Copper (II) Biosorption Characteristic of Pleurotus Spent Mushroom Compost

Chia-Chay Tay1,2, Ghufran Redzwan2, Hong-Hooi Liew1,3, Soon-Kong Yong4, Salmijah Surif5, Suhaimi Abdul-Talib1

1Institute for Infrastructural Engineering and Sustainable Management (IIESM) Faculty of Civil Engineering, Universiti Teknologi MARA

40450 Shah Alam, Selangor, Malaysia 2Institute of Biological Sciences

University of Malaya, 50603 Kuala Lumpur, Malaysia

3Faculty of Civil and Environmental Engineering Universiti Tun Hussein Onn Malaysia

84600 Batu Pahat, Johor, Malaysia 4International Education Centre (INTEC)

Section 17 Campus, Universiti Teknologi MARA 40200 Shah Alam, Selangor, Malaysia

5School of Environmental and Natural Resource Sciences Faculty of Science & Technology, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor, Malaysia esuhaimi@hotmail.com

Abstract—Pleurotus spent mushroom compost is usually discarded as agricultural waste. This study investigated the biosorption characteristic of copper by Pleurotus spent mushroom compost. Parameters including biosorbent concentration, initial pH, contact time, initial copper (II) concentration and temperatures were examined in batch mode. Half saturation constant of copper (II) biosorption was obtained at 1.4 %(w/v) biosorbent concentration, unadjusted pH of 5.5, 10 minutes contact time and at 50 mg/L copper (II) solution. Copper (II) biosorption process well fitted to Langmuir isotherm and pseudo second order kinetic model. Generally, biosorption was not a spontaneous exothermic reaction. Rapid biosorption process and highly potential in reusability of Pleurotus spent mushroom compost are very useful for pilot or industrial wastewater purification application, which to be favorable for the continuous and reusable operation in a column.

Keywords — Biosorption; copper (II); Pleutotus; Spent mushroom compost

I. INTRODUCTION

Copper (II) is a common toxic compound found in industrial waste water. Its toxic and persistent characteristics causes concern when effluents containing copper (II) are discharged to receiving water bodies without proper treatment. The copper ions can then accumulate throughout the food chain, eventually becoming a health hazard for humans.

Conventional methods for heavy metals removal include precipitation, electrodialysis, ultrafiltration, reverse osmosis and ion exchange are well established practice in the industry [1]. Besides technical and economical constrains, there are risk

and impact to the environment through practice by using non-biodegrable materials or non-environmental friendly techniques. Therefore, recently interest focusing on sustainable technology such as biosorption for copper (II) removal has intensified.

Biosorption is categorized as an alternative method as well as sustainable technology for heavy metals removal. It is defined as a passive, metabolic independent process and involves physico-chemical binding of metal ions by using nonliving biological materials. Biosrption offers two major advantages over conventional treatment methods, namely cost effectiveness and minimum environmental impact [2-3]. These advantages come from the use of agro-waste, where biodegradablility of biosorbent is high and recovery of metals from biosorbent with acid solution can be easily achieved.

This paper focuses on copper (II) biosorption characteristics of Pleurotus ostreatus spent mushroom compost from aqueous solutions under different conditions in order to establish an alternative, sustainable technology for heavy removal.

II. METHODOLOGY

A. Biosorbent preparation Sample of Pleurotus ostreatus spent mushroom compost

was collected from C & C Mushroom Cultivation Farm, Johor, Malaysia. Collected sample was autoclaved at 121 oC, under pressure of 18 psi for 15 minutes and dried in the oven at a temperature of 60 o, after which it was ground and sieved to particle size of 710nm. This sample was rinsed with ultra pure

2010 International Conference on Science and Social Research (CSSR 2010), December 5 - 7, 2010, Kuala Lumpur, Malaysia

978-1-4244-8986-2/10/$26.00 ©2010 IEEE 6

water to remove impurities. Finally, the prepared biosorbent was dried in an oven at 60 ºC and stored in a desiccator.

B. Copper (II) solution proparation Copper (II) solutions were prepared by using analytical

grade copper (II) sulphate anhdydrous salt (CuSO4, Merck, Germany) in ultra pure water with resistance of 18.2 M .cm.

