Synthesis of CeOx@SiO2 with tandem effect of mass transfer and activation for enhancing sulfanilamide degradation with ozone

In this work, a hollow mesoporous CeO x @SiO 2 was synthesized and used to promote sulfanilamide (SA) mineralization in ozonation . SA mineralization was promoted to 68.2% by O 3 /CeO x @SiO 2 in 120 min, but only 30.0% in O 3 process. O 3 /CeO x @SiO 2 behaved the better at acidic and alkaline condition than that at neutral condition. CeO x @SiO 2 had the great ability in enhancing O 3 utility rate. Silanol (Si OH) in pore channel of SiO 2 shell was non-reactive with O 3 but could provide transmission way for O 3 to reach the inner CeO x core. Lewis sites, oxygen vacancies and surface hydroxyl groups induced by CeO x favored for the activation of O 3 . The excess electron at oxygen vacancies would be transferred to the absorbed O 3 molecular, which then generated reactive oxygen species (ROS) to mineralize SA. Hydroxyl radicals ( OH) and superoxide radicals ( O 2 − ) were the main ROS, which were recorded by EPR. The interfacial electron transfer process was revealed by LSV and ESI characterizations. SA degradation intermediates were also identified by HPLC-MS and IC, a possible degradation pathway was proposed. Moreover, CeO x @SiO 2 showed a good reusability, no obvious decline of TOC removal was found in four times’ uses. Water matrix would complete ROS with SA, which inhibited the SA removal of both O 3 and O 3 /CeO x @SiO 2 processes, but the better TOC removal efficiency was still obtained by O 3 /CeO x @SiO 2 in actual water.