metal oxide nanocomposites

metal oxide nanocomposites

Accepted Manuscript Title: Sun-light driven rapid photocatalytic degradation of methylene blue by Poly(methyl methacrylate)/metal oxide nanocomposites...

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Accepted Manuscript Title: Sun-light driven rapid photocatalytic degradation of methylene blue by Poly(methyl methacrylate)/metal oxide nanocomposites Authors: Manviri Rani, Uma Shanker PII: DOI: Reference:

S0927-7757(18)31111-7 https://doi.org/10.1016/j.colsurfa.2018.09.040 COLSUA 22840

To appear in:

Colloids and Surfaces A: Physicochem. Eng. Aspects

Received date: Revised date: Accepted date:

4-6-2018 19-8-2018 14-9-2018

Please cite this article as: Rani M, Shanker U, Sun-light driven rapid photocatalytic degradation of methylene blue by Poly(methyl methacrylate)/metal oxide nanocomposites, Colloids and Surfaces A: Physicochemical and Engineering Aspects (2018), https://doi.org/10.1016/j.colsurfa.2018.09.040 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Sun-light driven rapid photocatalytic degradation of methylene blue by Poly(methyl methacrylate)/metal oxide nanocomposites

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*Department of Chemistry Dr B R Ambedkar National Institute of Technology Jalandhar, Punjab, India-144011

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Manviri Rani, Uma Shanker*

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* Corresponding Author Dr Uma Shanker (Assistant Professor) Office Number-CE-306 Department of Chemistry Dr B R Ambedkar National Institute of Technology Jalandhar, Jalandhar, Punjab, India-144011 Email: [email protected], [email protected] Contact number: +91- 7837-588-168 (Mobile)

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+91-0181-269-301-2258 (Office)

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Fax: +91-0181-269-0932

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GRAPHICAL ABSTRACT



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Research highlights

Green synthesis and photocatalytic activity measurement of Metal Oxides -

First order degradation of MB: ZnO-PMMA>Ni2O3-PMMA>CuO-PMMA>Fe3O4-

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poly(methyl methacrylate) (MO-PMMA) nanocomposite

PMMA

Photodegradation was dependent on dye concentration, pH and catalyst dose



Degradation pathways involving hydroxylation, oxidation and ring opening via •OH



Small by-products and excellent reusability confirms high efficiency of MO-PMMA

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Abstract

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Discharge of dyes (major industrial coloring agents ~700,000 tonnes) in environment is of concern due to their high perseverance, toxicity and carcinogenicity. Thus, effective

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elimination of organic dye (methylene blue) was carried out by poly(methyl methacrylate) (PMMA) incorporated metal oxide nanocomposites. Spherical and semi crystalline Fe3O4PMMA, ZnO-PMMA, CuO-PMMA and Ni2O3-PMMA were self-assembled via green route

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employing Sapindus mukkorossi (Plant extract). At optimised conditions (dye conc: 2 mg L-1; catalyst: 80 mg: neutral pH) MO-PMMA showed maximum degradation efficiency (90-99%; t1/2=5.1-5.6 h) than that of individual MO (74-80%; t1/2=5.8-6.8 h) credited to improved thermal stability and surface area via incorporation of MO into PMMA matrix. Like MO, highest degradation with ZnO-PMMA (99%; Xm=0.135 mg/g) followed by Ni2O3-PMMA

(98%), CuO-PMMA (93%) and Fe3O4-PMMA (90%) could be attributed to its high surface area (85.32 m2g-1) and least zeta potential (-22.5 eV). Adsorption of MB over catalyst was statistically significant with Langmuir isotherms (R2: 0.99 and p value: 0.0005) and first order kinetics with greatly reduced half-life. Comparatively higher degradation in sunlight than dark, and involving hydroxylation, oxidation and ring opening clearly reinforced

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boosted oxidation of MB by •OH. Moreover, reduction in degradation (50-40%) in presence of •OH scavengers supported the photocatalytic activity of nanocomposites. MB was

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degraded into minor non-toxic by-products such as (Z)-hexa-3,5-dien-1-ol and (Z)-buta-1,3dien-1-ol and benzoquinone. Overall, by virtue of greater active sites, high surface activity

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and semiconducting nature, the as-synthesized MO-PMMA photocatalyst is a promising,

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recyclable (n=10) and eco-friendly panorama in the treatment of organic- pollutants in water

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and wastewater-treatment.

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Keywords: Metal oxides-PMMA nanocomposites, photocatalysis, water, dye removal

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Introduction

In the few decades, the environmental concerns caused by recalcitrant toxic pollutants and

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hazardous industrial effluents have become major public issues[1-5]. Being old use of

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organic dyes for coloring the items, they are still massively produced from textile and paper industries processes. There are nearly 10,000 types of dyes out of which, more than 700, 000 metric tons of dyes are commercially available[6-9]. Almost 40% of dye is estimated to be

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consumed [10] and at the end of dyeing procedure, the unfixed portions (~60%) of dye with the large disbursed dyeing bath generated enormous volume of contaminated discharge [11]. Dye containing wastewater is being recognized as chief source for contaminating aquatic bodies with adverse effect even at trace amount [12]. Most of synthetic dyes are toxic (a few are carcinogenic) as well as difficult to degrade and produced undesirable color to water [12-

15]. Extensively used toxic methylene blue (MB) is a cationic thiazine dye for photocatalytic and industrial studies. It has many uses like colorants, photosensitizer, an antioxidant, an antiseptic, a stain for fixed and living tissues [12-13, 16]. Since it rapidly crosses cell membranes it could accumulates (5–10 mg/kg) in parathyroid glands and central nervous system [17-19]. On inhalation, MB causes problems in breathing whereas intake via oral

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cavity creates a scorchingimpression and might cause sickness, plentifulperspiring, cerebralmisperception and methemoglobinemia [20-21]. In view of omnipresence coupled

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with toxicity of the dye and related chemicals, the development of efficient removal techniques (low-cost and/or easy to handle) are indispensable.Towards dye removal efforts,

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adsorption, filtration, coagulation and biodegradation have been developed and applied in

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water treatment industry [22-24]. Most popular method adsorption could not completely

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eliminate these harmful textile dyes from the environment. Therefore, photocatalytic

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degradation involving transition metal oxides (TMOs) have been emerged as successful technologies for waste water removal. The most accepted catalyst for MB removal isZnO or

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Cu, Ag doped ZnO, TiO2 alone or with other additives like H2O2 or UV source [25-26]. However, the drawback of TiO2 is its cost, large band gap and limited photosensitivity within

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ultra violet region [27-29]. Consequently, consideration has been moved to new-fangled and cost-effective low-bandgap catalysts that can perform in solar spectrum (visible light).