C. Batch biosorption study Experiments were carried out with biosorbent in 50 mL

copper (II) solution in 250 mL Erlenmeyer flasks on an orbital shaker operating at 125 rpm. Parameters studied include biosorbent concentration of 0.4-16 %(w/v), initial pH of 1-5.4, contact time of 0.5-60 min, initial copper (II) concentration of 10-250 mg/L and temperature in range of 5-35 oC. Samples were filtered and the filtrates were analyzed by ICP-OES (7300DV, Perkin Elmer, USA). All experiments were conducted in duplicates.

D. Statistical and mathematical analysis The experimental data were analyzed using (1) in order to

obtain the percentage of copper (II) biosorption.

(1)

where Co = the initial copper (II) concentration (mg/L), Cf = the concentration of copper (II) in solution (mg/L)

The biosorption parameters were calculated from the isotherm using linear Langmuir plot of Ce/qe versus Ce (2):

(2)

where qe = copper (II) uptake by biosorbent (mg/g), qmax = maximum copper(II) uptake (mg/g), Ce = copper (II) concentration at the equilibrium stage (mg/L), b = Langmuir constant (L/mg).

The copper (II) biosorption were calculated from the pseudo second order kinetic model (3):

(3)

where qe = copper (II) uptake by biosorbent at equilibrium (mg/g), qt = copper (II) uptake by biosorbent at time (mg/g), t = time (min), k2 = rate constant of pseudo second order (g/mg/min).

Thermodynamic parameters such as change in Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were determined using the following equations [4]:

e

ec C

qK = (4)

R

SRT

HK c 303.2303.2log Δ+Δ−= (5)

ΔG = ΔH – TΔS (6)

where Kc (L/g) is the distribution coefficient, qe (mg/g) and Ce (mg/L) are the biosorption capacity and copper (II) concentration at equilibrium, respectively, T is temperature in Kelvin and R is the gas constant. ΔG is free energy (kJ/mol). ΔH and ΔS were obtained from the slope and intercept of the plots of log Kc versus 1/T.

III. RESULTS AND DISCUSSION

A. Biosorbent concentration Fig. 1 shows a two-stage biosorption process for copper

(II), beginning with a steady increase in biosorption and then followed by a saturation stage. Copper (II) biosorption was increased from 30 % to 89 % when biosorbent concentration increased from 0.4 %(w/v) to 16 %(w/v). Increase in biosorbent concentration increases the active binding sites and surface area of biosorbent, thus increasing the percentage of copper (II) biosorption. Veghetti et al. [5] reported the similar trend of observation by using agricultural waste of pecan nutshell biosorbent. Half saturation constant of copper (II) biosorption was determined by Michaelis-Menten derivation plot of Hanes-Woolf. From the slope and intercept shown in Fig. 2, the calculated half saturation constant was at 1.4 % (w/v). This value of half saturation constant was used in designing subsequent experiments in order to obtain results in shorter time and minimizing the used of biosorbent.

0102030405060708090

100

0.0 5.0 10.0 15.0

Biosorbent concentration (%w/v)

Cu

(II) b

ioso

rptio

n (%

)

Figure 1. Effect of biosorbent concentration on copper (II) biosorption

%100)(

)( xC

CCnbiosorptioIIcopperofpercentage

o

fo −=

eet qt

qkqt += 2

2

1

maxmax

1qbq

CqC e

e

e +=

7

y = 1.1928x + 1.6777R2 = 0.9974

0.0000

5.0000

10.0000

15.0000

20.0000

25.0000

0.0 5.0 10.0 15.0 20.0

Biosorbent concentration (%w/v)

Bio

sorb

ent c

once

ntra

tion/

ra

te o

f Cu(

II) b

ioso

rptio

n (%

w/v

/ m

g/L/

min

)

Figure 2. Hanes-Woolf plot for determination of half saturation constant on copper (II) biosorption

B. Initial pH Efficiency of copper (II) biosorption is pH dependent as

illustrated in Fig. 3. Maximum biosorption of copper (II) at pH 5.5 was observed with 43 % removal. At low pH, active binding sites of biosorbent are being protonated and charge repulsion formed, leading to preclude in copper (II) biosorption. As pH increases, active binding sites of biosorbent such as carboxyl group and hydroxyl group are deprotonanted and the charge attraction are strengthened, resulting in a remarkable increase in copper (II) biosorption. Copper (II) precipitation was observed at pH 6 and above due to hydrolysis of copper (II) ions which consequently limits the biosorption process. Findings documented by Babarinde et al. [6] and Zhu et al. [7] reported similar trend and order of magnitude for copper (II) biosorption in a study using plant based biosorbents. This inferred that pH not only affects efficiency of biosorption by influencing the active binding sites of biosorbent but also species of copper (II). Taking this into consideration, since solution of copper (II) has pH of 5.5, pH was not adjusted for further experiments as this represent the optimal range for biosorption.

