Synthesis of -MnO : Characterization and Comparative Adsorption...

Research ArticleSynthesis of 120572-MnO

2Nanomaterial from a Precursor

120574-MnO2 Characterization and Comparative Adsorption of

Pb(II) and Fe(III)

Van-Phuc Dinh1 Ngoc-Chung Le2 Thi-Phuong-Tu Nguyen1 and Ngoc-Tuan Nguyen3

1Dong Nai University Tan Hiep Ward Bien Hoa City ETHng Nai Province Vietnam2Dalat University Dalat City Lam ETHng Province Vietnam3Vietnam Atomic Energy Institute Hanoi Vietnam

Correspondence should be addressed to Van-Phuc Dinh dinhvanphuc82gmailcom

Received 27 July 2016 Accepted 8 September 2016

Academic Editor Frederic Dumur

Copyright copy 2016 Van-Phuc Dinh et alThis is an open access article distributed under the Creative CommonsAttribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

120572-MnO2 nanostructure was successfully synthesized via hydrothermal treatment of a precursor 120574-MnO2 Structure morphologyand BET surface area were characterized using X-ray powder diffraction (XRD) Scanning Electron Microscopy (SEM) andBrunauer-Emmett-Teller nitrogen adsorption (BET-N2 adsorption) Thermal analysis result showed that 120572-MnO2 nanorods wereformed from 120574-MnO2 at 600

∘C In addition Pb(II) and Fe(III) adsorptive properties were investigated in an optimal conditionResults showed that equilibrium adsorption was obtained after 60 minutes for Pb(II) at pH = 40 and 80 minutes for Fe(III) atpH = 35 with 240 rpm of shaking speed overall Experimental data was analyzed using three models Langmuir Freundlich andSips Adsorption capacities (119902119898) from the Langmuir isotherm models are 12487mgg for Pb(II) and 3083mgg for Fe(III) Alongwith the highest corelation coefficients it is clear that the adsorption of Pb(II) and Fe(III) ions on 120572-MnO2 surface followed Sipsmodel Kinetic studies indicated that the uptake of Pb(II) and Fe(III) occurred in the pseudo-second-order model with two stagesfor Pb(II) and three stages for Fe(III)

1 Introduction

Nowadays the human health and the environment are indanger owing to the increase in industrial and mining activi-ties [1] Lead and iron ions seriously affect human life even intrace concentrations According to the Environmental Qual-ityAct the limit for lead and iron inwater is less than 01mgLand 10mgL Therefore there are many physicochemicaltreatments used to remove them such as chemical precip-itation adsorption and ionic exchange membrane technol-ogy and solvent extraction One of the most efficient andpromising methods for treatment of lead and iron ions froman aqueous solution is the adsorption technology because ofits high enrichment efficiency and ease of phase separation[2]

Being well known as a low-cost and environmentallyfriendly material manganese oxides have been studied and

applied to different areas since they have a great number ofcrystalline structures (120572 120573 120574 120575 etc) and excellent chemicalcharacteristics Li batteries which are one of the importantapplications have been widely studied [3ndash9] In additionMnO2 has been used for catalysts [10ndash13] supercapacitors[7 14ndash17] and so forth In recent years MnO2 has beenstudied as an adsorbent to remove inorganic aswell as organiccompounds from aqueous solution [8 18ndash22] Howeveradsorptive properties of 120572-MnO2 nanomaterial as well ascomparative adsorption of Pb(II) and Zn(II) onto this mate-rial are seldom reported

In this study 120572-MnO2 was synthesized from heatingprecursor 120574-MnO2 and used as an adsorbent to removePb(II) and Zn(II) from an aqueous solution in an optimalcondition Comparative adsorption of two ions on 120572-MnO2was also investigated using three isothermmodels LangmuirFreundlich and SipsTheuptake kinetics were analyzed using

Hindawi Publishing CorporationJournal of ChemistryVolume 2016 Article ID 8285717 9 pageshttpdxdoiorg10115520168285717

2 Journal of Chemistry

pseudo-first-order and pseudo-second-order models Inaddition intraparticle diffusion kinetics were also studied toascertain the mechanism of the uptake

2 Materials and Methods

21 Preparation of 120572-MnO2 from 120574-MnO2 120574-MnO2 whichwas successfully synthesized by Le and Van Phuc [2] fromethanol and potassium permanganate was heated at 600∘CThe product after being investigated by XRD SEM and BETwas used as an absorbent to remove lead and iron ions fromthe aqueous solution

22 Adsorbent Lead(II) and iron(II) ionswere used as adsor-bates 1000mgL standard stock solution of each metal ionwas prepared by dissolving Pb(NO3)2 and Fe(NO3)3 in dis-tilled water

23 Instruments X-ray diffractometer D5000 made in Ger-many by Siemens with X-ray radiation CuK120572 120582 = 154056 Awas used to examine the phase of the crystalline structure

Themorphology of thematerial was investigated by UltraHigh Resolution Scanning Electron Microscopy S-4800 atransmission electron microscope

Atomic Absorption Spectrophotometer (Atomic Absorp-tion Spectrometer AA-7000made in Japan by Shimadzu) wasused to determine the BET surface area and pore site

The pH measurements were done with a pH meter(Martini Instruments Mi-150 Romania) the pH meter wasstandardized using Hanna Instruments buffer solutions withpH values of 401 plusmn 001 701 plusmn 001 and 1001 plusmn 001

A temperature-controlled shaker (Model IKA R5) wasused for equilibrium studies

24 Diagram for These Studies See Figure 1

25 Adsorption Study 50mL solution of heavy metal (Pb2+andZn2+) ionswas placed into a 100mL conical flask contain-ing 01 g 120572-MnO2 During the uptake influence of pH of theinitial solution was adjusted within 2ndash5 range using HNO301M or NaOH 01M solutions Adsorption studies werealso conducted in batch experiments with various adsorptiontimes (20ndash240 minutes) and concentrations of metal ion(100ndash500mgL) Concentrations of heavy metal ions in thefiltrate before and after uptake were determined using AAS