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Besides, photocatalytic efficiency of TMO could be improved by coupling/doping or deposition on the support likes chitosan, graphene and methyl methacrylates [30-31]. Since,

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the unaccompanied metal oxides nanoparticles liberally dispersed in water media suffer poor recovery and reusability, which could limit their catalytic efficiency [32]. Gan et al. [33-34] synthesized Konjac glucomannan/graphene oxide hydrogel and magnetic CoFe2O4/graphene nanocomposites for improved catalytic adsorption of dyes. Carbon aerogel supported copper oxide was used in ozonation of dyeing stuff with 46% COD removal after 60 min [35-36].

Polystyrene-schiff

base,

GO-polymer,

sandwiched

Fe3O4/Carboxylate

GO,

metal

nitride/carbon-gold nanocomposites showed preferable catalytic efficiency in contaminants removal [37-39]. As well, mesoporous polymeric micelle assembly of TiO2/SiO2 hybrid films [40]

concluded the highly improved photocatalytic activity of the catalysts upon their

combination with some mesoporous support. Poly(methyl methacrylate) (PMMA) a

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commonly used thermoplastic matrix is tough, robust, and light material with density of 1.17–1.20 g/cm3[30,31] or brash-resistant alternative and has very good impact strength

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which is even higher than both polystyrene and glass [41-42]. The PMMA film is a nonspongy solid and low-cost, is stable at elevated temperatures with high pH-values. PMMA

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get swale and dissolves in a lot of organic solvents but has poor resistance to many chemicals

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because it has ester groups that easily hydrolysed [43]. The mixing or interaction of PMMA

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with metal oxides provided the composites of high mechanical strength and electro-thermal

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stability [44]. Moreover, PMMA improved UV-light absorption and visible light transparency along with storage modulus of material [45]. Polymer nanocomposite based on PMMA and

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MO are—cerium doped magnetite (Fe3O4)/PMMA and PMMA/ZnO that extremely useful heterogeneous and recoverable catalysts [46-47].Those composites are effectively used for

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UV protecting films and sheets including advanced characteristics materials [48]. PMMA provided stability, surface area to materials due to which pollutant adsorbed easily on

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materials and •OH may get easy access for degradation. Concerning these advantages, synthesis of MO-PMMAs by advanced green methods based on biogenic source is highly

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appreciating. Of late, to avoid the use of hazardous and toxic solvent and reagents, green source like plants or biogenic supplies are in great demand for manufacturing of a number of technological materials and compounds. In view of this, synthesis of different nanocomposites of MO/PMMA— Fe3O4-PMMA, ZnO-PMMA,CuO-PMMAand Ni2O3PMMA were carried out using Sapindusmukkorossi(natural surfactant) and water. S.

mukorossi containing saponins and polyphenols is a commonly found plant in India. To avoid environmental toxicity and increase bulk fabrication, natural sources preferably plant based extract must be used. Along with control in morphology and size, phytochemicals greatly helped in manufacturing of nano-sized particles. Later, the as-prepared nanocomposites were evaluated for photocatalytic efficacy in degradation of toxic MB dye from spiked water as to

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represent wastewater exposed to natural sunlight. To avoid the environmental accumulation of TiO2 other alternative substances such as Fe3O4, ZnO, CuO and Ni2O3 were chosen.

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Moreover, selected metals are relatively less-toxic and also biocompatible in nature.CuO (1.2 eV) a p-type semiconductor have shown many attractive properties of different morphologies,

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low cost, non-toxicity and easily grown on various substrates [48-50]. NiO band gap varies

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from 3.6 eV to 4 eV have been used in the fabrication of nanodevices such as energy storage

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devices, gas sensors, dye-sensitized solar cells, and as an optical active counter-electrode tool

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[51]. The selection of Fe3O4 was based on their magnetic character, safe and green nature. To enhance the mechanical strength and surface area along with compacting the size and guard

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the metal from corrosion, MO-incorporated PMMA nanocomposites was synthesized via green and simple approach. Under sunlight irradiation, concentration of target, catalyst dose,

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suitable pH and kinetics were examined for effective removal of MB. The properties including size, morphology and chemical composition of MO-PMMA nanocomposites were

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confirmed through PXRD, FE-SEM, and FTIR. Adsorption isotherm and degradation pathways were explored in order to comprehend the adsorbing behavior and types of

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metabolites or mineralization occurred via catalytic potential of MO-PMMA nanocomposites. To the best of our knowledge, preparation and photocatalytic efficiency of metal oxide incorporated PMMA nanocomposites involving S.mukrossi has not been reported. Study has engineering significance of preparation of efficient nanophotocatalyst via cheap and green

method and catalytic degradation of organic dye under sunlight i.e., no involvement of toxic reagents or high energy radiation; UV-light (artificial irradiation). 2. Material and Methods 2.1 Reagents

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Zn(NO3)2, Cu(NO3)2, Ni(NO3)2, Anh.FeCl3, NaOH, Ammonium peroxydisulfateand Methyl Methacrylate (MMA) used in present study were of analytical grade and procured from

Merck (Germany). All solutions were prepared using deionized water. Plant extract (10mg

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mL-1) was prepared by crushing the dried leaves of S.mukorossi. Characterization of

nanocomposites were carried by PAN analytical X-PRT PRO instrument (Netherland), FT-

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IR Agilent (USA), FE-SEM Quanta 200 FEG, TECNAI GII, Malvern Zetasizer (Nano ZS),

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while for degradation studies, UV Spectrophotometer (Agilent Pro) and gas chromatograph

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(GC 1300) coupled with mass spectrometer (TSQ8000) were used. Details of instrumentation

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are given in supporting information.

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and adsorption isotherms (Langmuir, Freundlich, Temkin, Sip and D-R) used in present study

2.1 Design of experiment for green synthesis of MO/PMMA nanocomposites

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Initially, colloidal solution of metal salt (0.56g) and S.Mukkorossi(0.12g) was formed in 25 mLof deionized water. To this, ammonium peroxydisulfate (0.12 g) was slowly added and

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ultrasonicated for 15 minute followed by in-situdrop wise addition of MMA (5 mL). Further, ammonium hydroxide (5mL) was added to the above mixture and black processor solution was refluxed with stirring at 150 ₒC for 4 h. Finally, obtained product wasallowed to cool,

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washed and dried at 50 0C for 12 h. The possible reaction mechanism for synthesis of MOPMMA is illustrated in Figure 1. 2.2 Design for degradation studies of dye The photodegradation of MB dye using different MO/PMMA was performed in water containing dye. The average temperature (C) and light intensity (W/m2) were 33±1.9and

458±189 W/m2.Photodegradation was evaluated as per the followings: (1) dipping 25-125 mg of catalyst into a 15 mL vial. (2) Addition of 10 mL of dye solution (2–10 mg L-1) at different pH (5-9) (3) For the kinetics study, the samples were kept under sunlight and the supernatant was withdrawn at varying time breaks (4) For adsorption isotherms of the dye, static adsorption proceeded for 3 h to reach the apparent adsorption equilibrium was recorded. In

