Comparative Study Using Chemical Wet Oxidation for Removal of Reactive Black 5 in the Presence of Activated Carbon

Abstract

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, H2O2 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 (0.5 g/L) were used; in the CWPO process, a lower temperature (0.25 g/L) was used but a high amount of H2O2 was added (0.1 mL/250 mL solution); and in the PCWAO process, a lower amount of H2O2 was added (0.01 mL/250 mL solution) and higher temperature (70°C) was necessary to achieve the required performance.