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This study focuses on investigating and comparing the influence of the surface functional groups and chemical matrices of macroporous resin on the Cr(III) exchange mechanism. The results discussed herein indicate that sulfonic resin removed Cr(III) ions with faster kinetics than carboxylic resin. Equilibrium was established within 15 and 7 min for the carboxylic and sulfonic resins, respectively, with a 99.5% removal efficiency at 333 K. The Langmuir exchange capacity was observed to be higher for the sulfonic resin (1.5 mmol∙g−1) than the carboxylic resin (0.80 mmol∙g−1) at 333 K. The adsorption isotherms obtained for the carboxylic and sulfonic resins were H and S types, respectively, representing a higher affinity of the carboxylic resin for Cr(III) removal at a low metal ion concentration. Additionally, it was noted that the carboxylic resin preferentially co-sorbed H+ and Cr(OH)2+ ions below Cr(III) concentrations of 6–8 mmol.L−1. The H+ ions co-sorption was almost negligible, whereas the Cr(III) exchange was 87 and 34.5% for the carboxylic acid resin and sulfonic acid resins, respectively. The data of the concentration studies were evaluated using non-linear forms of Freundlich, Langmuir, and Dubinin–Radushkevich adsorption isotherm models, and the kinetic data were analyzed using pseudo-Ist- and pseudo-IIst-order kinetic models. The activation energy Ea for Amberlite IRC-50 (Na+) was greater (22.4 kJ∙mol−1) than that of Amberlyst-15 (Na+) 17 kJ∙mol−1, indicating a higher energy barrier for the ion exchange reaction on carboxylic resin. As per the findings of a statistical error analysis (RMSE and SSE) and absolute average relative distribution (AARD) statistical model, a close agreement between the experimental and theoretical values suggested that the Langmuir isotherm was well-fitted to the current adsorptive investigations. The interaction of the COO− and SO3− functional sites of the resins for the exchange of Cr(III) ions was validated through an FT-IR analysis. The macroporous resins used in the current study for Cr(III) exchange showed promising performances compared to other resins. The current investigations revealed valuable insights for choosing macroporous resins as adsorbents in water filtration systems. [ABSTRACT FROM AUTHOR]

In this study, biochar was prepared from Sidr plant leaves and used for the treatment of ciprofloxacin (CIP)-contaminated water. CIP is important class of emerging water pollutants from pharmaceutical industries. The biochar showed 65% adsorption efficiency and 43.48 mg/g adsorption capacity of CIP. Adsorption efficiency as well as adsorption capacity were improved to 91% and 62.50 mg/g, respectively, by phosphoric acid (H3PO4) modified biochar. Removal of CIP by the prepared biochar was due to different surface functional groups of CIP and biochar as revealed from the study of different characterization analyses. The presence of PO43– group in modified biochar led to maximum binding of CIP. Also, the modified biochar showed higher reusability potential and less leaching of ions when compared to the raw biochar. Removal of CIP was affected by concentrations of CIP, the amount of biochar and different pH's; the maximum removal of CIP was achieved at pH 4. The Freundlich and pseudo-first-order models best fitted the removal of CIP by modified biochar. Advanced characterization techniques were applied to investigate surface and physiological characteristics of the biochar and modified biochar. The modification showed high impact on the performance and stability of biochar. The study showed significant impacts of modification on the potential of the biochar for treatment of CIP-contaminated water. [ABSTRACT FROM AUTHOR]

[Display omitted] • Treatment of CIP was compared by different activated PMS-based process. • The UV-C/Fe2+/PMS-based process gave better performance in the removal of CIP. • The activated PMS yielded ●OH and SO 4 ●− which showed high reactivity with CIP. • The Cu2+ improve production rate of ●OH and SO 4 ●− and facilitated removal of CIP. • Degradation products and ecotoxicities of CIP and its DPS were analyzed. Ciprofloxacin (CIP) is a valuable antibiotic and discharged in huge quantities in aquatic environment. Different •OH and SO 4 •−-based advanced oxidation technologies (AOTs), e.g., Fe2+/PMS, UV-C/PMS, and UV-C/Fe2+/PMS are developed for treatment of CIP. The removal of CIP by Fe2+/PMS, UV-C/PMS and UV-C/Fe2+/PMS was 63, 77, and 87 %, respectively, under identical conditions which showed better performance of UV-C/Fe2+/PMS. The UV-C/Fe2+/PMS also caused high removal of total organic carbon of CIP. This high performance of UV-C/Fe2+/PMS-based AOTs possibly looked due to dual activation of PMS by UV-C and Fe2+. The removal of CIP by the three AOTs was found due to •OH and SO 4 •− and the later showed high reactivities with CIP, i.e., 2.45 × 109 and 2.35 × 109 M−1 s−1, respectively. The study of factors affecting the reactivities and/or yield of •OH and SO 4 •− diminished CIP degradation efficiency. The change in pH of solution and temperature and doses of Fe2+, PMS, and CIP exhibited significant impacts on the removal of CIP. The addition of inorganic ions showed strong inhibiting effects of NO 2 –, CO 3 2–, and HCO 3 – while Cu2+ showed facilitating role. Analysis of degradation of CIP by GC–MS was used to develop proposed pathways. Acute and chronic toxicities of CIP and its products were measured by ECOSAR program and showed the resulting products to be non-toxic. [ABSTRACT FROM AUTHOR]