Adsorption capacity was calculated by using the massbalance equation for the adsorption [1]

119902 = (1198620 minus 119862119890) sdot 119881119898 (1)

And the adsorption efficiency ()was calculated from theformula

Removal = (1198620 minus 119862119890) sdot 1001198620 (2)

where 119902 is the adsorption capacity (mgg) at equilibrium1198620 and 119862119890 are the initial and the equilibrium concentrations(mgL) respectively 119881 is the volume (L) of the solution and119898 is the mass (g) of the adsorbent used

Removal of heavy metals

KMnO4

Agitated in 8h

C2H5OH + H2O

Sol MnO2

Dried at 100∘C

Heated at 600∘C

120574-MnO2

120572-MnO2

Figure 1

8007006005004003002001000

TG (m

g)

0minus05minus1minus15minus2minus25minus3minus35minus4

Exo

Sample temperature (∘C)

T 18641∘C

T 53593∘C

T 9031∘Cminus35minus25minus15minus5

515

Hea

t flow

(mW

)

Δm (mg) minus3108Δm () minus16359


Figure 2 TG-DTA analysis

3 Results and Discussion

31 Characterization of 120572-MnO2 Nanostructures311 Thermal Analysis Result Thermal analysis (Figure 2)showed that there were two specific peaks corresponding tothe decrease in volume of a product From 100∘C to 300∘Cthe endothermic process occurred which combined witha significant reduction of volume (approximately 1640)showed chemical dehydration as well asmelting ofmaterial at18641∘C From 300∘C to 800∘C there was a slight decrease involume of about 540 which was the continued melting Inaddition there was an endothermic peak at 53593∘C corre-sponding to allotropic transformation It was predicted that120572-MnO2 crystalline structure can be formed at above 536∘C

312 X-Ray Analysis Results XRD analysis results showedthat 120572-MnO2 crystalline structure was not formed at 400∘C(Figure 3) At higher temperatures 600∘C and 800∘C 120572-MnO2 crystalline structurewas completely formedwith somespecific peaks at 2120579 = 2858 3748 4978 5998 and 6898 cor-responding to the Miller indices (3 1 0) (2 1 1) (4 1 1) (5 2 1)

Journal of Chemistry 3

Inte

nsity

(au

)

2120579 (deg)

(d)

(c)

(a)

(b)

706050403020

Figure 3 XRD image of MnO2 at different temperatures gamma-MnO2 (a) 119905 = 400∘C (b) 119905 = 600∘C (c) and 119905 = 800∘C (d)

(a) (b)

(c) (d)

(e) (f)

Figure 4 SEM images of material at 100∘C (a) 400∘ (b) 600∘C ((c) (d)) and 800∘C ((e) (f))


Table 1 BET and BJH analysis results of 120574-MnO2 and 120572-MnO2

Material BET surface area BJH adsorption pore size BJH desorption pore size120574-MnO2 6500m2sdotgminus1 41783 A 34023 A120572-MnO2 937m2sdotgminus1 16295 A 73437 A

100

80

60

40

20

0

re

mov

al

FePb

pH00 20 40 60

(a)

100

80

60

40

20

0

Time (minutes)

re

mov

alFePb

250200150100500

(b)

Figure 5 Influence of pH (a) and contact time (b) on adsorption of Pb(II) and Fe(III) at room temperature with 240 rpm of shaking speed

and (5 4 1) respectively (ref code 01-072-1982)These resultscorresponded with prognostication from thermal analysis

313 Scanning ElectronMicroscopy Analysis Results Figure 4showed that although 120574-MnO2 particles were flocculated at400∘C the morphology of material was not changed It canbe concluded that 120572-MnO2 nanostructures were not formedAt 600∘C and 800∘C the morphology of the material waschanged from nanospheres to nanorods which coincidedwith 120572-MnO2 crystalline nanostructure corresponding toXRD results However these nanorods were broken andsmashed at 800∘C

314 BET Surface Area and BJH Analysis The BET surfacearea as well as BJH adsorption-desorption pore size of120572-MnO2 and 120574-MnO2 was provided in Table 1 Whereasprecursor 120574-MnO2 had a BET surface area of about 65m2sdotgminus1the synthesized 120572-MnO2 had smaller surface approximately94m2sdotgminus1 This can be explained by the fact that 120574-MnO2was composed of nanospheres had a porous surface and wassmall in size at room temperature When heating 120574-MnO2to form 120572-MnO2 at 600

∘C nanospheres were melted floccu-lated and showed an increase in size As a result120572-MnO2 hada smaller surface area than precursor 120574-MnO2 Both 120574-MnO2and 120572-MnO2 had BJH adsorption average pore width from20 A to 50 A which were mesopores materials Howeverwith the fact that BJH adsorption pore size of 120574-MnO2 issmaller than that of 120572-MnO2 it was revealed that adsorptiveproperties of 120574-MnO2 were better than those of 120572-MnO2

32 Adsorption Studies321 Effective Factors pH plays an important role in absorb-ing Pb(II) and Fe(III) ions onto 120572-MnO2 material surface

At higher pH value hydroxo ion MOH119899+ orand insolublehydroxide M(OH)119899 was easily formed which inhibits theadsorption of these ions In contrast at low pH valueadsorption sites may be decreased because part of the MnO2nanomolecules can be dissolved in an acid solution as in thefollowing reaction

MnO2 + 4H+ + eminus 997888rarr Mn2+ + 2H2O (3)

As a result adsorption reached a maximum at pH = 40for Pb(II) and pH = 35 for Fe(III) (Figure 5(a))

Adsorption time is one of the important factors whichhelps us to predict kinetics as well as the mechanism of theuptake of heavy metals on material surface The influence ofcontact time on the adsorption process of Pb(II) and Fe(III)onto 120572-MnO2 was shown in Figure 5(b) As a result theadsorption equilibrium was obtained after 60 minutes forPb(II) and 80 minutes for Fe(III)

