solutionplasma-assistedgreensynthesisofmno adsorbentand … · 2019. 1. 15. · this reduction...

Research ArticleSolutionPlasma-AssistedGreenSynthesis ofMnO2Adsorbent andRemoval of Cationic Pollutant

Hye-min Kim,1 Nagahiro Saito,2 and Dae-wook Kim 1

1Department of Materials Chemistry, Shinshu University, Wakasato, Nagano 3808553, Japan2Department of Chemical Systems Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 4648603, Japan

Correspondence should be addressed to Dae-wook Kim; [email protected]

Received 15 January 2019; Revised 26 February 2019; Accepted 11 March 2019; Published 25 March 2019

Academic Editor: Sylvain Franger

Copyright © 2019 Hye-min Kim et al..is is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In this study, we proposed the solution plasma- (SP-) assisted green synthesis method using plants extracts, i.e., glucose, with theexpectation of acting as a reducing agent and promotor for the formation of powder state of nanostructured MnO2. MnO2 wassimply and rapidly synthesized within 10min by the SP-assisted method. .e structural features and morphology of as-synthesized MnO2 were characterized by XRD, Raman, FE-SEM, and TEM analyses. For potential application of as-synthesizedMnO2, cationic dye, i.e., methylene blue (MB), removal performance was investigated by batch experiment at an initial con-centration of C0 �100mg L−1. .e obtained MnO2 exhibited effective dye removal ability given high C0, and simultaneouslyapplied plasma discharging further enhanced removal efficiency. .ese contributions therefore open a new window not onlyon a powerful and environmentally benign synthesis route for efficient adsorbents but also on supporting multipleremoval mechanism.

1. Introduction

Advances in scientific technology have made human lifemore comfortable but also these amenities are usually ac-companied with environmental load. Especially, waterpollution is a serious problem of all over the world. One ofthe main contributions of water pollution was organicpollutants derived from industrial waste. .erefore, diversewastewater treatment techniques have been extensivelystudied, and these can be largely categorized as physical,chemical, and biological approach and can serve as an ex-ample of physical adsorption, oxidative degradation, co-agulation, photo degradation, etc., concretely [1–3]. Amongthem, removal of synthetic organic dye by adsorption hasbeen widely applied as the most economical method due toits cost-effectiveness and simple and efficient solid adsor-bents [4, 5].

As the representative adsorbents, there are carbon-basedinorganic adsorbent, transitionmetal oxide, hybrid compositeand so on. In particular, nanostructured manganese dioxide(MnO2) has been considered as attractive and promising

green material because of not only its low cost, earthabundance [6, 7], and nontoxicity but also its structuralflexibility combined with outstanding physicochemicalproperties for applications in various fields such as envi-ronmental applications (e.g., decomposition of organic dyeand oxidation of volatile organic compounds), electrodematerials for sustainable energy system (e.g., metal-air bat-tery, lithium secondary battery, and fuel cell), and photo-catalyst [8–10]. Notably, MnO2 presented multifunctionalproperties which are the physical adsorption, catalytic oxi-dation with hydrogen peroxide (H2O2), and photocatalyticoxidation due to different crystallographic polymorphs ofMnO2 (i.e., α-, β-, c-, δ- and λ-type). Of which, birnessite-MnO2 (δ-MnO2) is known as the most reactive type [11]. .ehighest negative-charge density of birnessite makes it a po-tential candidate for removal of cationic pollutants. However,it still exhibited not enough removal capability without ad-ditional agents. To overcome this problem, design and syn-thesis of nanostructured MnO2 are essential for improvingadsorption capability through the expanding interfacial area.Although various synthesis techniques such as hydrothermal,

