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Hindawi Publishing CorporationJournal of SpectroscopyVolume 2013 Article ID 254517 8 pageshttpdxdoiorg1011552013254517

Research ArticleSpectroscopic and Microscopic Characterization ofVolcanic Ash from Puyehue-(Chile) Eruption PreliminaryApproach for the Application in the Arsenic Removal

Irma Lia Botto1 Mariacutea Elena Canafoglia1 Delia Gazzoli2 and Mariacutea Joseacute Gonzaacutelez13

1 CEQUINOR Facultad de Ciencias Exactas (CONICET La Plata-UNLP) 47 y 115 1900 La Plata Argentina2Dipartimento di Chimica Universita di Roma La Sapienza Piazzale Aldo Moro 5 00185 Roma Italy3 INREMI Facultad de Ciencias Naturales y Museo (CICPBA-UNLP) 64 y 120 1900 La Plata Argentina

Correspondence should be addressed to Irma Lia Botto bottoquimicaunlpeduar

Received 17 May 2013 Revised 17 July 2013 Accepted 2 August 2013

Academic Editor Niksa Krstulovic

Copyright copy 2013 Irma Lia Botto 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

Volcanic ash fromPuyehueCordonCaulleVolcanicComplex (Chile) emitted on June 4 2011 anddeposited inVilla LaAngostura atsim40 kmof the source was collected and analyzed byRaman spectroscopy optical and scanning electronmicroscopy (SEM-EDS) X-ray diffraction (XRD) surface area (BET) and chemical analysis (ICP-AES-MS technique)Themineralogical and physicochemicalstudy revealed that the pyroclastic mixture contains iron oxides in the form of magnetite and hematite as well as pyroxeneand plagioclase mineral species and amorphous pumiceous shards Carbonaceous material was also identified Physicochemicaltechniques allow us to select two representative samples (average composition and Fe-rich materials) which were used to analyzetheir performances in the adsorption process to remove arsenic from water Additional iron activation by means of ferric salts wasperformed under original sample Results showed that the low-cost feedstock exhibited a good adsorption capacity to remove thecontaminant depending on the iron content and the water pH

1 Introduction

The south-andes Cordillera is one of the world regions withintense volcanic and tectonic activity The last eruptionstarted on June 4 2011 was associated with the activity ofPuyehue Cordon Caulle Volcanic Complex (PCCVC) Chilelocated at 40∘3410158405710158401015840S-72∘0610158405310158401015840W emitting more than 5 times106m3 of pyroclastic material [1] The dominance of ldquowest-erliesrdquo regional winds was responsible for the dispersion andsedimentation of ash on a large region along eastern SouthAmerica particularly Patagonia and Argentine PampeanPlain

Although the preliminary characterization of the ashshowed a composition predominantly rhyolitic the ejectedmaterial was composed of different types of particles Erup-tion stages and distance from the volcanic source affectedthe chemical composition of the mixture but in generalthe material was nearly amorphous to the XRD with atexture characterized by the presence of vesicles However in

the early stages of the volcanic event a dark (brownish-black)and heavy particulate matter with variable size and hardnesswas emitted [2]

The application of the volcanic ash depends on severalfactors such as themineralogy and chemical composition [3ndash5] so that the thorough understanding of physicochemicalproperties of the phases present in the feedstock can play adecisive role in the evaluation of their technological potential

As for arsenic removal from contaminated aqueousmedium different iron-rich minerals can be used [6 7] thechemical affinity between Fe-O-H-arsenate groups can beapplied to develop low-cost technologies particularly usefulin rural zones without any other water sources for humanconsumption [8 9] In fact the presence of arsenate (V) iswidespread in groundwater reaching values exceeding thoserecommended by theWHO(10120583g Lminus1) situation that leads tomany chronic health problems [10] In this sense Argentinais one of the most affected countries of South America [11]where the contamination has become a serious problem

2 Journal of Spectroscopy

The aim of this work is to study the physicochemicalbehavior of the ash and tephras deposited in Villa La Angos-tura (40∘4510158404810158401015840S-71∘3810158404610158401015840W) and collected five monthsafter the eruption and the need to approach the potentialapplication (in the original form and activated with ferricphases) to remove arsenic from groundwater

Scanning electron microscopy (SEM-EDS) optical mea-surements surface (BET) and chemical analysis (by induc-tively coupled plasma (ICP) technique for major and traceelements) X-ray diffraction and Raman spectroscopy weredirected to the mineralogical and chemical characterizationof the material

