Photocatalytic oxidation performance and kinetics of simulated organic wastewater in circulating slurry photocatalytic reactor

The technique of photocatalytic oxidation was used in the treatment of simulated wastewater with benzamide as a model pollutant. The photocatalytic oxidation performance and kinetics of the simulated organic wastewater in a circulating slurry photocatalytic reactor was investigated. The effects of operation conditions, such as dosage of photocatalyst, illumination time, initial benzamide concentration, pH value, anions and cations in wastewater, on the photocatalytic oxidation performance were discussed. The results showed that the application of photocatalytic oxidation to the treatment of wastewater was feasible and efficient, but it was affected by the operation conditions. There existed optimum value of the dosage of catalyst, initial benzamide concentration and pH value for the photocatalytic oxidation performance. H₃PO^-₄, Cl^-, Cu²⁺ and Al³⁺ showed obvious inhibition to the photocatalytic oxidation. Compared with the results obtained from a stirred slurry reactor and a bubble column slurry reactor, the circulating slurry photocatalytic reactor provided not only excellent blend of catalysts and reactants, but also high efficiency of UV light. It could increase the throughtput of treatment and reduce the dosage of catalyst. The kinetics study of the photocatalytic oxidation with different photocatalyst loadings and initial concentrations showed that the photocatalytic degradation rate followed pseudo-first order kinetics with respect to benzamide concentration, and the surface reaction rate constant (k₀) and adsorption equilibrium constant (K_TiO2) of TiO₂ catalyst were 0.0279 min^-1 and 17.99 L · g^-1 respectively.