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order to calculate standard deviation and reproducibility of data, each sample of MBphotodegradation were prepared as triplicates. The % degradation of MB was determined

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from the equation i.e., (Ci-Ct)/Ci×100, where Ci and Ct were initial and final concentration,

respectively. On dissolving in water the blue solution appears with characteristic

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spectrophotometric absorbance at 665 nm. Identification of possible degradation byproducts

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after quantitative analysis of dyedegradationwas ascertained by GC-MS analysis.Sigma Plot

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ver. 10.0 (SPSS) was used for the statistical analysis.On the basis of the real results,

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degradation modes of dye have been proposed. Results and Discussion

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FE-SEM

The FE-SEM images of all the MOs/PMMA nanocomposites that uniformly distributed ZnO-

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PMMA, Ni2O3-PMMA, CuO-PMMA nanocomposites were spherical-spirals containing MO as core bounded with PMMA matrix while fine powder of Fe3O4-PMMA was obtained

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(Figure 2). Energy Dispersive Spectroscopic (EDS) analysis was performed for elemental composition of nanocomposites. C, S, O and Cu showed weight % of 50.80, 0.98, 39.45 and

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8.77, respectively, in CuO-PMMA. ZnO-PMMA nanocomposite were found to contain 66.78%, 30.58 and 2.64 for C, O and Zn, respectively. C, S, O and Fe were found with 9.40%, 4.00%, 23.40% and 63.19%, respectively, in Fe3O4-PMMA whereas, in Ni2O3PMMA, the C, O and Ni showed weight % of 65.63%, 32.46% and 1.91%, respectively. On the other hand, MOs exhibited different morphologies and showed the presence of O and

respective metal only [8]. Further, nanoclusters of MO-PMMA were of large size (10-1000 nm) in compared to unaccompanied MOs with size of <10-100 nm (Figure 1S) clearly revealed the successful merging of PMMA around MO. PXRD

The comparison of PXRD spectra of MO-PMMA semi-crystalline composite (clear and mixed

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broad, sharp peaks) and respective MO (sharp peaks) revealed that distribution of PMMA in

the lattice of metal oxides decreased the crystallanity led to fairly amorphous nanomaterials.

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The difference in peaks clearly indicate the formation of MO-PMMA nanocomposites (Figure 2S) while, absence of secondary peaks indicates their purity (Figure 3). The PXRD data was found to be concordant with the ICSD values (ZnO-PMMA: Card No. 98-009-5687;

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Ni2O3-PMMA: Card No. 98-025-1316; CuO -PMMA: Card No. 98-005-8099; Fe3O4-PMMA:

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Card No. 98-002-3105 and 98-015-8741). The 2θ and d values are given in Table 1S.

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Reusability of nanocomposites was also tested with the help of PXRD by analyzing sample of

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first and last run.

FTIR

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The peaks in FT-IR spectrum of synthesized MO-PMMA nanocomposites confirmed the bonding/functional groups in their formation (Figure 4). Common peaks in all MO-PMMA

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were obtained at 1,150 cm−1 (C–O–C stretching), 1389 cm−1, 750 cm−1 (α-methyl), 987 cm−1 (absorption vibration of PMMA), 1,727 cm−1 (acrylate carboxyl group), 1,437 cm−1 (–CH3

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bending) and 2,954 cm−1 (C–H stretching). Moreover, the slight shift of peaks with decrease in intensity obtained in nanocomposites advises the interaction of MOs and PMMA. The characteristic peak of the respective metal oxides was also observed in the spectra of each composite (Cu-O: 482 cm-1; Zn-O: 478 cm-1; Fe-O: 537 cm-1 and Ni-O: 482 cm-1).

From above results, it could be concluded that the designed structure for prepared spirals MO-PMMA nanocomposite consist of immobilized MO nanoparticles in the polymeric layers i.e., incorporated in the plastic matrix of PMMA as explained in figure 1. MO-PMMA is assumed to stabilized by internal forces between the MO and the oxygen of acrylic group of PMMA. Cao et al. [47] explained the shape of Fe3O4-PMMA having large number of

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congeries with the tiny Fe3O4 nanoparticles dispersed in the polymer matrix. The rough

surface seen on the MO-PMMA nanocomposites is due to the small MO particles [38].

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Similar irregular spherical MO-PMMA was obtained in other studies [47, 63]. Moreover, the other interaction force such as chemical bonds formed by the hydroxyl groups on the surface

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of MO and the carboxyl groups on the chain of PMMA could result in its formation (Figure

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1). BET Surface Area

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The BET surface area of ZnO-PMMA nanocomposite was found to be 85.32 m2g-1which was

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higher than that of Ni2O3-PMMA (80.132 m2g-1), CuO-PMMA (55.291 m2g-1) and Fe3O4-

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PMMA (52.763 m2g-1) nanocomposites (Figure 3S a). BET surface area of the nanocomposites was obtained by gas isotherms. The obtained results were also compared

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with the unaccompanied metal oxides surface area (ZnO: 12.099 m2g-1; Ni2O3: 35.711 m2g-1;

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CuO: 17.629 m2g-1; Fe3O4: 8.992 m2g-1;)(Figure 3S b).Comparatively, high specific surface area of MO-PMMA nanocomposite suggested their greater activity and thus catalytic potential.

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Photodegradation studies of dye The photocatalytic efficiency of synthesized nanocomposites was evaluated for the dye degradation at varying concentration (2-10 mg L-1), catalyst dose (25-125 mg) and pH (5-9) under sunlight (Figure 5). The decrease in dye concentration was obtained at lowest concentration of MB (2 mg L-1), 80 mg of dose of nanocomposite at neutral pH under

sunlight. It is important to mention here that while optimizing each parameter, other factors were kept constant. Under optimized conditions, ZnO-PMMA showed highest photocatalytic removal capacity (99%) followed by Ni2O3-PMMA (98%)>CuO-PMMA (93%)> Fe3O4PMMA (90%). While the unaccompanied MO showed comparatively lesser degradation ability (ZnO: 80%; Ni2O3: 78%; CuO: 76%; Fe3O4: 74%) at optimized conditions and under

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sunlight (Figure 4Sa). To verify the photo-activity of investigated MO-PMMA nanocomposite, studies were also carried out under dark. Lower removal of MB (46-55%)

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with MO-PMMA and MO (38-45%) under dark exposure was due to only adsorption (Figure 5). Under natural sunlight, catalyst became photo-active (excitation of electron from VB to

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CB and formation of •OH) due to availability of sufficient energy for photodegradation [52-

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53]. Compared to the constituents, MO-PMMA has higher surface area which made the

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composite be able to capture the MB in aqueous solution more easily through pi-pi stacking and ionic interaction.