2 Materials and Methods

The material from Villa La Angostura (about 40 km fromthe volcanic source) having particle sizes between 10 and3000 120583m was dried at 100∘C and identified as pyroclasticmaterial (PM) No thermal transformations were observedin the 60ndash100∘C range The humidity elimination (sim30of water) was necessary to perform the physicochemicalcharacterization The selection of the mixture componentswas done with the aid of the binocular microscope Glassand light shards with vesicular microcavities were identifiedas pumiceous-type material (PT) whereas the dark particlesalso vesiculated were named as scoria-type (ST) materialLithoclasts of size lower than the PT and ST materialsof intense black color and smooth uniform surfaces wereidentified as rounded blocks (RB) The material densitiesfollowed the sequence RB gt ST gt PT The former presentsalso a magnetic behavior Additional optical measurementswere useful to reveal the difference between crystalline andvitreous particles

PT and ST materials were washed with ethanol by theultrasonic technique to facilitate the separation of very thinadhered particles and then dried at 80∘C

Scanning electron microscopy and electron diffractionspectroscopy (SEM-EDS) measurements were performed inan ESEM (FEI Quanta 200) with tungsten filament and anETD (high vacuum secondary electron) detector Microanal-ysis was carried out with an EDAX Detector Apollo 40Chemical results were expressed as oxides

Chemical analysis was performed by ICP-AES for majorelements (expressed as oxides) and ICP-MS for trace RareEarth Elements (REE) (in ppm) (ALS Chemex Lab Canada)The geochemical behavior was analyzed from variance dia-grams of REE normalized to chondrite igneous system

The BET surface area was measured by N2adsorption

using a Micromeritics ASAP 2020 Automated Brunauer-Emmett-Teller Sorptometer

X-ray diffraction patterns for crystalline phase analysiswere collected with a Philips PW 1710 diffractometer Cu K120572Ni-filtered radiation

Raman spectroscopic analyses were carried out withinVia Renishaw micro-Raman spectrometer equipped withan air-cooled CCD detector and edge filters A 7850 nmemission line from a diode laser was focused on the sampleby a Leica DLML microscope using 5x or 20x objectives

The power of the incident beam is about 5mW Five 10 saccumulations were generally acquired for each sample Theresolution was 2 cmminus1 and the spectra were calibrated usingthe 5205 cmminus1 line of a silicon wafer Spectral analysis wasdone by background subtraction and curve fitting

Preliminary tests for As removal by adsorption werecarried out at room temperature (20∘C) using PM material(up to 3000120583m) and ST material (about 1000ndash2000120583m)without grinding The chemical activation of PMmaterial bymeans of ferric chloride to give PMA sample was made fol-lowing the procedure reported by Chen et al [12] The batchexperiments to study the removal of As from solution werecarried out by reacting 10 g solid with 100mL contaminatedwater The arsenic-containing solution of 134 120583g Lminus1 simu-lating conditions of affected groundwater in Buenos Airesprovince [13] was obtained from hydrated sodium arsenate(Na2HAsO

4sdot7H2O) and deionized water The mixture was

kept at room temperature for 1 h by stirring at 200 rpmto ensure complete homogenization The slurries were keptat room temperature for 24 h The supernatant was filteredthrough a 045 120583m membrane filter The initial and finalconcentration of arsenic in the solution was determined bya Perkin Elmer Analyst 200 (equipped with a Perkin ElmerHGA900Graphite-Furnace)TheAs retained in the solidwascalculated according to the expression

Re =([119862

0minus 119862

119903] times 100)

119862

0

(1)

where Re is the arsenate removal () and 1198620and 119862

119903are the

initial and residual (after 24 h) As concentrations expressedin 120583g Lminus1

The pH of suspensions was adjusted between 3 and 9by using 01M solutions of HCl or NaOH The values weremonitored by means of the Denver Instrument UltrabasicBenchtop pHmeter In order tomaintain a relatively constantionic strength the arsenic solutions contain 001M NaClas background electrolyte The experiments were done bytriplicate

3 Results and Discussion

31 Physicochemical Characterization According to the re-flection microscope the volcanic material shows a predom-inance (70ndash80) of pumice fragments (glass blabbing) To alesser extent (30ndash20) crystals and crystal fragments ofmetaloxide and silicate phases were observed

Figure 1(a) shows the SEM images of the ejected volcanicpyroclasticmixture (PM) whereas Figure 1(b) corresponds tothe major component named pumiceous type (PT) TypicalSEM images of dark particles classified as scoria type (ST)in the original form and after ultrasonic washing (STW)to remove fine particles (adhered at the surface and fillingthe vesicles) are shown in Figures 1(c) and 1(d) with thecorrelative images at different magnification Black roundedblocks (RB) also at different magnification are shown inFigure 1(e) It is possible to notice that the texture andmorphology among PT ST and RB samples were different

Journal of Spectroscopy 3

(a)(b)

(c)

(d)

(e)

Figure 1 SEM micrographs of samples (a) PM (b) PT (c) ST (d) STW and (e) RB PM volcanic pyroclastic mixture PT pumiceous typeST scoria type STW washed scoria type RB rounded block


