Kinetics of clofibric acid degradation by UV/persulfate system in aqueous solution

UV/PS process was employed to remove clofibric acid (CA), one of the typical pharmaceuticals and personal care products. The effect of six kinds of factors (initial concentration of CA, persulfate dosage, initial pH, concentration of bicarbonate, chloride and humic acid) on the kinetics of CA removal by UV/PS process was investigated. CA degradation fitted well with the pseudo-first-order kinetics (R²>0.95). The pseudo-first-order-constant was decreased with the increase of the initial CA concentration. Meanwhile, the degradation rate of CA was increased with the increase of the PS dosage in a certain range. Different pH environment had certain effect on the degradation of CA. When the pH was changed from acidic to alkaline and then to strong alkaline, the degradation rate of CA had a tendency to elevate and drop. Bicarbonate or chloride inhibited the degradation of CA, and the inhibition extent was in the order of HCO₃^->Cl^-. The presence of humic acid also retarded the removal of CA to a certain extent.