322 Isotherm Equation Studies To understand the natureof the adsorption of Pb(II) and Fe(III) on material surfacesome isotherm equations such as Langmuir Freundlich andSips were investigated While Langmuir model can help usto calculate the maximum adsorption capacity on a mono-layer Freundlich model shows the interaction between theabsorbent and amultilayer Plots of these nonlinear equationsand equilibrium isotherm parameters were shown in Figure 6and Table 2 Results showed that the maximum adsorptioncapacities calculated from Langmuir model were 12487mggfor Pb(II) and 3083mgg for Fe(III)This can be explained bythe fact that lead ion is more satisfied with adsorption poresize because it has ion radius larger than iron In addition


Ce (mgL) Ce (mgL)

qe(m

gg)

160

120

80

40

0

qe(m

gg)

160

120

80

40

0

qe(m

gg)

160

120

80

40

0

150100500120100806040200

Ce (mgL)

120100806040200

Ce (mgL) Ce (mgL)

100806040200

Pb

Pb

Pb

Fe

Fe

Fe

0 50 100 150

Ce (mgL)

0 50 100 150

ExperimentLangmuir

ExperimentLangmuir

ExperimentFreundlich

ExperimentSips

ExperimentSips


0

5

10

15

20

25

30

35

qe(m

gg)

0

10

20

30

40

qe(m

gg)

0

5

10

15

20

25

30

35

qe(m

gg)

Figure 6 Plots of adsorption isotherm models Langmuir Freundlich and Sips models

the separation factor 119878119865 which is a dimensionless constantequilibrium parameter was given by

119878119865 = 11 + 119870119871 sdot 1198620 (4)

Based on the 119878119865 value it can be revealed that the smallerthe value of 119878119865 is the more favorable the adsorption is Thecalculated 119878119865 values which were smaller than 1 and higherthan 0 in both the lowest and the highest concentrationsshowed that 120572-MnO2 was an appropriate adsorbent for

Fe(III) and Pb(II) However 119878119865 value of Pb(II) gt Fe(III)indicated that Fe(III) will compete for binding sites fasterthan Pb(II) in a mixed metal ions system

Moreover the 1119899 values calculated from Freundlichmodel for Fe(III) higher than Pb(II) indicated that theinteraction between 120572-MnO2 and Fe(III) is more favorablethan 120572-MnO2 and Pb(II)

However the material surface shows heterogeneityHence the uptake of heavy metal ions onto MnO2 can occuron different mechanisms Sips model which is Langmuir and


Table 2 Equilibrium isotherm parameters

Isotherm Nonlinear forms Isotherm parametersPb(II) Fe(III)

Langmuir 119902119890 = 119902119898 sdot 119870119871 sdot 1198621198901 + 119870119871 sdot 119862119890

119870119871 03340 0135119902119898 (mgg) 1249 3083RMSE 3529 15041198772 09109 090421205942 06618 07603

119878119865 (at the lowest 1198620) 00291 00689119878119865 (at the highest 1198620) 595sdot10minus3 00146

Freundlich 119902119890 = 119870119865 sdot 11986211989011198991119899 01115 02033119870119865 7476 1152

RMSE 1493 06951198772 09840 097951205942 01148 01296

Sips 119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890

119870119878 675 1184120572119878 minus09142 01986120573119878 00070 03442

RMSE 14689 062721198772 09846 098331205942 01133 01122

119902119890 adsorption capacity at equilibrium (mgg) 119902119898 maximum adsorption capacity (mgg) 119862119890 equilibrium concentration (mgL)119870119871 Langmuir constant119870119865Freundlich constant 119899 adsorption intensity 119870119878 Sips constant 120572119878 Sips isotherm model constant (Lmg) 120573119878 Sips isotherm model exponent 1198772 correlationcoefficient RMSE root mean square error 1205942 nonlinear chi-square test

Freundlichmodels combined generally described exactly thenature of adsorption Sips isotherm equation was given byformula [1]

119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890 (5)

where 120572119878 is Sips isotherm model constant (Lmg) 120573119878 is Sipsisotherm model exponent 119870119878 is Sips constant 119862119890 (mgL) isthe equilibrium concentration and 119902119890 (mgg) is adsorptioncapacity Sips equation is a three-parameter model and thusit can be solved by Solver Add-In in Microsoft Excel

In comparison with the correlation coefficients (1198772) therootmean square error (RMSE) and the nonlinear chi-squaretest (1205942) values of the three models it was clear that theadsorption of Pb(II) and Fe(III) onto 120572-MnO2 followed Sipsmodel due to the highest 1198772 value as well as the lowest RMSEand 1205942 ones323 Kinetic Studies Pseudo-first-order and pseudo-second-order models are often used to describe the uptake ofheavy metal ions onto material surface for adsorption timeKinetic parameters give essential information for designingand modeling the adsorption processes However the twomodes cannot determine clearly the nature of the adsorptionof Pb(II) and Fe(III) onto 120572-MnO2 nanomaterial Thereforeintraparticle diffusion model which was developed byWeberand Morris was applied for ascertaining a mechanism ofthe uptake of Pb(II) and Fe(III) onto 120572-MnO2 Plots of

these kinetic models were shown in Figure 7 and kineticparameters were given in Table 3

Results showed that the theoretical 119902119890 values whichwere calculated from pseudo-second-order kinetic modelswere more accordant with the experimental values 119902119890(exp)than pseudo-first-order kinetic ones In addition correlationcoefficients in these pseudo-second-order kinetic models forboth Pb(II) and Fe(III) were higher than 09950 It wasrevealed that pseudo-second-order models were satisfiedwith describing kinetics of the uptake of Pb(II) and Fe(III)on 120572-MnO2

