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This study explored the efficiency of UV-C-based advanced oxidation processes (AOPs), i.e., UV/S2O8(2-), UV/HSO5(-), and UV/H2O2 for the degradation of endosulfan, an organochlorine insecticide and an emerging water pollutant. A significant removal, 91%, 86%, and 64%, of endosulfan, at an initial concentration of 2.45 μM and UV fluence of 480 mJ/cm(2), was achieved by UV/S2O8(2-), UV/HSO5(-), and UV/H2O2 processes, respectively, at a [peroxide]0/[endosulfan]0 molar ratio of 20. The efficiency of these processes was, however, inhibited in the presence of radical scavengers, such as alcohols (e.g., tertiary butyl alcohol and isopropyl alcohol) and natural organic matter (NOM). The inhibition was also influenced by common inorganic anions in the order of nitrite > bicarbonate > chloride > nitrate ≈ sulfate. The observed pseudo-first-order rate constant decreased while the degradation rate increased with increasing initial concentration of the target contaminant. The degradation mechanism of endosulfan by the AOPs was evaluated revealing the main by-product as endosulfan ether. Results of this study suggest that UV-C-based AOPs are potential methods for the removal of pesticides, such as endosulfan and its by-products, from contaminated water., (Copyright © 2013 Elsevier B.V. All rights reserved.)

• Chemistry, properties, and issues of pharmaceuticals contamination in water are discussed. • Conventional technologies proved ineffective in treating pharmaceuticals wastewater. • Efficiency, mechanisms and pathways of different •OH and SO 4 •−-based AOPs are discussed. • Effects of different process parameters and cost associated with different AOPs are discussed. • The proposed pathways and ecotoxicities of pharmaceuticals degradation are discussed. Pharmaceuticals comprises different drugs used for treating different infections in human being and animals. The huge quantities of pharmaceuticals used are found to discharge into different water resources and cause different health and environmental problems. The continuous and large-scale discharge of pharmaceuticals increases their persistency which can consequently make them more toxic. The different advanced oxidation processes (AOPs) were found to effectively treat pharmaceuticals contaminated water. The AOPs showed high efficiency in the treatment of acetaminophen, sulfamethoxazole, metronidazole. ciprofloxacin. sulfadiazine, sulfamethazine, amoxicillin, ibuprofen, carbamazepine, and tetracycline. The pharmaceuticals, amitrole, norfloxacin, atenolol, chloramphenicol, berberine, diclofenac, and sulfadiazine showed persistency to some AOPs. The AOPs yield different reactive radicals with predominantly hydroxyl radical (•OH)- and sulfate radical (SO 4 •−) which showed fast reactivity with pharmaceuticals. Different mechanistic approaches were systematically reviewed which verify the yield, reactivities, and degradation pathways of •OH and SO 4 •−. Different factors, such as pH, dose of peroxides and activators, level of pharmaceuticals contamination, and common inorganic anions were found to influence the effectiveness of AOPs. The effectiveness of the AOPs in term of cost and detoxification of target pharmaceuticals suggested to select preferably AOPs which are economical and form non-toxic and/or less toxic products. The different challenges, such as treatment of mixture of pharmaceuticals and treatment in real wastewater which can further increase potential of treatment are discussed. [ABSTRACT FROM AUTHOR]

In this study, a stable ionic liquid (IL) mediated zero‐valent copper nanoparticle (nZVCu), namely IL‐nZVCu, has been evaluated for catalytic properties towards H2O2‐mediated TMB (3, 3',5,5'‐tetramethylbenzidine) reaction under normal conditions of temperature and pH. The various analytical techniques like Fourier Transform Infrared Spectroscopy (FT‐IR), UV–Vis diffuse reflectance spectroscopy (UV‐Vis DRS), X‐ray powder diffraction (XRD), scanning electron microscope (SEM), Transmission electron microscopy (TEM) and X‐ray photoelectron spectroscopy (XPS) were used to confirm the structure and nano size of nZVCu. The simple protic IL 1‐hydrogen‐3‐methylimidazolium acetate (HmimOAc) with its cation 1‐methylimidazole and anion acetate was synthesized, characterized, and coated on nZVCu to prepared IL‐nZVCu. As a novel mimic peroxidase, IL‐nZVCu could quickly catalyze the oxidation reaction of specific chromogenic substrate TMB, when H2O2 acts as an oxidant, followed by a remarkable color change in the solution measured by UV/Vis Spectrophotometry. The enhanced catalytic activity and significant color change were greatly dependent on the catalyst dosage, the volume of IL taken, incubation time, H2O2 concentration, and TMB concentration. Also, IL‐nZVCu showed no response toward ascorbic acid, cholesterol, dopamine, urea and uric acid. Based on these findings, IL‐nZVCu could be effectively used for visual colorimetric sensing of H2O2 with a limit of detection (LOD) of 44 μM over the dynamic linear range from 40 μM to 1000 μM concentration. [ABSTRACT FROM AUTHOR]