In this study, activated carbon (AC) and nano-zerovalent copper (nZVCu) functionalized hydroxyapatite (HA) and alginate beads were synthesized and used for the removal of As3+ from aqueous solution. The characterization by X-ray diffraction, scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, high resolution transmission electron microscopy, BET surface area analysis, thermogravimetric analysis, and Fourier transform infrared spectroscopy revealed successful formation of the AC/nZVCu/HA-alginate, nZVCu/HA-alginate, AC/HA-alginate, and HA-alginate beads. The scanning electron microscopy and surface analysis revealed the prepared beads to be highly mesoporous which led to the maximum adsorption of As3+, i.e., 13.97, 29.33, 30.96, and 39.06 mg/g by HA-alginate, AC/HA-alginate, nZVCu/HA-alginate, and AC/nZVCu/HA-alginate beads, respectively. The thermogravimteric analysis showed the nZVCu/HA-alginate beads to be highly stable while the AC composite beads as the least stable to heat treatment. The HA-alginate beads achieved 39% removal of As3+, however, removal efficiency was promoted to 95% by coupling AC and nZVCu with HA-alginate beads at a reaction time of 120 min. The removal of As3+ by the prepared AC & nZVCu coupled HA-alginate beads was promoted with increasing [As3+] 0 and [AC/nZVCu/HA-alginate] 0. The pH of aqueous solution significantly influenced the removal of As3+ by AC/nZVCu/HA-alginate beads and maximum removal was achieved at pH 5.8. Freundlich adsorption isotherm and pseudo-second-order kinetic models were found to best fit the removal of As3+ by the synthesized beads. The high performance of AC/nZVCu/HA-alginate beads in the removal of As3+ even after seven cyclic treatment as well as least leaching of Cu ions into aqueous solution suggest enhanced reusability and stability of HA-alginate beads by coupling with AC and nZVCu. The results suggest that the synthesized beads have good potential for the removal of As3+ from aqueous solutions. Image 1 • Characterization techniques proved nZVCu and AC coupled HA-Alginate beads formation. • Coupling AC and nZVCu enhanced performance and reusability of HA-Alginate beads. • Removal of As3+ best fitted Freundlich isotherm and pseudo-second-order models. • Removal of As3+ was significantly affected by the pH of aqueous solution. [ABSTRACT FROM AUTHOR]

Nitrogen-doped titanium dioxide (N-TiO 2) nanoparticles were prepared using a modified sol-gel method. The as-prepared nanoparticles were characterized by state-of-the-art techniques for their optical, structural and morphological properties. The crystallite size, surface area and bandgap energy of reference TiO 2 and N-TiO 2 nanoparticles were found to be 16.1 and 10.9 nm, 83.6 and 131.8 m2 g−1 and 3.23 and 2.89 eV, respectively. The photocatalytic activities, in terms of 2,4-dichlorophenol (2,4-DCP) degradation, of reference TiO 2 and N-TiO 2 were found to be 46.9% and 65.4% at 120 min of treatments under UV light irradiation and 21.5% and 77.6% at 240 min of treatment under visible light irradiation, employing 153.4 µM 2,4-DCP, 1 g/L photocatalyst dosage, and pH 5.6. Interestingly, considerable H 2 production rate (i.e., 386 μmol h−1 g−1) was observed for visible/N-TiO 2 system in presence of 0.2 wt% Pt. The study revealed that visible/N-TiO 2 photocatalytic system can be used as an economically viable technology for environmental sustainability. [Display omitted] • Kinetic and mechanistic studies of 2,4-dichlorophenol were performed by visible/N-TiO 2 system. • 82.4% reduction in toxicity of 2,4-dichlorophenol solution was achieved by visible/N-TiO 2. • The rate of H 2 production was 386 μmol h−1 g−1 by using visible/0.2 wt% Pt/N-TiO 2 system. • Visible/N-TiO 2 is an economic and promising technology for environmental sustainability. • A waste to energy concept towards circular economy [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Highly stable nZVMn was synthesized by chemical reduction method. • Addition of S 2 O 8 2− promoted the performance of nZVMn. • Second-order rate constants of CIP with OH and SO4 − were calculated. • Proposed pathways for conversion of CIP into TPs were developed. • Acute and chronic toxicities of CIP and its TPs were evaluated. Abstract Nano zerovalent manganese (nZVMn, Mn0) materials have been synthesized in this study and used for degradation of ciprofloxacin (CIP), an emerging water pollutant. The investigation of physiological characteristics of Mn0 by different characterization techniques proved successful formation of Mn0 by the chemical reduction method and found it to be highly crystalline. The Mn0 was highly efficient and resulted in 63% degradation of CIP using [CIP] 0 = 10 mg/L and [Mn0] 0 = 1.0 g/L at a reaction time of 80 min. Addition of S 2 O 8 2− to Mn0 promoted removal efficiency of CIP from 63 to 95% at a reaction time of 80 min using the conditions of [CIP] 0 = 10 mg/L, [Mn0] 0 = 1.0 g/L, and [S 2 O 8 2−] 0 = 50 mg/L. The presence of OH and SO 4 − scavengers inhibited the degradation of CIP by Mn0/S 2 O 8 2−. The comparable second-order rate constants of CIP with OH and SO 4 − were calculated to be 2.35 × 109 and 2.10 × 109 M−1 s−1, respectively. High S 2 O 8 2− and Mn0 concentrations and low pH accelerated the degradation of CIP. However, removal efficiency of CIP by Mn0 with the added S 2 O 8 2− was inhibited using high CIP concentration, high pH, inorganic anions, and NOM. Degradation pathways from OH and SO 4 − based degradation of CIP were developed. Acute and chronic toxicities of CIP and its products were estimated, showing the final product to be non-toxic. The as-synthesized Mn0 was found to be stable as well as environmentally friendly for treating CIP. This study suggests that Mn0 with the added S 2 O 8 2− is a promising alternative for potential remediation and detoxification of CIP and other emerging water pollutants. [ABSTRACT FROM AUTHOR]

The oxidative degradation of CV dye in aqueous media has been evaluated using Fenton (Fe2+/H2O2) and photo-Fenton (Fe2+/H2O2/UV) processes. Various operational parameters like H2O2 dosages, Fe2+ dosages and [CV]0 were optimized of both Fenton and photo-Fenton processes for the removal of CV dye from aqueous media. Kinetic results indicated that photo-Fenton process (kobs=0.0097 min−1, t1/2=71.45 min) is more effective than Fenton process (kobs=0.0074 min−1, t1/2=93.66 min). Second order rate constant of ˙OH radical with CV dye was calculated to be 3.96×109 M−1s−1. De-methylated organic intermediates of CV dye detected by LC-MS and some other intermediates like CH3COO−, HCOO−, NH4+ and Cl− were identified by ion-chromatography. [ABSTRACT FROM AUTHOR]