HindawiJournal of ChemistryVolume 2019, Article ID 7494292, 7 pageshttps://doi.org/10.1155/2019/7494292

mailto:[email protected]://orcid.org/0000-0001-5099-5753https://creativecommons.org/licenses/by/4.0/https://doi.org/10.1155/2019/7494292

microwave irradiation, template-assist method, coprecipita-tion, and microemulsion method are utilized for preparation,they required toxic chemical agents or longer process timeand higher temperature [12–15]. .us, a significant currentfocus in the advancement of green synthesis is satisfying bothecofriendly and energy-saving. In this regard, plasma in liquidnamed solution plasma (SP) has great potential for the greenapproach [16]. Since the electron temperature (Te, ∼104K) ismuch higher than that of heavy particles such as ions orneutrons (Ti, Tn, ∼300K), the thermal motion of heavyparticles can be ignored, and thus, the solution temperature iskept close to ambient temperature or slightly high duringplasma discharge [17, 18]. .erefore, these unique charac-teristics of SP opened up the new route for synthesizing thespecific materials.

In our previous work, we successfully synthesized col-loidal MnO2 nanosheets in the KMnO4 aqueous solution byone-pot SP process without additional chemical reagentsand verified possible reaction mechanism [19]. Since thecolloidal state adsorbents are difficult to recover due to easyaggregation with solid absorbents in the aqueous solution[20], we have tried to synthesize the powder state of MnO2by the SP-assisted green synthesis method using sugar,i.e., glucose. We expected that glucose acts as the reducingagent and promotor for the formation of powder stateMnO2. Furthermore, the SP was utilized as an assistant fordecomposition of organic pollutants. Recently, plasma-assisted water treatments, including thermal/nonthermalplasma, microwave plasma, or arc plasma [21–23], havebeen demonstrated to be the effective way for remediation ofwaste water. Plasma-based techniques could oxidize anddecompose the toxic organic molecules to less toxic ornontoxic small by-products. Although the above techniquesare highly efficient under low-level pollutants, they do notpresent sufficient capability under high-level pollutants.Hence, we focused on the simultaneous adsorption anddegradation reactions for enhancing removal ability throughhighly reactive species including electrons, radicals (H•, H+,O2–, and OH•), and ions generated from decomposition ofwater molecules. To verify the potential application of as-synthesized MnO2 by the SP-assisted method, removal ca-pability of cationic pollutant, i.e., methylene blue (MB), wasexamined.

2. Materials and Methods

2.1. Synthesis of MnO2 by SP. .e MnO2 was successfullysynthesized by SP process in the sugar (i.e., glucose) addedpotassium permanganate (KMnO4) aqueous solution.KMnO4 was selected as the MnO2 source, and glucose wasutilized as a promoter for powder form of MnO2. Allchemicals were obtained from Wako Pure Chemical In-dustries Ltd., Japan, and used without further purification..e precursor was prepared by following steps: 1.0 g ofKMnO4 was mixed sufficiently by magnetic stirring in100ml volume of DI water, and then, 0.15 g of glucose wasput in this solution. Figure 1 shows the experimental setup ofthe SP system. As-prepared precursor was moved to a glassreactor for SP treatment. To generate the plasma in solution,

bipolar pulse power supply (Kurita, Japan) was utilized anddischarge conditions of frequency and pulse width wereadjusted at 20 kHz and 2.0 μs, respectively. After SPP for10min, powder form of MnO2 was synthesized and samplewas obtained by filtration and oven-dry procedures. .e as-obtained MnO2 was used as the adsorbent material.

2.2. Characterizations. .e structural properties of as-prepared MnO2 were evaluated by using an X-ray diffrac-tometer (XRD, Rigaku Ultima IV, Rigaku Corp., Japan) andRaman spectroscopy with 532.5 nm laser wavelength (NRS-1000, JASCO corp., Japan). .e morphology was observedby field emission scanning electron microscopy (FE-SEM,S-4800, HITACHI High-Technologies Co., Ltd., Japan) andtransmission electron microscopy (TEM, JEM-2500SE,Japan). Optical emission spectroscopy (OES, Ocean opticsInc., USB4000+) was carried out to investigate the reactivespecies during plasma discharging. Ultraviolet-visiblespectroscopy (UV-vis, Shimadzu UV-3600, Japan) wasused to observe the dye removal performance.

