Green Synthesis of Copper Nanoparticles for Dye Removal (PDF)

Environ Sci Pollut Res DOI 10.1007/s11356-015-5223-y RESEARCH ARTICLE Green synthesis of copper nanoparticles for the efficient removal (degradation) of dye from aqueous phase Tanur Sinha 1 & M. Ahmaruzzaman 1 Received: 28 May 2015 / Accepted: 11 August 2015 # Springer-Verlag Berlin Heidelber...

Environ Sci Pollut Res DOI 10.1007/s11356-015-5223-y RESEARCH ARTICLE Green synthesis of copper nanoparticles for the efficient removal (degradation) of dye from aqueous phase Tanur Sinha 1 & M. Ahmaruzzaman 1 Received: 28 May 2015 / Accepted: 11 August 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract The present work reports the utilization of a com- been presented, and the degraded intermediates have been mon household waste material (fish scales of Labeo rohita) identified using the liquid chromatography-mass spectroscopy for the synthesis of copper nanoparticles. The method so de- technique. The high efficiency of nanoparticles as veloped was found to be green, environment-friendly, and photocatalysts has opened a promising application for the re- economic. The fish scale extracts were acting as a stabilizing moval of hazardous dye from industrial effluents contributing and reducing agents. This method avoids the use of external indirectly to environmental cleanup process. reducing and stabilizing agents, templates, and solvents. The compositional abundance of gelatin may be envisaged for the Keywords Copper nanoparticles. Gelatin. Methylene blue. effective reductive as well as stabilizing potency. The mecha- Photodegradation nisms for the formation of nanoparticles have also been pre- sented. The synthesized copper nanoparticles formed were predominantly spherical in nature with an average size of Introduction nanoparticles in the range of 25–37 nm. The copper nanopar- ticles showed characteristic Bragg’s reflection planes of fcc Nowadays, fast urbanization, industrialization, and unplanned which was supported by both selected area electron diffraction activities of human beings have increased the environmental and X-ray diffraction pattern and showed surface plasmon pollution especially air and water. These are generally caused resonance at 580 nm. Moreover, the energy dispersive spec- by effluents from various industries and a major part is con- troscopy pattern also revealed the presence of only elemental stituted by the dye industries. copper in the copper nanoparticles. The prepared nanoparti- Dyes are used in the production of various consumer prod- cles were used for the remediation of a carcinogenic and nox- ucts, such as paints, textiles, printing inks, papers, plastics, etc. ious textile dye, Methylene blue, from aqueous solution. and exhibit significant environmental toxicity to all living or- Approximately, 96 % degradation of Methylene blue dye ganisms and contribute to eutrophication (Safavi and Momeni was observed within 135 min using copper nanoparticles. 2012). These possess a threat to our ecosystem and water The probable mechanism for the degradation of the dye has bodies. Hence, their complete dislodgement is essential for minimizing water pollution which is a very cumbersome task Responsible editor: Santiago V. Luis on account of their complicated structure and high stability. Several methodologies have been formulated in the past Electronic supplementary material The online version of this article (doi:10.1007/s11356-015-5223-y) contains supplementary material, employing biological, chemical, and physical remediation which is available to authorized users. processes, but all these methods have certain demerits (Wang et al. 2010). * M. Ahmaruzzaman On the contrary, a photocatalytic approach in the presence [email protected] of suitable nanocatalyst using sunlight offers a potential meth- od for the complete elimination of pollutants from the envi- 1 Department of