Furthermore intraparticle diffusion models showed thatthe uptake of Pb(II) followed two stages firstly Pb(II) ionswere quickly adsorbed on 120572-MnO2 surface secondly therewas gradual diffusion of absorbents from surface sites into theinner pores And it was observed that there are three stagesin the sorption of Fe(III) ion on the material surface In thefirst one Fe(III) ion was rapidly transferred from the solutionto 120572-MnO2 surface In the next one intraparticle diffusionwhich is the controlling factor gradually occurred Lastlythe adsorption equilibrium was obtained to correspond withthe saturation of absorbent sites The intraparticle diffusionconstants for all these stages were given in Table 3

4 Conclusion

In this report 120572-MnO2 nanostructure synthesized from aprecursor 120574-MnO2 was used as an adsorbent to removePb(II) and Fe(III) from an aqueous solution at an optimal


Time (minutes)250 300200150100500

tqt

tqt = 00091t + 00075R2 = 10000

25

20

15

10

05

00

(a)

16

12

08

04

00

minus04

minus08

minus12

Time (minutes)300250200150100500

minus q) = minus00062t + 07350

R2 = 05998

log (qe

log (

qeminus

q)

(b)

Time (minutes)250 300200150100500

tqt

tqt = 00558t + 06927

R2 = 09958

160

140

120

100

80

60

40

20

00

(c)

Time (minutes)300250200150100500

= minus00006t + 12582

R2 = 06173

13

12

11

log (

qeminus

qt)

log (qe minus qt)

(d)

120

100

80

60

40

20

0

Time (minutes)

qe(m

gg)

y = 03722x + 948185R2 = 09469

250200150100500

y = 00038x + 1088872R2 = 09887

Stage 1

Stage 2

(e)

Time (minutes)250200150100500

Stage 1

Stage 2

Stage 3

20

16

12

8

4

0

qe(m

gg)

y = 00309x + 112703

R2 = 09347

y = 01759x + 24774

R2 = 10000

y = 00017x + 164800

R2 = 08607

(f)

Figure 7 Pseudo-first-order kinetic plots for the adsorption of Pb(II) (a) and Fe(III) (c) Pseudo-second-order kinetic plots for the adsorptionof Pb(II) (b) and Fe(III) (d) Intraparticle diffusion kinetic plots for the adsorption of Pb(II) (e) and Fe(III) (f)

condition Results showed that the maximum capacities were12487mgg for Pb(II) and 3083mgg for Fe(III) at pH = 40for Pb(II) and pH = 35 for Fe(III) Experiment data whichwas analyzed using three isothermmodels that is LangmuirFreundlich and Sips indicated that Sips model was fittedbetter than the other two Kinetics studies showed that bothPb(II) and Fe(III) corresponded with pseudo-second-ordermodel with corelation coefficient constants (1198772) higher than

09950 Intraparticle diffusion kinetics confirmed that theuptake of Pb(II) on 120572-MnO2 includes two stages while itincludes three stages for Fe(III)

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper


Table 3 Kinetic parameters

Kinetic models Linear forms Kinetic parametersPb(II) Fe(III)

119902119890(exp) (mgg) 10980 1680

Pseudo-first-order model119889119902119889119905 = 1198701 (119902119890 minus 119902)

log (119902119890 minus 119902119905) = log 119902119890 minus 1198701 sdot 11990523031198701 (minminus1) 001428 138sdot10minus31198772 05998 06873

119902119890(cal) (mgg) 5433 1812

Pseudo-second-order model119889119902119889119905 = 1198702 (119902119890 minus 119902)

2

119905119902 =111987021199022119890 + (

1119902119890 ) sdot 119905

1198702 (gsdotmgminus1sdotminminus1) 001108 45sdot10minus31198772 1000 09958

119902119890(cal) (mgg) 10989 1792

Intraparticle diffusion model 119902119905 = 11987011988911990512 + 1198621198701198891 03722 003091198701198892 00038 017591198701198893 00017

References

[1] K Y Foo and B H Hameed ldquoInsights into the modeling ofadsorption isotherm systemsrdquo Chemical Engineering Journalvol 156 no 1 pp 2ndash10 2010

[2] N C Le and D Van Phuc ldquoSorption of lead (II) cobalt (II) andcopper (II) ions from aqueous solutions by 120574-MnO2 nanostruc-turerdquo Advances in Natural Sciences Nanoscience and Nanotech-nology vol 6 no 2 Article ID 025014 2015

[3] M M Thackeray and A De Kock ldquoSynthesis of 120574-MnO2 fromLiMn2O4 for LiMnO2 battery applicationsrdquo Journal of SolidState Chemistry vol 74 no 2 pp 414ndash418 1988

[4] S Sarciaux A Le Gal La Salle A Verbaere Y Piffard and DGuyomard ldquo120574-MnO2 for Li batteries Part I 120574-MnO2 relation-ships between synthesis conditionsmaterial characteristics andperformances in lithiumbatteriesrdquo Journal of Power Sources vol81-82 pp 656ndash660 1999

[5] K S Abou-El-Sherbini ldquoStructure investigation and elec-trochemical behavior of 120574-MnO2 synthesized from three-dimensional framework and layered structuresrdquo Journal of SolidState Chemistry vol 166 no 2 pp 375ndash381 2002

[6] L I Hill A Verbaere and D Guyomard ldquoMnO2 (120572- 120573-120574-) compounds prepared by hydrothermal-electrochemicalsynthesis characterization morphology and lithium insertionbehaviorrdquo Journal of Power Sources vol 119ndash121 pp 226ndash2312003

[7] Y Li H Xie J Wang and L Chen ldquoPreparation and electro-chemical performances of 120572-MnO2 nanorod for supercapaci-torrdquoMaterials Letters vol 65 no 2 pp 403ndash405 2011

[8] J Li B Xi Y Zhu Q Li Y Yan and Y Qian ldquoA precursor routeto synthesize mesoporous 120574-MnO2 microcrystals and theirapplications in lithium battery and water treatmentrdquo Journal ofAlloys and Compounds vol 509 no 39 pp 9542ndash9548 2011