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Maximum degradation of dye achieved at 2 mg L-1 (Figure 5a), might be attributed to the fact

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that greater number of active site on the catalyst surface are available for the degradation at lowest pollutant concentration [54]. Moreover, the surface area of catalyst is such that it

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could adsorb limited number of molecules of MB, beyond this limit the adsorption hence degradation decreases. In addition to this at higher dye concentration the molecules of dye

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may absorb the light entering into the mixture and hence its availability for the catalysts activity decreases [55].

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Degradation of dyeincreased in a sharp way with gradual addition of catalysts dose equal to 100 mg followed by declination (Figure 3b). Invariably, degradation of organic pollutants depend on enough active sites of catalysts that increases consecutively with initial increase in dose and produced bulk of •OH radicals for rapid degradation of the investigated PAHs [55].

Further, decrease in the initial rate might be due to shrinkage of total active surface area resulted from deactivation of catalyst by pile-up with other molecules [56]. Moreover, light penetration was prevented because of screening effect caused by accumulation of solid particlesof excess catalyst [57]. Other than this agglomeration of catalyst particles in a limited volume of vessel may also cause the decrease in degradation at high dosage [58]. Therefore,

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optimum amount of the catalyst is required for augmenting photodegradation via generation of of e-/h+ pairs and subsequenthuge number of •OH radicals.

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Dye sequestration significantly depends upon the pH of the reaction mixture (Figure 5c). The

degradation of MB was enhanced with neutral pH and then suppressed (Figure 5c).Literature

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reveals that PMMA is unreactiveunder neutral medium and cannot be hydrolyzed during the

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reaction [59].The photocatalytic efficiency of catalysts has crucial effect due toacid-base properties of catalyst/pollutant surfaces.Under acidic pH the holes are deliberated as the main

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oxidation species, while •OH are considered as the chief species at neutral or basic pH. However, in basic medium repulsion between the negative charged surface of photocatalyst

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and the OH- affects the photodegradationefficiency [58]. Agglomeration of catalyst under acidic medium reduces the dye removal activity by limiting the surface area [55]. Moreover,

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at lower pH values, the hydrogen ion in the solution tended to integrate with the COO- on the PMMA surface which hindered the adsorption of MB dye . Suchissues might be absent at

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neutral pH and resulted in fast degradation of MB over catalyst. Furthermore, the point of zero charge (Pzc) and the surface charge properties of MO-PMMA changes with change in

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pH of the solution. Pzc for MO ranges in 6.2 to 8 [8]. Therefore the zeta potential, of the MOPMMA at neutral pH was recorded and as per established fact that surface charge can greatly influence the stability of nanoparticles through the electrostatic repulsion between the particles. The particles might be stabilized due to high negative value of zeta potential that suppressed the tendency of particles to get aggregated [52]. The zeta potential of ZnO-

PMMA, Ni2O3-PMMA,CuO-PMMA and Fe3O4-PMMA i.e. -22.5eV, -21.5, -21.3 and -20.6 mV, respectively were measured at pH~7 (Figure 6). In order to stop aggregation high absolute zeta potential value stipulates a highrepulsive force among the nanoparticles. The highest surface activity of ZnO-PMMA attributed due to high zeta potential value among

PMMA could be held responsible for its interaction with the cationic MB. Reaction kinetics

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other nanocomposites used. Moreover, it is supposed that the oxygen on the acrylic group of

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In order to define the kinetics of photocatalysis reaction, exposure time depended degradation of MB was studied with 80 mg of MO-PMMA at pH~7. During the reaction concentrations

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of MB decreased to 60% within half an hour whereas, only 25% removal was obtained with

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unaccompanied MO nanoparticles within half an hour (Figure 4Sb). The kinetics linear

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simulation curves of photocatalytic degradation over different composites should follow the

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Langmuir-Hinshelwood apparent first-order kinetics model (Figure 7a). Maximum sequestration with ZnO-PMMA was supported with highest k-value (0.1349). The dye

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concentration remaining after 30 minutes was (0.78±0.0014), (0.83±0.0015), (0.85±0.0013) and (0.91±0.0017) mg L-1 with ZnO-PMMA, Ni2O3-PMMA, CuO-PMMA and Fe3O4-PMMA,

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respectively. The obtained results were also confirmed by the total organic carbon (TOC) analysis (Figure 7b). The carbon content remained after 30 min was 60%, while 40% MB

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was converted into CO2. In comparison to blank, half-life of MB was reduced several times indicating the elevated photo-catalytic ability of nanocomposite (Table 1).

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Here almost 90% degradation is observed with all the MO-PMMA nanocomposites with in 3 h. However, the same amount of unaccompanied metal oxides were able to degrade almost 80% of MB within 180 minutes (Cr2O3 (88.24%) >ZnO (87.96%) >CuO (86.86%) >NiO (85.89%)> Co3O4 (80.35%)) [8].The working mechanism of MO-PMMA might be explained (Figure 8) as-

MO-PMMA + hv → MO(e−+ h+)-PMMA ………(1) H2O + h+→ OH. + H+ …….(2) OH− + h+→ OH• ……(3)

MB + OH•/ O2•/ h+→ degraded products or mineralization …..(5)

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e− + O2 → O2•− ……(4)

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Overall, similar trends in MB degradation at concentration, dose and neutral pH has been

observed, but the degradation ability observed with MO-PMMA could be attributed to the

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large surface area provided by the PMMA, while the main semiconducting property is of

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metal oxides [8-9].

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Various adsorption isotherms were evaluated for adsorption analysis of dye on MO-PMMA

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nanocomposites like Langmuir, Freundlich, Temkin, Sips and Dubinin–Radushkevich (DRK) (Figure 5S). Most significant data was obtained with Langmuir isotherms (R2 =0.996; p-value

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= 0.0001)(Figure 9). Xm(maximum amount of MB adsorbed; mg/g), kL (Langmuir adsorption constant; dm3/mol) and R2 values were witnessedas perin the order: ZnO-PMMA(0.135; 0.6;

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0.99) >Ni2O3-PMMA (0.120; 0.6; 0.99) >CuO-PMMA (0.115; 0.69; 0,99) >Fe3O4-PMMA Highest value of XmforZnO-PMMA indicated its high adsorption

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(0.105; 0.933; 0.99).

capacity due to highest surface area and negative zeta potential. Photocatalyticdegradation products of MB using MO-PMMA nanocomposite