Chemistry, National Institute of Technology, ronment. In the photocatalytic pathway, sunlight activated the Silchar 788010, Assam, India nanoparticles (NPs) and forms a redox atmosphere in aqueous  Environ Sci Pollut Res solution and acts as a sensitizer for a light-induced redox In this study, for the first time, direct sunlight has been mechanism (Beydoun et al. 1999). However, the survey of utilized for the photodegradation of MB dye in presence of literature revealed that the doping of noble NPs with various Cu NPs. The photodegradation using solar irradiation is com- semiconductor metal oxide NPs, such as tin oxide (SnO2) and paratively greener approach than that with UV-light. titanium dioxide (TiO2), acts as photocatalyst for the removal of the dyes (Sinha et al. 2013). Here, we have chosen copper NPs on account of their high surface area and large number of active sites alone as photocatalysts without doping with any Experimental semiconducting metal oxide. To the best knowledge of the authors, such type of photocatalyst has not been formulated Materials in the past (Kou and Varma 2012). Copper nanoparticles (Cu NPs) are of significant interest Copper sulfate (CuSO4·5H2O), Methylene Blue (MB) of AR compared to gold, silver, and platinum NPs because of its Grade was procured from Sigma-Aldrich and used as re- lesser cost, extensive availability, and various applications in ceived. Double-distilled water was used in all the experiments. the field of catalysis, electrical, sensors, inkjets, field emission Fish scale was collected from the local household and was emitters, etc. (Sinha et al. 2015; Jeong et al. 2011). washed thoroughly with double-distilled water and then dried Further, controllable synthesis of Cu NPs is a challenging in oven at 60 °C until constant weight. The dry biomass was task owing to their low redox potential and prone to oxidation then ground in a stainless steel grinder and sieved. when exposed to air (Guo et al. 2013). Moreover, the literature on this field is very meager, and the synthesis protocol often employs the use of expensive, harsh, and toxic chemicals Preparation of aqueous extract of fish scale (Sannegowda et al. 2014). Therefore, in this pursuit, the development of new green Fine powdered L. rohita scales (10 g) were placed in a 500-ml chemistry synthetic procedures using environment-friendly Erlenmeyer flask containing 450 ml distilled water and then materials, non-toxic solvents, and reagents is highly required heated at 70 °C for 20 min. This was followed by centrifuga- with minimal wastage in terms of raw materials and energy. In tion at 4000 rpm for 20 min, and the supernatant was then this aspect, we wish to report the utilization of fish scale of filtered. The extract was stored in a refrigerator at 4 °C for Labeo rohita, a common household waste material for the further use. The prepared extract was used within 1 week of preparation of Cu NPs. The compositional abundance of type preparation. I collagen fibers (41–84 %) has been reported (Ikoma et al. 2003). Type I collagen is a heterotrimeric copolymer com- posed of two α1 (I) and one α2 (I) polypeptide chains, con- Synthesis of Cu NPs taining approximately 1050 amino acids each (Sinha et al. 2014a, b). These components may be envisaged for the effec- The Cu NPs were synthesized by the following procedure tive reduction and stabilization of Cu NPs generated using fish (Scheme 1). In a typical synthesis, 0.5 g of CuSO4·5H2O scale extract by a greener route. was dissolved in 10 g of double-distilled water and 50 ml of The present work addresses the development of environ- 10 % of fish scale extract was added to it at pH=9. The mix- ment-friendly, green, and facile method for the rapid synthesis ture was then refluxed at 100 °C with continuous stirring and of Cu NPs using the fish scale extract of L. rohita and their heating for 1 h until the color changed to dark brown. These