05

101520253035404550

0 1 2 3 4 5 6

pH

Cu(

II) b

ioso

rptio

n (%

)

Figure 3. Effect of initial pH on copper (II) biosorption

C. Contact time Biosorption of copper (II) was rapid initially and then

achieved equilibrium as depicted in Fig. 4. The saturation stage for copper (II) biosorption was 40%, achieved after 5 minutes

of contact time. This indicated that initial active binding sites on biosorbent are easily occupied by copper (II) ions and subsequent saturation phase was due to saturation of active binding sites thus, the observed equilibrium status. A similar trend of observation for tree leaves biosorbents was reported by Sangi et al. [8] and Kilic et al. [9] whereby reaction proceeded with a high rate initially and followed by a stage of no significant changes with further increase in contact time. Based on this result, further experiments were conducted under equilibrium status with 10 minutes of contact time.

Figure 4. Effect of contact time on copper (II) biosorption

D. Initial copper (II) concentration Fig. 5 shows that an increased in initial copper (II)

concentration had resulted in a decreased of copper (II) biosorption efficiency. Copper (II) biosorption decreased from 53 % to 19 % as initial copper (II) concentration was increased from 10 mg/L to 250 mg/L. Mass transfer resistances were overcome by initial copper (II) concentration which acted as a driving force. As initial concentration of copper (II) increased, the availability of active binding sites of biosorbent relatively decreased, which resulted in reduction of biosorption efficiency. This phenomenon is consistent with Meena et al. [10] which utilized treated Acacia sawdust as biosorbent. The results obtained indicate that this biosorbent has high potential as an alternative treatment for diluted copper (II) decontamination.

0

10

20

30

40

50

60

0 50 100 150 200 250 300

Initial Cu(II) concnetration, mg/L

Cu(

II) b

ioso

rptio

n, %

Figure 5. Effect of initial copper (II) concentration on copper (II) biosorption

E. Temperature The effect of temperature on copper (II) biosorption was

investigated at four different temperatures. As seen from Fig. 6,

8

y = 0.22x + 12.782R2 = 0.9908

0

10

20

30

40

50

60

70

0 50 100 150 200 250

Ce

Ce/

qebiosorption of copper decreased from 44 % to 39 % when temperature increased in the range of 5 oC to 35 oC. It was observed that, similar trend for temperature profile was reported in the study by Arslanoglu et al. [11] on the use of esterified lemon as biosorbent. With increase of temperature, an important driving force is provided to overwhelm mass transfer resistance and increase diffusion rate of copper (II) ions in external mass transport, so greater biosorption process was observed. This implied that biosorption process of copper (II) ions by Pleurotus ostreatus spent mushroom compost was an exothermic reaction. However, these results need to be validated and evaluated by various biosorption thermodynamic parameters.

38

39

40

41

42

43

44

45

0 5 10 15 20 25 30 35 40

Temperature (oC)

Cu(II

) bio

sorp

tion

(%)

Figure 6. Effect of temperature on copper (II) biosorption

F. Langmuir Isotherm Langmuir isotherm acts to estimate the constants of

complete monolayer of biosorption occurring at specific sites on the surface of biosorbent. Regression analysis on the linearized isotherm of Langmuir is listed in Fig. 7. Based on calculation of the slope and the intercept, maximum biosorption capacity, the Langmuir constant and coefficient of determination values were 4.55 mg/g, 0.017 L/mg and 0.9908 respectively. Table I summarizes the comparison of the maximum copper (II) biosorption capacity with that of different sawdust and fungus based biosorbents reported in the literature recently. Pleurotus ostreatus spent mushroom compost biosorbent shows comparable biosorption capacity and rapid biosorption process when compared to others biosorbents.

Figure 7. Langmuir plot of Copper(II) biosorption.