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The reaction mixture of neutral pH yielded colourless productsas revealed by the GC-MS analysis. The GC-MS spectra shows formation of several smaller products and the degradation pathway of MB have been illustrated as Figures 10 and 11. Hydroxyl radical may first attack the C–S + =C groups in MB, along with imino group cleavage of this might have generated short lived intermediate named as 3-(3-(dimethylamino) cyclohexa-2,4-dien-1-

yl)sulfinyl-N,N-dimethylbenzene-1,4diamine [12].The NH2 in the intermediate might be substituted with the OH radical, further oxidation along with ring opening of this may form two smaller by-products. Those by-products were identified as (Z)-hexa-3,5-dien-1-ol (1; m/z=98) and phenol (2; m/z=94) (Figure 6S). The oxidation of 1 may result into formation of (Z)-buta-1,3-dien-1-ol having m/z value 71, while the second compound may undergo

products

upon

extensive

hydrolysis

along

with

oxidation

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hydrolysis along with dehydrogenation to formbenzoquinone (2a; m/z=108). These smaller may

result

into

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mineralization.Mineralization was confirmed by the total organic carbonresults of the ultimate sample (Dye: 2 mg L-1; Catalyst dose: 80 mg; ZnO-PMMA). After 3 hours 70% of

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the total organic carbon content was removed (Figure 7b). The little amount of organic

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content left might be due to the presence of smaller by-products as explained in degradation

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pathway [56]. The comprehensivesequestrationmode has been illustrated as Figure 10. The

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by-products of MB treated with MO-PMMA nanocomposites were slightly different (lesser number of by-products) than previously reported only with MO.With metal oxide various by-

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products with large molecular mass like 3,7-bis(dimethylamino)phenothiazin-5-ium (m/z=285); 6-formyl-3,4-dihydroxy-5,8-dioxo-5,8-dihydrophthalene-2-sulphonic acid (m/z=

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295); 3,7-bis(dimethylamino)-9-formyl-4aH-phenothiazine-1-carboxylic acid) (m/z=355) have been reported earlier. Some similar products with present study have also been found

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like phenol, benzoquinone etc. This might be due to more surface area of the composite material that will facilitate the generation and attack of OH radical on MB [56].

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Since hydroxyl radicals play vital role in dye degradation, thus its presence was investigated. Batch studies were carried out with the ethanol being hydroxyl scavenger, declination of about 40-50% in degradation was obtained with all the samples. Consequently, the presence of hydroxyl radicals in the degradation mechanism could be justified. Comparison with other methods

A literature comparison was made to evaluate the efficacy of MO-PMMA with other studies carried out for removal of MB. Tabulated data clearly revealed the potential of coupled nanoparticles (Table 2). Being semiconductor and worth adsorbant, TiO2 alone or paired with other materials could completely decolorize the dye, yet UV source is required in these cases. The gel nanocomposites (Konjac glucomannan/GO hydrogel and mesoporous carbon aerogel

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supported copper oxide) removed dye via adsorption [33, 35-36]. MO incorporated

nanocomposites (Fe3O4/Carboxylate graphene oxide, metal nitride/carbon nano-layered

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materials-gold) showed preferable catalytic adsorption and photocatalytic degradation [37-38]. However, currently synthesized nanomaterials of transition metals (ZnO, CuO, Co3O4, NiO

U

and Cr2O3, KCuHCF and Ag) have virtue of dye removal in short span of time that too in

N

natural sunlight. Moreover, presences of PMMA in catalyst solve many problems related to

A

bioaccumulation of metal atoms on earth and enhance the surface area, stability and

M

durability of the catalyst for multiple uses. The green synthesized MO-PMMA nanocomposites also successfully removed the 99% of dye in natural sunlight within 3 hours.

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Moreover, in nanocompositesmetal oxides semiconductors undergo electronic excitation, produced multiples of •OH radicals and can easily access to the organic pollutants adsorbed

PT

on PMMA. The use of S.mukrossi stabilized MO-PMMA is also economical, green (sunshine based) and rapid. Moreover, exploration of next-gen nanomaterialsshould be upheldin order

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to evade the enrichment of traditionally used materials. Reusability of the catalyst

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The test of reusability of used nanocomposite during the reaction has been performed. It was observed that the nanocomposite was reusable up to 10 times without significant change in the structure as revealed by the XRD analysis. The data was also found consistent in respect to degradation of dye (Figure 13, 13b). This confirmed the recyclability and reusability of the catalyst approximately 99% of degradation in first run and 96% in 10th run (Figure 13a).

Conclusions A facile and newgreen route involving S. Mukorossi (plant surfactant) for synthesis of different MO-PMMA was successfully established. The particles were formed almost spherical and of semicrystalline nature. The benefit of current performance smears in its trouble-free reproducibility, cost-effectiveness and eco-friendliness. The prepared self-

IP T

assembled composites show high degradation efficiency for dyes under neutral conditions.

ZnO-PMMA with high surface area (85.32 m2g-1) and zeta potential (-22.5 eV) degraded 99%

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of the MB followed by other MO-PMMA. The high adsorption (%) with ZnO-PMMA (0.135 mg g-1) is probably due to its higher acidity than other MO-PMMA. Nanocomposites were

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easily keyed up indaylightthat initiated the reaction of H2O/O2 with the pair of electron and

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hole producedover the catalyst. Due to this the so formed•OH were capable to degrade MB

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into smaller and safe by-products ((Z)-hexa-3,5-dien-1-ol and (Z)-buta-1,3-dien-1-ol and

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benzoquinone), further OH radical formation was reduced upon introducing OH radical scavengers.In addition to this, the reusability (n=10) of the nanocompositewillmake method

ED

comparatively cheap. The results seem to new support for constructing new self-assembly nanostructures to develop promising composite nanomaterials.

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Acknowledgements

Authors are thankful to DST-FIST New Delhi for providing the equipment (UV-VIS

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spectrophotometer) used in characterization of the samples. Authors are also thankful to MNIT Jaipur for Zeta potential analysis and IIT, Roorkee for FE-SEM analysis.

A

References

[1]Rani M. Studies on decay profiles of quinalphos and thirampesticides.Ph.D Thesis, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India, Chapter 1; 2012:5

[2]Rani M, Shanker U. Degradation of traditional and new emerging pesticides in water by nanomaterials: recent trends and future recommendations. Int J Environ SciTechnol 2017:134:DOI 10.1007/s13762-017-1512-y [3]Rani

M,

Shanker

U.

Removal

of

carcinogenic

aromatic

amines

by metal

hexacyanoferratesnanocubes synthesized via green process. J EnvChemEngg 2017; 5: 5298-

IP T

5311.

[4]Rani M, Shanker U. Effective adsorption and enhanced degradation of various pesticides

SC R

from aqueous solution by prussian blue nanorods. J EnvChemEngg 2018;6:1512-1521

[5]Rani M, Shanker U. Advanced Treatment Technologies, In: C. M. Hussain (ed.),

U

Handbook of Environmental Materials Management, Springer International Publishing AG

N

2018, https://doi.org/10.1007/978-3-319-58538-3_33-1 (2018).