utilization for the removal of a toxic dye Methylene Blue were then filtered, centrifuged, and the obtained precipitates (MB) under sunlight. were washed several times with absolute ethanol and distilled MB is a water-soluble heterocyclic aromatic chemical com- water. pound and used as a colorant and as pharmaceutical drugs. It is lethal and causes cardiovascular, dermatological, gastrointes- tinal, genitor-urinal, and hematological problems. Their com- Refluxed at 1000C plete dislodgement from the environment is required. The synthesized NPs were characterized using various With continuous heating and stirring techniques, such as UV-visible spectroscopy (UV–vis spec- for 1 h, pH=9 troscopy), Fourier transformer infrared spectroscopy (FTIR spectroscopy), transmission electron spectroscopy (TEM), se- lected area electron diffraction (SAED) pattern, scanning elec- tron microscopy-energy dispersive spectroscopy (SEM- Copper sulphate+ Fish Scale extract Cu NPs EDAX), and X-ray spectroscopy (XRD) analyses. Scheme 1 Synthesis of Cu NPs Environ Sci Pollut Res 1.50 Characterization of the nanoparticles The UV–Vis absorption spectra of the synthesized nanoparti- 1.35 cles were recorded on Cary 100 Bio spectrophotometer (λ max in nm) equipped with 1-cm quartz cell. The TEM, HR- Absorbance (a.u.) 1.20 TEM images, and SAED pattern were recorded using JEOL- JEM 2100 transmission electron microscope operated at an 1.05 accelerating voltage of 200 kV. The TEM samples of the nanoparticles were prepared by placing the solution drops 0.90 over the carbon-coated copper grids and allowing the solvent to evaporate at room temperature. The FEG-SEM was exam- 0.75 ined using JSM-7600F scanning electron microscope, and the samples was first gold coated using Sputter Coater, Edwards 500 550 600 650 700 750 800 S150, which provides conductivity to the sample, and then the Wavelength (nm) SEM micrograph were taken. The FTIR spectra were mea- Fig. 1 UV-visible spectra of the synthesized Cu NPs using fish scale sured using Bruker Hyperion 3000 FTIR spectrometer using extract thin, transparent KBr pellets prepared by pressing a mechan- ically homogenized mixture of dried sample with dehydrated KBr. The XRD pattern was recorded using a Phillips X’Pert characteristic surface plasmon resonance band (SPR) of Cu Pro Diffractometer with CuKα radiation of wavelength NPs centered at ∼580 nm (Fig. 1). 1.5418 A0. TEM and SAED studies Evaluation of photocatalytic activity The morphology and size of the Cu NPs have been analyzed The photocatalytic activity was evaluated by using the aque- using TEM and SAED studies. The TEM and HRTEM ous solution of MB dye. For this reason, 10 mg of synthesized (Fig. 2a, b) revealed the formation of spherical NPs with an Cu NPs was dispersed separately in 200 ml of 10−4 M solution average size of (31 ± 6 nm). The HRTEM micrographs of MB dye. To attain the adsorption–desorption equilibrium of (Fig. 2b) showed clear lattice fringes with fringe spacing of dye on the surface of the NPs, the suspended solution was 0.21 nm which corresponds to (111) plane of fcc Cu NPs allowed to stand for 1 h in the dark before solar irradiation. (JCPDS-71-4610). Thus, the TEM images confirmed the for- The dye was then exposed to sunlight. The experiments were mation of Cu NPs using the fish scale extract of L. rohita as carried out on a sunny day at Silchar city between 10 a.m. and both reducing as well as stabilizing agent. The SAED pattern 3 p.m. (atmospheric temperature 32–36 °C). At regular inter- (Fig. 2c) exhibits a series of diffraction rings corresponding to vals of time, 4 ml of suspensions was withdrawn and imme- (111), (200), (220), and (311) lattice planes for the fcc struc- diately centrifuged. The progress of the reaction was moni- ture of Cu NPs (JCPDS- 71–4610), and no other diffraction tored using UV-visible spectroscopy at regular intervals of rings belonging to CuO