Research Article Oxidative Precipitation of Manganese …downloads.hindawi.com/journals/jchem/2013/287257.pdf · Research Article Oxidative Precipitation of Manganese from Acid Mine

Hindawi Publishing CorporationJournal of ChemistryVolume 2013 Article ID 287257 8 pageshttpdxdoiorg1011552013287257

Research ArticleOxidative Precipitation of Manganese from Acid MineDrainage by Potassium Permanganate

Regeane M Freitas Thomaz A G Perilli and Ana Claudia Q Ladeira

Centre for Development of Nuclear Technology (CDTN) Av Antonio Carlos 6627 Campus UFMG31270901 Belo Horizonte MG Brazil

Correspondence should be addressed to Regeane M Freitas rmdf2camacuk

Received 8 May 2013 Accepted 4 October 2013

Academic Editor Eva Pocurull

Copyright copy 2013 Regeane M Freitas et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Although oxidative precipitation by potassium permanganate is a widely recognised process for manganese removal researchdealing with highly contaminated acid mine drainage (AMD) has yet to be performedThe present study investigated the efficiencyof KMnO

4in removing manganese from AMD effluents Samples of AMD that originated from inactive uranium mine in Brazil

were chemically characterised and treated by KMnO4at pH 30 50 and 70 Analyses by Raman spectroscopy and geochemical

modelling using PHREEQC code were employed to assess solid phases Results indicated that the manganese was rapidly oxidisedbyKMnO

4in a process enhanced at higher pHThe greatest removal that is 99 occurred at pH 70 when treatedwaters presented

manganese levels as low as 10mgL the limit established by the Brazilian legislation Birnessite (MnO2) hausmannite (Mn

3O4)

and manganite (MnOOH) were detected by Raman spectroscopy These phases were consistently identified by the geochemicalmodel which also predicted phases containing iron uranium manganese and aluminium during the correction of the pH as wellas bixbyite (Mn

2O3) nsutite (MnO

2) pyrolusite (MnO

2) and fluorite (CaF

2) following the KMnO

4addition

1 Introduction

The oxidation of sulphide minerals exposed to oxygen andwater produces acid effluents commonly referred to asacid mine drainage (AMD) described in detail elsewhere[1] Although the generation of acid drainage is a naturalphenomenon mining activities can dramatically increase itsproduction due to the large amounts of material usuallyexposed In addition to its main characteristics (eg highacidity and sulphate levels) AMD features extensive chemicaldiversity including metals such as iron aluminium andmanganese in elevated concentrations [2] These effluentsare potentially hazardous to the environment Howevertechnologies available to deal with AMDare either unsuitableor costly [3] Furthermore practices are fairly exclusive andvarying significantly from one site to another which charac-terises several problems in terms of the implementation ofavailable methodologies

In Brazil for instance as a consequence of high contentsof manganese in the soil the concentration of this metal in

AMD can be up to 150 times the limit of 10mgL recognisedby CONAMA Resolution 430 (Brazilian legislation) [4]However the majority of studies performed so far haveaddressed the removal of manganese from waters with lowcontamination such as drinking water (eg [5ndash8]) Themanagement of AMD with exceptionally high concentrationof manganese sets a totally new and challenging scenariowithin the remediation technologies and research on thistopic is still necessary

Overall challenges in removing manganese from AMDarise from two main factors First the conditions of efflu-ents that is pH and Eh are unfavourable for manganeseprecipitation second AMD effluents are very complexin terms of chemical composition Currently the mostwidely employed treatment consists of active systems usingchemical-neutralising agents such as sodium hydroxide andlimestone to precipitate manganese [1 9] However the needfor high pH condition (ie pH gt 11) raises expenses due tochemical consumption and yet leads to unsatisfactory treatedwaters considering the recommended pH range between

2 Journal of Chemistry

5 and 9 (CONAMA Resolution 430) [4] Furthermore thisprocess also generates large amounts of bulky sludge whichrequires further treatment and appropriate disposal [1 10]

In this context oxidative precipitation seems to be amoresuitable alternative for removing manganese from AMD[11] Manganese reacts with an oxidant agent generating acolloidal precipitate which is then separated by filtration orsedimentation [12] Several oxidant agents such as air [13]chlorine [14] ozone [15] sulphur dioxide and oxygen [16]were evaluated in studies that focused mainly on slightlycontaminated effluents In general potassium permanganate(KMnO

4) stands out with the advantage of removing other

contaminants such as iron and organic compounds responsi-ble for taste and odour [17] Therefore there is great interestin establishing optimised operating conditions that enable theuse of KMnO

4for remediating highly contaminated AMD

The assessment of reaction rates as well as solid phasesformed during remediation procedures provide valuableinformation in designing and optimising efficient treatmentmethods Van Benschoten et al [12] published an extensivework on the kinetics of manganese oxidation by KMnO

4

According to these authors oxidation rates depend on con-centrations of oxidant hydroxyl ions manganese oxidesand free manganese Other factors such as coprecipitationadsorption [18] and the autocatalytic effect of precipitates[19] were also reported to affect the removal of manganeseand other contaminants which indicates the importance ofinvestigating the solid phases produced

Geological models are particularly appropriate to assesssolid phases in aqueous systems such as AMD For instancethe software PHREEQC [20] has proved extremely useful inproviding conceptual models focusing on water treatmentand environmental remediation technologies [10 21ndash23]Based on ionic associations the program amongst otheroptions allows saturation-index calculations and chemicalspeciation PHREEQC employs a solubility approach toidentify thermodynamically possible solid phases whichmay potentially support the conception and management ofefficient treatment systems for AMD