Table 1 EDS data for volcanic pyroclastic mixture (PM) and selected typical components

oxide PM ST STW RB PT PTW

CO2 412 730 615 1256 364 244Na2O 465 405 344 Nd 558 537MgO 208 282 302 1007 141 057Al2O3 1485 1701 1789 472 1384 1452SiO2 6125 5456 5160 3748 6276 6828K2O 148 121 060 Nd 319 236CaO 275 490 561 370 252 185TiO2 101 088 157 447 107 106Fe2O3 781 727 1012 2700 599 355PM volcanic pyroclastic mixture ST scoria type PT pumiceous type RB rounded block w washed

Inte

nsity

()

20 25 30 35 40 45 50 55 602120579

Figure 2 XRD pattern of ST sample (see text)

Table 2 Major and minor elements (expressed as oxides) by ICPAES

Sample PM PT STSiO2 6703 7030 6052TiO2 089 065 117Al2O3 1417 1335 1452Fe2O3 558 456 892MnO 014 012 016MgO 105 056 277CaO 295 202 576Na2O 504 512 377K2O 237 252 149P2O5 017 013 033Cr2O3 001 001 001BaO 008 008 005SrO 002 002 004LOI 050 056 049PM volcanic pyroclastic mixture ST scoria type PT pumiceous type

Table 1 gives typical EDS results (average of ten deter-minations) The iron content of the samples increases in

Dacite

Andesite

Rhyolite

12

18

0

15

9

6

3 Basalt

Trachyandesite

Trachyte

Hawaiite

Mugearite

Benmorite

Phonolite

Nepheli

n

PTPMST

35 45 60 65 75

Na 2

O+

K 2O

(wt

)

SiO2 (wt)

Bminus

A

B +T

P minus TP minus N

Figure 3 Total alkali-silica (TAS) plot for PT PM and ST samples

the order PT lt ST lt RB whereas the PM pyroclasticmaterial reveals the contribution of the mixture componentsRounded blocks (RB) of intense black color are the Fe and Tirichest samples Dark color can be associated with the Fe(II)-Fe(III) intervalence charge transfer process [14]

According to EDS results the SiO2Al2O3ratio in the

ST particles is near 3 value that increases to sim5 in the PTsamplesThe diminution of Al content can be associated withthe enrichment of Si species (crystalline or glassy) Likewisethe RB particles are characterized by the absence of alkalineelements (K and Na) and the presence of Mg and Ca Thisfact suggests the existence of mixed valence iron oxides orrelated phases (magnetite-type) containing Fe Mg Al andTi The presence of Ca can be associated with some silicate(probably plagioclase) It is evident that the finest particles aremobilized by the ultrasonic treatment affecting the relative


Table 3 REE trace elements (expressed as ppm) by ICP MS

Sample La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb LuPM 29 657 9 40 813 2 8 1 8 171 535 082 54 087PT 31 696 9 37 857 2 8 1 8 186 545 088 58 092ST 20 455 6 26 651 2 6 1 6 135 398 060 38 059PM volcanic pyroclastic mixture ST scoria type PT pumiceous type

PTPMST

100

20La

CePr

NdEu

GdTb

DyHo

ErTm

YbLu

200

Sm

Sam

ple

C1 ch

ondr

ite

Figure 4 Spider diagram of REE for PT PM and ST samples

SiFe composition The washing of ST samples facilitates theexposition of iron species by elimination of Si-rich particlesadhered in vesicles Finally the presence of carbonaceousmaterials is observed particularly in the dark particles

Moreover Table 2 presents the bulk chemical analysisby ICP-AES (major and minor elements) whereas Table 3gives the ICP-MS data for REE trace elements Comparisonbetween bulk and EDS chemical data suggests that ironphases are concentrated in the surface of siliceous materialsOn the other hand round blocks of iron phases can beisolated and also viewed immersed in the glassy matrix asit is observed in Figure 1(a)

The X-ray diffraction pattern of the volcanic pyroclasticmixture (PM) indicates the presence of an absolute majorityof a vitreous amorphous phasewhereas the PT samples is alsocharacterized by a very low resolution However the XRDpattern of the dark-ST material shown in Figure 2 revealsthe presence of crystalline phases X-ray diffraction lines canbe correlated to siliceous phases in the form of substitutedcalcium plagioclase (CaAl

2Si2O8) and pyroxene (Mg

2Si2O6)

(PDF 89-1463 85-1740 88-2377) both showing the strongerpeaks in the zone of sim28∘ sim30∘ of 2120579 angles Likewise

iron oxides observed as weak reflections can be assignedto binary andor mixed oxide for example magnetite-typestructures PDF 80-0390 (more intense lines at sim30∘ sim35∘of 2120579) as well as hematite or related phases PDF 89-2810(stronger reflections at sim33∘ sim35∘ of 2120579) For the ST samplecontaining the majority of crystalline phases it is possibleto estimate the presence of plagioclase as major phase (sim50ndash60) with sim10ndash14 of piroxene sim10 of iron oxides and alow proportion (lt5) of K-feldspar not detected clearly byXRDThe remainder of material is vitreous