[9] M R Bailey and S W Donne ldquoStructural effects on the cycla-bility of the alkaline 120574-MnO2 electroderdquo Electrochimica Actavol 56 no 14 pp 5037ndash5045 2011

[10] L Jin C-H Chen V M B Crisostomo L Xu Y-C Son andS L Suib ldquo120574-MnO2 octahedral molecular sieve preparationcharacterization and catalytic activity in the atmospheric oxi-dation of toluenerdquoApplied Catalysis A General vol 355 no 1-2pp 169ndash175 2009

[11] T Lin L YuM Sun G Cheng B Lan and Z Fu ldquoMesoporous120572-MnO2 microspheres with high specific surface area con-trolled synthesis and catalytic activitiesrdquo Chemical EngineeringJournal vol 286 pp 114ndash121 2016

[12] Y Wu S Li Y Cao S Xing Z Ma and Y Gao ldquoFacile syn-thesis ofmesoporous120572-MnO2 nanorodwith three-dimensionalframeworks and its enhanced catalytic activity for VOCsremovalrdquoMaterials Letters vol 97 pp 1ndash3 2013

[13] X Fu J FengHWang andKMNg ldquoManganese oxide hollowstructures with different phases synthesis characterization andcatalytic applicationrdquo Catalysis Communications vol 10 no 14pp 1844ndash1848 2009

[14] H Wei J Wang S Yang Y Zhang T Li and S Zhao ldquoFacilehydrothermal synthesis of one-dimensional nanostructured 120572-MnO2 for supercapacitorsrdquo Physica E Low-dimensional Systemsand Nanostructures vol 83 pp 41ndash46 2016

[15] N Boukmouche N Azzouz L Bouchama A Lise Daltin JPaul Chopart and Y Bouznit ldquoSupercapacitance ofMnO2 filmsprepared by pneumatic spray methodrdquo Materials Science inSemiconductor Processing vol 27 no 1 pp 233ndash239 2014

[16] M Pang G Long S Jiang et al ldquoOne pot low-temperaturegrowth of hierarchical 120575-MnO2 nanosheets on nickel foam forsupercapacitor applicationsrdquo Electrochimica Acta vol 161 pp297ndash304 2015

[17] Z Li Z Liu B Li et al ldquoLarge area synthesis of well-dispersed120573-MnO2 nanorods and their electrochemical supercapacitiveperformancesrdquo Journal of the Taiwan Institute of ChemicalEngineers vol 65 pp 544ndash551 2016

[18] D Nguyen Thanh M Singh P Ulbrich N Strnadova and FStepanek ldquoPerlite incorporating 120574-Fe2O3 and 120572-MnO2 nano-materials preparation and evaluation of a new adsorbent forAs(V) removalrdquo Separation and Purification Technology vol 82no 1 pp 93ndash101 2011

[19] M Wang P Pang L K Koopal G Qiu Y Wang and F LiuldquoOne-step synthesis of 120575-MnO2 nanoparticles using ascorbicacid and their scavenging properties to Pb(II) Zn(II) andmethylene bluerdquo Materials Chemistry and Physics vol 148 no3 pp 1149ndash1156 2014

[20] Y Du G Zheng J Wang L Wang J Wu and H DaildquoMnO2 nanowires in situ grown on diatomite highly efficientabsorbents for the removal of Cr(VI) and As(V)rdquo Microporousand Mesoporous Materials vol 200 pp 27ndash34 2014

[21] X Ge J Liu X Song et al ldquoHierarchical iron containing 120574-MnO2 hollow microspheres a facile one-step synthesis and


effective removal of As(III) via oxidation and adsorptionrdquoChemical Engineering Journal vol 301 pp 139ndash148 2016

[22] M Gheju I Balcu and G Mosoarca ldquoRemoval of Cr(VI)from aqueous solutions by adsorption on MnO2rdquo Journal ofHazardous Materials vol 310 pp 270ndash277 2016

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pseudo-first-order and pseudo-second-order models Inaddition intraparticle diffusion kinetics were also studied toascertain the mechanism of the uptake

2 Materials and Methods

21 Preparation of 120572-MnO2 from 120574-MnO2 120574-MnO2 whichwas successfully synthesized by Le and Van Phuc [2] fromethanol and potassium permanganate was heated at 600∘CThe product after being investigated by XRD SEM and BETwas used as an absorbent to remove lead and iron ions fromthe aqueous solution

22 Adsorbent Lead(II) and iron(II) ionswere used as adsor-bates 1000mgL standard stock solution of each metal ionwas prepared by dissolving Pb(NO3)2 and Fe(NO3)3 in dis-tilled water

23 Instruments X-ray diffractometer D5000 made in Ger-many by Siemens with X-ray radiation CuK120572 120582 = 154056 Awas used to examine the phase of the crystalline structure

Themorphology of thematerial was investigated by UltraHigh Resolution Scanning Electron Microscopy S-4800 atransmission electron microscope

Atomic Absorption Spectrophotometer (Atomic Absorp-tion Spectrometer AA-7000made in Japan by Shimadzu) wasused to determine the BET surface area and pore site

The pH measurements were done with a pH meter(Martini Instruments Mi-150 Romania) the pH meter wasstandardized using Hanna Instruments buffer solutions withpH values of 401 plusmn 001 701 plusmn 001 and 1001 plusmn 001

A temperature-controlled shaker (Model IKA R5) wasused for equilibrium studies

24 Diagram for These Studies See Figure 1

25 Adsorption Study 50mL solution of heavy metal (Pb2+andZn2+) ionswas placed into a 100mL conical flask contain-ing 01 g 120572-MnO2 During the uptake influence of pH of theinitial solution was adjusted within 2ndash5 range using HNO301M or NaOH 01M solutions Adsorption studies werealso conducted in batch experiments with various adsorptiontimes (20ndash240 minutes) and concentrations of metal ion(100ndash500mgL) Concentrations of heavy metal ions in thefiltrate before and after uptake were determined using AAS