In this study the oxidative precipitation of manganese byKMnO

4was investigated with the objective of achieving an

effective treatment method for highly contaminated AMDExperiments were divided into two parts the first one wasperformed with MnSO

4solutions prepared in the laboratory

and the second with AMD samples collected in an inactiveuranium mine at the Plateau of Pocos de Caldas southeastof Brazil Processes were conducted at pH 30 50 and 70Precipitates were characterised by spectroscopy techniquesand electron microprobe In addition a geochemical modelusing the PHREEQC software was developed to predict solidphases possibly formed at each stage of the remediationprocess

2 Methodology

21 Liquid Samples Laboratory solutions were prepared bydiluting 031 g of MnSO

4sdotH2O (Vetec Brazil) in 10 L of

deionizedwater Acidmine drainage samples identified as A1

and A2 were collected in two different water dams locatedin one former and inactive uranium mine Effluents werechemically characterised and results are shown in Table 1

22 Bench Experiments Experiments were carried out inglass beakers with 200mL of liquid samples Initially understirring and at room temperature (25∘Cplusmn 05) the pH wasadjusted by adding sodium hydroxide or sulphuric acid Onealiquot was taken to determine the initial concentration ofmanganese which ranged from 90 to 105mgL AfterwardsKMnO

44 (wv) was added to the solutions based on pre-

determined ratios 163mg KMnO4mg Mn for experiments

at pH 30 and 154mg KMnO4mg Mn for pH 50 and 70

Samples were collected at pre-established time and filteredin 045 120583m membranes Ratio and reaction time values weredetermined in a previous study based on statistic factorialdesign considering four parameters concentration of the oxi-dant agent reaction time stoichiometry and pH Sulphuricacid solution and sodium bisulphite 5 (wv) were addedto the filtrate as quenching agents Manganese aluminiumcalcium iron and zinc were determined by atomic absorp-tion spectrophotometry (VARIAN model AA240FS) Ura-nium was assessed by X-ray fluorescence spectrophotometry(SHIMADZUmodel EDX-720)

23 Solid Samples Solid samples at pH 70 were dried atroom temperature and then analysed byRaman Spectroscopy(JOBIN-YVON LABRAM model HR-800) Scanning Elec-tron Microscope (JEOL JSM model 840A) and ElectronProbe Microanalysis coupled to EDS detector (JEOL JXAmodel 8900 RT)

24 PHREEQC Modelling The oxidative precipitation ofmanganese was modelled using the geochemical programPHREEQC-Version 2 [20] The consistent thermodynamicdatabase WATEQ4F [24] was used to construct forwardmodels focusing on the assessment of saturation index(SI) The developed speciation-solubility model compriseddefined amounts of the KMnO

44 (wv) allowed to react

reversibly with aqueous solutions simulating the composi-tions of MnSO

4and AMD samples Based on the conditions

of the system each phase precipitated when SI gt 0 wasreached or dissolved completely when SI lt 0 to achieve theequilibrium SI = 0 It is worth saying that the conditionof equilibrium SI = 0 does not guarantee that the solidphysical state will prevail but taking into consideration thatAMD effluents are highly concentrated the precipitation isrelatively favourable The simulation was conducted in threesteps (i) simulation of initial KMnO

4 MnSO

4and AMD

solutions (ii) addition of potassium permanganate and (iii)equilibrium between solid phases and generating solution Inaddition to the phases identified by Raman spectroscopy allthermodynamically possible phases were also considered

3 Results and Discussion

31 Oxidation Rates Data for MnSO4solutions prepared

in laboratory including different pH values are presented

Journal of Chemistry 3

Table 1 Chemical characterization of acid mine drainage solutions

A1 A2 Maximum limits for effluents dischargeMn 1026 923 10Fe 28 08 15Zn 32 28 5Ni 01 02 2Co 01 002 lowast

U 95 95 lowast

Ca 2519 1422 lowast

Al 1948 1762 lowast

Pb 01 lt005 05Fminus 652 794 10SO4

2minus 1818 1230 lowast

TOC 15 24 lowast

pH 31 36 50 to 90Concentrations of all components are in mgL lowastCONAMA Resolution 430has no limits for these components [4]

in Figure 1 where the region of low concentrations was high-lighted Laboratory solutions were firstly employed to eval-uate oxidation rates of manganese without the interferenceof other contaminants The equilibrium was reached withinapproximately 20min of reaction when manganese wasalmost completely removed Comparatively performances ofexperiments conducted at pH 50 and 70 were similar withmanganese contents being practically constant and below01mgL after 10min of reaction On the other hand at pH30 the lowest manganese concentration was approximately03mgL after 60min of reaction Nevertheless all processesaccomplished final concentrations of manganese lower than10mgL [4] demonstrating that KMnO

4doses and pH

conditions chosen were appropriateAs expected owing to the reduced availability of reac-

tants oxidation rates initially high in all trials decreasedover time Overall reactions at pH 50 and 70 were moreefficient compared to pH 30 These results are consistentwith those given by Van Benschoten et al [12] reportinga trend of higher oxidation rates as the pH increasesThese authors however have found significant differencesbetween reactions at pH 55 and 70 which were not observedherein Processes involving higher concentrations are moreinfluenced by adsorption phenomenon due to the largeramount of precipitates Indeed those authors investigatedinitial concentrations approximately 100 times lower thanthose employed in the present study

