Modeling and Optimization of Photocatalytic Degradation of Methylene Blue Using Lanthanum Vanadate

Methylene blue (MB) is one of the commonly used dyes in the textile industry and can be used as a model pollutant for the textile industry wastewater. In this work, the photocatalytic degradation of MB by synthesized nanoparticles of lanthanum vanadate (LaVO4) was assessed. The effects of pH, initial MB concentration and catalyst dose on the removal performance of MB were investigated and measuring the optimum values of these operational conditions was performed using response surface methodology (RSM). Catalyst dose of 0.43 g/L, initial MB concentration of 5.0 mg/L, and pH of 6.86 were found to be the optimum conditions in reaction time of 60 min. A mathematical model was formed to relate the removal efficiency of MB to the aforementioned operating parameters. The removal efficiency of MB was 91% without any scavengers at a catalyst dose of 0.3 g/L, pH of 7 and initial MB concentration of 10 mg/L. The trapping experiments confirmed the participation of different reactive species in the photo-degradation process. The degradation rates of MB were 91%, 86%, 81%, 77.70% and 72% in five successive runs using LaVO4.