In this study, solar light responsive Bi 3+ and Fe 2+ doped ZnO were synthesized and used for photocatalytic degradation of norfloxacin (NOR), an emerging water pollutant. Analysis with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and UV–vis diffuse reflectance spectroscopy (DRS) confirmed coupling of dopants (i.e., Bi 3+ and Fe 2+ ) or co-dopants (Bi 3+ /Fe 2+ ) with ZnO and suggested small narrow size as well as highly crystalline and porous nature of the doped ZnO. Metal ions doping lowered band gap energy and inhibited recombination of electron-hole pair in the as-synthesized ZnO. Consequently, BiFe-ZnO showed enhanced photocatalytic activity and reusability, giving 80% removal of NOR as compared to 36% by un-doped ZnO at a reaction time of 120 min. The analysis with photoluminescence (PL) technique verified high yield of OH from solar light activation of BiFe-ZnO compared to Bi-ZnO, Fe-ZnO and ZnO. Performance of the as-prepared photocatalysts was promoted with the added HSO 5 − and increased with increasing [HSO 5 − ] 0 . Degradation of NOR by BiFe-ZnO with the added HSO 5 − was due to OH and SO 4 − and NOR showed high reactivity with OH and SO 4 − . The removal efficiency of NOR was inhibited using OH and SO 4 − scavengers. Photocatalytic activity of the as-synthesized photocatalysts with the added HSO 5 − was highly dependent on [NOR] 0 , [pH] 0 , co-existing ions, and natural organic matter. Degradation pathways were suggested from the pattern of NOR degradation and identified transformation products. The mineralization of NOR as well as formation of non-toxic end product suggests co-doped ZnO with added HSO 5 − to be a potential technology for treating antibiotics contaminated water. [ABSTRACT FROM AUTHOR]

Ciprofloxacin (CIP) is a widespread emerging water pollutant and thus its removal from aquatic environment is vital. The use of Fe3+/H2O2 and Fe2+/H2O2 resulted in 38 and 64% removal of CIP (8.0 ppm), respectively, within 80 min reaction time (pH 5.8, [H2O2]0 = 80 ppm, and [iron]0 = 20 ppm). Low pH, high temperature, high dose of H2O2 and Fe2+, and low CIP concentration facilitated removal of CIP. The radical scavenger studies proved in situ generated OH to be involved primarily in the removal of CIP. The effect of temperature was used to estimate enthalpy and activation energies of the removal of CIP. At 800 min reaction time, the Fe2+/H2O2 resulted in 54% mineralization of CIP using 16.0 ppm [CIP]0, 320.0 ppm [H2O2]0, and 40.0 ppm [Fe2+]0. The potential degradation pathways of CIP established from the degradation of CIP by OH and products evolved was found to be initiated at C6 through the loss of fluoride ion. The acute and chronic toxicities of CIP and its degradation products were estimated with the final product found to be non-toxic. The results suggest that Fe2+/H2O2-mediated AOPs have high potential for degradation as well as toxicity elimination of CIP and its degradation products. [ABSTRACT FROM AUTHOR]

• The presence of H 2 O 2 with iron promoted the removal of CIP. • The presence of OH scavengers inhibited removal of CIP by Fe2+/H 2 O 2. • Mineralization of CIP by Fe2+/H 2 O 2 -mediated AOPs was explored. • Potential pathways for conversion of CIP into degradation products were developed. • Acute and chronic toxicities of CIP and its degradation products were estimated. Ciprofloxacin (CIP) is a widespread emerging water pollutant and thus its removal from aquatic environment is vital. The use of Fe3+/H 2 O 2 and Fe2+/H 2 O 2 resulted in 38 and 64% removal of CIP (8.0 ppm), respectively, within 80 min reaction time (pH 5.8, [H 2 O 2 ] 0 = 80 ppm, and [iron] 0 = 20 ppm). Low pH, high temperature, high dose of H 2 O 2 and Fe2+, and low CIP concentration facilitated removal of CIP. The radical scavenger studies proved in situ generated OH to be involved primarily in the removal of CIP. The effect of temperature was used to estimate enthalpy and activation energies of the removal of CIP. At 800 min reaction time, the Fe2+/H 2 O 2 resulted in 54% mineralization of CIP using 16.0 ppm [CIP] 0 , 320.0 ppm [H 2 O 2 ] 0 , and 40.0 ppm [Fe2+] 0. The potential degradation pathways of CIP established from the degradation of CIP by OH and products evolved was found to be initiated at C 6 through the loss of fluoride ion. The acute and chronic toxicities of CIP and its degradation products were estimated with the final product found to be non-toxic. The results suggest that Fe2+/H 2 O 2 -mediated AOPs have high potential for degradation as well as toxicity elimination of CIP and its degradation products. [ABSTRACT FROM AUTHOR]

Bromate, a potential carcinogen, is a well known highly persistent and environmentally recalcitrant contaminant. UV-254/sulfite-based advanced reductive pathways (ARPs) were proposed to eliminate bromate successfully from water. Experiments with N 2 , N 2 O, 2-chlorophenol, inorganic ions, and different pH (highly acidic to highly basic) proved that UV-254/sulfite successfully provides aqueous electron that effectively participate in bromate removal from water. Significant removal, 86%, of initially 39.0 µM bromate was achieved by UV-254/sulfite under conditions that dominate aqueous electron based pathways. The high second-order rate constant of 5.3 × 10 9 M −1 s −1 determined proved high reactivity of aqueous electron with bromate. The kinetic and removal efficiency of bromate showed linear relationship with the rate of aqueous electron formation. An increase in kinetic and removal efficiency of bromate was observed with increasing initial sulfite concentration and decreasing bromate concentration. The impacts of different initial concentrations of the typical ions commonly found in water were studied in detail to extend the UV-254/sulfite-based process for potential practical applications. The lower molar absorptivity of bromate at 254 nm determined proved insignificant removal of bromate under direct photolysis. The impacts of initial sulfite concentration on removal of bromate in UV-254/sulfite-based process also minimized role of direct photolysis. The cost evaluation and rapid decomposition of bromate into bromide proved UV-254/sulfite-based ARPs to be economical and highly rewarding in efficient decomposition of bromate and other inorganic oxyhalides. [ABSTRACT FROM AUTHOR]