Overall results demonstrated that in the absence of othercontaminants there is directly proportional relation betweenthe pH and the efficiency of processes in terms of manganeseremovalUnder conditions of high redox potentialMn (IV) isthermodynamically favourable and predominant in aqueoussystems containing manganese As the Eh decreases slightlyother compounds such as Mn

2O3and Mn

3O4can be also

formed However all these phases might also develop evenat lower Eh condition providing that the pH is raised as pre-sented in the Figure 2Therefore the improved efficiency thatis the greater precipitate development observed in higher pH

0

20

40

60

80

100

120

0 20 40 60 80 100 120

0 20 40 60 80 100

0

05

1

15

2

25

Mn(

II) (

mg

L)

Time (min)

minus05

pH 3pH 5pH 7

Figure 1 Effect of pH on manganese removal from laboratorysolutions containing initial Mn (II) concentrations about 100mgLTemperature 25∘Cplusmn 05

levels was expected and consistent with results found in theliterature [6ndash8 12] Further investigation however is neededto identify chemical mechanisms to explain the dependenceof the rate of solid-phase formation on pH of the media

32 Characterization of Acids Effluents Table 1 presents thechemical composition of both mine waters identified as A1and A2 as well as the limits for discharge of effluents set bythe Brazilian legislation CONAMAResolution 430 [4] Man-ganese fluoride and pH were outside the established limits[4] In addition although the Brazilian legislation does notindicate any restriction the levels of calcium aluminium andsulphate were particularly high compared to concentrationsusually found in natural waters The elevated concentrationof these contaminants might result from the typical oxisolpresent in the mining region which is extremely weatheredand contains high aluminium calcium and fluoride levelsThese elements are leached from piles of waste rock andtailings where the generation of AMD takes place Highsulphate is a typical characteristic of AMD product of themultistep reaction between the pyrite and the oxygen inaqueous media

33 Oxidative Precipitation with KMnO4 Figure 3 shows

the variation of manganese contents in the effluents A1and A2 throughout the oxidative precipitation by KMnO

4

in bench scale Similarly to the results obtained for theMnSO

4solutions not only the reaction rates were higher

but also the efficiency improved when the pH increasedoffering a thermodynamically more favourable condition forthe development of precipitates as previously described (Item31) For instance at pH 70 in the first 4min of reaction997 and 983 of manganese were removed respectivelyfrom the effluents A1 and A2While at pH 30 removals were


25

2

15

1

05

0

minus05

minus1

minus15

minus20 161412108642

Mn(+2a)

MnO2

MnO4(minusa)

Mn3O4Mn2O3

MnO4(minus2a)

Mn(OH)2

Mn

Mn-H2O-system at 25∘C

Eh (V

)

Figure 2 Eh-pH diagram showing the predominant manganeseforms Mn-H

20 systems Temperature 25∘Cplusmn 05

854 and 961 Based on the established discharge limit of10mgL [4] only processes at pH 70 were efficient

Results also evidenced impacts of the presence of othercontaminants inAMDon the overall efficiency of the processIn contrast with experiments conducted with MnSO

4solu-

tions (Item 31) the process was not as much effective whenapplied for AMD samples Unexpectedly removals obtainedat pH 50 were lower than those obtained at pH 30 and70 and significant differences were observed between trialscarried out at pH 50 and 70 Mechanisms by which otherelements interfere in the oxidative precipitation by KMnO

4

require further investigation Higher KMnO4consumption

is possibly not the major source of the observed differencesMost of the elements were already in oxidised form with theexception of the iron originally found in divalent form Fe2+at very low concentration in the AMD samples studied

On the other hand adsorption and coprecipitation werereported on the available literature as essential elementson aqueous systems containing manganese [12 25 26]Therefore these factors may be also important in the scopeof this research It seems reasonable to suggest that thenumber of available sites formanganese adsorption decreasesin the presence of other elements since this process is neitherpreferential nor particularly selective towards manganeseions [25]

Adsorption also supports manganese removal in KMnO4

ratios lower than the stoichiometric ones considering theMnO2formation summarised in (1) that is 192mg de

KMnO4mg de Mn II [12 27] The amount of KMnO

4used

in the present study represents only 85 of the stoichiometryratio Hence it is inferred that 15 of soluble Mn wasremoved by adsorption on manganese oxides surface insteadof oxidative precipitation [25] In fact the adsorption ofunoxidisedmanganese (II) also depends on the pH conditionas pointed out by Murray et al [28]

119860 = 12058711990323Mn2+ + 2KMnO

4+ 2H2O

997888rarr 5MnO2(s) + 2K

++ 4H+

(1)

Table 2 presents the concentration of other contaminantsaluminium calcium fluorine iron manganese zinc anduranium in the effluents A1 and A2 at each step of thetreatment procedure that is correction of the pH andoxidative precipitation by KMnO

4 In fact the oxidation at

pH 70 had the advantage of being less subjected to the actionof other components such as iron zinc and uranium largelyremoved during the correction of the pH

34 Characterisation of Solid Samples As experiments con-ducted at pH 70 effectively removed manganese from AMDand MnSO

4solutions precipitates produced in these trials

were appropriately characterised Solids were found poorlycrystalline and Raman spectroscopy was selected to identifythe phases Figure 4 shows Raman spectra for precipitates(Figures 4(b) 4(c) and 4(d)) and also for a standard syn-thetic birnessite (Figure 4(a)) Although several points ofsurfaces were selected no distinct absorption outlines weredetected indicating homogeneity of samples By comparingthe vibrational modes [29] presented in Figures 4(a) and4(b) it is reasonable to assume that processes performed withMnSO