According to the total alkali versus silica diagram (TAS)for the volcanic rocks shown in Figure 3 obvious signals offractionation process are observed whereas ST materials arelocated in the andesite-type stability field the PT fragmentsbelong to rhyolite type Alkali depletion observed in STsamples can be related to the concentration thereof in themelted phase

Figure 4 shows the spider diagram for the samplesobtained from REE trace elements The REE depletionobserved for ST samples (more pronounced for the heavyelements HREE) can be attributed to dissimilar degree offractionationThis can be associated not only with the chem-istry of the source but also with the crystal-melt equilibriumduring the magmatic evolution Partition coefficients arehigher with increasing silica content of themelt Likewise theEu(II) negative anomaly can be attributed to its compatibilitywith feldspars and silicate species (similar ionic potential forEu(II) and alkaline-earth species) So differences between thefractionation of the light REE (LREE) with respect to HREEmay be related to the presence of other silicate species suchas pyroxenes and accessory phasesThe behavior observed inFigure 4 is similar to that reported for volcanicmaterials fromprevious eruptions of the PCCVC [15]

Surface area (BET) of the pyroclastic material (PM) is223m2 gminus1 while the ST sample presented a relatively lowervalue (173m2 gminus1) The difference can be attributed to thepresence of crystalline phases [16]

The micro-Raman spectroscopy is a useful techniqueto define the mineralogy of composite materials becominga sensor for identifying promptly the species isolated orembedded in the matrix [17] Figures 5(a)ndash5(d) correspondto the Raman spectra of samples collected from varioussample spotsThepresence of a complex compositionmixtureis revealed alkali aluminosilicate hematite and magnetiteassociated with siliceous phases and carbonaceous materialdispersed in the glassy matrix Hence the Raman spectracover a wide range of Na K Mg and Ca silicates [18]Experimental Raman data of Figure 5(a) with lines atabout 325 380 530 665 888 and 999 cmminus1 corroborate


Inte

nsity

325

380

530

665

888

999

500 1000 1500 2000Wavenumbers (cmminus1)

(a)

Inte

nsity

221 29

040

648

560

5 1308


(b)

Inte

nsity

305

546

665

993

1100 13

51


(c)

Inte

nsity 13

70

1595


(d)

Figure 5 Micro-Raman spectra registered in different spots (see text)

100

80

60

40

20

02 3 4 5 6 7 8 9 10

pH

STPMPMA

Re (

)

Figure 6 Arsenic removal by using volcanic pyroclastic mixture(PM) scoria-type (ST) material and activated pyroclastic mixture(PMA) at different pH

the presence of clinopyroxene and plagioclase The firstspecies is characterized by three strong Raman signals at322 667 and 997 cmminus1 whereas plagioclase (eg anorthite)

presents typical strong signal at 510 cmminus1 and weak signals inthe 1000 cmminus1 region [18] Hematite in natural samples or inany iron oxide mixtures is reliably identified by lines at sim225291 411 611 and 1321 cmminus1 whereas magnetite shows twoweak bands at sim300 and sim530 cmminus1 and an intense signal atsim665 cmminus1 which is the most conspicuous and diagnosticallyuseful [17ndash19]

Spectrum of Figure 5(b) shows bands at 221 290 406605 and 1308 cmminus1 attributed with hematite phase whereasa shoulder at 662 cmminus1 could be assigned to magnetite

Likewise the spectrum of Figure 5(c) is more complexHowever the magnetite presence can be corroborated fromthe Raman line at 665 cmminus1 Other lines at low frequencies(in the range 305ndash546 cmminus1 surely associated with the partialoxidation ofmagnetite) and between 990 and 1400 cmminus1 (9931100 1351 cmminus1) usually observed in some plagioclases [18]reveal the strong interaction between phases with differentcomposition and crystal structure Differences between spec-tra of Figures 5(b) and 5(c) are surely related to the alterationduring the evolution of the eruption process

Spectrum of Figure 5(d) is characterized by two intensesignals centered at 1370 and 1595 cmminus1 which can be assignedto active modes of carbon particles (ordered and disorderedgraphite species resp) [20ndash22] These seem to be associatedto the natural chaoite mineral species formed by heatinggraphite at high pressure associated with zircon rutilepseudobrookite and magnetite among other species


32 Potentiality in the As Sorption Process Although thevolcanic ash constitutes a significant environmental hazard[23] investigations have been carried out in order to analyzeits potential use as raw material in the preparation ofadsorbents cement and so forth In this context the useof ferric impregnated volcanic ash has been proved in thearsenate adsorption process [12 24]

The As content in the PM PT and ST studied materials(123 157 and 124 ppm resp) is comparable to that observedin the loess of Argentinean aquifers [13] However it wasobserved that the As was not leached according to the EPAinternational method [25] These aspects were a good signalto prove the capability of the raw material without chemicalmodification to retain the toxic On this basis tentative assaysfor As removal were done

