Degradation of dye in a continuous zig-zag flow pattern photocatalytic reactor using a Doehlert matrix

Abstract

Rhodamine B-containing wastewater was thoroughly treated in a photocatalytic reactor operated in a continuous mode with a zig-zag type of flow pattern. The effect of operating parameters such as pH (1−9) and initial dye concentration (10–40 ppm) on Rhodamine B degradation was studied at 1 g/L of TiO2 and H2O2 in order to determine the optimal operating parameters for combined treatment schemes. At a concentration of 10 ppm and a loading of 1 g/L TiO2 and H2O2 at a pH of 3, the maximum rate of degradation was 94.02%, and 96.68% obtained and follows pseudo-first order kinetics, respectively. Further studies of the influence of initial dye concentration and solution pH were investigated using an optimized range of TiO2 and H2O2 loading based on the surface response of the Doehlert matrix design. Based on the surface response, it was observed that the lower initial concentration with a higher loading of TiO2 and H2O2 accelerates the production of hydroxyl radicals and thereby, higher degradation of pollutants was achieved. Complete degradation with 84.76% COD reduction of Rhodamine B was observed at 0.8 g/L of H2O2 and 2 pH of dye solution with a total treatment cost of US $0.009/L. Overall, the current study found that the novel photocatalytic reactor operated in a continuous mode can treat large volumes of waste water using hybrid methods with optimum catalyst loading, has high potential, and may be successfully applied for the removal of hazardous dyes from aqueous solutions with intensification benefits.