Degradation kinetics of photoelectrocatalysis on landfill leachate using codoped TiO2/Ti photoelectrodes

Abstract

The photoelectrocatalytic (PEC) oxidation degradation of landfill leachate rejected by reverse osmosis (RO) using a Cu/N codoped TiO2/Ti photoelectrode was kinetically investigated in terms of COD concentration. The key factors affecting the reaction rate of PEC oxidation and the removal efficiency of COD concentration were studied, including the COD concentration of landfill leachate, potential bias applied, pH value of landfill leachate, and the reaction temperature of photoelectrocatalytic reactor. The apparent kinetic model was applied to describe the photoelectrocatalysis reaction. The results showed that the kinetic equation for photoelectrocatalytic oxidation of landfill leachate was fitting well with the experimental data (R 2 = 0.9670.998), with average activation energy Ea = 6.35 × 104 J · mol-1. It was found that there was an optimal bias voltage of 20 V and low pH value was favorable for COD removal in landfill leachate. The reaction order of initial COD concentration (1.326) is higher than that of potential bias (1.102) and pH value (0.074), which indicates that the reaction rate can be controlled efficiently through adjusted initial concentration. The experiments demonstrated that potential bias would approach its statured value with increasing potential bias.