TABLE I. COMPARISON OF BIOSORBENTS FOR COPPER (II) BIOSORPTION

Biosorbent qe, mg/g Contact time, min Ref. Sawdust Betula sp. 4.9 300 [12]

Sawdust Acacia arabica 5.6 2880 [10] Treated rubber wood

sawdust 5.6 210 [13]

Saachromyces cereviceae 2.6 1440 [14] Pleurotus ostreatus 3.6 10 [15]

Pleurotus ostreatus spent mushroom compost

4.6 10 This study

G. Pseudo second order kinetic model Regression analysis of the linearized model of pseudo second order kinetic is shown in Fig. 8. According to calculation from the slope and the intercept, the calculated qe value, and pseudo second order rate constant were 1.45 mg/g and 5.72 g/mg/min respectively. The high regression coefficient of 0.9998, together with the calculated qe value of 1.45 that is very close to actual experimental value of 1.44, indicate the validity of this model for biosoprtion. This model indicates that chemisorption involving valency forces through sharing of electrons between copper (II) ions and biosorbent may be the limiting step for biosorption process. Both Saeed et al. [16] and Bhainsa and D’Sauza [17] also concur that pseudo second order kinetic model aptly describe the biosorption process by fungal and wood based biosorbent. Hence, based on previous findings and those presented here, it is clear that chemisorption contributes a major portion in the mechanism of copper (II) biosorption.

Figure 8. Pseudo second order kinetic model of copper (II) biosorption

H. Thermodynamic study Thermodynamic parameters namely free energy (ΔG),

enthalpy changes (ΔH) and enthropy changes (ΔS) were calculated from slope and intercept of linear regression plot of Fig. 9. Table II shows the calculated value of the thermodynamic parameters. The value of ΔG increased with increasing temperature, indicating that the biosorption process would become less favorable if temperature rises. The negative value of ΔH at -4.66 kJ/mol signified the exothermic nature of the copper (II) biosorption process. This conforms to the findings from temperature profile which indicates that

9

bisorption is the exothermic reaction. The ΔS value of -0.04 kJ/mol suggest that weaker and reversible bonds were formed from the biosorption reaction. Similar results were found by Qaiser et al. [18] and Yao et al. [19]. This indicates that the biosorbent has good potential for regeneration as well as metal recovery.

y = 243.15x - 2.1328R2 = 0.9966

-1.35-1.34-1.33-1.32-1.31-1.3

-1.29-1.28-1.27-1.26-1.25

0.0032 0.0033 0.0033 0.0034 0.0034 0.0035 0.0035 0.0036 0.0036 0.0037

1/T (1/K)

log

Kc

Figure 9. The plot of log Kc versus 1/T for copper (II) biosorption

TABLE II. THERMODYNAMIC PARAMETERS FOR COPPER (II) BIOSORPTION

IV. CONCLUSION Pleurotus ostreatus spent mushroom compost has been

evaluated as a biosorbent that is derived from agricultural waste. Half saturation constant for 50 mg/L copper (II) solution was determined at 1.4 %(w/v) biosorbent. The optimum copper (II) biosorption at half saturation constant concentration was attained at unadjusted pH in range of 5-5.5, 10 minutes contact time and initial concentration of 50 mg/L copper (II) solution. Biosorption of copper fitted with the Langmuir isotherm with a maximum biosorption capacity of 4.6 mg/g. The experimental data corresponded with pseudo second order model and this rapid process may involve several mechanisms simultaneously. Chemisorption was found to be the main governing mechanism and copper (II) biosorption is not a spontaneous exothermic reaction in nature. Weak and reversible bonding formed after biosorption of copper (II) indicated good reusability of biosorbent and metal recovery. Therefore, this biosorbent has potential to be developed into a sustainable heavy metal remediation technology.

ACKNOWLEDGMENT The authors acknowledge the research grant provided by e-

sciencefund, MOSTI. We also wish to acknowledge Universiti

Teknologi MARA and C & C Mushroom Cultivation Farm Sdn. Bhd.

REFERENCES [1] B. Volesky, “Biosorption and me,” Water Res., Vol 41, pp. 4017-4029,

2007. [2] J. Wang, and C. Chen, “Biosorbent for heavy metals removal and their

future,” Biotechnol. Adv., vol. 27, pp. 195-226, 2009 [3] D. Park, Y. Yun, and J. M. Park, “The past, present, and future trends of

biosorption,” Biotechnol. Bioprocess. Eng., Vol. 15, pp. 86-102, 2010. [4] L. Guo, C. Sun, G. Li, C. Liu, and C. Ji, “Thermodynamics and kinetics

of Zn (II) adsorption on crosslink starch phosphates,” J. Hazard. Mater., vol. 161, pp. 510-515, 2009.

