Search

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, the degradation of a major pollutant present in terephthalic acid wastewater, benzoic acid, was investigated by several advanced oxidation methods using catalysts derived from walnut shells. The 10% Fe or 10% Fe-TiO 2 (wt/wt, 1:99 as Fe:TiO 2 ) catalysts were loaded on an AC prepared from walnut shells by physical activation or chemical activation methods with different chemical reagents. The effect of the activation method was investigated using catalyst screening tests. The most efficient catalyst for the Fenton-like oxidation and catalytic wet air oxidation was determined as B-FAC and for photocatalytic/photo-Fenton-like oxidation was the N-FTAC from the screening experiments. After the catalyst screening, the effect of operating conditions such as catalyst loading, temperature, initial pH, etc. on the catalytic activity were tested in terms of degradation efficiency by determining their optimum values. Maximum degradation efficiencies from parametric studies for each method were 40% for the Fenton-like oxidation, 70% for the catalytic wet air oxidation, and 90% for photocatalytic oxidation. The highest degradation efficiency was achieved by the photo-Fenton-like oxidation in the presence of the N-FTAC catalyst with a degradation efficiency of 95% at 0.5 g/L catalyst loading, 6 W UV light, 2 mM initial H 2 O 2 concentration, and an initial pH of 3 or 6, with a reaction time of 80 min. [ABSTRACT FROM AUTHOR]

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]