2.3. Batch Experiment for Cationic Dye Removal. To de-termine the cationic dye removal or degradation capability,methylene blue (MB, C16H18ClN3S·nH2O) was utilized astypical cationic dye. .e dye removal capability of adsorbent(MO), plasma (SP), and adsorbent/plasma (MO+SP) sys-tem were observed under following conditions. Firstly, theinitial concentration (C0) of MB aqueous solution was fixedat 100mg L−1 because dye removal capability in low con-taminant concentration is difficult to clearly verify the effectof each system due to the rapid adsorption or degradation inthe first few minutes. All of the batch tests were carried outunder natural pH (6.5–6.8) and temperature (298K), anddetails were as follows: (i) adsorbent system (MO): 0.06 g ofMO was put into the 100ml volume of MB stock solution,

Bipolar pulse power supply

Magnetic stirrer

Silicone plug

Reactor Precursor

Tungsten electrode

Ceramic tube

Plasma

HV

Ground

W W Φ1mm

20kHz 2.0μs

Discharge condition

U (V

)

t1 t2

Time (s)T

+

–

Figure 1: Schematic configuration of solution plasma (SP) reactorsetup for synthesis of MnO2.

2 Journal of Chemistry

and UV-vis spectrum was measured after 30min of contacttime; (ii) plasma system (SP): the plasma was generated inMB solution using bipolar DC pulse power supply (fre-quency; 20 kHz, pulse width; 1.5 μm) for 30min; (iii)adsorbent/plasma system (MO+ SP): the plasma wasgenerated in MB solution including 0.06 g of MO for30min.

.e dye removal efficiency (equation (1)) and adsorptioncapacity (equation (2)) of the adsorbents (MO) were de-termined by the following equations:

removal efficiency(%) �C0 −Ct(

C0× 100, (1)

adsorption capacity(mg/g) �C0 −Ct( V

W, (2)

whereC0 and Ct (mg L−1) are the initial and the absorbed dyeconcentration at contact time, respectively. .e V (L) is thevolume of dye stock solution and W (mg) is the amount ofdosage.

3. Results and Discussion

3.1. Plasma-Assisted Synthesis of MnO2. .e glucose isclassified as reducing sugars since it can reduce metal ions(M+ to M0) owing to its free aldehyde groups in the mo-lecular structure [24]..erefore, MnO4– could be reduced toMnO2 by glucose in the KMnO4 aqueous solution. However,this reduction process is a very sluggish chemical reactionwithout reactive agents, which was determined in ourpreliminary study. It took more than 12 hours to formpowder state MnO2 completely. Hence, the SP was in-troduced to accelerate chemical reaction. Reductionmechanism of MnO4– to MnO2 in the presence of plasmawas already proposed in our previous work [19]. Briefly,highly reactive species are generated from decomposition ofwater molecules during plasma discharging in aqueoussolution, which promote rapid reduction reaction fromMnO4– to MnO2. Since these reactive species are very active,reactions occur with multiplicity. .e main chemical re-action could be suggested by the following equations:

H2O⟶ H•

+ OH•(in the plasma zone) (3)

MnO4−(VII) + 3H•⟶ MnO2(IV) + OH

−

+ H2O(chemical reduction)(4)

Especially in liquid phase where molecules are closelypacked, a remarkably high reaction rate could be achieved[16]. As a result, we obtained MnO2 powders within 10min..e effect of SP was verified by the OES spectrum that wasmeasured during plasma discharge in aqueous solution inSection 3.4.