This study reported Fe doped zinc oxide (Fe-ZnO) synthesis to degrade chlorpyrifos (CPY), a highly toxic organophosphate pesticide and important sources of agricultural wastes. Fourier transform infrared, X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectroscopic analyses showed successful formation of the Fe-ZnO with highly crystalline and amorphous nature. Water collected from agricultural wastes were treated with Fe-ZnO and the results showed 67% degradation of CPY by Fe-ZnO versus 39% by ZnO at 140 min treatment time. Detail mechanism involving reactive oxygen species production from solar light activated Fe-ZnO and their role in degradation of CPY was assessed. Use of H 2 O 2 , peroxydisulfate (S 2 O 8 2−) and peroxymonosulfate (HSO 5 −) with Fe-ZnO under solar irradiation promoted removal of CPY. The peroxides yielded hydroxyl (OH) and sulfate radical (▪) under solar irradiation mediated by Fe-ZnO. Effects of several parameters including concentration of pollutant and oxidants, pH, co-existing ions, and presence of natural organic matter on CPY degradation were studied. Among peroxides, HSO 5 − revealed to provide better performance. The prepared Fe-ZnO showed high reusability and greater mineralization of CPY. The GC-MS analysis showed degradation of CPY resulted into several transformation products (TPs). Toxicity analysis of CPY as well as its TPs was performed and the formation of non-toxic acetate imply greater capability of the treatment technology. [Display omitted] • Fe doped ZnO was successfully synthesized by sol-gel method. • Fe doping and use of peroxides synergistically promoted performance of ZnO. • Degradation of chlorpyrifos was inhibited by h vb + and OH scavengers. • Second-order rate constants of chlorpyrifos with OH and ▪ were calculated. • Toxicities of chlorpyrifos and its transformation products were estimated. [ABSTRACT FROM AUTHOR]

Highlights: [•] Degradation of atrazine was investigated in UV, UV/H2O2, UV/HSO5 − and UV/S2O8 2− AOPs. [•] UV/S2O8 2− process was found to be more efficient as well as more economical. [•] The pH affected UV/S2O8 2− but had no significant influence on UV, UV/H2O2 and UV/HSO5 −. [•] Second order rate constants of atrazine with SO4 − and OH were found to be comparable. [•] Degradation mechanism was investigated by GC–MS and LC–MS/MS analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Different peroxides-based oxidative pathways were compared towards NOR degradation. • The peroxide HSO 5 − performed best in the degradation of NOR under UV-C and Fe2+. • The peroxides yield ●OH and SO 4 ●− under activation by UV-C and Fe2+ activation. • The ●OH and SO 4 ●− scavengers inhibited degradation of NOR. • Degradation products and ecotoxicities of NOR as well as its DPS were estimated. The removal of norfloxacin (NOR), a widely used pharmaceutical and emerging water pollutant, was studied using UV-C and Fe2+ catalyzed peroxides-based oxidative processes (e.g., UV-C/Fe2+/H 2 O 2 , UV-C/Fe2+/S 2 O 8 2− and UV-C/Fe2+/HSO 5 −) and compared with UV-C and UV-C/Fe2+. The UV-C and UV-C/Fe2+ degraded NOR to 38 and 55 %. However, use of peroxides, i.e., H 2 O 2 , S 2 O 8 2−, HSO 5 − with UV-C and UV-C/Fe2+ promoted NOR %degradation to 75, 83, and 90 % using [peroxides] 0 = 50 mg/L, [Fe2+] 0 = 1 mg/L, and [NOR] 0 = 10 mg/L, respectively. The significant impact of peroxides on NOR degradation was due to their decomposition into ●OH and SO 4 ●− which showed high activity towards NOR degradation. The ●OH and SO 4 ●− formation from peroxides decomposition and their contribution in NOR degradation was verified by different scavenger studies. Among the UV-C/Fe2+/peroxides processes, UV-C/Fe2+/HSO 5 − showed better performance. The changing concentrations of peroxides, Fe2+, and NOR affected degradation of NOR. The use of different pH and inorganic anions also influenced NOR degradation. The degradation pathways of NOR were established and analyzed acute as well as chronic toxicities of NOR and its DPs. [ABSTRACT FROM AUTHOR]