4solution (Figure 4(b)) results mainly in Birnessite

(MnO2) Lovett [27] reported that the transitions of aqueous

systems containing manganese to more oxidising conditionsthat is higher pH and Eh facilitate formation of oxidesAmong several possibilities (eg hausmannite manganiteand pyrolusite) birnessite and feitknechtite forms are morelikely to be formed Birnessite was also found during thebiological treatment of AMD by Tan et al [21]

In contrast significant alterations of intensity and pos-sible overlays were verified for precipitates arising from thetreatment of A1 and A2 effluents (Figures 4(c) and 4(d))In Figure 4(c) lower intensity in 5740 cmminus1 and higher in6542 cmminus1 possibly indicate hausmannite (Mn

3O4) [29]

while higher intensity around 6165 cmminus1 in Figure 4(d)suggests manganite (MnOOH) [29] Lower definition andoverlays (Figures 4(c) and 4(d)) evidence the impact ofthe presence of other elements on manganese oxides gridDistinct structures were also revealed by scanning electronmicroscopy analysis Solids formed from effluents (Figures5(b) and 5(c)) are less porous when compared with precip-itates from solution MnSO

4(Figure 5(a)) The presence of

other elements filling the structure of manganese oxides wasconfirmed in microanalysis by electron microprobe associ-atedwith EDSdetector Analyses identified othermetals suchas aluminium calcium zinc iron uranium and rare earthsas well as fluoride and oxygen in solids generated during thetreatment of the effluents A1 and A2

35 Modeling with PHREEQC PHREEQC software and theWATEQ4F database were employed to provide an enhancedunderstanding of the process given the extensive chemi-cal complexity of AMD effluents The geochemical modeldeveloped included all thermodynamically possible phasesand successfully simulated the treatment process Evaluationsfocused exclusively on saturation index (SI) and phases wereassumed to be formed when SI ge 0 [20]


0 10080604020

0

100

80

60

40

20

120

0 10 20 30 40 50 60 70 80 90 100

0

3

6

9

12

15

18

Mn(

II) (

mg

L)

Time (min)pH 3pH 5pH 7

0

1

2

3

4

5

A1 A2

pH 3pH 5pH 7

0 10080604020Time (min)

0 10 20 30 40 50 60 70 80 90 100

0

100

80

60

40

20

120

Mn(

II) (

mg

L)

Figure 3 Effect of pH on the manganese removal with KMnO4from AMD effluents A1 and A2 Temperature 25∘Cplusmn 05 The dotted line

represents the limit for manganese discharge (ie 10mgL) set by CONANA Resolution 430 [4]

Table 2 Removal percentages of chief components from AMD effluents A1 and A2 over pH adjustment and oxidative precipitation withKMnO4

Stage Removals () at pH adjustment steplowast Removals () at oxidative precipitation steplowast

Effluent A1 A2 A1 A2pH 30 50 70 30 50 70 30 50 70 30 50 70Al 16 168 832 61 419 975 104 52 832 23 262 17Ca 24 24 98 09 31 195 0 125 144 206 172 54F 656 153 686 617 364 620 0 564 87 257 0 111Fe 241 241 855 0 100 100 759 553 145 100 0 0Mn 0 123 223 0 0 195 974 831 776 979 962 795Zn 293 294 295 71 112 696 198 218 705 224 183 304U 295 242 295 263 211 211 179 232 179 0 0 263lowastRemovals percentages are related to initial concentrations presented in Table 1

Based on simulations during the correction of the pHpossible solid phases formed include Fe(OH)

3 Fe3(OH)8

goethite (FeOOH) hematite and maghemite (Fe2O3)

magnetite (Fe3O4) gibbsite (Al(OH)

3) basaluminite

(Al4(OH)10SO4) boehmite and diaspore (AlOOH) jurbanite

(AlOHSO4) UO

2(OH)2and schoepite (UO

2(OH)2sdotH2O)

hausmannite manganite and pyrolusite Therefore onlyiron uraniummanganese and aluminiumwould be removedat this stage Experimentally however removal of calciumand zinc was verified Table 2 whereas removal of bothelements was not thermodynamically feasible and this maybe another evidence of adsorption processes

Addition of KMnO4was characterised by large removals

of calcium and manganese as birnessite pyrolusite andnsutite (MnO

2) hausmannite (Mn

3O4) bixbyite (Mn

2O3)

manganite (MnOOH) and fluorite (CaF2) The final step

simulated the prolonged contact between formed phasesand resultant solution Subsequent to the equilibrium man-ganese was found mainly in oxidation state IV as birnessitepyrolusite and nsutite (MnO

2) This result was coherent

with those presented by Hem and Lind [30] who studiedmodels to predict the formation of manganese oxides inaqueous systems According to these authors in extendedcontact the degree of oxidation of manganese increases bythe disproportionation of phases such as manganite andhausmannite

Overall it is worth mentioning that speciation-solubilitymodels do not offer temporal and special information thatis kinetics and distribution parameters were not consideredTherefore although solid phases were thermodynamicallypossible kinetically the development of determined phasemight not be favourable In fact whether solid phases for


240

160

80

0150 12001050900750600450300

Wavenumber (cmminus1)

5706

5054

6538

Inte

nsity

(au

)

(a)

5072

5758 6583

150 12001050900750600450300Wavenumber (cmminus1)