3.2. Structure and Morphology Analysis. Structure featureswere observed by XRD and Raman analysis. As can be seenin Figure 2(a), the observed peaks (marked with ▽) at2θ�12.37°, 24.97°, 37.18°, and 66.21° correspond with the

birnessite-type potassium manganese oxide hydrate (JCPDSNo. 52-0556). It is layered MnO2 composed of edge-sharing[MnO6] octahedral with K+ ions and water molecules in theinterlayer (∼0.7 nm) [25]. For further information ofstructural properties, Raman spectroscopy measurementswere performed. As shown in Figure 2(b), the predominantthree peaks marked with ]1 (∼637 cm−1), ]2 (∼566 cm−1),and ]3 (∼501 cm−1), respectively, well correspond with themajor vibration peaks of the birnessite-type MnO2; ]1 in-dicates symmetric stretching vibration of Mn–O in the[MnO6] octahedral, and ]2 indicates stretching vibrationmode of Mn–O in the [MnO6] octahedral layers [26].Figure 2(c) shows the XPS survey spectra. As expected, Mn2p, O 1s, and K 2s peaks were detected, and narrow-scanspectra for Mn 2p shows a clear peak splitting at 653.76 and642.02 eV, corresponding to the Mn 2p1/2 andMn 2p3/2. .ispeak separation value (11.74 eV) is consistent with the lit-erature of birnessite-typeMnO2 [27]..e FE-SEM and TEMimages are shown in Figure 3. .e FE-SEM image revealedthat MnO2 has spherical aggregated nanoparticles with20–100 nm size (Figure 3(a)). .is nanoporous structuremight have an advantage in pollutants removal due tofrequent contact between MnO2 and pollutant. .e nano-structure was further evidenced in the TEM image(Figure 3(b)). Meanwhile, the selected area electron dif-fraction (SAED) pattern showed that MnO2 has amorphouscrystalline structure (Figure 3(b) inset) and it is in goodagreement with broad and weak XRD pattern.

3.3. Cationic Dye Removal Test. To confirm the cationic dyeremoval capability of adsorbent (MO), plasma (SP), andadsorbent/plasma (MO+SP) systems, batch experimentswere performed under natural pH, ambient temperature,adsorbent dosage of 0.06 g L−1, and contacting or treatmenttime of 30min. Preliminary experiments to find out equi-librium contact time demonstrated about 30min. In addi-tion, when the plasma discharge was performed more than30min in MB stock solution, solution temperature in-creased. Considering these points, we set the treatment timefor 30min to compare the dye removal capability by eachsystem excluding other external factors.

Figure 4(a) shows the UV-vis spectra of MB solutionbefore and after treatment. .e predominant three peaks at665, 611, and 292 nm represent monomer, dimer, and ar-omatic ring of MB molecules, respectively [28]. .e removalcapability of MB was determined by measuring the intensityof absorbance spectra at 665 nm after treatment. After30min, the absorption intensities of all systems diminishedand dye removal capability is of the following order:adsorbent/plasma (MO+SP)> adsorbent (MO)> plasma(SP). .e calculated values of removal efficiency (left side,gray bar) and capacity (right side, --■--) using equations (1)and (2) based on the UV-vis results are presented inFigure 4(b). Notably, the adsorbent/plasma system(MO+SP) showed higher capability for dye removal thanthe adsorbent (MO) and plasma (SP) systems. .is resultdemonstrated that the dual-treatment system with plasmaand adsorbent is the effective method for dye removal.

Journal of Chemistry 3

3.4. SP-Assisted Pollutants Removal Mechanism. To clarifythe effects of SP on pollutant removal, the OES spectrumwasmeasured during plasma discharging in an aqueous solution.As shown in Figure 5(a), hydrogen (Hα; 665 nm and Hβ;486 nm), oxygen (O I; 777 and 845 nm) and hydroxyl (OH;309 nm) radicals were detected. It is believed that reactivespecies generated from decomposition of water molecules byplasma discharging. .e formation of plasma in the aqueoussolution can be described as follows. When the voltage is

applied between submerged electrodes, water evaporationand microbubbles are generated by Joule heating. Afterapplied voltage is high enough to reach the breakdownvoltage, discharge is initiated [29]. During the plasma dis-charging, energetic electrons and ions could contribute todegradation of organic molecules, i.e., MBmolecules. In fact,the SP process has been used for organic compound de-composition, and it efficiently destroyed aromatic ringstructure [30]. .erefore, as can be seen in Figure 5(b), an

100nm

(a)

100nm 101nm

(b)

Figure 3: (a) FE-SEM image and (b) TEM image of as-synthesized MnO2 (SAED pattern inset).