The literature reports of adsorption data for ferric-impregnated volcanic ash showed that an increase of sim5as Fe2O3(by treatment of ferric solution (FeCl

320 g Lminus1))

greatly elevates the As(V) removal ability by the formationof iron (hydro)oxides [12] This modification also affectsthe range of adsorption capability through an electrostaticattraction as well as surface complexation processes betweenthe As species (H

2AsO4

minus HAsO4

minus2) and iron oxide surfacesites [16 26] In our work conditions the increase of ironcontent in the activated sample (PMA) can be correlated witha great increase of the surface area (7369m2 gminus1)

Figure 6 gives the average values of As adsorbed in thePM ST and PMA materials (558 892 and 1040 Fe

2O3

resp) at the conditions indicated in the experimental sectionversus pH The comparison of the results reveals that theAs retention increases with acidity Maximums of 58587 and 9627 for PM ST and PMA were observed atpH 5 4 and in the 4ndash6 range respectively These acidicconditions can be correlated with those reported in theliterature working with volcanic ash chemically modifiedwith iron [12] The pH effect can be attributed to the increaseof adsorption sites by surface protons (formation of Fe-O-H and eventually Al-O-H previous to the dealuminationprocess) facilitating the interaction with the (H

2AsO4

minus orHAsO

4

minus2) predominant species This behavior at the surfacelevel shows that arsenate has a direct chemical bond withiron species with a specific sorption mechanism followinga surface complexation model (inner sphere complexes) as itis widely reported [16]

4 Conclusions

The components of the volcanic ash emitted by PCCVCeruption were identified by means of spectroscopic andmicroscopic techniques which revealed a mixture of alkalisilicates (predominantly glass) and microcrystals of ironoxides (hematite magnetite) phases of plagioclase typepyroxene type and carbonous material The pyroclastic- andthe scoria-type materials with bulk iron contents of 558 and892 Fe

2O3 have not shown arsenic leaching retaining the

arsenic in solution On the other hand the ldquoin siturdquo chemicalmodification with a small proportion of iron oxide (sim5 asFe2O3) led to a useful adsorbent for arsenic removal from

aqueous solution increasing also the effective range of pHComparatively the good performance can be attributed to theincrease of the adsorption sites through the formation of Fe-O-H groups On the basis of physicochemical characteriza-tion the studied ash seems to be an interesting raw materialfor the arsenic removal transforming the volcanic waste in asuitable inexpensive and abundant adsorbent

Acknowledgments

Theworkwas done by financial support of ANPCyT BID 2011PICT-2186 Argentina and CUIA (Italy-Argentina) AuthorsthankMr R Vina (LANADI Lab University of La Plata) andEng A Kang (LIMFLab University of La Plata) for technicalmeasurements

References

[1] SERNAGEOMIN 2011 Reportes Especiales de ActividadVolcanica Complejo Volcanico PuyehuemdashCordon Caullehttpwwwsernageomincl

[2] M E Canafoglia M Vasallo V Barone and I L BottoldquoProblems associated to natural phenomena potential effectsof the Puyehue Cordon Caulle Volcanic Complex (PCCVC)eruption on the health and the environment in different zonesof Villa La Angostura Neuquenrdquo AUGM-DOMUS vol 4 p 12012

[3] M Koshino ldquoFertilizers with new functionsrdquo in Environmen-tal Conservation and Innovative Fertilization Technologies TYashuda and M Koshino Eds p 116 Tokyo Japan 2001

[4] B Langmann K Zaksek and M Hort ldquoVolcanic ash asfertilizerrdquo Atmospheric Chemistry and Physics vol 10 p 38912010

[5] XQuerol J CUmana F Plana et al ldquoSynthesis of zeolites fromfly ash at pilot plant scale Examples of potential applicationsrdquoFuel vol 80 no 6 pp 857ndash865 2001

[6] V Zaspalis A Pagana and S Sklari ldquoArsenic removal fromcontaminated water by iron oxide sorbents and porous ceramicmembranesrdquo Desalination vol 217 no 1ndash3 pp 167ndash180 2007

[7] J Gimenez M Martınez J de Pablo M Rovira and LDuro ldquoArsenic sorption onto natural hematite magnetite andgoethiterdquo Journal ofHazardousMaterials vol 141 no 3 pp 575ndash580 2007

[8] W Driehaus ldquoTechnologies for asenic removal from potablewaterrdquo in Natural Arsenic in Groundwater Occurrence Remedi-ation and Management J Bundschuh P Bhattacharya and DChandrasekharam Eds p 189 CRCPress-Balkema Taylor andFrancis London UK 2005

[9] M Litter M Alarcon-Herrera M Arenas et al ldquoSmall-scaleand household methods to remove arsenic from water fordrinking purposes in Latin Americardquo Science of the TotalEnvironment vol 429 pp 107ndash122 2012

