000

2000

3000

4000

5000

6000

7000

8000

Inte

nsity

(au

)

10 20 30 40 50 60 70

2120579 (deg)

∘

∘

∘∘

∘

+

+

+

+

+++

110110

004 200

105 211 204301

101

(d)

(c)

(b)

(a)



2


(b)

(a)

0 20 40 60 80 100 120 140 160 180Time (min)

00

01

02

03

04

05

06

07

08

09

Qt

(mg

g)



2yeast-carbon


2yeast-carbon may







2 4 6 8 10 1200

05

10

15

20

C0 (mgg)

C0 (mgg)

Adso

rptio

n ca

paci

tyQe

(mg

g)

Congo red

Adso

rptio

n ca

paci

tyQe

(mg

g)

0 1 2 3 4 5 6

00

05

10

15

20

25

Methylene blue




2yeast-









119876119890=

119876119898119870119871119862119890

1 + 119870119871119862119890

(3)










119877119871=

1

1 + 1198701198711198620119898

(4)

where 1198620119898



favorable (0 lt 119877119871



119871= 1)


119876119890= 119870119865119862119890

1119899 (5)




119876119890= 119860 sdot ln (119861 sdot 119862

119890) (6)



119876119890=

119860KC sdot 119862120573

119890

1 + 119861KC119862120573

119890

(7)


120573








Ce (mgL)04 06 08 10 12 14 16 18 20

02

22

04

06

08

10

12



qe

(mg

g)





Langmuir isotherm

119876119898(mgg) 220 162

119870119871(lmg) 065 0571198772 06745 09128

119877119871 02346 02597


119870119865[(mgg)(mgminus1)1119899] 0840 0033

1198772 05832 09920



119860KC 863 003119861KC 708 522120573 420 1541198772 09745 09883




















2 3 4 5 6 7 8

01

02

03

04

05

06

07



Ce (mgL)

08

qe

(mg

g)


2yeast-carbon










40 mgL 50 mgL

5 10 15 20 25

000

025

050

075

Time (min)

ln(qeminusqt)

(a)


40 mgL 50 mgL

5 10 15 20 250

30

60

90

120

150

Time (min)

tqt

(minmiddotg

mg)

(b)



50mgL resp)


ln (119876119890minus 119876119905) = ln119876

119890minus 1198961sdot 119905 (8)

where 119876119890(mgg) and 119876







119905

119876119905

=

1

(1198962sdot 1198762

119890)

+

119905

119876119890

(9)



119905against 119905


SSE () =radic

sum(119876119890exp minus 119876

119890cal)2

119873

(10)





119890values



2yeast-carbon did


119890values (119876



2yeast-







1198620(mgL) 119876


119890cal (mgg) 1198772 SSE () 119896


119890cal (mgg) 1198772 SSE ()



5 10 15 20 25

minus4

minus3

minus2

minus1

0

Time (min)

30mgL90 mgL110 mgL

ln(qeminusqt)

(a)

5 10 15 20 25

20

40

60

80

100

Time (min)

30mgL90 mgL110 mgL

tQt

(minmiddotg

mg)

(b)



resp)










2 4 6 8 10 12 14 16 18

08

06

04

02

00

h

h

Rem

oval

rate

Time (h)

1 2 3

In dark

In dark

In dark Light on

Light on

Light on


(a)

(a)(a)

(b)(b)

(b)


posite microspheres



2yeast-





2yeast-



2yeast-




2nanoparticles
















2yeast-

















2particles





1198772 0980 0838 0834 0870 0866 0904


1198772 0992 0917 0946 0968 0894 0946









2






2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)


∙OH (13)


2+O2

∙minus (14)

O2



2particle Then







4 Conclusions



















Acknowledgments


References


2H2O2





















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







119877119871=

1

1 + 1198701198711198620119898

(4)

where 1198620119898



favorable (0 lt 119877119871



119871= 1)


119876119890= 119870119865119862119890

1119899 (5)




119876119890= 119860 sdot ln (119861 sdot 119862

119890) (6)



119876119890=

119860KC sdot 119862120573

119890

1 + 119861KC119862120573

119890

(7)


120573








Ce (mgL)04 06 08 10 12 14 16 18 20

02

22

04

06

08

10

12



qe

(mg

g)