Removal of chlorendic acid, an emerging water pollutant and potential carcinogenic, was investigated by gamma radiation in the absence and presence of peroxymonosulfate (PMS, HSO 5 − ). The removal of chlorendic acid (1.40 μM initial concentration) by gamma radiation was promoted with PMS, i.e., 95% compared to 82% in the absence of PMS, at an absorbed dose of 1000 Gy. The removal of chlorendic acid by gamma-ray/PMS process was due to OH and SO 4 − . Second-order rate constants of 5.90 × 10 9 , 1.75 × 10 9 , and 2.05 × 10 9 M −1 s −1 for chlorendic acid with e aq − , OH, and SO 4 − , respectively, were determined. The removal efficiency of chlorendic acid was promoted with increasing initial PMS concentration and decreasing initial target contaminant concentration. The removal of chlorendic acid by gamma-ray/PMS was inhibited in the presence of CO 3 2− , NO 2 − , p -CBA, m -TA, and alcohols. The presence of Fe 2+ , Cu + , and Fe 3+ with gamma-ray/PMS promoted removal efficiency of chlorendic acid from 78% to 99, 94, and 89%, respectively, at 592 Gy. The degradation of chlorendic acid by OH and SO 4 − was found to be initiated at the carboxylate group as could be revealed from nature of the transformation by-products. Nevertheless, this study concluded that gamma-ray/PMS is of practical importance in treatment of natural water containing chlorendic acid, as potential detoxification of chlorendic acid solution can be revealed from 83% loss of chloride ion at 3000 Gy. In addition, gamma-ray/PMS process achieved efficient removal of chlorendic acid even in the presence of commonly found inorganic ions in natural water. [ABSTRACT FROM AUTHOR]

Norfloxacin (NOR), an important antibiotic used for the treatment of different infections which is reportedly causing huge quantity of water pollution and severe environmental issues. In this study, biochar prepared from Phoenix dactylifera roots biomass (PB) and composited with mesoporous nano-zerovalent cerium (nZVCe) was used for treatment of NOR solutions. The various characterization and treatment studies showed successful formation of the nZVCe and PB composite. The nZVCe was found to improve physiological characteristics and catalytic efficiency of PB. The nZVCe/PB composite caused 52% removal of NOR as compared to 23% by the individual PB. The use of peroxydisulfate (PDS) with PB and nZVCe/PB showed further improvement in the removal of NOR and caused 58 and 84% removal efficiencies of NOR by PB/PDS and nZVCe/PB/PDS, respectively. The use of PDS with PB and nZVCe/PB was found to yield ●OH and SO 4 ●– which improved degradation of NOR, however, addition of ●OH and SO 4 ●– scavengers impeded NOR degradation. The PB was found to have several oxygen functional groups which decomposed PDS into ●OH and SO 4 ●–. The nZVCe/PB showed high recovery, reusability, and stability and caused high removal of NOR even at fifth cycle of treatment both in the absence and presence of PDS. The treatment of NOR by nZVCe/PB-catalyzed PDS showed encouraging results under different pH, and varying concentrations of PDS, nZVCe/PB, and NOR as well as in real water samples which suggest potential practical applications of NOR contaminated water. Degradation of NOR resulted into several products and the resulting final product proved to be non-toxic. [Display omitted] • nZVCe and biochar composite was prepared and nZVCe improved properties of biochar. • Biochar and nZVCe/PB effectively decomposed PDS into.●OH and SO 4 ●–. • Radical scavengers inhibited role of.●OH and SO 4 ●– in degradation of norfloxacin. • The PB and nZVCe/PB effectively degraded norfloxacin in real water also. • The composite of biochar and nZVCe showed enhanced stability and reusability. [ABSTRACT FROM AUTHOR]

This study investigated iron-mediated oxidative processes for the photochemical degradation of endosulfan, a chlorinated insecticide and central nervous system disruptor. At UV fluence of 360 mJ/cm 2 , 52.4% and 32.0% removal of 2.45 μM initial endosulfan was observed by UV/Fe 3+ and UV/Fe 2+ processes, respectively, at an initial concentration of 17.8 μM iron. The degradation of endosulfan by UV/Fe 3+ or UV/Fe 2+ was dramatically enhanced by adding peroxide (i.e., H 2 O 2 , S 2 O 8 2− or HSO 5 − ). Among the UV/peroxide/Fe processes, the highest degradation efficiency of 99.0% at UV fluence of 360 mJ/cm 2 was observed by UV/HSO 5 − /Fe 2+ with 2.45 μM [endosulfan] 0 , 17.8 μM [Fe 2+ ] 0 , and 49.0 μM [HSO 5 − ] 0 . The observed degradation rate constant of endosulfan was promoted either by increasing [Fe 2+ ] 0 and/or [peroxide] 0 or by decreasing [endosulfan] 0 , while the initial degradation rate of endosulfan increased with increasing [Fe 2+ ] 0 , [peroxide] 0 , or [endosulfan] 0 . At UV fluence of 6000 mJ/cm 2 , 45.0% mineralization as represented by the decrease in total organic carbon content was observed by UV/HSO 5 − /Fe 2+ at 9.80 μM [endosulfan] 0 , 980 μM [HSO 5 − ] 0 , and 17.8 μM [Fe 2+ ] 0 . The major by-product of endosulfan was observed in all cases to be endosulfan ether which was further degraded with an extended reaction time. The results suggest that iron-mediated advanced oxidation processes (AOPs) have a high potential for the removal of endosulfan and its by-product from contaminated water. [ABSTRACT FROM AUTHOR]

The degradation of atrazine was investigated in aqueous solution by gamma-ray irradiation. 8.11 μM initial atrazine concentration could be completely removed in N 2 saturated solution by applying 3500 Gy radiation dose at a dose rate of 296 Gy h −1 . Significant removal of atrazine (i.e., 39.4%) was observed at an absorbed dose of 1184 Gy in air saturated solution and the removal efficiency was promoted to 50.5 and 65.4% in the presence of N 2 O and N 2 gases, respectively. The relative contributions of hydrated electron, hydroxyl radical and hydrogen radical toward atrazine degradation were determined as ratio of observed dose constant ( k obs ) and found to be 5: 3: 1 for k eaq − : k OH : k H , respectively. The degradation efficiency of atrazine was 69.5, 55.6 and 37.3% at pH 12.1, 1.7 and 5.7, respectively. A degradation mechanism was proposed based on the identified degradation by-products by gas chromatography–mass spectrometry. Taking the relative contributions of oxidative and reductive species to atrazine degradation into account, reductive pathway proved to be a better approach for the radiolytic treatment of atrazine contaminated water. [ABSTRACT FROM AUTHOR]