10 20 30 40 50 60 70 80

Inte

nsity

(a.u

.)

2θ (°)

K0.27MnO2(H2O)0.54: JCPDS #52-0556

Birnessite-type potassium manganese oxide(K0.27MnO2·xH2O)

H2O K+ ion

(a)

300 450 600 750 900 1050

Inte

nsity

(a.u

.)

Raman shift (cm–1)

ν1

ν2

ν3

(b)

1100 1000 900 800 700 600 500 400 300

Inte

nsity

(a.u

.)

Binding energy (eV)

Mn 2p O 1s

K 2s

660 655 650 645 640 635

11.74eV

Mn 2p1/2

Mn 2p3/2

(c)

Figure 2: (a) Powder-XRD and (b) Raman spectrum for MnO2. (c) Wide-scan XPS spectrum of MnO2 powder and narrow-scan spectrumof Mn 2p (inset).

4 Journal of Chemistry

200 300 400 500 600 700 800

Abs

orba

nce (

a.u.)

Wavelength (nm)

MB (before)MO

SPMO + SP

(a)

0

20

40

60

80

100

MO + SPMO

Rem

oval

effic

ienc

y, R

(%)

SP0

25

50

75

100

125

150

Capa

city

, qe (

mg·

g–1 )

35.4

72.481.5

59.0

121.2135.8

(b)

FIGURE 4: (a) UV-vis spectra for MB solution before and after treatment using adsorbent (MO), plasma (SP), and adsorbent/plasma(SP +MO) systems, respectively. (b) MB removal efficiency (gray bar) and capacity (--■--) of each approach (C0 �100mg L−1, 297K, contactor treatment time� 30min).

200 300 400 500 600 700 800 900

Emiss

ion

inte

nsity

(a.u

.)

Wavelength (nm)

O I

(845

nm)

O I

(777

nm)

Hα (

656n

m)

Hβ (

485n

m)

OH

(309

nm)

(a)

•OH

H+

O2–H+

+S

N N

N+

Cl–

S

N

N

N +

Cl –+

MO

Plasma

Degraded products Plasma

Adsorption

UV

(b)

Figure 5: (a) OES spectrum collected during plasma discharging in aqueous solution, and (b) schematic presentation of the adsorbent/plasma system for pollutant removal in aqueous solution.


adsorption and chemical degradation simultaneously oc-curred. Moreover, chemical degradation could be classifiedto three types of mechanisms. First, since the generated Oand OH radicals have higher oxidation potential [21, 31],which mainly contribute to degradation of MB molecules.Moreover, repetitive generation of abundant OH radicalsduring discharging (equation (3)) could continuously affectthe MB degradation. And also, the SP provides UV radiationeffect and strong electric fields that are composed of ener-getic electrons, which could support degradation [32–34].Note that the small plasma zone and weaker radiation energythan the solar simulator limited a radiation range and power,respectively, and thus, we assume that a UV radiation effectplays a subsidiary role in this system. On the basis of theabove discussion, we believe that these multiple reactionmechanisms could be enhancing removal efficiency underhigh-level pollutants.

4. Conclusions

In this study, we have investigated a SP for both synthesisand pollutant removal as a prospective green route. SP-assisted synthesis significantly reduces process time withouttoxic reactive agents through reactive species (energeticelectrons, radicals, and ions) generated during plasma dis-charging. Successfully synthesized MnO2 nanoparticlespresented a removal efficiency of 72.4% for C0 �100mg L−1within 30min. In addition, simultaneously applying plasmadischarge increased a removal efficiency to 81.5% due to thegenerated O and OH radicals with UV radiation and electricfields. .ese findings will be useful for designing an in-novative green approach for MnO2 absorbent and un-derstanding multiple reaction mechanisms for cationicpollutant removal.