240

160

80

0

Inte

nsity

(au

)

(b)

Inte

nsity

(au

)

120

60

0

5061

574

6542

7418


(c)

Inte

nsity

(au

)

140

70

0150 12001050900750600450300


5061

5764

6165

6542

(d)

Figure 4 Raman spectra (a) standard synthetic birnessite (MnO2) (b) precipitate fromMnSO

4solution (c) precipitate from effluent A1 (d)

precipitate from effluent A2 Trials at pH 70 25∘C plusmn 05 and 1 atm

instance goethite UO2(OH)2and manganite were actually

formed or whether most of metals are incorporated into themanganese oxides phase is difficult to predict

4 Conclusions

Manganese present in highly contaminatedAMDwas rapidlyand effectively oxidised by KMnO

4in a process enhanced at

higher pH At pH 70 the process removed 99 ofmanganeseinitially present meeting the limit established by Brazilianlegislation of 10mgL within 20min of reaction Resultsevidenced that adsorption and coprecipitation are importantfactors in the removal of manganese and other contaminantssuch calcium and zinc Consistent with instrumental analy-ses the developed geochemical model using PHREEQC codesuccessfully predicted the formation of birnessite (MnO

2)

hausmannite (Mn3O4) and manganite (MnOOH) as well

as phases containing aluminium calcium iron and ura-nium in the precipitates Overall although experiments wereperformed in a bench scale results obtained support theoxidative precipitation byKMnO

4as a potential treatment for

heavily contaminated AMD However further investigationremains necessary to clarify chemical mechanisms involvedin the control of the oxidation rates of manganese present inhighly concentrated solutions as well as the influence of thepH in this process

Acknowledgments

The authors are grateful to the Brazilian agencies CAPESFapemig and CNPq for the financial support


5120583m

(a)

5120583m

(b)

5120583m

(c)

Figure 5 Micrographs 8000X of precipitates obtained by manganese oxidation by KMnO4at pH 70 (a) MnSO

4solution (b) effluent A1

(c) effluent A2

References

[1] D B Johnson ldquoChemical andmicrobiological characteristics ofmineral spoils and drainage waters at abandoned coal andmetalminesrdquo Water Air and Soil Pollution vol 3 no 1 pp 47ndash662003

[2] D B Johnson and K B Hallberg ldquoAcid mine drainage reme-diation options a reviewrdquo Science of the Total Environment vol338 no 1-2 pp 3ndash14 2005

[3] A Akcil and S Koldas ldquoAcid Mine Drainage (AMD) causestreatment and case studiesrdquo Journal of Cleaner Production vol14 no 12-13 pp 1139ndash1145 2006

[4] CONAMA Conselho Nacional do Meio Ambiente Resolution430 Brazil Ministerio do Meio Ambiente MMA 2011 httpwwwmmagovbrportconamaresres11propresol lanceflue30e31mar11pdf

[5] J W Zhu Z Zhang X-M Li X-H Xu and D-H WangldquoManganese removal from the Qiantang River source water bypre-oxidation a case studyrdquo Journal of Zhejiang University Avol 10 no 3 pp 450ndash457 2009

[6] P Roccaro C Barone G Mancini and F G A VagliasindildquoRemoval of manganese from water supplies intended forhuman consumption a case studyrdquo Desalination vol 210 no1ndash3 pp 205ndash214 2007

[7] R Raveendran B Ashworth and B Chatelier ldquoManganeseremoval in drinking water systemsrdquo in Proceedings of the 64thAnnual Water Industry Engineers and Operations Conferencepp 92ndash100 Bendigo Australia 2001

[8] D Ellis C Bouchard and G Lantagne ldquoRemoval of iron andmanganese from groundwater by oxidation and microfiltra-tionrdquo Desalination vol 130 no 3 pp 255ndash264 2000

[9] A M Silva E C Cunha F D R Silva and V A Leao ldquoTreat-ment of high-manganese mine water with limestone andsodium carbonaterdquo Journal of Cleaner Production vol 29-30pp 11ndash19 2012

[10] A F S Gomes L L Lopez and A C Q Ladeira ldquoCharacteriza-tion and assessment of chemicalmodifications ofmetal-bearingsludges arising from unsuitable disposalrdquo Journal of HazardousMaterials vol 199-200 pp 418ndash425 2012

[11] W Zhang and C Y Cheng ldquoManganese metallurgy reviewPart II manganese separation and recovery from solutionrdquoHydrometallurgy vol 89 no 3-4 pp 160ndash177 2007

[12] J E van Benschoten W Lin and W R Knocke ldquoKineticmodeling of manganese (II) oxidation by chlorine dioxide andpotassium permanganaterdquo Environmental Science and Technol-ogy vol 26 no 7 pp 1327ndash1333 1992

[13] Degremont Water Treatment Handbook Degremont ParisFrance 6th edition 1991


[14] O J Hao A P Davis and P H Chang ldquoKinetics of manganese(II) oxidation with chlorinerdquo Journal of Environmental Engi-neering vol 117 no 3 pp 359ndash375 1991

[15] S J Tewalt M Sato F T Dulong S G Neuzil A Kolker and KODennen ldquoUse of ozone to remediate from coalmine drainagewatersrdquo in Proceedings of the National Meeting of the AmericanSociety of Mining and Reclamation pp 19ndash23 BreckenridgeColo USA 2005

[16] W Zhang P Singh and D M Muir ldquoSO2O2 as an oxidant inhydrometallurgyrdquoMinerals Engineering vol 13 no 13 pp 1319ndash1328 2000