A

[6]Prillo S, Ferreira ML, Rueda EH.The effect of pH in the adsorption of Alizarin and

M

Eriochrome Blue Black R onto iron oxides.J Hazard Mater 2009; 168: 168. [7]Kurepa J, Paunesku T, Vogt S, Arora H, Rabatic BM, Lu J, Wanzer MB, Woloschak GE,

ED

Smalle JA. Uptake and distribution of ultrasmallanatase TiO2 Alizarin red S nanoconjugates in Arabidopsis thaliana. Nano Lett 2010;10:2296-2302.

PT

[8] Shanker U, Jassal V, Rani M. Catalytic removal of organic colorants from water using some transition metal oxide nanoparticles synthesized under sunlight. RSC Adv

CC E

2016;6:94989.

[9]Shanker U, Jassal V, Rani M. Degradation of hazardous organic dyes in water by

A

nanomaterials. Environ ChemLett 2017; 15: 623-642 [10] Rosa JM, Fileti AMF, Tambourgi EB, Santana JCC. Dyeing of cotton with reactive dyestuffs: the continuous reuse of textile wastewater effluent treated by ultraviolet/hydrogen peroxide homogeneous photocatalysis. J Clean Prod 2015; 90: 60-65.

[11] Allegre C, Moulin P, Maisseu M, Charbit F. Treatment and reuse of reactive dyeing effluents. 2006; Membr Sci http://dx.doi.org/10.1016/j.memsci.2005.06.014. [12]Houas A, Lachheb H, Ksibi M, Elaloui E, Guillard C, Herrmann JM. Photocatalytic degradation pathway of methylene blue in water.ApplCatal B: Environ 2001; 31: 145. [13]Bedekar PA, Kshirsagar SD, Gholave AR, Govindwa SP. Degradation and detoxification

bioreactors by novel microbial consortium-SB. RSC Adv 2015; 5: 99228

IP T

of methylene blue dye adsorbed on water hyacinth in semi continuous anaerobic–aerobic

SC R

[14]Jassal V, Shanker U, Kaith BS. Aeglemarmelos mediated green synthesis of different

nanostructured metal hexacyanoferrates: activity against photodegradation of harmful organic

U

dyes. Scientifica 2016;2016: 1–13

N

[15]Jassal V, Shanker U, Kaith BS, Shanker S. Green synthesis of potassium zinc

A

hexacyanoferratenanocubes and their potential application in photocatalytic degradation of

M

organic dyes. RSC Adv 2015; 5: 26141-26149

[16] El Hajj Hassan MA, El Jamal MM. Kinetic Study of the Electrochemical Oxidation of

ED

Methylene Blue with Pt Electrode Portugaliae.ElectrochimicaActa 2012; 30: 351-359 [17] Peter C, Hongwan D, Kupfer A, Lauterburg BH. Pharmacokinetics and organ

PT

distribution of intravenous and oral methylene blue.Eur J ClinPharmacol 2000; 56:247–50 [18]Marana R, Catalano GF, Muzii L: Salpingoscopy. CurrOpinObstetGynecol 2003;

CC E

15:333–6

[19]Kuriloff DB, Sanborn KV. Rapid intraoperative localization of parathyroid glands

A

utilizing methylene blue infusion.Otolaryngol Head Neck Surg 2004;131:616–22 [20]Ghosh D, Bhattacharyya KG. Adsorption of methylene blue on kaolinite.Appl Clay Sci 2002;20: 295-300 [21]Tan IAW, Ahmad AL, Hameed BH. Adsorption of basic dye using activated carbon prepared from oil palm shell: batch and fixed bed studies.Desalination 2008;225:13-28

[22]Robinson T, McMullan G, Marchant R, Nigam P, Remediation of dyes in textile effluent: a critical review on current treatment technologies with a proposed alternative. BioresourTechnol 2001;77:247−255 [23]Tripathi KM, Tyagi A, Sonker AK, Sonkar SK, Waste derived Nanocarbons: A Cleaner Approach towards Water Remediation. In Nanomaterials for Water Remediation: Carbon-

IP T

Based Materials; SmithersRapra Publication, 2016; 1.

[24]Singh A, Khare P, Verma S, Bhati A, Sonker AK, Tripathi KM, Sonkar SK. Pollutant

SC R

Soot for Pollutant Dye Degradation: Soluble GrapheneNanosheets for Visible Light Induced Photodegradation of Methylene Blue. ACS Sustainable ChemEng 2017; 5: 8860−8869

U

[25]Kong JZ, Li AD, Li XY, Zhai HF, Zhang WQ, Gong YP, Li HWu D. Photo-degradation

N

of methylene blue using Ta-doped ZnO nanoparticle. J Solid State Chem 2010;183:1359–

A

1364.

M

[26]Vanaja M, Paulkumar K, Baburaja M, Rajeshkumar S, Gnanajobitha G, Malarkodi C, Sivakavinesan M, Annadurai G. Degradation of methylene blue using biologically

ED

synthesized silver nanoparticles. BioinorgChem App 2014;2014:742346–742353.

PT

[27]Kuvarega AK, Mamba BB. TiO2-based Photocatalysis: Toward Visible Light-Responsive

CC E

PhotocatalystsThrough Doping and Fabrication of Carbon-Based Nanocomposites. Crc Cr Rev Sol State 2017; 42: 295-346 [28]Rani M, Rachna, Shanker U. Metal hexacyanoferrates nanoparticles mediated

A

degradation of carcinogenic aromatic amines. Environ Nanotechnol Monitor Manage 2018; https://doi.org/10.1016/j.enmm.2018.04.005 [29]Rani M, Shanker U. Promoting sunlight-induced photocatalytic degradation of toxic phenols by efficient and stable double metal cyanide nanocubes. Environ SciPollut R 2018; doi:10.007/s11356-018-2214-9

[30]Deng C, Lin W, Agnus G, Dragoe D, Pierucci D, Ouerghi A, Eimer S, Barisic I, Ravelosona D, Chappert C, Zhao W. Reversible Charge-Transfer Doping in Graphene due to Reaction with Polymer Residues. J. Phys. Chem. C, 2014; 118: 13890–13897 [31]Sul O, Kim K, Choi E, Kil J, Park W, Lee SB. Reduction of hole doping of chemical

Nanotechnology 2016;27:505205

IP T

vapor deposition grown graphene by photoresist selection and thermal treatment.

[32]Ray C, Pal T. Recent advances of metal–metal oxide nanocomposites and their tailored in

numerous

catalytic

applications.