The gamma irradiation was investigated for potential removal of endosulfan sulfate, an emerging water pollutant and central nervous system disruptor. A removal efficiency of 99.5% of initially 1.30 μM endosulfan sulfate was observed at an absorbed dose of 1020 Gy. Aqueous electron (e aq − ) was found to play primary role in the removal of endosulfan sulfate which was possibly due to greater reactivity of e aq − with endosulfan sulfate, considering the second-order rate constant of 8.1 × 10 9 and 3.4 × 10 10 M −1 s −1 for hydroxyl radical ( OH) and e aq − , respectively, with endosulfan sulfate. The removal efficiency of endosulfan sulfate was affected by the pH of aqueous solution, with observed removal efficiency of 99.5%, 98.3% and 31.3% at pH 6.2, pH 10.0, and pH 2.6, respectively. The efficiency was also influenced by inorganic anions and humic acid in the order of nitrate > nitrite > bicarbonate > carbonate ≃ humic acid. The initial degradation rate increased while degradation constant decreased with increasing initial concentrations of endosulfan sulfate. The degradation pathways showed that oxidative pathway was initiated at the SO 2 bond while reductive pathways at the chlorine attached to the ring of endosulfan sulfate. The mass balance showed removal of 98% chloride and 72% sulfate ions from endosulfan sulfate at an absorbed dose of 1020 Gy. The removal of endosulfan sulfate followed by subsequent loss of by-products under extended treatment showed that gamma irradiation is potential technique for the remediation of organic pollutants from a water environment. [ABSTRACT FROM AUTHOR]

The removal of endosulfan, an emerging water pollutant, from water was investigated using gamma irradiation based advanced oxidation and reduction processes (AORPs). A significant removal, 97% of initially 1.0 µM endosulfan was achieved at an absorbed dose of 1020 Gy. The removal of endosulfan by gamma-rays irradiation was influenced by an absorbed dose and significantly increased in the presence of aqueous electron (eaq-). However, efficiency of the process was inhibited in the presence of eaq- scavengers, such as N2O, NO3-, acid, and Fe3+. The observed dose constant decreased while radiation yield (G-value) increased with increasing initial concentrations of the target contaminant and decreasing dose-rate. The removal efficiency of endosulfan II was lower than endosulfan I. The degradation mechanism of endosulfan by the AORPs was proposed showing that reductive pathways involving eaq- started at the chlorine attached to the ring while oxidative pathway was initiated due to attack of hydroxyl radical at the SO bond. The mass balance showed 95% loss of chloride from endosulfan at an absorbed dose of 1020 Gy. The formation of chloride and acetate suggest that gamma irradiation based AORPs are potential methods for the removal of endosulfan and its by-products from contaminated water. [ABSTRACT FROM AUTHOR]

Conventional titanium dioxide (TiO2) materials can be activated only by ultraviolet (UV) light, which is only 4-5% of the whole solar spectrum. As a result, visible light (vis)-active TiO2-based photocatalysts have recently received significant attention in the field of TiO2 photocatalytic treatment and purification of water and air. This study reports the preparation of UV-visible light-active phosphorous (P)-doped, fluorine (F)-doped, and PF-co-doped anatase TiO2 nanoparticles via an innovative sol-gel method. Prepared nanoparticles were characterized by UV-vis diffuse reflectance spectroscopy, X-ray diffraction analysis, Raman spectroscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy (FTIR), and porosimetry analysis. Synthesized materials exhibited improved structural properties, including high surface area, small crystallite size, reduced band gap energy, mesoporous structure, and high porosity. Due to doping with P and F, light absorption of TiO2 in the visible light region was efficiently enhanced with effective band gap energy of 2.70 eV. Brunauer-Emmett-Teller (BET) surface area for PF-co-doped, P-doped, F-doped, and reference TiO2 nanoparticles was 212.0, 175.0, 88.8, and 79.7 m2/g, respectively. PF-co-doped TiO2 showed the highest photocatalytic degradation of atrazine, which could be attributed to the beneficial effects including small crystallite size, high BET surface area, and light absorption in UV-visible region, induced by co-doping of TiO2 with P and F. Finally, reaction intermediates were determined, which confirms the photocatalytic degradation of atrazine using the synthesized catalysts under UV-visible light illumination. [ABSTRACT FROM AUTHOR]

• The nZVMn/PBC showed high activity in adsorptive and oxidative removal of Congo-red. • The physical properties of biochar were improved with the coupling of nZVMn. • The nZVMn/PBC-catalyzed H2O2 into ●OH that caused oxidative removal of Congo-red. • Congo-red removal was promoted with the high dose of adsorbent and H2O2. • Degradation pathways of Congo-red in ●OH-mediated oxidative system were proposed. Congo-red (CR), a precursor of textile products and a contaminant of great concern, has contaminated aquatic environments. Here, we explored the synthesis of mesoporous nano-zerovalent manganese (nZVMn) and Phoenix dactylifera leaves biochar (PBC) composite for the removal of CR from water. The nZVMn/PBC adsorbed 117.647 mg/g of CR versus 25.316 mg/g by PBC at [CR] 0 = 20 mg/L and [PBC] 0 = [nZVMn/PBC] 0 = 500 mg/L. Variation of [nZVMn/PBC] 0 , [CR] 0 and pH influenced the adsorption of CR. Freundlich adsorption isotherm and pseudo-first-order kinetic models best fitted CR adsorption. The H 2 O 2 coupling with nZVMn/PBC promoted removal of CR possibly due to the formation of hydroxyl radical (●OH) and caused 95 % removal of CR versus 77 % by nZVMn/PBC alone. The ●OH scavengers inhibited the removal of CR. The nZVMn/PBC showed a good reusability and efficient removal of CR up to the seventh cycle of treatment. Results reveal that nZVMn improved performance, thermal stability and reusability of biochar. Degradation products from ●OH-mediated degradation of CR were studied by ultraperformance liquid chromatography with mass spectrometric detector to establish degradation pathways. The ion-chromatographic analysis showed the formation of non-toxic inorganic acetate product, which suggests high potential of the newly fabricated adsorbent in the removal of CR. [ABSTRACT FROM AUTHOR]

