Photodegradation of 4-tert-butylphenol in aqueous solution by UV-C, UV/H2O2 and UV/S2O82- system

The photolytic degradation of 4-tert-butylphenol (4-t-BP) in aqueous solution was investigated using three kinds of systems: UV-C directly photodegradation system, UV/H2O2 and UV/S2O82- system. Under experimental conditions, the degradation rate of 4-t-BP was in the order: UV/S2O82- > UV/H2O2 > UV-C. The reaction kinetics of UV/S2O82- system were thoroughly investigated. The increase of S2O82- concentration enhanced the 4-t-BP degradation rate, which was inhibited when the concentration of S2O82- exceeded 4.0mM. The highest efficacy in 4-t-BP degradation was obtained at pH 6.5. The oxidation rate of 4-t-BP could be accelerated by increasing the reaction temperature and irradiation intensity. The highest rate constant (k(obs) = 8.4 x 10(-2) min(-1)) was acquired when the reaction temperature was 45 degrees C. The irradiation intensity was measured by irradiation distance, and the optimum irradiation distance was 10cm. Moreover, the preliminary mechanism of 4-t-BP degradation was studied. The bond scission of the 4-t-BP molecule occurred by the oxidation of SO4 center dot-, which dimerized and formed two main primary products. Under the conditions of room temperature (25 degrees C +/- 1 degrees C) and low concentration of K2S2O8 (0.5mM), 35.4% of total organic carbon (TOC) was removed after 8.5-h irradiation. The results showed that UV/S2O82- system was effective for the degradation of 4-t-BP.