SC R

nanostructures

J Mater Chem A 2017;5: 9465-9487

U

[33] Gan L, Shang S, Hu E, Wah C, Yuen M, Jiang S. Konjac glucomannan/graphene oxide

N

hydrogel with enhanced dyesadsorption capability for methyl blue and methyl orange. Appl

A

Surf Sci 2015; 357: 866–872

M

[34] Gan L, Shang S, Wah C, Yuen M, Jiang S, Hu E. Hydrothermal synthesis of magnetic CoFe2O4/graphenenanocomposites with improved photocatalytic activity. Appl Surf Sci

ED

2015; 351: 140–147

[35] Hu E, Shang S, Tao X, Jiang S, Chiu K. Regeneration and reuse of highly polluting

PT

textile dyeing effluents through catalytic ozonation with carbon aerogel catalysts. J Clean

CC E

Prod 2016; 137: 1055-1065

[36] Hu E, Wu X, Shang S, Tao X, Jiang S, Gan L. Catalytic ozonation of simulated textile dyeing wastewater using mesoporous carbon aerogel supported copper oxide catalyst. J Clean

A

Prod 2016; 112: 4710-4718 [37] Guo R, Jiao T, Li R, Chen Y, Guo W, Zhang L, Zhou J, Zhang Q, Peng Q. Sandwiched Fe3O4/Carboxylate graphene oxide nanostructures constructed by layer-by-layer assembly for highly efficient and magnetically recyclable dye removal. ACS Sustainable Chem Eng 2017; DOI: 10.1021/acssuschemeng.7b03635

[38] Li K, Jiao T, Xing R, Zou G, Zhou J, Zhang L, Peng Q. Fabrication of tunable hierarchical [email protected] nanocomposites constructed by self-reduction reactions with enhanced catalytic performances. Sci China Mater 2018; | https://doi.org/10.1007/s40843017-9196-8 [39] Zhou J, Gao F, Jiao T, Xing R, Zhang L, Zhang Q, Peng Q. Selective Cu(II) ion removal

IP T

from wastewater via surface charged self-assembled polystyrene-Schiff base nanocomposites. Colloid Surface A 2018; 545: 60–67

SC R

[40] Li Y, Bastakoti BP, Imura M, Hwang SM, Sun Z, Kim JH, Dou SX, Yamauchi Y. Synthesis of Mesoporous TiO2/SiO2 Hybrid Films as an Efficient Photocatalyst by Polymeric Micelle Assembly. Chem Eur J 2014; 20: 6027-6032

U

[41]Demir MM, Castignolles P, Akbey U. Wegner, G. In-situ bulk Polymerization of Dilute

N

Particle/MMA Dispersions. Macromolecules 2007; 40: 4190-4198

A

[42]Demir MM, Memesa M, Castignolles P, Wegner G. PMMA/Zinc Oxide Nanocomposites

M

Prepared by In-Situ Bulk Polymerization. Macromol Rapid Commun2006;10:763-770 [43] Hadi AN, Oleiwi JK. Improving Tensile Strength of Polymer Blends as Prosthetic Foot

ED

Material Reinforcement by Carbon Fiber. J Material SciEng 2015; 4:158 [44] Liang B, Tang S, Jiang Q, ChenC, ChenX, LiS, Yan X. Preparation and characterization

PT

of PEO-PMMA polymer composite electrolytes doped with nanoAl2O3. ElectrochimicaActa

CC E

2015;169:334-341

[45] Anzlovar A, Orel ZC, Zigon M. Polyol-mediated synthesis of zinc oxide nanorods and nanocomposites with poly(methyl methacrylate). J Nanomate 2012;2012:31 Zhang

Y,

Zhuang

S,

Xu

X,

Hu

J.

Transparent

and

UV-shielding

A

[46]

[email protected] Mater 2013;36:169-172 [47] Cao Z, Jiang W, Ye X, Gong X. Preparation of superparamagnetic Fe 3O4/PMMA nano composites

and

their

2008;320:1499-1502

magnetorheological

characteristics.

J

MagenMagen

Mater

[48]Zhang Q, Zhang K, Xu D, Yang G, Huang H, Nie F, Liu C, Yan S. CuO nanostructures: Synthesis, characterization, growth mechanisms, fundamental properties, and applications. Prog Mater Sci. 2014;60:208-337 [49] Jassal V, Shanker U, Gahlot S. Green synthesis of some iron oxide nanoparticles and their interaction with 2-Amino, 3-Amino and 4-Aminopyridines. Mater Today Proc 2016;

IP T

3:1874–1882.

[50]Jassal V, Shanker U, Gahlot S, Kaith BS, Kamaluddin, Iqubal MA, Samuel P.

SC R

Sapindusmukorossi mediated green synthesis of some manganese oxide nanoparticles interaction with aromatic amines. ApplPhysA 2016; 122: 271–282.

U

[51] Alagiri M, Ponnusamy S, Muthamizhchelvan C. Synthesis and characterization of NiO

N

nanoparticles by sol–gel method.J Mater Sci-Mater El 2012; 23:728–732.

A

[52]Shanker U, Jassal V, Rani M. Degradation of toxic PAHs in water and soil using

M

potassium zinc hexacyanoferratenanocubes. J Environ Manage 2017;204:337–348. [53]Shanker U, Jassal V, Rani M. Green synthesis of iron hexacyanoferrate nanoparticles:

ED

Potential candidate for the degradation of toxic PAHs. J Environ ChemEng 2017; 5: 4108– 4120.

PT

[54]Satheesh R, Vignesh K, Suganthi A, Rajarajan M. Visible light responsive photocatalytic applications of transition metal (M= Cu, Ni and Co) doped α-Fe2O3 nanoparticles. J Environ

CC E

ChemEng 2014;2:1956-1968

[55]Rani M, Shanker U. Removal of chlorpyrifos, thiamethoxam, and tebuconazole from

A

water using green synthesized metal hexacyanoferrate nanoparticles. Environ SciPollut Res 2018;25:10878-10893 [56]Rachna, Rani M, Shanker U. Enhanced photocatalytic degradation of chrysene by [email protected] nanocubes.ChemiEng J (2018) https://doi.org/10.1016/j.cej.2018.04.185

[57]Chiou CH, Wu CY, Juang RS. Influence of operating parameters on photocatalytic degradation of phenol in UV/TiO2 process. ChemEng J 2008;139:322-329 [58]Riga A, Soutas K, Ntampegliotis K, Karayannis V, Papapolymerou.Effect of system parameters and of inorganic salts on the decolorization and degradation of procion Hexyl dyes.Comparison of H2O2/UV, Fenton, UV/Fenton, TiO2/UV and TiO2/UV/H2O2

IP T

processes. Desalination 2007;211:72-86.

[59]Kolon AJ, Milewski A,Zdybal D, Mitko K, Laskowska E, Mielanczyk A, BaduraJB.Zinc

SC R

Sorption on Modified Waste Poly(methyl methacrylate).Materials 2017; 10: 755.