• Congo-red dye and its DPs were found highly toxic. • Gamma-ray with the added H 2 O 2 and S 2 O 8 2− efficiently degraded CR. • Reactivity of congo-red dye with OH and SO 4 − were calculated. • Proposed degradation pathways of CR were developed from the DPs evolved. Gamma radiation has received increasing attention due to their high potential in degradation of recalcitrant pollutants. Thus in the present study, gamma radiation was used for degradation of congo-red (CR) dye, a highly toxic and carcinogenic pollutant, in the presence of H 2 O 2 and S 2 O 8 2−. The CR was significantly degraded by gamma radiation (i.e., 53%), however, presence of H 2 O 2 and S 2 O 8 2− promoted degradation of CR to 98 and 87%, respectively, at 1184 Gy absorbed dose. The radical scavengers and electron spin resonance studies revealed that gamma radiation decompose H 2 O 2 and S 2 O 8 2− into OH and SO 4 − and both OH and SO 4 − caused degradation of CR. The CR showed high reactivity, i.e., 3.25 × 109 and 8.50 × 108 M−1 s−1 with OH and SO 4 −, respectively, and removal of CR was inhibited in the presence of OH and SO 4 − scavengers. The removal of CR was promoted with elevating initial concentrations of H 2 O 2 and S 2 O 8 2− and decreasing initial concentrations of CR. pH of aqueous solution also significantly influenced removal of the dye. The proposed degradation pathways of CR were established from the OH mediated degradation of CR and nature of identified degradation products. The greater mineralization of CR, formation of small molecular mass degradation product, and decline in concentration of acetate after extended treatment suggest the gamma-ray mediated peroxide based process to be a promising alternative for potential degradation of CR. [ABSTRACT FROM AUTHOR]

Chlorpyrifos (CPY), an organophosphate pesticide is largely used throughout the world on different crops for the control of pests and causes severe health and environmental issues. In this study, highly efficient, crystalline, and nm-rang sized zerovalent zinc (nZVZn) catalyst was synthesized and used for removal of chlorpyrifos at semi-pilot scale. The nZVZn showed high activity and caused 55% removal of CPY at 90 min time under the conditions of [CPY] 0 = 10 mg/L, [nZVZn] 0 = 1.0 g/L, and flow rate of the reactor = 0.2 L/min. Using identical conditions of [CPY] 0 , [nZVZn] 0 and flow rate, the use of peroxymonosulfate (PMS) promoted the performance of nZVZn and caused 99.5% removal of CPY at [PMS] 0 = 40 mg/L. The electron spin resonance (ESR) spectroscopy studies revealed that nZVZn catalyzed PMS reactions yield hydroxyl and sulfate radicals that degraded CPY and removal of CPY was suppressed by applying radical scavengers. The nZVZn catalyzed PMS based removal of CPY was optimum at high [PMS] 0 , [nZVZn] 0 and low pH of solution. The flow rate of the pilot plant reactor also influenced the degradation efficiency of CPY. High pH of solution, high [CPY] 0 as well as use of alcohols, NOM, and some inorganic ions inhibited removal of CPY by nZVZn catalyzed PMS. The analysis of degradation products (DPs) of CPY were used to propose degradation pathways of CPY. The high TOC removal of CPY, low leaching of Zn2+ from Zn0 into aqueous solution, and toxicity reduction of CPY suggest the nZVZn catalyzed PMS process to be highly effective and environmental benign for treatment of CPY. Image 1 • Nano zerovalent zinc was used for removal of chlorpyrifos at semi-pilot scale. • Removal of chlorpyrifos by zerovalent zinc was promoted by peroxymonosulfate. • Hydroxyl and sulfate radical rate constants with chlorpyrifos were calculated. • Proposed degradation pathways of chlorpyrifos were suggested. • Toxicities of treated chlorpyrifos solutions and zinc ion leaching were evaluated. [ABSTRACT FROM AUTHOR]

Abstract This study presents the synthesis of a novel Mn2+ and Co2+ co-doped TiO 2 (Mn-Co-TiO 2) for the photocatalytic degradation of enoxacin (ENX) under solar light irradiation. The as-synthesized photocatalysts were fully characterized by X-ray diffraction (XRD) analysis, field emission-scanning electron microscopy (FE-SEM), and UV-diffuse reflectance spectroscopy (UV-DRS). The structural appearance of the Mn-Co-TiO 2 suggests porous cylindrical type morphology. Moreover, the co-doping of Mn2+ and Co2+ has successfully reduced the band gap of TiO 2 from 2.81 eV to 2.10 eV. Applying Langmuir Hinshelwood kinetic model, the photocatalytic degradation of ENX by Mn-Co-TiO 2 followed pseudo-first-order kinetics. A total of twelve (12) DPs of ENX were identified by UPLC/MS-MS. The natural water constituents such as CO 3 2−, HCO 3 −, Cl− and Fe3+ had great influence on the photocatalytic degradation of ENX by Mn-Co-TiO 2 under solar light irradiation. The as-synthesized Mn-Co-TiO 2 showed appreciable results for the photocatalytic degradation of ENX in synthetic wastewater (SWW) and real wastewater (RWW) samples. Furthermore, the toxicity assessment of ENX and its DPs towards aquatic organisms (i.e., fish, daphnia and green algae) was measured which are helpful for the practical implementation of this technology for wastewater treatment. The Mn-Co-TiO 2 materials also showed good peroxidase-like activity towards the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H 2 O 2 and followed Michaelis-Menten kinetics. Graphical abstract Unlabelled Image Highlights • Efficient Solar light driven photocatalysis of Enoxacin. • Narrowing the band gap of TiO 2 by co-doping with Mn2+ and Co2+ • Total of twelve (12) new photocatalytic degradation byproducts of ENX were found. • Toxicity assessment revealed that some of the degradation byproducts are more toxic than ENX. • Additional peroxidase like activity of Mn/Co-TiO 2 was found. [ABSTRACT FROM AUTHOR]