[10] WHO Arsenic Environmental Health Criteria 18 IPCS Interna-tional Programme of Chemical Safety Vammalan KoirjapainoOy Vammala Finland 1981

[11] J Bundschuh M I Litter F Parvez et al ldquoOne century ofarsenic exposure in Latin America a review of history andoccurrence from 14 countriesrdquo Science of the Total Environmentvol 429 pp 2ndash35 2012

[12] R Chen Z Zhang Y Yang et al ldquoUse of ferric-impregnatedvolcanic ash for arsenate (V) adsorption from contaminated


water with various mineralization degreesrdquo Journal of Colloidand Interface Science vol 353 no 2 pp 542ndash548 2011

[13] H Nicolli J Bundschuh M Blanco et al ldquoArsenic and associ-ated trace-elements in groundwater from the Chaco-Pampeanplain Argentina results from 100 years of researchrdquo Science ofthe Total Environment vol 429 pp 36ndash56 2012

[14] D M Sherman ldquoMolecular orbital theory of metal-metalcharge transfer processes in minerals Fe(II)-Fe(III) CT andElectron delocalization in mixed valence iron oxides andsilicatesrdquo Physics and Chemistry of Minerals vol 14 no 4 pp355ndash363 1987

[15] R Daga S Ribeiro Guevara M L Sanchez and M ArribereldquoSource identification of volcanic ashes by geochemical analysisof well preserved lacustrine tephras in Nahuel Huapi NationalParkrdquo Applied Radiation and Isotopes vol 66 no 10 pp 1325ndash1336 2008

[16] Y Mamindy-Pajany C Hurel N Marmier and M RomeoldquoArsenic adsorption onto hematite and goethiterdquo ComptesRendus Chimie vol 12 no 8 pp 876ndash881 2009

[17] S Das and M J Hendry ldquoApplication of Raman spectroscopyto identify iron minerals commonly found in mine wastesrdquoChemical Geology vol 290 no 3-4 pp 101ndash108 2011

[18] L A Haskin A Wang K M Rockow B L Jolliff R LKorotev and K M Viskupic ldquoRaman spectroscopy for mineralidentification and quantification for in situ planetary surfaceanalysis a point count methodrdquo Journal of Geophysical ResearchE vol 102 no 8 pp 19293ndash19306 1997

[19] M Hanesch ldquoRaman spectroscopy of iron oxides and(oxy)hydroxides at low laser power and possible applicationsin environmental magnetic studiesrdquo Geophysical JournalInternational vol 177 no 3 pp 941ndash948 2009

[20] Y Wang D C Alsmeyer and R L McCreery ldquoRamanspectroscopy of carbon materials structural basis of observedspectrardquo Chemistry of Materials vol 2 no 5 pp 557ndash563 1990

[21] C Domınguez and G Santoro ldquoEspectroscopıa Raman denanotubos de carbonordquo Optica Pura y Aplicada vol 40 p 1752007

[22] O Beyssac B Goffe C Chopin and N Rouzaud ldquoRamanspectra of carbonaceous material in metasediments a newgeothermometerrdquo Journal of Metamorphic Geology vol 20 pp859ndash871 2002

[23] C J Horwell and P J Baxter ldquoThe respiratory health hazards ofvolcanic ash a review for volcanic risk mitigationrdquo Bulletin ofVolcanology vol 69 no 1 pp 1ndash24 2006

[24] N Jaafarzadeh H Amiri and M Ahmadi ldquoFactorial experi-mental design application in modification of volcanic ash asa natural adsorbent with Fenton process for arsenic removalrdquoEnvironmental Technology vol 33 no 1ndash3 pp 159ndash165 2012

[25] US EPA ldquoTest methods for evaluating solid wasterdquo MethodEPA1311 Toxicity Characteristic Leaching Procedure (TCLP)SW-846 Office of Solid Waste and Emergency ResponseUnited States Environmental Protection Agency WashingtonDC USA 1990

[26] H Guo D Stuben and Z Berner ldquoRemoval of arsenic fromaqueous solution by natural siderite and hematiterdquo AppliedGeochemistry vol 22 no 5 pp 1039ndash1051 2007

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The aim of this work is to study the physicochemicalbehavior of the ash and tephras deposited in Villa La Angos-tura (40∘4510158404810158401015840S-71∘3810158404610158401015840W) and collected five monthsafter the eruption and the need to approach the potentialapplication (in the original form and activated with ferricphases) to remove arsenic from groundwater

Scanning electron microscopy (SEM-EDS) optical mea-surements surface (BET) and chemical analysis (by induc-tively coupled plasma (ICP) technique for major and traceelements) X-ray diffraction and Raman spectroscopy weredirected to the mineralogical and chemical characterizationof the material