NPs were observed, illustrating the time. pure nature of the Cu NPs. XRD studies Results and discussions XRD analysis has been carried out to determine the phase UV-visible spectroscopy identification of the crystal structure of the synthesized Cu NPs (Fig. 3). The diffraction peaks at 2θ=440, 510, and 750 Cu NPs exhibits a unique UV-visible absorption band derived corresponds to the crystal facets of (111), (200), and (220), from the collective oscillation of conduction electrons upon respectively (JCPDS- 71–4610). The XRD pattern revealed interaction with electromagnetic radiation, which is known as face-centered cubic structure (fcc) which is in accordance with localized surface plasmon resonance (LSPR). The shifting of the SAED results. The pattern was very clean, with no indi- these bands provides information of the particle size, chemical cation of impurities such as copper oxides (CuO, Cu2O). surrounding, and adsorbed species on the surface. Figure 1 displays the UV–visible spectra of the synthesized Cu NPs. FT-IR studies The absorption bands for Cu NPs have been reported in the range of 550–600 nm (Kumar et al. 2013). The UV–vis ab- The FT-IR studies were carried out to identify the biomole- sorption spectrum recorded from these solutions shows the cules responsible for the reduction as well as capping of the  Environ Sci Pollut Res Fig. 3 XRD pattern of the synthesized Cu NPs stretching vibration overlapped with N–H stretching shifted to 3268 cm−1 and became relatively broad and strong. In addi- tion, the band due to C═O stretching of amide and NH2, N–H wagging or out of plane O–H bending vibration shifted to 1596 and 683 cm−1 respectively in case of the synthesized Cu NPs. Hence, the abovementioned data indicated that O–H, am- ide C═O, and N–H could be present in the fish scale extract. These functional groups can be assigned because of the pres- ence of denatured collagen (gelatin) in the extract (Ikoma et al. 2003). The peak changes in the IR spectra of the synthesized NPs were related to NH2 groups, indicating that these func- tional groups were involved in their synthesis and capping. EDAX analysis EDAX analysis was carried out to determine the elemental composition of the synthesized Cu NPs. The EDAX spectrum given in Fig. 5 showed the presence of copper as the only elementary component which confirmed the formation of Cu NPs. 1.0 Fig. 2 a TEM micrograph, b HRTEM image, and c SAED pattern of the synthesized Cu NPs 0.9 synthesized Cu NPs (Fig. 4). The assignments of the FT-IR Transmittance [%] 665 bands of the fish scale extract and the synthesized NPs have 0.8 1632 been summarized in Table 1. The main peaks that were iden- 1596 tified in the IR spectrum of the fish scale extract were at 3440, 0.7 1632, and 665 cm−1 which could be assigned to hydrogen 683 bonded O–H stretching vibration overlapped with N–H 0.6 3440 Fish Scale Extract stretching, C═O stretching of amide, and NH2,N–H wagging 3268 Cu NPs or out of plane O–H bending vibration, respectively (Sinha 0.5 and Ahmaruzzaman 2015a). 4000 3500 3000 2500 2000 1500 1000 500 -1 However, for the fish scale extract-mediated synthesis of Wavenumber (cm ) Cu NPs, the peaks corresponding to hydrogen bonded O–H Fig. 4 FTIR spectra of the fish scale extract and synthesized Cu NPs Environ Sci Pollut Res Table 1 FT-IR spectra of the fish scale extract and synthesized Cu NPs reduction of remaining metal ions present in the solution via Samples νO–H overlapped νC═O of νNH2/νN–H autocatalysis (as shown in Scheme 2) (Kundu 2013). with νN–H (cm−1) amide (cm−1) wagging/ out of Henceforth, it was observed that gelatin played the dual role plane νO–H of reducing as well as stabilizing for the formation of Cu NPs. bending (cm−1) Fish scale extract 3440 1632 665 Evaluation of the photocatalytic activity of the synthesized Cu NPs 3286 1596 683 Cu NPs The dye, namely MB, was selected for evaluating the Probable mechanism