Data Availability

.e data used to support the findings of this study are in-cluded within the article.

Conflicts of Interest

.e authors declare that there are no conflicts of interest.

Acknowledgments

.is research was financially supported by the Core Researchfor Evolutional Science and Technology (CREST) of JapanScience and Technology Agency (JST) (JST/CREST GrantGJPMJCR12L1).

References

[1] A. Subramani and J. G. Jacangelo, “Emerging desalinationtechnologies for water treatment: a critical review,” WaterResearch, vol. 75, no. 15, pp. 164–187, 2015.

[2] I. Gehrke, A. Geiser, and A. Somborn-Schulz, “Innovations innanotechnology for water treatment,” Nanotechnology, Sci-ence and Applications, vol. 8, pp. 1–17, 2015.

[3] C. R. Holkar, A. J. Jadhav, D. V. Pinjari, N. M.Mahamuni, andA. B. Pandit, “A critical review on textile wastewater

treatments: possible approaches,” Journal of EnvironmentalManagement, vol. 182, pp. 351–366, 2016.

[4] M. T. Yagub, T. K. Sen, S. Afroze, and H. M. Ang, “Dye and itsremoval from aqueous solution by adsorption: a review,”Advances in Colloid and Interface Science, vol. 209, pp. 172–184, 2014.

[5] M. Rafatullah, O. Sulaiman, R. Hashim, and A. Ahmad,“Adsorption of methylene blue on low-cost adsorbents: areview,” Journal of Hazardous Materials, vol. 177, no. 1–3,pp. 70–80, 2010.

[6] D. Bélanger, L. Brousse, and J. W. Long, “Manganese oxides:battery materials make the leap to electrochemical capaci-tors,”

[20] Y.Wang, X. Zhang, X. He,W. Zhang, X. Zhang, and C. Lu, “Insitu synthesis of MnO2 coated cellulose nanofibers hybrid foreffective removal of methylene blue,” Carbohydrate Polymers,vol. 110, pp. 302–308, 2014.

[21] B. R. Locke, M. Sato, P. Sunka, M. R. Hoffmann, andJ.-S. Chang, “Electrohydraulic discharge and nonthermalplasma for water treatment,” Industrial and EngineeringChemistry Research, vol. 45, no. 3, pp. 882–905, 2006.

[22] M. C. Garćıa, M. Mora, D. Esquivel et al., “Microwave at-mospheric pressure plasma jets for wastewater treatment:degradation of methylene blue as a model dye,” Chemosphere,vol. 180, pp. 239–246, 2017.

[23] D. R. Merouani, F. Abdelmalek, F. Taleb, M. Martel,A. Semmoud, and A. Addou, “Plasma treatment by gliding arcdischarge of dyes/dye mixtures in the presence of inorganicsalts,” Arabian Journal of Chemistry, vol. 8, no. 2, pp. 155–163,2015.

[24] M. Darroudi, M. Mansor Bin Ahmad, A. H. Abdullah,N. A. Ibrahim, and K. Shameli, “Green synthesis and char-acterization of gelatin-based and sugar-reduced silvernanoparticles,” International Journal of Nanomedicine, vol. 6,pp. 569–574, 2011.

[25] X. Yang, Y. Makita, Z.-H. Liu, K. Sakane, and K. Ooi,“Structural characterization of self-assembled MnO2 Nano-sheets from birnessite manganese oxide single crystals,”Chemistry of Materials, vol. 16, no. 26, pp. 5581–5588, 2004.

[26] C. Julien, M. Massot, R. Baddour-Hadjean et al., “Ramanspectra of birnessite manganese dioxides,” Solid State Ionics,vol. 171, no. 4356, pp. 737-738, 1953.

