[Efficiency and Kinetics of Triclosan Degradation in Aqueous Solution by UV/Sodium Persulfate].

UV activated sodium persulfate was employed to remove triclosan (TCS) in aqueous solution. The effects of several factors such as UV wavelength,UV254 intensity,sodium persulfate dosage,pH value,and HA on TCS degradation were investigated. The second-order rate constants of free radicals (·OH, SO4·-) reacting with TCS and their contributions to TCS removal were determined,respectively. The dominant free radical was also identified. Furthermore, the TCS degradation efficiency in natural water by UV254/SPS and UV254/H2O2 was compared. Finally,the possible pathway and intermediate products of TCS degradation were analyzed with GC/MS. The results indicated that UV254 activated sodium persulfate could effectively remove TCS. The removal rate of TCS could reach 98.15% within 100s under the conditions of UV wavelength of 254 nm,UV intensity of 11.5μW·cm-2,sodium persulfate dosage of 1mmol·L-1,and TCS initial concentration of 275 μg·L-1. TCS degradation followed the pseudo-first-order kinetic model and the pseudo-first-order rate constant was determined to be 0.0392 s-1. Pseudo-first-order rate constant for TCS degradation increased with the increase of UV254 intensity(I)and sodium persulfate dosage within experiment ranges. The effect of UV wavelength on TCS removal was not notable. Neutral condition was detrimental to TCS degradation. TCS removal was inhibited in the presence of HA. The reaction rate constants for·OH and SO4·- reacting with TCS were 7.62×109 L·mol-1·s-1 and 9.86×109 L·mol-1·s-1,respectively. SO4·- was the dominant free radical and its contribution rate to TCS removal was 97.63% in UV254/SPS system. The K value of UV254/SPS was 4.13 times higher than that of UV254/H2O2 process,which demonstrated that UV254/SPS process could remove TCS more effectively than UV254/H2O2. The main intermediate products found were 2,4-DCP and phenol in the degradation process of TCS in Milli-Q water by UV254/SPS.