Adsorption capacity was calculated by using the massbalance equation for the adsorption [1]

119902 = (1198620 minus 119862119890) sdot 119881119898 (1)

And the adsorption efficiency ()was calculated from theformula

Removal = (1198620 minus 119862119890) sdot 1001198620 (2)

where 119902 is the adsorption capacity (mgg) at equilibrium1198620 and 119862119890 are the initial and the equilibrium concentrations(mgL) respectively 119881 is the volume (L) of the solution and119898 is the mass (g) of the adsorbent used

Removal of heavy metals

KMnO4

Agitated in 8h

C2H5OH + H2O

Sol MnO2

Dried at 100∘C

Heated at 600∘C

120574-MnO2

120572-MnO2

Figure 1

8007006005004003002001000

TG (m

g)

0minus05minus1minus15minus2minus25minus3minus35minus4

Exo

Sample temperature (∘C)

T 18641∘C

T 53593∘C

T 9031∘Cminus35minus25minus15minus5

515

Hea

t flow

(mW

)



Figure 2 TG-DTA analysis

3 Results and Discussion

31 Characterization of 120572-MnO2 Nanostructures311 Thermal Analysis Result Thermal analysis (Figure 2)showed that there were two specific peaks corresponding tothe decrease in volume of a product From 100∘C to 300∘Cthe endothermic process occurred which combined witha significant reduction of volume (approximately 1640)showed chemical dehydration as well asmelting ofmaterial at18641∘C From 300∘C to 800∘C there was a slight decrease involume of about 540 which was the continued melting Inaddition there was an endothermic peak at 53593∘C corre-sponding to allotropic transformation It was predicted that120572-MnO2 crystalline structure can be formed at above 536∘C

312 X-Ray Analysis Results XRD analysis results showedthat 120572-MnO2 crystalline structure was not formed at 400∘C(Figure 3) At higher temperatures 600∘C and 800∘C 120572-MnO2 crystalline structurewas completely formedwith somespecific peaks at 2120579 = 2858 3748 4978 5998 and 6898 cor-responding to the Miller indices (3 1 0) (2 1 1) (4 1 1) (5 2 1)


Inte

nsity

(au

)

2120579 (deg)

(d)

(c)

(a)

(b)

706050403020


(a) (b)

(c) (d)

(e) (f)





100

80

60

40

20

0

re

mov

al

FePb

pH00 20 40 60

(a)

100

80

60

40

20

0

Time (minutes)

re

mov

alFePb

250200150100500

(b)













Ce (mgL) Ce (mgL)

qe(m

gg)

160

120

80

40

0

qe(m

gg)

160

120

80

40

0

qe(m

gg)

160

120

80

40

0

150100500120100806040200

Ce (mgL)

120100806040200

Ce (mgL) Ce (mgL)

100806040200

Pb

Pb

Pb

Fe

Fe

Fe

0 50 100 150

Ce (mgL)

0 50 100 150

ExperimentLangmuir

ExperimentLangmuir


ExperimentSips

ExperimentSips


0

5

10

15

20

25

30

35

qe(m

gg)

0

10

20

30

40

qe(m

gg)

0

5

10

15

20

25

30

35

qe(m

gg)



119878119865 = 11 + 119870119871 sdot 1198620 (4)









119870119871 03340 0135119902119898 (mgg) 1249 3083RMSE 3529 15041198772 09109 090421205942 06618 07603


Freundlich 119902119890 = 119870119865 sdot 11986211989011198991119899 01115 02033119870119865 7476 1152

RMSE 1493 06951198772 09840 097951205942 01148 01296

Sips 119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890

119870119878 675 1184120572119878 minus09142 01986120573119878 00070 03442

RMSE 14689 062721198772 09846 098331205942 01133 01122



119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890 (5)






4 Conclusion



Time (minutes)250 300200150100500

tqt

tqt = 00091t + 00075R2 = 10000

25

20

15

10

05

00

(a)

16

12

08

04

00

minus04

minus08

minus12

Time (minutes)300250200150100500


R2 = 05998

log (qe

log (

qeminus

q)

(b)

Time (minutes)250 300200150100500

tqt

tqt = 00558t + 06927

R2 = 09958

160

140

120

100

80

60

40

20

00

(c)

Time (minutes)300250200150100500

= minus00006t + 12582

R2 = 06173

13

12

11

log (

qeminus

qt)

log (qe minus qt)

(d)

120

100

80

60

40

20

0

Time (minutes)

qe(m

gg)

y = 03722x + 948185R2 = 09469

250200150100500

y = 00038x + 1088872R2 = 09887

Stage 1

Stage 2

(e)

Time (minutes)250200150100500

Stage 1

Stage 2

Stage 3

20

16

12

8

4

0

qe(m

gg)

y = 00309x + 112703

R2 = 09347

y = 01759x + 24774

R2 = 10000

y = 00017x + 164800

R2 = 08607

(f)




Competing Interests





119902119890(exp) (mgg) 10980 1680



119902119890(cal) (mgg) 5433 1812


2

119905119902 =111987021199022119890 + (

1119902119890 ) sdot 119905


119902119890(cal) (mgg) 10989 1792


References


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Inte

nsity

(au

)

2120579 (deg)

(d)

(c)

(a)

(b)

706050403020


(a) (b)

(c) (d)

(e) (f)





100

80

60

40

20

0

re

mov

al

FePb

pH00 20 40 60

(a)

100

80

60

40

20

0

Time (minutes)

re

mov

alFePb

250200150100500

(b)













Ce (mgL) Ce (mgL)

qe(m

gg)

160

120

80

40

0

qe(m

gg)

160

120

80

40

0

qe(m

gg)

160

120

80

40

0

150100500120100806040200

Ce (mgL)