[27] Y. Liu, X. Miao, J. Fang et al., “Layered-MnO2 nanosheetgrown on nitrogen-doped graphene template as a compositecathode for flexible solid-state asymmetric supercapacitor,”ACS Applied Materials and Interfaces, vol. 8, no. 8,pp. 5251–5260, 2016.

[28] M. A. Rauf, M. A. Meetani, A. Khaleel, and A. Ahmed,“Photocatalytic degradation of methylene blue using a mixedcatalyst and product analysis by LC/MS,” Chemical Engi-neering Journal, vol. 157, no. 2-3, pp. 373–378, 2010.

[29] N. Saito, M. A. Bratescu, and K. Hashimi, “Solution plasma: anew reaction field for nanomaterials synthesis,” JapaneseJournal of Applied Physics, vol. 57, no. 1, article 0102A4, 2018.

[30] D.-w. Kim, O. L. Li, P. Pootawang, and N. Saito, “Solutionplasma synthesis process of tungsten carbide on N-dopedcarbon nanocomposite with enhanced catalytic ORR activityand durability,” RSCAdvances, vol. 4, no. 32, pp. 16813–16819,2014.

[31] J. Hoigné and H. Bader, “.e role of hydroxyl radical re-actions in ozonation processes in aqueous solutions,” WaterResearch, vol. 10, no. 5, pp. 377–386, 1976.

[32] A. M. Anpilov, E. M. Barkhudarov, Y. B. Bark et al., “Electricdischarge in water as a source of UV radiation, ozone andhydrogen peroxide,” Journal of Physics D: Applied Physics,vol. 34, no. 6, pp. 993–999, 2001.

[33] W. A. M. Hijnen, E. F. Beerendonk, and G. J. Medema,“Inactivation credit of UV radiation for viruses, bacteria andprotozoan (oo)cysts in water: a review,” Water Research,vol. 40, no. 1, pp. 3–22, 2006.

[34] K. P. V. Lekshmi, S. Yesodharan, and E. P. Yesodharan,“MnO2 and MnO2/TiO2 mediated, persulphate enhancedphotocatalysis for the removal of indigo carmine from water,”European Chemical Bulletin, vol. 6, no. 5, pp. 177–191, 2017.


TribologyAdvances in

Hindawiwww.hindawi.com Volume 2018


International Journal ofInternational Journal ofPhotoenergy


Journal of

Chemistry


Advances inPhysical Chemistry

Hindawiwww.hindawi.com

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwww.hindawi.com Volume 2018

SpectroscopyInternational Journal of


Hindawi Publishing Corporation http://www.hindawi.com Volume 2013Hindawiwww.hindawi.com

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of


NanotechnologyHindawiwww.hindawi.com Volume 2018

Journal of

Applied ChemistryJournal of



Biochemistry Research International


Enzyme Research


Journal of

SpectroscopyAnalytical ChemistryInternational Journal of


MaterialsJournal of



BioMed Research International Electrochemistry

International Journal of


Na

nom

ate

ria

ls


Journal ofNanomaterials

Submit your manuscripts atwww.hindawi.com
https://www.hindawi.com/journals/at/https://www.hindawi.com/journals/ijp/https://www.hindawi.com/journals/jchem/https://www.hindawi.com/journals/apc/https://www.hindawi.com/journals/jamc/https://www.hindawi.com/journals/bca/https://www.hindawi.com/journals/ijs/https://www.hindawi.com/journals/tswj/https://www.hindawi.com/journals/ijmc/https://www.hindawi.com/journals/jnt/https://www.hindawi.com/journals/jac/https://www.hindawi.com/journals/bri/https://www.hindawi.com/journals/er/https://www.hindawi.com/journals/jspec/https://www.hindawi.com/journals/ijac/https://www.hindawi.com/journals/jma/https://www.hindawi.com/journals/bmri/https://www.hindawi.com/journals/ijelc/https://www.hindawi.com/journals/jnm/https://www.hindawi.com/https://www.hindawi.com/

solutionplasma-assistedgreensynthesisofmno adsorbentand … · 2019. 1. 15. · this reduction...

Documents