Comparison of the Photocatalytic Degradation of Congo Red Dye Using NiO and NiO-NiFe2O4 Composite

Abstract

NiO and NiO-NiFe2O4, composite had been synthesized by the coprecipitation method and characterized using XRD, FTIR, UV-DRS, and SEM-EDS. The photocatalytic degradation performances of the photocatalyst were investigated using visible irradiation, in which Congo red dye was used as a model. The photocatalytic degradation process was assessed through three variables: the pH of the solution, Congo red dye initial concentration, and irradiation time. The removal efficiency of photocatalytic degradation of 98.45% was achieved using NiO-NiFe2O4 at a pH of 6, an initial concentration of the dye of 100 mg/L, and an irradiation time of 120 minutes was higher than that obtained using NiO, which was 78.5%. Pseudo-first-order was suitable to describe the kinetics of photocatalytic degradation of Congo red, with values of k = 0.0114 min-1 and t1/2 = 60.789 min using NiO as the photocatalyst, and with k =0.0225 min-1 and t1/2 = 30.8 min using NiO-NiFe2O4. The removal efficiency of the NiO-NiFe2O4 composite of consecutive reuse three-time was 98.45, 97.13, and 96.21%, while NiO was 78.30, 77.12, and 75.32%. Therefore, NiO-NiFe2O4 was considered more effective in reducing Congo red concentration than NiO.