[17] CM Kao K D Huang J YWang T Y Chen andH Y ChienldquoApplication of potassium permanganate as an oxidant for insitu oxidation of trichloroethylene-contaminated groundwatera laboratory and kinetics studyrdquo Journal of HazardousMaterialsvol 153 no 3 pp 919ndash927 2008

[18] J Skousen and P Ziemkiewicz Acid Mine Drainage Controland Treatment National Research Center for Coal and EnergyNational Mine Land Reclamation Center Morgantown WvaUSA 1996

[19] M A Kessick and J J Morgan ldquoMechanism of autoxidationof manganese in aqueous solutionrdquo Environmental Science andTechnology vol 9 no 2 pp 157ndash159 1975

[20] D L Parkhurst and C A J Appelo ldquoUserrsquos guide to PHREEQC(version 2)mdasha computer program for speciation batch-reaction one-dimensional transport and inverse geochemicalcalculationsrdquo U S Geological Survey Water-Resources Investi-gations Report 99-4259 1999

[21] H Tan G Zhang P J Heaney S M Webb and W DBurgos ldquoCharacterization ofmanganese oxide precipitates fromAppalachian coal mine drainage treatment systemsrdquo AppliedGeochemistry vol 25 no 3 pp 389ndash399 2010

[22] W M Gitari L F Petrik D L Key and C Okujeni ldquoPartition-ing of major and trace inorganic contaminants in fly ash acidmine drainage derived solid residuesrdquo International Journal ofEnvironmental Science and Technology vol 7 no 3 pp 519ndash5342010

[23] M A Robinson-Lora and R A Brennan ldquoBiosorption of man-ganese onto chitin and associated proteins during the treatmentofmine impacted waterrdquoChemical Engineering Journal vol 162no 2 pp 565ndash572 2010

[24] J W Ball and D K Nordstrom ldquoWATEQ4F-userrsquos manual withrevised thermodynamic data base and test cases for calculatingspeciation ofmajor trace and redox elements in natural watersrdquoU SGeological Survey Open-File 1991

[25] J E Post ldquoManganese oxide minerals crystal structures andeconomic and environmental significancerdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 96 no 7 pp 3447ndash3454 1999

[26] K Lange R K Rowe and H Jamieson ldquoMetal retentionin geosynthetic clay liners following permeation by differentmining solutionsrdquoGeosynthetics International vol 14 no 3 pp178ndash187 2007

[27] R J Lovett ldquoRemoval of manganese from acid mine drainagerdquoJournal of Environmental Quality vol 26 pp 1017ndash1024 1997

[28] J W Murray J G Dillard R Giovanoli H Moers and WStumm ldquoOxidation of Mn(II) initial mineralogy oxidationstate and ageingrdquoGeochimica et Cosmochimica Acta vol 49 no2 pp 463ndash470 1985

[29] C M Julien M Massot and C Poinsignon ldquoLattice vibrationsofmanganese oxides part I Periodic structuresrdquo SpectrochimicaActa A vol 60 no 3 pp 689ndash700 2004

[30] JDHemandC J Lind ldquoNonequilibriummodels for predictingforms of precipitated manganese oxidesrdquo Geochimica et Cos-mochimica Acta vol 47 no 11 pp 2037ndash2046 1983

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5 and 9 (CONAMA Resolution 430) [4] Furthermore thisprocess also generates large amounts of bulky sludge whichrequires further treatment and appropriate disposal [1 10]

In this context oxidative precipitation seems to be amoresuitable alternative for removing manganese from AMD[11] Manganese reacts with an oxidant agent generating acolloidal precipitate which is then separated by filtration orsedimentation [12] Several oxidant agents such as air [13]chlorine [14] ozone [15] sulphur dioxide and oxygen [16]were evaluated in studies that focused mainly on slightlycontaminated effluents In general potassium permanganate(KMnO

4) stands out with the advantage of removing other

contaminants such as iron and organic compounds responsi-ble for taste and odour [17] Therefore there is great interestin establishing optimised operating conditions that enable theuse of KMnO

4for remediating highly contaminated AMD

The assessment of reaction rates as well as solid phasesformed during remediation procedures provide valuableinformation in designing and optimising efficient treatmentmethods Van Benschoten et al [12] published an extensivework on the kinetics of manganese oxidation by KMnO

4

According to these authors oxidation rates depend on con-centrations of oxidant hydroxyl ions manganese oxidesand free manganese Other factors such as coprecipitationadsorption [18] and the autocatalytic effect of precipitates[19] were also reported to affect the removal of manganeseand other contaminants which indicates the importance ofinvestigating the solid phases produced

Geological models are particularly appropriate to assesssolid phases in aqueous systems such as AMD For instancethe software PHREEQC [20] has proved extremely useful inproviding conceptual models focusing on water treatmentand environmental remediation technologies [10 21ndash23]Based on ionic associations the program amongst otheroptions allows saturation-index calculations and chemicalspeciation PHREEQC employs a solubility approach toidentify thermodynamically possible solid phases whichmay potentially support the conception and management ofefficient treatment systems for AMD

In this study the oxidative precipitation of manganese byKMnO

4was investigated with the objective of achieving an

effective treatment method for highly contaminated AMDExperiments were divided into two parts the first one wasperformed with MnSO

