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In the present study, peroxymonosulfate and hydrogen peroxide activation performances of various layered double hydroxide (LDH) catalysts were tested for the removal of the model food dye, tartrazine, from aqueous solutions. Catalytic activities of Cu-Fe-LDH, Co-Fe-LDH and Ni- Fe-LDH were compared in the presence of peroxymonosulfate and hydrogen peroxide. In the catalyst screening experiments performed by using different oxidants, Co-Fe-LDH and peroxymonosulfate were determined as the most suitable catalyst and the oxidant, respectively. The interactive effects of the catalyst loading, pH and the molar ratio of the oxidant to dye were investigated and the reaction conditions were optimized by using Box-Behnken Design and response surface methodology. Under the optimum reaction conditions determined as 2 g/L of catalyst loading, pH 3, and 11.36 oxidant/dye molar ratio, 87.35% organic matter removal and 97.47% decolorization efficiencies were achieved. [ABSTRACT FROM AUTHOR]

In this study, catalytic wet air oxidation using lanthanum cobalt oxide (LaCoO3) as catalyst was employed for the efficient treatment of synthetic sugar industry wastewater in a single process. A parametric study was performed to determine the optimum conditions. The results showed that reaction temperature and theoretical air percentage were the most effective parameters. Sugar derivatives were almost completely destroyed at the optimum conditions and total organic carbon (TOC) and chemical oxygen demand (COD) removals were determined as 91% and 87%, respectively, indicating a high mineralization degree, which was the main goal of advanced oxidation. The reaction kinetics were investigated by pseudo‐homogeneous and heterogeneous models based on two different parameters: sucrose and TOC concentration. The degree of fit showed that the reaction order was determined as two for the pseudo‐homogeneous approach. According to the surface concentration calculations for heterogeneous models, the presence of mass transfer limitations was only observed for oxygen as gas reactant. All heterogeneous models also fitted the reaction rate data accurately, but the Mars–van Krevelen was the selected model for sucrose and TOC oxidation with the best fit. [ABSTRACT FROM AUTHOR]

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Methylene Blue which has a wide usage area in various sectors including the medicine, pharmaceutics, chemistry and textile is one of the common pollutants found in industrial wastewaters. In this study, the catalytic performance of LaFeO3 perovskite type of catalyst under different reaction conditions in Fentonlike oxidation of the target micropollutant, Methylene Blue was compared. In the parametric study the initial H2O2 concentration was fixed at 1 ppm (1000 μg/L). The aromatic degradation and the decolorization efficiencies were evaluated as 74.5% and 94.6%, respectively, under the optimum reaction conditions which were determined as 0.05 g/L of catalyst loading, 3.5 of pH, 0.1 mM of the initial H2O2 concentration and 45°C. The iron leaching under the optimum conditions was 0.63 ppm. The toxicity tests were performed by the comparison of the Lepidium sativum root lengths growing in the treated dye solution and the distilled water. The toxicity was evaluated as 1.2% in terms of root growth inhibition. In the kinetic study a reaction mechanism was proposed and the reaction rate equation was derived. The decolorization reaction followed pseudo first order reaction kinetics. The activation energy and the pre-exponential factor were calculated as 130.8 kJ/mole and 1.2 ×1020 min-1, respectively. [ABSTRACT FROM AUTHOR]

Methylparaben was degraded in the presence of ABO3perovskite catalysts (A: La, Bi, and B: Ti-Fe, Fe) synthesized on a monolithic structure using the sol–gel method. The catalysts were characterized by BET, SEM, XRD, and FTIR. The highest degradation was observed using BiFeO3on the monolithic structure. The methylparaben degradation and iron leaching were 82.8% and 0.06 ppm, respectively, under the optimum conditions, which were pH=7, [H2O2]0=0.5 mM, and 0.1 g/L BiFeO3loading. The toxicity tests were carried out by cress seeds and 1.09% inhibition was observed. Methylparaben degradation followed the second-order reaction kinetics, whereas the activation energy was 54 kJ/mol. [ABSTRACT FROM PUBLISHER]

The catalytic activities of the iron catalysts over activated carbon supports prepared by different activation methods in the heterogeneous Fenton-like oxidation of Procion Red MX-5B were investigated. The activated carbons were prepared from walnut shells by applying physical and three chemical activation methods, including HNO3, ZnCl2, and KOH activations to obtain various catalyst supports. KOH-activated carbon catalyst was assessed to be the most efficient one. Under the optimum reaction conditions, 47.5% COD removal, 51.6% degradation, and 91.6% decolorization efficiencies were achieved in the presence of this catalyst. In the kinetic study, the activation energy was evaluated as 47.36 kJ/mol. [ABSTRACT FROM PUBLISHER]

The objective of this study was to assess the feasibility of various chemical wet oxidation techniques to remove azo dyes from wastewater. The performances of three different catalytic wet oxidation techniques were evaluated: catalytic wet air oxidation (CWAO), catalytic wet peroxide oxidation (CWPO), and hydrogen peroxide promoted wet air oxidation (PCWAO), using activated carbon as a catalyst to evaluate the degradation and decolorization of Reactive Black 5 in aqueous solution. The experiments were also conducted to investigate the optimum operating conditions of the processes, such as temperature, pH, activated carbon loading, loading, and reaction time. This investigation revealed that all of the wet oxidation techniques showed similar results and rather high removal efficiencies, but at different operating conditions. At the optimized conditions, the degradation was generally approximately 85% and decolorization was nearly 95% in each case. The operating conditions were as follows: in the CWAO process, higher temperature (70°C) and higher activated carbon loading () were used; in the CWPO process, a lower temperature () was used but a high amount of was added ( solution); and in the PCWAO process, a lower amount of was added ( solution) and higher temperature (70°C) was necessary to achieve the required performance. [ABSTRACT FROM AUTHOR]

The degradation of ethylparaben using photo-Fenton-like oxidation was investigated in the presence of a BiFeO3 catalyst. Firstly, the catalyst was synthesized using the sol-gel method and characterized via BET and FT-IR analyzes and then, a parametric study was carried out in order to determine the optimum reaction conditions for the degradation of ethylparaben. In this context, the effects of catalyst loading, [H2O2]°, pH, and temperature on the degradation were investigated. According to the results, the optimum reaction conditions were determined for a 5 ppm ethylparaben solution as 0.25 g/L catalyst loading, a pH of 3, and 2 mM [H2O2]° and a 97.7% degradation of ethylparaben was accomplished. Iron leaching at the optimum conditions was evaluated as 1.53 ppm and it is lower than the E.U. iron concentration limitation (2 ppm) in the water. The kinetic study was carried out at the optimum reaction conditions at three different temperatures (25, 35, and 45 °C). The degradation of ethylparaben using photo-Fenton-like oxidation fitted the first order reaction kinetic model. The reaction rate constants were determined as 0.041, 0.050, and 0.069 min-1 for 25, 35, and 45 °C, respectively. The activation energy was found as 20.4 kJ/mol. [ABSTRACT FROM AUTHOR]