[60]Zheng F, Zhu Z. Flexible, Freestanding, and Functional SiO2 Nanofibrous Mat for Dye-

U

Sensitized Solar Cell and Photocatalytic Dye Degradation. ACS Appl Nano Mater 2018;DOI:

N

10.1021/acsanm.7b00316

A

[61]Fahel J, Kim S, Durand P, André E, Cartereta C. Enhanced catalytic oxidation ability of

M

ternary layered double 1 hydroxides for organic pollutants degradation.Dalton Trans 2016;45: 8224-8235

ED

[62] Klaysria R, Wichaidita S, Piticharoenphunb S, Mekasuwandumrong O, PraserthdamP. Synthesis of TiO2-grafted onto PMMA film via ATRP: Using monomer as a coupling agent

A

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and reusability in photocatalytic application. Mater Res Bullet 2016; 83: 640–648.

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Figure 1.Possible reaction mechanism for the formation of MO-PMMA nanocomposites in presence of leaf extract of Sapindus mukrossi.

IP T SC R U N A M ED PT CC E A Figures2. FE-SEM & EDS patterns of ZnO-PMMA, Ni2O3-PMMA, CuO-PMMA, Fe2O3PMMA nanocomposite

I N U SC R

(b)

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(d)

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(c)

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M

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(a)

Figure 3. PXRD patterns of (a) ZnO-PMMA(b) Ni2O3-PMMA (c) CuO-PMMA (d) Fe2O3-PMMA nanocomposites

I (b)

P-2

100 98

3219 2834

96

3651 3743

2360 3168

2893

2998

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ED

80 78

617

842

478

753

986

1242

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1437

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%Transmittance

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%Transmittance

3263

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%Transmittance

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%Transmittance

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(a)

1437 1242

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Figure 4. FTIR spectra of (a) ZnO-PMMA (b) Ni2O3-PMMA (c)CuO-PMMA (d) Fe2O3-PMMA nanocomposites

200

0

(a)

(b) ZnOPMMA Ni2O3PMMA CuOPMMA Fe3O4PMMA

100

Blank PMMA

80 60 40

80 60 40

4

6

8

20

10

Conc (mg L-1)

120

ZnOPMMA Ni2O3PMMA

100

CuOPMMA Fe3O4PMMA

60

80

Dose (mg)

(d) 120

100

120

140

ZnOPMMA Ni2O3PMMA

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(c)

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100

Degradation (%)

Blank PMMA

60 40

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80

60

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20

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2

IP T

0

0

Degradation (%)

CuOPMMA Fe3O4PMMA PMMA

100

20

20

80

ZnOPMMA Ni2O3PMMA

120

Degradation (%)

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120

20

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6

pH

8

10

12

M

2

0

A

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MB Sunlight

MB Dark

A

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Figure 5.Effect of (a) concentration, (b) catalytic dosage and (c) pH (d) source on degradation of MB over photocatalysts

(b)

(c)

(d)

SC R

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(a)

2.5

3.0

ZnOPMMA Ni2O3PMMA

2.5

M

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TOC (mg L-1)

Blank

2.0

1.0

0.5

0.0 0

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Ce (Remaining concentration mgL-1)

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Figure 6. Zeta potential of (a) ZnO-PMMA (b) Ni2O3-PMMA (c)CuO-PMMA (d) Fe2O3PMMA nanocomposites

50

100

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Time (mins)

1.5

1.0

0.5

0.0 150

200

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Figure 7 (a) Reaction kinetics for degradation of MB over the nanocomposites (b) TOC disappearance of MB using ZnO-PMMA with time

200

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Figure 8.Schematic representation of adsorption and photocatalyticdegradation mechanism of MB over photocatalysts

4

120

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Ce/Xe (L/g)

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Figure 9.Adsorption isotherm (a) and Langmuir adsorption model (b) for Methylene Blue treated with nanocomposites under optimized conditions (Concentration; 2 mg/L-1; pH:7; catalyst dose: 80 mg; natural sunlight)

IP T SC R U N A

A

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Figure 10.Proposed degradation pathway for the degradation of MB over ZnO-PMMA nanocomposite (Concentration; 2 mg/L-1; pH:~7; catalyst dose: 80 mg; natural sunlight).

IP T SC R U

A

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Figure 11. Representative mass spectra of the by-products formed during the degradation of MB over the nanocomposites surface. (a)

M

(b)

ZnOPMMA Ni2O3PMMA

100

CuOPMMA Fe3O4PMMA

ED

102

96

5 th Cycle

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94 92 90

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Degradation (%)

98

1 st Cycle

88

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86 84

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A

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Figure 12. (a) Reusability analysisof nanocomposites for MB degradation; (b) XRD pattern of ZnO-PMMAnanocompositephotocatalystsupto 10 cycle

Table 1: Rate constant and half-life values of methylene blue dye with MO and MO-PMMA nanocomposites at optimised conditions

0.1349 0.1321 0.1263 0.1231 0.1201 0.1114 0.1045 0.1012 0.0162

5.13 5.24 5.48 5.62 5.77 6.22 6.63 6.84 42.77

0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99 0.99

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ZnO-PMMA Ni2O3-PMMA CuO-PMMA Fe3O4-PMMA ZnO Ni2O3 CuO Fe3O4 Blank

R2

t1/2 (h)

SC R

k

A

CC E

PT

ED

M

A

N

U

Catalyst

I N U SC R

3

M

CC E

4

ED

2

Nanomaterials Properties Degradation Reference 2 -1 TiO2−SiO2 SiO2 pressed into TiO2 layers with ~10nm size and 57.97 mg g65% in sunlight [60] surface area. ZnO, CuO, Tube shaped ZnO, rods of CuO, hexagonal Co3O4, extremely 88% in sunlight [8] Co3O4, NiO small NiO and Cr2O3 with surface area ZnO: 12.099 m2g-1; and Cr2O3 Ni2O3: 35.711 m2g-1; CuO: 17.629 m2g-1; Fe3O4: 8.992 m2g-1. Co3Cu1Al2 Highly crystalline and agglomerated hydrotalcites plates, 50 Complete [61] 2 -1 mg g aurface area. degradation in H2O2 TiO2 Morinda tinctoria leaf extract synthesised TiO2 Decolorized in 60 [12] mins in UV light TiO2-PMMA TiO2 patterned PMMA with 21.4 mg2 g-1 surface area Decolorized in UV [62] light 2 -1 KCuHCF <50 nm sized with 95.32 mg g surface area 95% in sunlight [14] Ag 72% in sunlight [26] Konjac 3D porous network structure with poresizes between 50 and 200 Completely [33] glucomannan/ μm immersed 50mg graphene MB oxide hydrogel CoFe2O4/grapheCoFe2O4 loaded on the sheet-structured grapheme with ~10nm ~100% in 2hours [34] nenanocompo size sites

PT

S.No 1

A

Table 2: Comparison data of methylene blue degradation reported by other studies

5

A

6 7 8

9

I N U SC R

ZnO-PMMA

-1 Spiral binded MO incorporated with PMMA with 85.32 mg2 g99% in 3h in Present Study surface are sunlight with 80 mg catalyst.

A

CC E

PT

ED

M

A

10