Langmuir isotherm

119876119898(mgg) 220 162

119870119871(lmg) 065 0571198772 06745 09128

119877119871 02346 02597


119870119865[(mgg)(mgminus1)1119899] 0840 0033

1198772 05832 09920



119860KC 863 003119861KC 708 522120573 420 1541198772 09745 09883




















2 3 4 5 6 7 8

01

02

03

04

05

06

07



Ce (mgL)

08

qe

(mg

g)


2yeast-carbon










40 mgL 50 mgL

5 10 15 20 25

000

025

050

075

Time (min)

ln(qeminusqt)

(a)


40 mgL 50 mgL

5 10 15 20 250

30

60

90

120

150

Time (min)

tqt

(minmiddotg

mg)

(b)



50mgL resp)


ln (119876119890minus 119876119905) = ln119876

119890minus 1198961sdot 119905 (8)

where 119876119890(mgg) and 119876







119905

119876119905

=

1

(1198962sdot 1198762

119890)

+

119905

119876119890

(9)



119905against 119905


SSE () =radic

sum(119876119890exp minus 119876

119890cal)2

119873

(10)





119890values



2yeast-carbon did


119890values (119876



2yeast-







1198620(mgL) 119876


119890cal (mgg) 1198772 SSE () 119896


119890cal (mgg) 1198772 SSE ()



5 10 15 20 25

minus4

minus3

minus2

minus1

0

Time (min)

30mgL90 mgL110 mgL

ln(qeminusqt)

(a)

5 10 15 20 25

20

40

60

80

100

Time (min)

30mgL90 mgL110 mgL

tQt

(minmiddotg

mg)

(b)



resp)










2 4 6 8 10 12 14 16 18

08

06

04

02

00

h

h

Rem

oval

rate

Time (h)

1 2 3

In dark

In dark

In dark Light on

Light on

Light on


(a)

(a)(a)

(b)(b)

(b)


posite microspheres



2yeast-





2yeast-



2yeast-




2nanoparticles
















2yeast-

















2particles





1198772 0980 0838 0834 0870 0866 0904


1198772 0992 0917 0946 0968 0894 0946









2






2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)


∙OH (13)


2+O2

∙minus (14)

O2



2particle Then







4 Conclusions



















Acknowledgments


References


2H2O2





















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




















2 3 4 5 6 7 8

01

02

03

04

05

06

07



Ce (mgL)

08

qe

(mg

g)


2yeast-carbon










40 mgL 50 mgL

5 10 15 20 25

000

025

050

075

Time (min)

ln(qeminusqt)

(a)


40 mgL 50 mgL

5 10 15 20 250

30

60

90

120

150

Time (min)

tqt

(minmiddotg

mg)

(b)



50mgL resp)


ln (119876119890minus 119876119905) = ln119876

119890minus 1198961sdot 119905 (8)

where 119876119890(mgg) and 119876







119905

119876119905

=

1

(1198962sdot 1198762

119890)

+

119905

119876119890

(9)



119905against 119905


SSE () =radic

sum(119876119890exp minus 119876

119890cal)2

119873

(10)





119890values



2yeast-carbon did


119890values (119876



2yeast-







1198620(mgL) 119876


119890cal (mgg) 1198772 SSE () 119896


119890cal (mgg) 1198772 SSE ()



5 10 15 20 25

minus4

minus3

minus2

minus1

0

Time (min)

30mgL90 mgL110 mgL

ln(qeminusqt)

(a)

5 10 15 20 25

20

40

60

80

100

Time (min)

30mgL90 mgL110 mgL

tQt

(minmiddotg

mg)

(b)



resp)










2 4 6 8 10 12 14 16 18

08

06

04

02

00

h

h

Rem

oval

rate

Time (h)

1 2 3

In dark

In dark

In dark Light on

Light on

Light on


(a)

(a)(a)

(b)(b)

(b)


posite microspheres



2yeast-





2yeast-



2yeast-




2nanoparticles
















2yeast-

















2particles





1198772 0980 0838 0834 0870 0866 0904


1198772 0992 0917 0946 0968 0894 0946









2






2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)


∙OH (13)


2+O2

∙minus (14)