The removal of brilliant green (BG), a toxic organic and cationic dye, has been examined by UV/S 2 O 8 2− (PS), UV/HSO 5 − (PMS) and UV/H 2 O 2 processes. BG showed insignificant direct photolysis at 254 nm (i.e., 8.6% after 30 min). However, enhanced BG degradation was observed in UV/PS, UV/PMS and UV/H 2 O 2 systems as revealed from 63.1, 47.0 and 34.8% BG degradation, respectively, at 30 min of reaction time, using 0.05 mM BG and 1.0 mM oxidant initial concentration. The bimolecular rate constants of OH and SO 4 − with BG were determined to be 2.35 × 10 9 and 2.21 × 10 9 M −1 s −1 , respectively. Electrical energy per order (EE/O) values for UV/PS, UV/PMS and UV/H 2 O 2 processes were calculated to be 5.4, 6.8, and 7.8 KWh/m 3 /order, respectively. The addition of humic acid (HA) and inorganic anions inhibited the degradation of BG by UV/PS in the order of NO 2 −  > HA > HCO 3 −  > Cl −   > NO 3 −  ≈ SO 4 2− . The results of frontier electron densities (FEDs) showed that C-atom holding the three rings (C7), and C-atoms at para positions to N-alkyl groups of the two rings (C4 and C14) are the predominant sites for radical addition. Furthermore, nine degradation products (DPs) of BG were detected experimentally using LC/MS/MS. [ABSTRACT FROM AUTHOR]

Carbamazepine (CBZ), a widely used antiepileptic drug, was removed by UV–254 nm based advanced oxidation processes. CBZ was found to be stable under sole UV, however, removal of CBZ was promoted using Fe3+ and Fe2+ with UV. Further, removal efficiency of CBZ was significantly enhanced by coupling H2O2 with UV and Fe3+/Fe2+. At 3600 mJ cm−2, 7.5, 60.2, 74.3 and 90.6% CBZ degradation was achieved in UV, UV/H2O2, UV/H2O2/Fe3+ and UV/H2O2/Fe2+, using CBZ, H2O2, Fe2+ and Fe3+ at 21.16, 1060.00, 17.91 and 17.91 μM, respectively. Higher CBZ degradation in the presence of H2O2 was attributed to HO whose second-order rate constant with CBZ was calculated to be (8.83 ± 0.27) × 109 M−1 s−1. Removal of CBZ by UV/H2O2/Fe2+ system was optimum at pH 3.0, as 80.8, 90.6 and 70.4% CBZ degradation was observed at pH 2.0, 3.0 and 6.5, respectively. The removal of CBZ by UV/H2O2/Fe2+ was retarded in the presence of Cl− and humic acid as revealed from 84.5 and 56.7% CBZ degradation in the presence of Cl− and humic acid, respectively, compared to 90.6% in their absence at 3600 mJ cm−2. The CBZ degradation products were found to be less toxic than the parent compound, suggesting important role of UV-assisted AOPs in efficient removal and toxicity reduction of CBZ and their degradation products. [ABSTRACT FROM AUTHOR]

• Degradation of carbamazepine was investigated in UV-assisted AOPs. • Carbamazepine was recalcitrant to sole UV but susceptible to UV/H 2 O 2 /Fe2+ oxidation. • Second order rate constant of carbamazepine with OH was (8.83 ± 0.27) × 109 M−1 s−1. • The UV/H 2 O 2 /Fe2+ treatment was efficient in toxicity reduction of CBZ. • Degradation mechanism was proposed from identified degradation products. Carbamazepine (CBZ), a widely used antiepileptic drug, was removed by UV–254 nm based advanced oxidation processes. CBZ was found to be stable under sole UV, however, removal of CBZ was promoted using Fe3+ and Fe2+ with UV. Further, removal efficiency of CBZ was significantly enhanced by coupling H 2 O 2 with UV and Fe3+/Fe2+. At 3600 mJ cm−2, 7.5, 60.2, 74.3 and 90.6% CBZ degradation was achieved in UV, UV/H 2 O 2 , UV/H 2 O 2 /Fe3+ and UV/H 2 O 2 /Fe2+, using CBZ, H 2 O 2 , Fe2+ and Fe3+ at 21.16, 1060.00, 17.91 and 17.91 μM, respectively. Higher CBZ degradation in the presence of H 2 O 2 was attributed to HO whose second-order rate constant with CBZ was calculated to be (8.83 ± 0.27) × 109 M−1 s−1. Removal of CBZ by UV/H 2 O 2 /Fe2+ system was optimum at pH 3.0, as 80.8, 90.6 and 70.4% CBZ degradation was observed at pH 2.0, 3.0 and 6.5, respectively. The removal of CBZ by UV/H 2 O 2 /Fe2+ was retarded in the presence of Cl− and humic acid as revealed from 84.5 and 56.7% CBZ degradation in the presence of Cl− and humic acid, respectively, compared to 90.6% in their absence at 3600 mJ cm−2. The CBZ degradation products were found to be less toxic than the parent compound, suggesting important role of UV-assisted AOPs in efficient removal and toxicity reduction of CBZ and their degradation products. [ABSTRACT FROM AUTHOR]

Desethyl-atrazine (DEA) and desisopropyl-atrazine (DIA) are the two major degradation by-products of atrazine (a suspected human carcinogen and endocrine disrupting herbicide), and show an equal toxicity to their parent compound. This study investigated the degradation of DEA and DIA with OH and SO 4 − generated from the activation of peroxides, i.e., persulfate (S 2 O 8 2− ), peroxymonosulfate (HSO 5 − ) and hydrogen peroxide (H 2 O 2 ), by UV-254 nm radiation in the presence or absence of Fe 2+ . Quantum yields of DEA and DIA were independent of pH (3.0–11.0). The higher quantum yield of reactive radicals from UV/S 2 O 8 2− , i.e., 1.8 compared to 1.04 for UV/HSO 5 − and 1.0 for UV/H 2 O 2 , resulted in greater efficiency of UV/S 2 O 8 2− for both DEA and DIA degradation. The second-order rate constants of DEA and DIA with SO 4 − were calculated to be (6.42 ± 0.12) × 10 8 and (1.70 ± 0.30) × 10 9 M −1 s −1 , and that with OH were (1.14 ± 0.09) × 10 9 and (2.22 ± 0.44) × 10 9 M −1 s −1 , respectively, suggesting a strong impact of side chains toward radical reactions. Fe 2+ promoted slightly the activation of the examined peroxides at pH 7.4. Presence of organic matter and alkalinity in field water samples negatively influenced the efficiency of UV/S 2 O 8 2− . Based on the identified degradation by-products by GC–MS, potential degradation pathways were proposed for both compounds. The results obtained suggested that DEA and DIA can be efficiently removed from the contaminated water by OH and SO 4 − based-AOPs. [ABSTRACT FROM AUTHOR]