for the formation of Cu NPs photocatalytic activity of the synthesized Cu NPs in aqueous medium under solar irradiation. The dye degra- The fish scale extract of L. rohita is rich in collagen dation does not take place immediately. The dye degra- whose major components are glycine, amino acids, and dation processes were monitored by recording the high levels of hydroxyproline and hydroxylsine (Ikoma changes in the UV spectrum of the reaction mixture, et al. 2003). Therefore, when the aqueous solutions of which was made free from the catalyst by centrifuga- these fish scales were heated at 70 °C for 20 min, the tion. It was observed that as the exposure time in- collagen present in them got denatured to a mixture of creased, the absorption peak corresponding to MB de- random-coil single, double, and triple strands which were preciated gradually and reached its minimum. In accompanied by changes in chemical and physical prop- Fig. 6a, the absorption peaks at 664 nm, corresponding erties due to the destruction of their triple helical struc- to MB, showed rapid degradation and disappeared after ture (Ikoma et al. 2003). Such denatured collagen is 135 min. called gelatin and can be evidenced from Fig. A1 To confirm the photocatalytic activity of the synthe- (Supplementary information), where a peak appeared at sized NPs, a control experiment was carried out. It was ∼270 nm corresponds to the absorption of gelatin (Sinha found that when the dye solution was kept under sun- and Ahmaruzzaman 2015b). We believe that when fish light in the absence of NPs, the dye showed no degra- scale extract is added to copper sulfate solution, they dation. Similarly, dye showed almost negligible degra- form an instantaneous complex because of the electro- dation when placed in the dark without sunlight in the static interaction between the negatively charged group presence of NPs. Figure 6b depicts the degradation ca- of gelatin and positively charged Cu (II) ions. Upon con- pability of the synthesized Cu NPs for MB, which tinuous heating and stirring, the complex starts reducing reached to 96 %. and ultimately formed self-assembled Cu NPs (Fig. A2) The rate of degradation of these dyes in the presence of NPs (Sinha and Ahmaruzzaman 2015b). was according to pseudo-first-order reaction and their kinetics Therefore, it is assumed that the formation of Cu NPs pro- may be expressed as follows (Sinha et al. 2014a, b): ceeds via autocatalytic pathway, where once a metal atom is .  evolved as a nucleation center, it can act as a catalyst for the ln C0 Ct ¼ kt ðiÞ where, Ct and C0 are the concentration of the dyes at time t and 0, respectively, k=pseudo-first-order rate constant, and t=time in min. Figure 6c represents the plot of ln (C0/Ct) vs irradiation time t for the dye. The plot represents a linear relationship, and hence, slope of the line represents the rate constant (k) for CuSO4.5H2O + Gelatin Gelatin-Cu(II) Complex Heating and stirring at 1000C,1 hour Element Weight% Atomic% Cu K 100 100 Total 100.00 100 Self-assembled Cu NPs Fig. 5 EDAX patterns of the synthesized Cu NPs Scheme 2 Mechanism for the formation of Cu NPs  Environ Sci Pollut Res a be effective for the removal of noxious Methylene Blue dye 1.0 from aqueous solution. 0.9 Initial 0.8 15 minutes Probable mechanism for the photocatalytic activity 30 minutes 0.7 45 minutes of the Cu NPs Absorbance (a.u.) 0.6 60 minutes 75 minutes 0.5 90 minutes A photocatalytic mechanism is correlated by two parts: 105 minutes photo and catalysis. The former portion consists of in- 0.4 120 minutes 0.3 135 minutes teraction with light material which is associated with 0.2 photon absorption, charge creation, dynamics, and sur- 0.1 face trapping. While the latter part is connected with 0.0 surface reactivity and surface radical formation that is 500 550 600 650 700 750 800 correlation among H 2 O, O 2 , and organic pollutants Wavelength (nm) (Kavitha et al. 2014). Hence, the photocatalytic mechanism can be summarized b 100 as follows (Ajmal et al. 2014). Percentage efficiency Firstly, when the solar irradiation is absorbed by the Cu NPs, then owing to SPR effect, the Cu NPs get photo excited 80 and undergoes plasmonic decay by three mechanisms (Dong Percentage efficiency et al. 2014a, b; Sun et al. 2015): 60 1. An elastic radiative re-emission of photons, where the 40 absorbed molecules absorbs photon and gains energy from the plasmonic structure of Cu NPs. 2. Then, the photon energy experiences a nonradiative 20 Landau damping and converts to a single e−/h+ pair exci- tations; the excited primary electrons then generate many 20 40 60 80 100 120 140 Time (minutes) other electrons via columbic inelastic scattering. c 3. Finally, the induction of a direct electron injection into the 3.5 adsorbate takes place owing to the interaction between the adsorbate and excited surface plasmons. 3.0 ln (C0/Ct) 2.5 Secondly, the electron and holes generated by plasmonic Linear fit of ln (C0/Ct) decay can react with O2 and H2O molecules to furnish active 2.0 specie; anionic super oxide radical (O2−.) and hydroxyl radical ln (C0/Ct) (OH.), respectively. 1.5 In the next step, hydro peroxyl radical (HO2.) is generated 1.0 by the protonation of the superoxide ion (O 2−.). These hydroperoxyl radical then converts to H2O2 which ultimately 0.5 dissociates into highly reactive hydroxyl radicals (OH.). 0.0 Finally, both oxidation as well as reduction takes place on the surface of the photocatalyst. 0 20 40 60 80 100 120 140 Henceforth, the complete degradation process can be rep- Time (minutes) resented by Scheme 3, and the related reactions are shown in Fig. 6 a Photodegradation of MB dye by solar irradiation using Eqs. ((1)–(9)). synthesized Cu NPs as photocatalyst. b Percentage efficiency of photodegradation of MB dye with time. c Plot of ln (Co/Ct) versus irradiation time t, for photodegradation of MB dye using synthesized Cu þ hν→hþ ðCuÞ þe− ðCuÞ ð1Þ Cu NPs H2 OðadsÞ þ hþ →OH⋅ þ Hþ ðadsÞ ð2Þ the degradation of dye. The value of k was found to be 2.37× 10−2 min−1. Thus, it can be concluded that Cu NPs is found to O2 þ e− →O2 −⋅ ðadsÞ ð3Þ Environ Sci Pollut Res Scheme 3 Schematic representation of the photodegradation process using Cu NPs under solar irradiation O2 −⋅ ðadsÞ þ Hþ ⇄HOO⋅ ðadsÞ ð4Þ methyl group substituent on the amine group. For ex- ample, the formation of azure A, B, and C and thionin 2HOO⋅ ðadsÞ→H2 O2 ðadsÞ þ O2 ð5Þ a H2 O2 ðadsÞ→2OH⋅ ðadsÞ ð6Þ 319.9 100 Dye þ OH⋅ →CO2 þ H2 Oðdye intermediatesÞ ð7Þ 80 Dye þ hþ →Oxidation products ð8Þ 60 k counts − Dye þ e →Reduction products ð9Þ 40 20 140 211.3 256 Identification of the intermediate products of Methylene 166 227.8 270 blue degradation 0 100 125 150 175 200 225 250 275 300 325 m/z The intermediates generated during the degradation pro- cess were analyzed using liquid chromatography-mass b spectroscopy (LC-MS) technique and were identified 80 100.2 by comparison with commercial standards and by inter- 70 pretation of their fragment ions in the mass spectra. Figure 7a depicts the LC-MS of MB dye solution 60 with Cu NPs initially. The figure clearly displays a 50 256 k counts prominent peak at m/z= 319.9 which is very close to 40 186.1 242 284.1 the formula mass of MB dye. Noticeably, no signals 142 30 123.1 319.9 corresponding to the formation of reaction intermediates 228 were observed. Figure 7b represents the LC-MS of MB 20 dye solution with Cu NPs after 135 min. Here, it was 10 found that the signal at m/z =319.9 is weakened, and 0 multiple mass signals corresponding to reaction interme- 100 125 150 175 200 225 250 275 300 325 m/z diates have appeared. The molecular structures of the possible reaction intermediates from fragmentation of Fig. 7 a LC-MS of MB dye solution with Cu NPs after 0 min, b LC-MS of MB dye solution with Cu NPs after 135 min, c