Solar light-facilitated oxytetracycline removal from the aqueous phase utilizing a H2O2/ZnWO4/CaO catalytic system

A CaO-supported ZnWO4 nanocomposite (ZnWO4/CaO) was successfully synthesized using a novel hydrothermal method and was characterized by scanning electron microscopy (SEM), tunnelling electron microscopy (TEM), X-ray diffraction (XRD), electron diffraction X-ray (EDX), Fourier transform infrared spectroscopy (FTIR) and UV–visible (UV–vis) spectral analysis. The ZnWO4/CaO composites exhibited rod-like morphologies with variable lengths from 45 nm to 147 nm and diameters from 26 nm to 36 nm. The catalytic efficiency of the synthesized ZnWO4/CaO composites was displayed for the photodegradation of oxytetracycline (OTC) antibiotic from the aqueous phase. The synergistic degradation of OTC was investigated in the presence of H2O2 and ZnWO4/CaO. The rate of photodegradation followed pseudo-first-order kinetics. The antibiotic removal was strongly influenced by the catalyst loading, H2O2 concentration, pH and OTC concentration. Using a solar/H2O2/ZnWO4/CaO catalytic system, 85% COD removal was attained for OTC degradation in 210 min. The oxidative degradation occurred through hydroxyl radicals. The prepared nanocomposites possessed high recyclability and were easily separated from the aqueous solution by a simple sedimentation process

Synthesis of Eu3+−doped ZnO/Bi2O3 heterojunction photocatalyst on graphene oxide sheets for visible light-assisted degradation of 2,4-dimethyl phenol and bacteria killing

We reported the immobilization of binary heterojunction Eu3+-ZnO/Bi2O3 over the surface of graphene oxide (GO) sheets by precipitation method to compose a visible light drive photocatalyst. The ternary nanocomposites were characterized by different spectral technique like FESEM, FTIR, XRD, XPS, EDX, HRTEM, UV–visible, PL, HPLC and LCMS analysis. The high specific surface area of 106.0 m2g-1 of Eu3+-ZnO/Bi2O3/GO nanocomposites was ascertained by BET adsorption-desorption isotherm. The nano-composite exhibit excellent photo-efficiency for the photodegradation of 2, 4-dimethyl phenol (DMP) under visible region and was almost completely mineralized in 100 min as compared to the bare and binary system. The mineralized products of DMP were analyzed by HPLC and LCMS analysis. The kinetic model suggests the degradation pathway obeys pseudo-first order kinetic. Their antibacterial property were assessed against E. coli bacteria and nearly 90% of gram negative bacteria were killed by using ternary photocatalyst as determined by CFU method. Also, Eu3+-ZnO/Bi2O3/GO nanocomposites possessed significant recycle efficiency up to six consecutive cycles which is beneficial to minimize the tariff. The improved photo-efficiency is due to the extension towards visible region, increase surface area, and high charge separation in ternary heterojunction

Photocatalytic mineralization and degradation kinetics of ampicillin and oxytetracycline antibiotics using graphene sand composite and chitosan supported BiOCl

In precedent work, nano-sized BiOCl was immobilized onto graphene sand composite (GSC) and chitosan (CT) to report efficient photocatalytic system for wastewater treatment. GSC was prepared by graphitization of sugar over river sand. The supported BiOCl was prepared by modified hydrolysis method to report BiOCl/GSC and BiOCl/CT photocatalysts. The citric acid directed nucleation and growth process resulted in well dispersed BiOCl nanoplates over GSC and CT. The supported catalysts were characterized by FESEM, TEM, HRTEM, FTIR, XRD, EDX, BET, Raman, photoluminescence and UV-vis diffuse reflectance spectral analysis. The optical band gap of BiOCl/GSC and BiOCl/CT was given by 3.31 and 3.33 eV, respectively. The size of BiOCl/GSC and BiOCl/CT was found to be 50 and 70 nm respectively. The catalytic efficiency of BiOCl/GSC and BiOCl/CT was tested for ampicillin (AMP) and oxytetracycline (OTC) removal. The adsorption of AMP and OTC followed pseudo second order kinetics. Both BiOCl/GSC and BiOCl/CT exhibited significant photocatalytic activity for the mineralization of ampicillin (AMP) and oxytetracycline (OTC) antibiotics under solar light. Simultaneous adsorption and degradation process (A+P) process showed higher antibiotic degradation rate. The applicability of power law model showed the complex nature of mineralization process. During A+P process, both antibiotics were mineralized to CO2, H2O and NO3- ions. BiOCl/GSC and BiOCl/CT exhibited significant recycle efficiency for 10 catalytic cycles in comparison to native BiOCl. (C) 2016 Elsevier B.V. All rights reserved

Low-cost removal of basic red 9 using cow dung ash

In the present study, basic red 9 had been removed from synthetic waste water using animal waste. Cow dung ash had been prepared and characterized by scanning electron microscope. Morphology analysis shows very fine particles of less than 1 μm. The pH analysis study favours a pH of 8.5 for maximum dye removal. The removal of basic red 9 was very fast on cow dung ash. Percentage dye removal was 80.24% and 95.24 in 5 minutes and 90 minutes, respectively at initial dye concentration of 10 ppm

