MOF derivative functionalized titanium-based catalytic membrane for efficient sulfamethoxazole removal via peroxymonosulfate activation

Developing high-efficient and stable catalytic membrane is of great significance for the removal of organic pollution from water. In this work, novel ZIF-67-derivative- functionalized Ti-based catalytic membranes (ZTM-T) with peroxymonosulfate (PMS) activation and membrane filtration dual-function was first designed and fabricated via a facile electro-deposition method combined with low temperature calcination. Changing deposition and calcination conditions could effectively tune the structure and thus catalytic performance of ZTM-T. Under optimal conditions, the as prepared ZTM-450 catalytic membrane exhibited superior sulfamethoxazole (SMX) removal efficiency of up to 96.3%, which was 216.7 and 3.8 times higher than that of membrane filtration alone and PMS alone, respectively. Meanwhile, ZTM-450 catalytic membrane also showed high treatment performance for real water matrix and long-term operation. The efficient SMX removal by ZTM-450 catalytic membrane was attributed to the combination of radical (SO4•− and •OH) and non-radical (1O2 and electron transfer) oxidation pathways, and 1O2 played the dominant role. In addition, it was found that the ZTM-450 catalytic membrane showed unique selectivity for SMX removal among six different antibiotics. Mechanism study demonstrated that this was mainly due to the preferential removal of negatively charged antibiotic pollutants based on electrostatic repulsion and electrophilic attack of 1O2, and SMX has the strongest hydrophobicity and the lowest redox potential among these antibiotic pollutants. Furthermore, a possible mechanism for the degradation of SMX was explored via density functional theory (DFT) analysis and HPLC-MS.