O2



2particle Then







4 Conclusions



















Acknowledgments


References


2H2O2





















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





40 mgL 50 mgL

5 10 15 20 25

000

025

050

075

Time (min)

ln(qeminusqt)

(a)


40 mgL 50 mgL

5 10 15 20 250

30

60

90

120

150

Time (min)

tqt

(minmiddotg

mg)

(b)



50mgL resp)


ln (119876119890minus 119876119905) = ln119876

119890minus 1198961sdot 119905 (8)

where 119876119890(mgg) and 119876







119905

119876119905

=

1

(1198962sdot 1198762

119890)

+

119905

119876119890

(9)



119905against 119905


SSE () =radic

sum(119876119890exp minus 119876

119890cal)2

119873

(10)





119890values



2yeast-carbon did


119890values (119876



2yeast-







1198620(mgL) 119876


119890cal (mgg) 1198772 SSE () 119896


119890cal (mgg) 1198772 SSE ()



5 10 15 20 25

minus4

minus3

minus2

minus1

0

Time (min)

30mgL90 mgL110 mgL

ln(qeminusqt)

(a)

5 10 15 20 25

20

40

60

80

100

Time (min)

30mgL90 mgL110 mgL

tQt

(minmiddotg

mg)

(b)



resp)










2 4 6 8 10 12 14 16 18

08

06

04

02

00

h

h

Rem

oval

rate

Time (h)

1 2 3

In dark

In dark

In dark Light on

Light on

Light on


(a)

(a)(a)

(b)(b)

(b)


posite microspheres



2yeast-





2yeast-



2yeast-




2nanoparticles
















2yeast-

















2particles





1198772 0980 0838 0834 0870 0866 0904


1198772 0992 0917 0946 0968 0894 0946









2






2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)


∙OH (13)


2+O2

∙minus (14)

O2



2particle Then







4 Conclusions



















Acknowledgments


References


2H2O2





















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





1198620(mgL) 119876


119890cal (mgg) 1198772 SSE () 119896


119890cal (mgg) 1198772 SSE ()



5 10 15 20 25

minus4

minus3

minus2

minus1

0

Time (min)

30mgL90 mgL110 mgL

ln(qeminusqt)

(a)

5 10 15 20 25

20

40

60

80

100

Time (min)

30mgL90 mgL110 mgL

tQt

(minmiddotg

mg)

(b)



resp)










2 4 6 8 10 12 14 16 18

08

06

04

02

00

h

h

Rem

oval

rate

Time (h)

1 2 3

In dark

In dark

In dark Light on

Light on

Light on


(a)

(a)(a)

(b)(b)

(b)


posite microspheres



2yeast-





2yeast-



2yeast-




2nanoparticles
















2yeast-

















2particles





1198772 0980 0838 0834 0870 0866 0904


1198772 0992 0917 0946 0968 0894 0946









2






2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)


∙OH (13)


2+O2

∙minus (14)

O2



2particle Then







4 Conclusions



















Acknowledgments


References


2H2O2





















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




2 4 6 8 10 12 14 16 18

08

06

04

02

00

h

h

Rem

oval

rate

Time (h)

1 2 3

In dark

In dark

In dark Light on

Light on

Light on


(a)

(a)(a)

(b)(b)

(b)


posite microspheres



2yeast-





2yeast-



2yeast-




2nanoparticles
















2yeast-

















2particles





1198772 0980 0838 0834 0870 0866 0904


1198772 0992 0917 0946 0968 0894 0946









2






2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)


∙OH (13)


2+O2

∙minus (14)

O2



2particle Then







4 Conclusions



















Acknowledgments


References


2H2O2





















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







1198772 0980 0838 0834 0870 0866 0904


1198772 0992 0917 0946 0968 0894 0946









2






2(119890cbminus+ ℎvb+) (11)

H2O + TiO

2(ℎ+) 997888rarr

∙OH +H+ (12)


∙OH (13)


2+O2

∙minus (14)

O2



2particle Then







4 Conclusions



















Acknowledgments


References


2H2O2





















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




















2coated










































2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials


















2













CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Documents

Research Article Adsorption of Organic Dyes by TiO @Yeast …downloads.hindawi.com/journals/jnm/2015/498304.pdf · 2019-07-31 · Research Article Adsorption of Organic Dyes by TiO