GdVO4 modified fluorine doped graphene nanosheets as dispersed photocatalyst for mitigation of phenolic compounds in aqueous environment and bacterial disinfection

The agglomeration of graphene based photocatalysts is major bottleneck for their applicability in slurry type photoreactors. In this work, we have prepared fluorine doped graphene (FG) as high dispersed adsorbent by sonochemical exfoliation method. GdVO4 nanoparticles were anchored on FG to fabricate GdVO4/FG photo catalyst. The high-dispersion of FG and GdVO4/FG was ascertained by zeta potential measurements and Tyndall effect. The atomic force microscope analysis depicted that thickness of FG and GdVO4/FG was less than 2.0 nm. The band gap of GdVO4/FG was 2.1 eV. The high surface area of GdVO4/FG was suited for adsorption coupled photocatalysis involving mineralization of phenol and 2, 4-dinitrophenol (DNP) in aqueous medium. The photodegradation process followed pseudo first order kinetics. The simultaneous adsorption and photocatalysis was most efficient process for degradation of selected phenolic compounds. Under visible light, both phenol and DNP mineralized in 7 and 9 h, respectively. The high performance liquid chromatography and mass spectrometry confirmed the formation of intermediate during degradation process which ultimately mineralized into CO2 and H2O. The photocatalytic activity of GdVO4/FG was also tested for bacterial disinfection of Pseudomonas fluorescence, Staphylococcus aureus, Streptococcus enterica, Bacillus subtilis and Escherichia coli bacteria. The oxidative radical species OH center dot and O-2(center dot-) played vital role in photodegradation and disinfection process. Due to high dispersion and recyclability, GdVO4/FG could be used as an efficient photocatalyst for removal of both biotic and abiotic pollutants present in water

Fabrication of fluorine doped graphene and SmVO4 based dispersed and adsorptive photocatalyst for abatement of phenolic compounds from water and bacterial disinfection

During heterogeneous photocatalysis, high dispersion of photocatalyst is vital for efficiency of slurry type photoreactors. In this work, we have prepared fluorine doped graphene (FG24) as a highly dispersible adsorbent by sonochemical exfoliation method. Moreover, SmVO4 (SV) nanoparticles were immobilized onto the surface of FG24 to prepare SV/FG24 photocatalyst, using post synthesis method. The zeta potential and Tyndall effect experiments confirmed the formation of highly dispersed SV/FG24 photocatalyst. The thickness of both FG24 and SV/FG24 was less than 2.0 nm. The band gap of SV/FG24 was 2.28 eV. The high surface area of SV/FG24 was suitable for adsorptive removal of phenol and 2, 4-dinitrophenol (DNP). The simultaneous process of adsorption and photocatalysis was the most effective for the degradation of selected phenolic compounds. Both phenol and DNP were mineralized in 10 h under visible light. The intermediates formation during the degradation process was proved by high-performance liquid chromatography and mass spectrometry analysis. The photocatalytic activity of SV/FG24 was also tested for photocatalytic bacterial disinfection of Escherichia coli, Bacillus subtilis, Pseudomonas fluorescence, Staphylococcus aureus, and Streptococcus enterica bacteria. The selected bacteria were deactivated using SV/FG24 in 3 h under visible light. Both OH˙ and O2˙¯ radicals played an important role during both degradation and disinfection process. Due to significant recyclability, SV/FG24 could be used as cost-effective photocatalyst for wastewater treatment. Unlike conventional slurry photo-reactors, no magnetic stirring was used during photocatalytic degradation reactions. We have successfully fabricated high-dispersed photocatalyst which remained dispersed for 10 h and effectively used for photocatalytic water purification process

Islanding of EuVO4 on high-dispersed fluorine doped few layered graphene sheets for efficient photocatalytic mineralization of phenolic compounds and bacterial disinfection

In present work, EuVO4 (EV) nanoparticles were dispersed over fluorine doped graphene sheets (FG24) to synthesize EV/FG24 nanocomposite. Few layered fluorine doped graphene sheets were prepared by sonochemical exfoliation method using NaF as fluorine source. FG24 and EV/FG24 composites were successfully characterized by FESEM, TEM, RAMAN, XRD, TGA, XPS, BET isotherm, FTIR, photoluminescence and UV–visible spectral techniques. AFM and RAMAN analysis confirmed the formation of fluorine doped graphene sheets. The high dispersion of EV/FG24 in water was ascertained by zeta potential measurement and Tyndall scattering experiment. The photocatalytic activity of EV/FG24 was tested for the degradation of phenolic compounds and bacterial disinfection under visible light. As compared to conventional slurry photocatalytic system, no magnetic stirring was used during degradation experiments. The photodegradation rate was substantially influenced by adsorption of 2, 4-dinitrophenol (DNP) and phenol onto EV/FG24. The DNP and phenol were completely mineralized in 10 h. The selected bacteria were inactivated by EV/FG24 in 3 h. The effect of various radical scavengers revealed the pivotal role of hydroxyl radicals during disinfection mechanism. EV/FG24 exhibited significant recycle efficiency during photocatalytic process. EV/FG24 was used as a stable photocatalyst to depollute contaminated water