4solutions prepared in the laboratory

and the second with AMD samples collected in an inactiveuranium mine at the Plateau of Pocos de Caldas southeastof Brazil Processes were conducted at pH 30 50 and 70Precipitates were characterised by spectroscopy techniquesand electron microprobe In addition a geochemical modelusing the PHREEQC software was developed to predict solidphases possibly formed at each stage of the remediationprocess

2 Methodology

21 Liquid Samples Laboratory solutions were prepared bydiluting 031 g of MnSO

4sdotH2O (Vetec Brazil) in 10 L of

deionizedwater Acidmine drainage samples identified as A1

and A2 were collected in two different water dams locatedin one former and inactive uranium mine Effluents werechemically characterised and results are shown in Table 1

22 Bench Experiments Experiments were carried out inglass beakers with 200mL of liquid samples Initially understirring and at room temperature (25∘Cplusmn 05) the pH wasadjusted by adding sodium hydroxide or sulphuric acid Onealiquot was taken to determine the initial concentration ofmanganese which ranged from 90 to 105mgL AfterwardsKMnO

44 (wv) was added to the solutions based on pre-

determined ratios 163mg KMnO4mg Mn for experiments

at pH 30 and 154mg KMnO4mg Mn for pH 50 and 70

Samples were collected at pre-established time and filteredin 045 120583m membranes Ratio and reaction time values weredetermined in a previous study based on statistic factorialdesign considering four parameters concentration of the oxi-dant agent reaction time stoichiometry and pH Sulphuricacid solution and sodium bisulphite 5 (wv) were addedto the filtrate as quenching agents Manganese aluminiumcalcium iron and zinc were determined by atomic absorp-tion spectrophotometry (VARIAN model AA240FS) Ura-nium was assessed by X-ray fluorescence spectrophotometry(SHIMADZUmodel EDX-720)

23 Solid Samples Solid samples at pH 70 were dried atroom temperature and then analysed byRaman Spectroscopy(JOBIN-YVON LABRAM model HR-800) Scanning Elec-tron Microscope (JEOL JSM model 840A) and ElectronProbe Microanalysis coupled to EDS detector (JEOL JXAmodel 8900 RT)

24 PHREEQC Modelling The oxidative precipitation ofmanganese was modelled using the geochemical programPHREEQC-Version 2 [20] The consistent thermodynamicdatabase WATEQ4F [24] was used to construct forwardmodels focusing on the assessment of saturation index(SI) The developed speciation-solubility model compriseddefined amounts of the KMnO

44 (wv) allowed to react

reversibly with aqueous solutions simulating the composi-tions of MnSO

4and AMD samples Based on the conditions

of the system each phase precipitated when SI gt 0 wasreached or dissolved completely when SI lt 0 to achieve theequilibrium SI = 0 It is worth saying that the conditionof equilibrium SI = 0 does not guarantee that the solidphysical state will prevail but taking into consideration thatAMD effluents are highly concentrated the precipitation isrelatively favourable The simulation was conducted in threesteps (i) simulation of initial KMnO

4 MnSO

4and AMD

solutions (ii) addition of potassium permanganate and (iii)equilibrium between solid phases and generating solution Inaddition to the phases identified by Raman spectroscopy allthermodynamically possible phases were also considered

3 Results and Discussion

31 Oxidation Rates Data for MnSO4solutions prepared

in laboratory including different pH values are presented




U 95 95 lowast

Ca 2519 1422 lowast

Al 1948 1762 lowast

Pb 01 lt005 05Fminus 652 794 10SO4


TOC 15 24 lowast



4doses and pH




2O3and Mn

3O4can be also


0

20

40

60

80

100

120

0 20 40 60 80 100 120

0 20 40 60 80 100

0

05

1

15

2

25

Mn(

II) (

mg

L)

Time (min)

minus05

pH 3pH 5pH 7






4





25

2

15

1

05

0

minus05

minus1

minus15

minus20 161412108642

Mn(+2a)

MnO2

MnO4(minusa)

Mn3O4Mn2O3

MnO4(minus2a)

Mn(OH)2

Mn


Eh (V

)





4solu-


4







4used


119860 = 12058711990323Mn2+ + 2KMnO

4+ 2H2O

997888rarr 5MnO2(s) + 2K

++ 4H+

(1)











3O4) [29]






0 10080604020

0

100

80

60

40

20

120

0 10 20 30 40 50 60 70 80 90 100

0

3

6

9

12

15

18

Mn(

II) (

mg

L)


0

1

2

3

4

5

A1 A2

pH 3pH 5pH 7

0 10080604020Time (min)

0 10 20 30 40 50 60 70 80 90 100

0

100

80

60

40

20

120

Mn(

II) (

mg

L)







3 Fe3(OH)8



3) basaluminite


(AlOHSO4) UO


2(OH)2sdotH2O)




2) hausmannite (Mn

3O4) bixbyite (Mn

2O3)







240

160

80

0150 12001050900750600450300


5706

5054

6538

Inte

nsity

(au

)

(a)

5072

5758 6583


240

160

80

0

Inte

nsity

(au

)

(b)

Inte

nsity

(au

)

120

60

0

5061

574

6542

7418


(c)

Inte

nsity

(au

)

140

70

0150 12001050900750600450300


5061

5764

6165

6542

(d)






4 Conclusions




2)





Acknowledgments



5120583m

(a)

5120583m

(b)

5120583m

(c)