120100806040200

Ce (mgL) Ce (mgL)

100806040200

Pb

Pb

Pb

Fe

Fe

Fe

0 50 100 150

Ce (mgL)

0 50 100 150

ExperimentLangmuir

ExperimentLangmuir


ExperimentSips

ExperimentSips


0

5

10

15

20

25

30

35

qe(m

gg)

0

10

20

30

40

qe(m

gg)

0

5

10

15

20

25

30

35

qe(m

gg)



119878119865 = 11 + 119870119871 sdot 1198620 (4)









119870119871 03340 0135119902119898 (mgg) 1249 3083RMSE 3529 15041198772 09109 090421205942 06618 07603


Freundlich 119902119890 = 119870119865 sdot 11986211989011198991119899 01115 02033119870119865 7476 1152

RMSE 1493 06951198772 09840 097951205942 01148 01296

Sips 119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890

119870119878 675 1184120572119878 minus09142 01986120573119878 00070 03442

RMSE 14689 062721198772 09846 098331205942 01133 01122



119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890 (5)






4 Conclusion



Time (minutes)250 300200150100500

tqt

tqt = 00091t + 00075R2 = 10000

25

20

15

10

05

00

(a)

16

12

08

04

00

minus04

minus08

minus12

Time (minutes)300250200150100500


R2 = 05998

log (qe

log (

qeminus

q)

(b)

Time (minutes)250 300200150100500

tqt

tqt = 00558t + 06927

R2 = 09958

160

140

120

100

80

60

40

20

00

(c)

Time (minutes)300250200150100500

= minus00006t + 12582

R2 = 06173

13

12

11

log (

qeminus

qt)

log (qe minus qt)

(d)

120

100

80

60

40

20

0

Time (minutes)

qe(m

gg)

y = 03722x + 948185R2 = 09469

250200150100500

y = 00038x + 1088872R2 = 09887

Stage 1

Stage 2

(e)

Time (minutes)250200150100500

Stage 1

Stage 2

Stage 3

20

16

12

8

4

0

qe(m

gg)

y = 00309x + 112703

R2 = 09347

y = 01759x + 24774

R2 = 10000

y = 00017x + 164800

R2 = 08607

(f)




Competing Interests





119902119890(exp) (mgg) 10980 1680



119902119890(cal) (mgg) 5433 1812


2

119905119902 =111987021199022119890 + (

1119902119890 ) sdot 119905


119902119890(cal) (mgg) 10989 1792


References


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




100

80

60

40

20

0

re

mov

al

FePb

pH00 20 40 60

(a)

100

80

60

40

20

0

Time (minutes)

re

mov

alFePb

250200150100500

(b)













Ce (mgL) Ce (mgL)

qe(m

gg)

160

120

80

40

0

qe(m

gg)

160

120

80

40

0

qe(m

gg)

160

120

80

40

0

150100500120100806040200

Ce (mgL)

120100806040200

Ce (mgL) Ce (mgL)

100806040200

Pb

Pb

Pb

Fe

Fe

Fe

0 50 100 150

Ce (mgL)

0 50 100 150

ExperimentLangmuir

ExperimentLangmuir


ExperimentSips

ExperimentSips


0

5

10

15

20

25

30

35

qe(m

gg)

0

10

20

30

40

qe(m

gg)

0

5

10

15

20

25

30

35

qe(m

gg)



119878119865 = 11 + 119870119871 sdot 1198620 (4)









119870119871 03340 0135119902119898 (mgg) 1249 3083RMSE 3529 15041198772 09109 090421205942 06618 07603


Freundlich 119902119890 = 119870119865 sdot 11986211989011198991119899 01115 02033119870119865 7476 1152

RMSE 1493 06951198772 09840 097951205942 01148 01296

Sips 119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890

119870119878 675 1184120572119878 minus09142 01986120573119878 00070 03442

RMSE 14689 062721198772 09846 098331205942 01133 01122



119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890 (5)






4 Conclusion



Time (minutes)250 300200150100500

tqt

tqt = 00091t + 00075R2 = 10000

25

20

15

10

05

00

(a)

16

12

08

04

00

minus04

minus08

minus12

Time (minutes)300250200150100500


R2 = 05998

log (qe

log (

qeminus

q)

(b)

Time (minutes)250 300200150100500

tqt

tqt = 00558t + 06927

R2 = 09958

160

140

120

100

80

60

40

20

00

(c)

Time (minutes)300250200150100500

= minus00006t + 12582

R2 = 06173

13

12

11

log (

qeminus

qt)

log (qe minus qt)

(d)

120

100

80

60

40

20

0

Time (minutes)

qe(m

gg)

y = 03722x + 948185R2 = 09469

250200150100500

y = 00038x + 1088872R2 = 09887

Stage 1

Stage 2

(e)

Time (minutes)250200150100500

Stage 1

Stage 2

Stage 3

20

16

12

8

4

0

qe(m

gg)

y = 00309x + 112703

R2 = 09347

y = 01759x + 24774

R2 = 10000

y = 00017x + 164800

R2 = 08607

(f)




Competing Interests





119902119890(exp) (mgg) 10980 1680



119902119890(cal) (mgg) 5433 1812


2

119905119902 =111987021199022119890 + (

1119902119890 ) sdot 119905


119902119890(cal) (mgg) 10989 1792


References


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Ce (mgL) Ce (mgL)

qe(m

gg)

160

120

80

40

0

qe(m

gg)

160

120

80

40

0

qe(m

gg)

160

120

80

40

0

150100500120100806040200

Ce (mgL)

120100806040200

Ce (mgL) Ce (mgL)

100806040200

Pb

Pb

Pb

Fe

Fe

Fe

0 50 100 150

Ce (mgL)

0 50 100 150

ExperimentLangmuir

ExperimentLangmuir


ExperimentSips

ExperimentSips


0

5

10

15

20

25

30

35

qe(m

gg)