2 Materials and Methods

The material from Villa La Angostura (about 40 km fromthe volcanic source) having particle sizes between 10 and3000 120583m was dried at 100∘C and identified as pyroclasticmaterial (PM) No thermal transformations were observedin the 60ndash100∘C range The humidity elimination (sim30of water) was necessary to perform the physicochemicalcharacterization The selection of the mixture componentswas done with the aid of the binocular microscope Glassand light shards with vesicular microcavities were identifiedas pumiceous-type material (PT) whereas the dark particlesalso vesiculated were named as scoria-type (ST) materialLithoclasts of size lower than the PT and ST materialsof intense black color and smooth uniform surfaces wereidentified as rounded blocks (RB) The material densitiesfollowed the sequence RB gt ST gt PT The former presentsalso a magnetic behavior Additional optical measurementswere useful to reveal the difference between crystalline andvitreous particles

PT and ST materials were washed with ethanol by theultrasonic technique to facilitate the separation of very thinadhered particles and then dried at 80∘C

Scanning electron microscopy and electron diffractionspectroscopy (SEM-EDS) measurements were performed inan ESEM (FEI Quanta 200) with tungsten filament and anETD (high vacuum secondary electron) detector Microanal-ysis was carried out with an EDAX Detector Apollo 40Chemical results were expressed as oxides

Chemical analysis was performed by ICP-AES for majorelements (expressed as oxides) and ICP-MS for trace RareEarth Elements (REE) (in ppm) (ALS Chemex Lab Canada)The geochemical behavior was analyzed from variance dia-grams of REE normalized to chondrite igneous system

The BET surface area was measured by N2adsorption

using a Micromeritics ASAP 2020 Automated Brunauer-Emmett-Teller Sorptometer

X-ray diffraction patterns for crystalline phase analysiswere collected with a Philips PW 1710 diffractometer Cu K120572Ni-filtered radiation

Raman spectroscopic analyses were carried out withinVia Renishaw micro-Raman spectrometer equipped withan air-cooled CCD detector and edge filters A 7850 nmemission line from a diode laser was focused on the sampleby a Leica DLML microscope using 5x or 20x objectives

The power of the incident beam is about 5mW Five 10 saccumulations were generally acquired for each sample Theresolution was 2 cmminus1 and the spectra were calibrated usingthe 5205 cmminus1 line of a silicon wafer Spectral analysis wasdone by background subtraction and curve fitting

Preliminary tests for As removal by adsorption werecarried out at room temperature (20∘C) using PM material(up to 3000120583m) and ST material (about 1000ndash2000120583m)without grinding The chemical activation of PMmaterial bymeans of ferric chloride to give PMA sample was made fol-lowing the procedure reported by Chen et al [12] The batchexperiments to study the removal of As from solution werecarried out by reacting 10 g solid with 100mL contaminatedwater The arsenic-containing solution of 134 120583g Lminus1 simu-lating conditions of affected groundwater in Buenos Airesprovince [13] was obtained from hydrated sodium arsenate(Na2HAsO

4sdot7H2O) and deionized water The mixture was

kept at room temperature for 1 h by stirring at 200 rpmto ensure complete homogenization The slurries were keptat room temperature for 24 h The supernatant was filteredthrough a 045 120583m membrane filter The initial and finalconcentration of arsenic in the solution was determined bya Perkin Elmer Analyst 200 (equipped with a Perkin ElmerHGA900Graphite-Furnace)TheAs retained in the solidwascalculated according to the expression

Re =([119862

0minus 119862

119903] times 100)

119862

0

(1)

where Re is the arsenate removal () and 1198620and 119862

119903are the

initial and residual (after 24 h) As concentrations expressedin 120583g Lminus1

The pH of suspensions was adjusted between 3 and 9by using 01M solutions of HCl or NaOH The values weremonitored by means of the Denver Instrument UltrabasicBenchtop pHmeter In order tomaintain a relatively constantionic strength the arsenic solutions contain 001M NaClas background electrolyte The experiments were done bytriplicate

3 Results and Discussion

31 Physicochemical Characterization According to the re-flection microscope the volcanic material shows a predom-inance (70ndash80) of pumice fragments (glass blabbing) To alesser extent (30ndash20) crystals and crystal fragments ofmetaloxide and silicate phases were observed

Figure 1(a) shows the SEM images of the ejected volcanicpyroclasticmixture (PM) whereas Figure 1(b) corresponds tothe major component named pumiceous type (PT) TypicalSEM images of dark particles classified as scoria type (ST)in the original form and after ultrasonic washing (STW)to remove fine particles (adhered at the surface and fillingthe vesicles) are shown in Figures 1(c) and 1(d) with thecorrelative images at different magnification Black roundedblocks (RB) also at different magnification are shown inFigure 1(e) It is possible to notice that the texture andmorphology among PT ST and RB samples were different


(a)(b)

(c)

(d)

(e)






Inte

nsity

()

