Degradation efficiency and kinetics of tetrabutyltin in aqueous solution by ozonation

The effects of parameters such as temperature and solution pH on ozonation of tetrabutyltin (TeBT) in aqueous solution were investigated. Oxidation kinetics of TeBT with ozone alone and hydroxyl radical were also investigated. Results show that the removal efficiency of TeBT increases from 36% to 43% with temperature increasing from 12°C to 22°C. However, the removal efficiency decreases to 32% when the temperature rises to 32°C, as a result of accelerated useless decomposition of ozone with increased temperature. Higher pH of solution favors the ozonation of TeBT. The degradation efficiency of TeBT in 10 min increases from 30% to 42% when solution pH changes from 5.9 to 8.0. Possible reason is that the decomposition of ozone is faster at a higher pH value and the transfer efficiency of ozone to the liquid phase increases (This may be due to the faster decompositon of ozone and the enhancement of transfer efficiency of ozone to the liquid phase at a higher pH value). The ozonation of TeBT is strongly inhibited by tert-Butyl alcohol (t-BuOH) and bicarbonate, the scavengers of ·OH, which indicated that degradation of TeBT is mainly affected by the yield of ·OH during TeBT ozonation process. According to the pseudo-first order kinetics, the rate constants for the reaction of TeBT with ozone alone, molecular ozone (k_O3) and ·OH (k_·OH) are determined as 435.79 L·mol^-1·s^-1 and 1.4×10⁹ L·mol^-1·s^-1, respectively.