0

10

20

30

40

qe(m

gg)

0

5

10

15

20

25

30

35

qe(m

gg)



119878119865 = 11 + 119870119871 sdot 1198620 (4)









119870119871 03340 0135119902119898 (mgg) 1249 3083RMSE 3529 15041198772 09109 090421205942 06618 07603


Freundlich 119902119890 = 119870119865 sdot 11986211989011198991119899 01115 02033119870119865 7476 1152

RMSE 1493 06951198772 09840 097951205942 01148 01296

Sips 119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890

119870119878 675 1184120572119878 minus09142 01986120573119878 00070 03442

RMSE 14689 062721198772 09846 098331205942 01133 01122



119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890 (5)






4 Conclusion



Time (minutes)250 300200150100500

tqt

tqt = 00091t + 00075R2 = 10000

25

20

15

10

05

00

(a)

16

12

08

04

00

minus04

minus08

minus12

Time (minutes)300250200150100500


R2 = 05998

log (qe

log (

qeminus

q)

(b)

Time (minutes)250 300200150100500

tqt

tqt = 00558t + 06927

R2 = 09958

160

140

120

100

80

60

40

20

00

(c)

Time (minutes)300250200150100500

= minus00006t + 12582

R2 = 06173

13

12

11

log (

qeminus

qt)

log (qe minus qt)

(d)

120

100

80

60

40

20

0

Time (minutes)

qe(m

gg)

y = 03722x + 948185R2 = 09469

250200150100500

y = 00038x + 1088872R2 = 09887

Stage 1

Stage 2

(e)

Time (minutes)250200150100500

Stage 1

Stage 2

Stage 3

20

16

12

8

4

0

qe(m

gg)

y = 00309x + 112703

R2 = 09347

y = 01759x + 24774

R2 = 10000

y = 00017x + 164800

R2 = 08607

(f)




Competing Interests





119902119890(exp) (mgg) 10980 1680



119902119890(cal) (mgg) 5433 1812


2

119905119902 =111987021199022119890 + (

1119902119890 ) sdot 119905


119902119890(cal) (mgg) 10989 1792


References


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





119870119871 03340 0135119902119898 (mgg) 1249 3083RMSE 3529 15041198772 09109 090421205942 06618 07603


Freundlich 119902119890 = 119870119865 sdot 11986211989011198991119899 01115 02033119870119865 7476 1152

RMSE 1493 06951198772 09840 097951205942 01148 01296

Sips 119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890

119870119878 675 1184120572119878 minus09142 01986120573119878 00070 03442

RMSE 14689 062721198772 09846 098331205942 01133 01122



119902119890 = 119870119878 sdot 119862120573119878119890

1 + 120572119878 sdot 119862120573119878119890 (5)






4 Conclusion



Time (minutes)250 300200150100500

tqt

tqt = 00091t + 00075R2 = 10000

25

20

15

10

05

00

(a)

16

12

08

04

00

minus04

minus08

minus12

Time (minutes)300250200150100500


R2 = 05998

log (qe

log (

qeminus

q)

(b)

Time (minutes)250 300200150100500

tqt

tqt = 00558t + 06927

R2 = 09958

160

140

120

100

80

60

40

20

00

(c)

Time (minutes)300250200150100500

= minus00006t + 12582

R2 = 06173

13

12

11

log (

qeminus

qt)

log (qe minus qt)

(d)

120

100

80

60

40

20

0

Time (minutes)

qe(m

gg)

y = 03722x + 948185R2 = 09469

250200150100500

y = 00038x + 1088872R2 = 09887

Stage 1

Stage 2

(e)

Time (minutes)250200150100500

Stage 1

Stage 2

Stage 3

20

16

12

8

4

0

qe(m

gg)

y = 00309x + 112703

R2 = 09347

y = 01759x + 24774

R2 = 10000

y = 00017x + 164800

R2 = 08607

(f)




Competing Interests





119902119890(exp) (mgg) 10980 1680



119902119890(cal) (mgg) 5433 1812


2

119905119902 =111987021199022119890 + (

1119902119890 ) sdot 119905


119902119890(cal) (mgg) 10989 1792


References


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Time (minutes)250 300200150100500

tqt

tqt = 00091t + 00075R2 = 10000

25

20

15

10

05

00

(a)

16

12

08

04

00

minus04

minus08

minus12

Time (minutes)300250200150100500


R2 = 05998

log (qe

log (

qeminus

q)

(b)

Time (minutes)250 300200150100500

tqt

tqt = 00558t + 06927

R2 = 09958

160

140

120

100

80

60

40

20

00

(c)

Time (minutes)300250200150100500

= minus00006t + 12582

R2 = 06173

13

12

11

log (

qeminus

qt)

log (qe minus qt)

(d)

120

100

80

60

40

20

0

Time (minutes)

qe(m

gg)

y = 03722x + 948185R2 = 09469

250200150100500

y = 00038x + 1088872R2 = 09887

Stage 1

Stage 2

(e)

Time (minutes)250200150100500

Stage 1

Stage 2

Stage 3

20

16

12

8

4

0

qe(m

gg)

y = 00309x + 112703

R2 = 09347

y = 01759x + 24774

R2 = 10000

y = 00017x + 164800

R2 = 08607

(f)




Competing Interests





119902119890(exp) (mgg) 10980 1680



119902119890(cal) (mgg) 5433 1812


2

119905119902 =111987021199022119890 + (

1119902119890 ) sdot 119905


119902119890(cal) (mgg) 10989 1792


References


































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




119902119890(exp) (mgg) 10980 1680



119902119890(cal) (mgg) 5433 1812


2

119905119902 =111987021199022119890 + (

1119902119890 ) sdot 119905


119902119890(cal) (mgg) 10989 1792


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

Synthesis of -MnO : Characterization and Comparative Adsorption...

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Transcript of Synthesis of -MnO : Characterization and Comparative Adsorption...