molecular structures of the main skeleton of MB dye were shown in Fig. 7c. the possible reaction intermediates from fragmentation of the main skel- It is supposed that the formation of the reaction inter- eton of MB dye, and d Tandem mass spectra of MB intermediate degra- mediates take place by cleavage of one or more of the dation product ion at m/z=242  Environ Sci Pollut Res N c -CH3. provided maximum exposure for the reactant to the ac- tive surface. As a whole, the photodegradation of dyes (H3C)2N S N(CH3)2 + using synthesized NPs in the visible light can be ex- m/z= 284.1 N plained because of the excitation of surface plasmon resonance, which is actually the oscillation of charge S density that can propagate at the interface between the (H3C)2N NHCH3 + Azure B m/z= 270 metal and the dielectric medium. -CH3. Conclusion N The present study highlighted the utilization of a com- (H3C)2N S + NH2 mon household waste material (fish scales of L. rohita) Azure A m/z= 256 in the domain of nanotechnology. The method so devel- oped depicted the dual functional ability of the fish -CH3. scale extract solution. The FT-IR data indicated that O–H, C═O, and N–H group may be present in the extract of fish scale and assigned to the presence of N protein in the fish scale extract. The peak changed in the IR spectra of Cu NPs was related to OH, NH2, and H3CHN S + NH2 C═O groups and indicated that these functional groups Azure C -CH3. m/z= 242 were involved in the synthesis of Cu NPs. The SPR peak also showed the presence of Cu NPs. The TEM N and SAED results showed the formation of well crystal- line, spherical Cu NPs with average size in the range of H2N S NH2 (31±6 nm). XRD indicated the fcc structure of Cu NPs + Thionin m/z= 228 as indicated by the electron diffraction data. Moreover, EDAX revealed the presence of only elemental copper d N in the Cu NPs. Thus, the method has several advantages over the available methods. The presented method is simple, green, environment-friendly, economical, non- S NH2 H3CHN + toxic, and free of the use of any organic solvents, sur- Azure C m/z= 242 factants, and specialized instruments. Thus, the present study indicated a simple shape and size controlled syn- thesis of Cu NPs. 186 N These synthesized NPs were utilized for the removal of a hazardous dye, MB, and was found to be highly efficient in the removal of this dye. This high efficien- H3CHN S NH2 cy of the NPs as photocatalysts may provide a prom- + 142 ising application for the degradation of dyes from in- 123 dustrial effluents. Therefore, the present study has Fig. 7 (continued) shown a simple and facile way for the synthesis of Cu NPs utilizing fish scale extract. These extract has no other use and considered as a common house hold (Fig. 7c) through the demethylation cleavage during the waste. Therefore, the synthesis of Cu NPs and its uti- photocatalytic degradation has been reported in the lit- lization in treatment of industrial effluents was quite erature (Rauf et al. 2010). It is then predicted from the justified. LC-MS (Fig. 7b) that the Azure C undergo fragmenta- tion to give intermediates at m/z = 186, 142, and 123 (Fig. 7d). Acknowledgments Tanur Sinha is grateful to TEQIP–II of NIT Silchar Henceforth, it could be concluded that the synthe- for providing the financial assistance and SAIF-NEHU Shillong, SAIF– sized Cu NPs showed marvellous photocatalytic activity IIT Bombay and Tezpur University for providing the TEM, FTIR, SEM- because of high surface area-to-volume ratio, which EDAX, LC-MS, and XRD facilities. Environ Sci Pollut Res References Safavi A, Momeni S (2012) Highly efficient degradation of azo dyes by palladium/ hydroxyapatite/ Fe3O4 nanocatalyst. J Hazard Mater 201:125–131 Ajmal A, Majeed I, Malik RN, Idriss H, Nadeem MA (2014) Principles Sannegowda LK, Reedy KRV, Shivaprasad KH (2014) Stable nano-sized and mechanisms of photocatalytic dye degradation on