In this study, for the first time, advanced oxidation process using low pressure UV light together with persulfate and hydrogen peroxide (UV/H2O2 and UV/S2O82−) was evaluated for the oxidation of salicylic acid. The influence of various parameters namely the initial concentrations of oxidants (H2O2 and S2O82−) and initial solution pH on the performance of both processes has been investigated. It was found that for treatment of 30 mg/L of salycilic acid, the optimum conditions were: oxidant dosage of 4.16 mM and pH = 4 for the UV/H2O2 process; as well, oxidant dosage of 5.2 mM and pH = 6 for the UV/S2O82− process. Under these conditions and at the constant reaction temperature of 25ºC, the obtained degradation efficiencies for the UV/H2O2 and UV/S2O82− processes exceed 92% and 94% respectively, after 120 min. Moreover, the rate of salicylic acid degradation via the processes were formulated adequately well on the base of pseudo-first-order kinetic model, with a rate constant of 0.060 min−1 and 0.039 min−1, respectively.