20 25 30 35 40 45 50 55 602120579





Dacite

Andesite

Rhyolite

12

18

0

15

9

6

3 Basalt

Trachyandesite

Trachyte

Hawaiite

Mugearite

Benmorite

Phonolite

Nepheli

n

PTPMST

35 45 60 65 75

Na 2

O+

K 2O

(wt

)

SiO2 (wt)

Bminus

A

B +T

P minus TP minus N








PTPMST

100

20La

CePr

NdEu

GdTb

DyHo

ErTm

YbLu

200

Sm

Sam

ple

C1 ch

ondr

ite






2Si2O6)








Inte

nsity

325

380

530

665

888

999


(a)

Inte

nsity

221 29

040

648

560

5 1308


(b)

Inte

nsity

305

546

665

993

1100 13

51


(c)

Inte

nsity 13

70

1595


(d)


100

80

60

40

20

02 3 4 5 6 7 8 9 10

pH

STPMPMA

Re (

)











320 g Lminus1))


2AsO4

minus HAsO4



2O3


2AsO4

minus orHAsO

4


4 Conclusions





Acknowledgments


References






































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


(a)(b)

(c)

(d)

(e)






Inte

nsity

()

20 25 30 35 40 45 50 55 602120579





Dacite

Andesite

Rhyolite

12

18

0

15

9

6

3 Basalt

Trachyandesite

Trachyte

Hawaiite

Mugearite

Benmorite

Phonolite

Nepheli

n

PTPMST

35 45 60 65 75

Na 2

O+

K 2O

(wt

)

SiO2 (wt)

Bminus

A

B +T

P minus TP minus N








PTPMST

100

20La

CePr

NdEu

GdTb

DyHo

ErTm

YbLu

200

Sm

Sam

ple

C1 ch

ondr

ite






2Si2O6)








Inte

nsity

325

380

530

665

888

999


(a)

Inte

nsity

221 29

040

648

560

5 1308


(b)

Inte

nsity

305

546

665

993

1100 13

51


(c)

Inte

nsity 13

70

1595


(d)


100

80

60

40

20

02 3 4 5 6 7 8 9 10

pH

STPMPMA

Re (

)











320 g Lminus1))


2AsO4

minus HAsO4



2O3


2AsO4

minus orHAsO

4


4 Conclusions





Acknowledgments


References






































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





Inte

nsity

()

20 25 30 35 40 45 50 55 602120579





Dacite

Andesite

Rhyolite

12

18

0

15

9

6

3 Basalt

Trachyandesite

Trachyte

Hawaiite

Mugearite

Benmorite

Phonolite

Nepheli

n

PTPMST

35 45 60 65 75

Na 2

O+

K 2O

(wt

)

SiO2 (wt)

Bminus

A

B +T

P minus TP minus N








PTPMST

100

20La

CePr

NdEu

GdTb

DyHo

ErTm

YbLu

200

Sm

Sam

ple

C1 ch

ondr

ite






2Si2O6)








Inte

nsity

325

380

530

665

888

999


(a)

Inte

nsity

221 29

040

648

560

5 1308


(b)

Inte

nsity

305

546

665

993

1100 13

51


(c)

Inte

nsity 13

70

1595


(d)


100

80

60

40

20

02 3 4 5 6 7 8 9 10

pH

STPMPMA

Re (

)











320 g Lminus1))


2AsO4

minus HAsO4



2O3


2AsO4

minus orHAsO

4


4 Conclusions





Acknowledgments


References






































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




PTPMST

100

20La

CePr

NdEu

GdTb

DyHo

ErTm

YbLu

200

Sm

Sam

ple

C1 ch

ondr

ite






2Si2O6)








Inte

nsity

325

380

530

665

888

999


(a)

Inte

nsity

221 29

040

648

560

5 1308


(b)

Inte

nsity

305

546

665

993

1100 13

51


(c)

Inte

nsity 13

70

1595


(d)


100

80

60

40

20

02 3 4 5 6 7 8 9 10

pH

STPMPMA

Re (

)











320 g Lminus1))


2AsO4

minus HAsO4



2O3


2AsO4

minus orHAsO

4


4 Conclusions





Acknowledgments


References






































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Inte

nsity

325

380

530

665

888

999


(a)

Inte

nsity

221 29

040

648

560

5 1308


(b)

Inte

nsity

305

546

665

993

1100 13

51


(c)

Inte

nsity 13

70

1595


(d)


100

80

60

40

20

02 3 4 5 6 7 8 9 10

pH

STPMPMA

Re (

)











320 g Lminus1))


2AsO4

minus HAsO4



2O3


2AsO4

minus orHAsO

4


4 Conclusions





Acknowledgments


References






































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





320 g Lminus1))


2AsO4

minus HAsO4



2O3


2AsO4

minus orHAsO

4


4 Conclusions





Acknowledgments


References






































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Documents

Research Article Spectroscopic and Microscopic Characterization …downloads.hindawi.com/journals/jspec/2013/254517.pdf · 2019-07-31 · 2. Materials and Methods e material from