TiO2 based copper and its oxide particles using cobalt tetraamino phthalocya- photocatalysts: a comparative overview. RSC Adv 4:37003–37026 nine as a stabilizer; application to electrochemical activity. RSC Adv Beydoun D, Amal R, Low G, McEvoy S (1999) Role of nanoparticles in 4:11367–11374 photocatalysis. J Nanopart Res 1:439–458 Sinha T, Ahmaruzzaman M (2015a) A novel green and template free Dong F, Li Q, Sun Y, Ho WK (2014a) Noble metal-like behavior of plas- approach for the synthesis of gold nanorice and its utilization as a monic Bi particles as a cocatalyst deposited on (BiO)2CO3 microspheres catalyst for the degradation of hazardous dye. Spectrochim Acta A for efficient visible light photocatalysis. ACS Catal 4:4341–4350 142:266–270 Dong F, Xiong T, Sun Y, Zaiwang Z, Ying Z, Feng X, Wu Z (2014b) A Sinha T, Ahmaruzzaman M (2015b) High-value utilization of egg shell to semimetal bismuth element as a direct plasmonic photocatalyst. synthesize silver and Gold-silver core-shell nanoparticles and their Chem Commun 50:10386–10389 application for the degradation of hazardous dyes from aqueous Guo H, Liu X, Xie Q, Wang L, Peng DL, Branco PS, Gawande MB phase-A green approach. J Colloid Interface Sci 453:115–131 (2013) Disproportionation route to monodispersed copper nanopar- ticles for the catalytic synthesis of propargylamines. RSC Adv 3: Sinha AK, Pradhan M, Sarkar S, Pal T (2013) Large scale solid-state 19812–19815 synthesis of Sn-SnO2 nanoparticles from layered SnO by sunlight: Ikoma T, Kobayashi H, Tanaka J, Walsh D, Mann S (2003) a material for dye degradation in water by photocatalytic reaction. Microstructure, mechanical and biomimetic properties of fish scales Environ Sci Technol 47:2339–2345 from Pagrus major. J Struct Bio 142:327–333 Sinha T, Ahmaruzzaman M, Sil AK, Bhattacharjee A (2014a) Jeong S, Song HC, Lee WW, Lee SS, Choi Y, Son W, Kim ED, Paik CH, Biomimetic synthesis of silver nanoparticles using the fish Oh SH, Ryu B (2011) Stable aqueous based Cu nanoparticle Ink for scales of Labeo rohita and their application as catalyst for printing well defined highly conductive features on a plastic sub- the reduction of aromatic nitro compounds. Spectrochim strate. Langmuir 27:3144–3149 Acta A 131:413–423 Kavitha SR, Umadevi M, Janai SR, Balkrishanan T, Ramanibai R (2014) Sinha T, Ahmaruzzaman M, Bhattacharjee A (2014b) A simple approach Fluorescence quenching and photocatalytic degradation of textile for the synthesis of silver nanoparticles and their application as a dyeing waste water by silver nanoparticles. Spectrochim Acta Part catalyst for the photodegradation of methyl violet 6B under solar A 127:115–121 irradiation. J Environ Chem Eng 2:2269–2279 Kou J, Varma RS (2012) Beet juice-induced green fabrication of plas- Sinha T, Ahmaruzzaman M, Bhattacharjee A, Asif M, Gupta VK (2015) monic AgCl/Ag nanoparticles. Chem Sus Chem 5:2435–2441 Lithium dodecyl sulphate assisted synthesis of silver nanoparticles Kumar B, Saha S, Basu M, Ganguli AK (2013) Enhanced hydrogen/ and its exploitation as a catalyst for the removal of toxic dyes. J Mol oxygen evolution and stability of nanocrystalline (4–6 nm) copper Liq 201:113–123 nanoparticles. J Mater Chem A 1:4728–4735 Sun Y, Zhao Z, Dong F, Zhang W (2015) Mechanism of visible light Kundu S (2013) Formation of self-assembled Ag nanoparticles on DNA photocatalytic NOx oxidation with plasmonic Bi cocatalyst- chains with enhanced catalytic activity. Phys Chem Chem Phys 15: enhanced (BiO)2CO3 hierarchical microspheres. Phys Chem Chem 14107–14119 Phys 17:10383–10390 Rauf MA, Meetani MA, Khaleel A, Ahmed A (2010) Photocatalytic Wang H, Sun F, Zhang Y, Li L, Chen H, Wu Q, Yu JC (2010) degradation of Methylene Blue using a mixed catalyst and product Photochemical growth of nanoporous SnO2 at the air-water interface analysis by LC/MS. Chem Eng J 157:373–378 and its high photocatalytic activity. J Mater Chem 20:5641–5645