• Eosin modified TiO 2 film with co-exposed {001} and {101} facets was synthesized. • Sulfite/Eosin-TiO 2 system was used as SO 4 − based Advanced Oxidation Process. • Degradation of PABA was performed by sulfite/Eosin-TiO 2 /solar system. • Under visible light irradiation, Eosin-TiO 2 showed appreciable H 2 production rate. • Solar/Eosin-TiO 2 (/SO 3 2–) is a promising method for environmental sustainability. Owing to the increasing photosensitivity and DNA damage properties of para -aminobenzoic acid (PABA), concerns have been raised over the exposure of humans to PABA. Solar light-driven photocatalysis (SPC) provides a promising solution for the effective removal of organic pollutants especially when directed towards sulfate radical (SO 4 −) production. Herein, we have developed a sulfite-enhanced SPC using Eosin-Y sensitized TiO 2 /Ti film as a photocatalyst. The removal efficiency of PABA was enhanced by coupling Eosin-Y with TiO 2 /Ti film as revealed from 23.6 and 48.9 % PABA degradation by reference-TiO 2 /solar and Eosin-TiO 2 /solar, respectively. The apparent rate constant of PABA degradation by Eosin-TiO 2 was improved by 4.7 times in presence of 5 mM sulfite. Interestingly, Eosin-TiO 2 showed appreciable H 2 production rate under visible light illumination. Solar/sulfite/Eosin-TiO 2 system is a promising technology for environmental sustainability by using the renewable solar energy and air pollutants since sulfite is a waste from flue gas desulfurization process. [ABSTRACT FROM AUTHOR]

• Highly stable and solar light responsive Bi-TiO 2 was synthesized. • The doping of Bi3+ induced Ti3+ and oxygen vacancy in the TiO 2 lattice. • The photocatalytic efficiency of TBi5 was enhanced by coupling with HSO 5 −. • SO 4 − and OH were dominant species involved in the degradation of FLU. • The contribution rate of SO 4 − was calculated to be 89% in the degradation of FLU. The present study is focused on the synthesis of a novel solar light responsive bismuth doped titania (Bi-TiO 2) through a facile so-gel technique by applying various wt% of Bi. The as-synthesized Bi-TiO 2 showed superior photocatalytic performance than un-doped TiO 2 towards degradation of flumequine (FLU) under solar light irradiation. The as-synthesized material was thoroughly characterized to examine its structure, morphology and chemical states. The EPR analysis revealed the existence of Ti3+ ion and oxygen vacancy, which is created due to Bi-doping. The as-synthesized Bi-TiO 2 with 5 wt% Bi (TBi5) showed excellent photocatalytic performance as compared to their counterparts. The photocatalytic activity of TBi5 was further improved when added with peroxymonosulfate (HSO 5 −) and increased with increasing [HSO 5 −] 0. The mechanistic investigation and radical scavenging studies revealed that OH and SO 4 − are involved in the degradation of FLU by the as-synthesized material. The bimolecular rate constants of OH and SO 4 − were calculated to be 9.1 × 109 M−1s−1 and 8.5 × 109 M−1s−1, respectively. The photocatalytic performance of the as-synthesized TBi5 coupled with HSO 5 − under solar light irradiation towards degradation of FLU in Milli-Q water (MW), tape water (TW) and synthetic wastewater (SWW) was 92, 82 and 70% with k app values of 0.093, 0.085 and 0.066 min−1, respectively. Furthermore, the degradation pathways of FLU were predicted on the basis of its degradation products (DPs). The high mineralization of FLU as well as the evaluation of non-toxic DPs suggests that solar light/TBi5/HSO 5 − is a promising advanced oxidation process for the future wastewater treatment applications. [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]

Abstract: The degradation of atrazine, a widely used endocrine disrupting, carcinogenic and persistent herbicide, was investigated by photo-Fenton and photo-Fenton-like advanced oxidation technologies (AOTs): UV/H2O2/Fe2+, UV//Fe2+ and UV//Fe2+. The study was carried out at two pH value conditions, i.e., pH 3.0 and pH 5.8. At pH 3.0, UV//Fe2+ was found to be the most efficient technology whereas UV//Fe2+ was observed to be the most effective at pH 5.8. The degradation of atrazine followed pseudo-first-order reaction with the highest observed rate constant of 2.00×10−2 cm2/mJ in UV//Fe2+ system at the initial concentrations of 4.64μM atrazine, 46.4μM (PMS) and 35.81μM Fe2+. The UV fluence required for the complete removal of 4.64μM atrazine at initially 92.80μM of oxidant and 8.95μM of Fe2+ concentrations at pH 3.0 was found to be 480, 720 and 960mJ/cm2 in UV//Fe2+, UV//Fe2+ and UV/H2O2/Fe2+ systems, respectively. Humic and fulvic acids were found to negatively impact the degradation of atrazine. The removal of TOC was not significant unless a high UV fluence was applied. At an initial concentration of 18.56μM atrazine, 1856.00μM oxidant and 17.91μM Fe2+, a 62.94%, 47.10% and 44.09% decrease in TOC was achieved at a UV fluence of 6000mJ/cm2 in UV/PS/Fe2+, UV/PMS/Fe2+ and UV/H2O2/Fe2+ systems, respectively. Nevertheless, it is suggested in this study that photo-Fenton and photo-Fenton-like technologies are capable of removing atrazine from water efficiently. [Copyright &y& Elsevier]