(c) effluent A2

References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




U 95 95 lowast

Ca 2519 1422 lowast

Al 1948 1762 lowast

Pb 01 lt005 05Fminus 652 794 10SO4


TOC 15 24 lowast



4doses and pH




2O3and Mn

3O4can be also


0

20

40

60

80

100

120

0 20 40 60 80 100 120

0 20 40 60 80 100

0

05

1

15

2

25

Mn(

II) (

mg

L)

Time (min)

minus05

pH 3pH 5pH 7






4





25

2

15

1

05

0

minus05

minus1

minus15

minus20 161412108642

Mn(+2a)

MnO2

MnO4(minusa)

Mn3O4Mn2O3

MnO4(minus2a)

Mn(OH)2

Mn


Eh (V

)





4solu-


4







4used


119860 = 12058711990323Mn2+ + 2KMnO

4+ 2H2O

997888rarr 5MnO2(s) + 2K

++ 4H+

(1)











3O4) [29]






0 10080604020

0

100

80

60

40

20

120

0 10 20 30 40 50 60 70 80 90 100

0

3

6

9

12

15

18

Mn(

II) (

mg

L)


0

1

2

3

4

5

A1 A2

pH 3pH 5pH 7

0 10080604020Time (min)

0 10 20 30 40 50 60 70 80 90 100

0

100

80

60

40

20

120

Mn(

II) (

mg

L)







3 Fe3(OH)8



3) basaluminite


(AlOHSO4) UO


2(OH)2sdotH2O)




2) hausmannite (Mn

3O4) bixbyite (Mn

2O3)







240

160

80

0150 12001050900750600450300


5706

5054

6538

Inte

nsity

(au

)

(a)

5072

5758 6583


240

160

80

0

Inte

nsity

(au

)

(b)

Inte

nsity

(au

)

120

60

0

5061

574

6542

7418


(c)

Inte

nsity

(au

)

140

70

0150 12001050900750600450300


5061

5764

6165

6542

(d)






4 Conclusions




2)





Acknowledgments



5120583m

(a)

5120583m

(b)

5120583m

(c)



(c) effluent A2

References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


25

2

15

1

05

0

minus05

minus1

minus15

minus20 161412108642

Mn(+2a)

MnO2

MnO4(minusa)

Mn3O4Mn2O3

MnO4(minus2a)

Mn(OH)2

Mn


Eh (V

)





4solu-


4







4used


119860 = 12058711990323Mn2+ + 2KMnO

4+ 2H2O

997888rarr 5MnO2(s) + 2K

++ 4H+

(1)











3O4) [29]






0 10080604020

0

100

80

60

40

20

120

0 10 20 30 40 50 60 70 80 90 100

0

3

6

9

12

15

18

Mn(

II) (

mg

L)


0

1

2

3

4

5

A1 A2

pH 3pH 5pH 7

0 10080604020Time (min)

0 10 20 30 40 50 60 70 80 90 100

0

100

80

60

40

20

120

Mn(

II) (

mg

L)







3 Fe3(OH)8



3) basaluminite


(AlOHSO4) UO


2(OH)2sdotH2O)




2) hausmannite (Mn

3O4) bixbyite (Mn

2O3)







240

160

80

0150 12001050900750600450300


5706

5054

6538

Inte

nsity

(au

)

(a)

5072

5758 6583


240

160

80

0

Inte

nsity

(au

)

(b)

Inte

nsity

(au

)

120

60

0

5061

574

6542

7418


(c)

Inte

nsity

(au

)

140

70

0150 12001050900750600450300


5061

5764

6165

6542

(d)






4 Conclusions




2)





Acknowledgments



5120583m

(a)

5120583m

(b)

5120583m

(c)



(c) effluent A2

References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0 10080604020

0

100

80

60

40

20

120

0 10 20 30 40 50 60 70 80 90 100

0

3

6

9

12

15

18

Mn(

II) (

mg

L)


0

1

2

3

4

5

A1 A2

pH 3pH 5pH 7

0 10080604020Time (min)

0 10 20 30 40 50 60 70 80 90 100

0

100

80

60

40

20

120

Mn(

II) (

mg

L)







3 Fe3(OH)8



3) basaluminite


(AlOHSO4) UO


2(OH)2sdotH2O)




2) hausmannite (Mn

3O4) bixbyite (Mn

2O3)







240

160

80

0150 12001050900750600450300


5706

5054

6538

Inte

nsity

(au

)

(a)

5072

5758 6583


240

160

80

0

Inte

nsity

(au

)

(b)

Inte

nsity

(au

)

120

60

0

5061

574

6542

7418


(c)

Inte

nsity

(au

)

140

70

0150 12001050900750600450300


5061

5764

6165

6542

(d)






4 Conclusions




2)





Acknowledgments



5120583m

(a)

5120583m

(b)

5120583m

(c)



(c) effluent A2

References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


240

160

80

0150 12001050900750600450300


5706

5054

6538

Inte

nsity

(au

)

(a)

5072

5758 6583


240

160

80

0

Inte

nsity

(au

)

(b)

Inte

nsity

(au

)

120

60

0

5061

574

6542

7418


(c)

Inte

nsity

(au

)

140

70

0150 12001050900750600450300


5061

5764

6165

6542

(d)






4 Conclusions




2)





Acknowledgments



5120583m

(a)

5120583m

(b)

5120583m

(c)



(c) effluent A2

References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


5120583m

(a)

5120583m

(b)

5120583m

(c)



(c) effluent A2

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 Oxidative Precipitation of Manganese …downloads.hindawi.com/journals/jchem/2013/287257.pdf · Research Article Oxidative Precipitation of Manganese from Acid Mine