[5] J. C. P. Veghetti et al., “Pecan nutshell as biosorbent to remove Cu(II), Mn(II), and Pb(II) from aqueous solutions,” J. Hazard. Mater., vol. 162, pp. 270-280, 2009.

[6] N. A. A. Babarinde, O. O.Oyesiku, and O. F. Dairo, “Isotherm and thermodynamic studies of the biosorption of copper ions by Erythrodontium barteri,” Int. J. Phys. Sci., vol. 2(11), pp. 300-304, 2007.

[7] B. Zhu, T. Fan, and D. Zhang, “Adsorption of copper ions from aqueous solution by citric acid modified soybean straw,” J. Hazard. Mater., vol. 153, pp. 300-308, 2008.

[8] M. R. Sangi, A. Shahmoradi, J. Zolgharnein, G. H. Azimi, and M. Ghorbandoost, “Removal and recovery of heavy metals from aqueous solution using Ulmus carpinifolia and Fraxinus excelsior tree leaves,” J. Hazard. Mater., vol. 155, pp. 513-522, 2008.

[9] M. Kilic, H. Yazici, and M. Solak, “A comprehensive study on removal and recovery of copper(II) from aqueous solutions by NaOH-pretreated Marrubium globosum ssp. globosum leaves powder: potential for utilizing the copper(II) condensed desorption solutions in agricultural applications,” Biores. Technol., vol. 100, pp. 2130-2137, 2009.

[10] A. K. Meena, K. Kadirvelu, G. K. Mishra, C., Rajagopal, and P. N. Nagar, “Adsorptive removal of heavy metals from aqueous solution by treated sawdust (Acacia arabica),” J. Hazard. Mater., vol. 150, pp. 604-611, 2008.

[11] H., Arslanoglu, H. S. Altundogan, and F. Tumen, “Heavy metals binding properties of esterified lemon,” J. Hazard. Mater., vol. 164, pp. 1406-1413, 2009.

[12] A. Grimm, R. Zanzi, E. Bjornbom, and A. L. Cukierman, “Comparison of different types of biomasses for copper biosorption,” Biores. Technol., vol. 99, pp. 2559-2565, 2008.

[13] H. Kalavathy M., I. Regupathi, M. G. Pillai, and L. R. Miranda., “Modelling, analysis and optimization of adsorption parameters H3PO4 activated rubber wood sawdust using response surface methodology (RSM),” Colloid Surface B., vol. 70, pp. 35-45, 2009.

[14] C. Cojocaru, M. Diaconu, I Cretescu, J. Savic, and V. Vasic, “Biosorption of Cu(II) ions from aqua solutions using dried yeast biomass,” Colloid Surfaces A., vol. 335, pp. 181-188, 2009.

[15] T. Chia-Chay, L. Hong-Hooi, Y. Soon-Kong, S. Surif, and S. Abdul-Talib, “Biosorption of lead(II) from aqueous solutions by Pleurotus as a toxicity biosorbent,” Paper of International Conference on Environmental Science and Technology 2010, in press.

[16] A. Saeed, M. W. Akhter, and M, Iqbal, “Removal and recovery of heavy metals from aqueous solution using papaya wood as a new biosorbent,” Sep. Purify.Technol., vol. 45, pp. 25-31, 2005.

[17] K. C. Bhainsa, and S. F. D’Sauza, “Removal of copper ions by filamentous fungas, Rhizopus oryzae from aqueous solution. Biores. Technol. vol. 99, pp. 3829-3825, 2008.

[18] S. Qaiser, A. R. Saleemi, and M. Umar, “Biosorption of lead from aqueous solution by Ficus religiosa leaves: batch and column study,” J. Hazard. Mater., vol. 166, pp. 998-1005, 2009.

[19] Z. Y. Yao, J. H. Qi, and L. H. Wang, “Equilibrium, kinetic and thermodynamic studies on the biosorption of Cu(II) onto chestnut shell,” J. Hazard. Mater., vol. 174, pp. 137-143, 2010.

T (K)

qe (mg/g)

Kc (L/g)

ΔG (kJ/mol)

ΔH (kJ/mol)

ΔS (kJ/mol/K)

278 1.61 0.06 6.70 -4.66 -0.04

288 1.53 0.05 7.10 298 1.48 0.05 7.50 308 1.40 0.05 7.93

10