Catalytic ozonation of dimethyl phthalate by Ti–MCM-41 in water†

Abstract

A Ti–MCM-41 mesoporous molecular sieve catalyst was prepared by a hydrothermal method. Nitrogen adsorption desorption, XRD, TEM and SEM characterization results showed that the catalyst had a large specific surface area, a regular hexagonal pore structure, and titanium doping was uniformly dispersed in MCM-41 molecular sieves. The amount of titanium doping, reaction temperature, and the initial solution pH had important effects on the catalytic ozonation of dimethyl phthalate (DMP) by Ti–MCM-41. In comparison to ozonation alone and MCM-41/O₃, Ti–MCM-41/O₃ exhibited the most effective degradation and mineralization of DMP, with a Si/Ti ratio of 80, a reaction temperature of 25 °C, and an initial solution pH of 5.4. Ozonation alone, MCM-41/O₃, and Ti–MCM-41/O₃ removed 94%, 96%, and 100% of DMP after 15 min of reaction. At 60 min of reaction, the TOC removal rate of the Ti–MCM-41/O₃ process reached 36%, which was 2.4 times that of the O₃ process and 1.9 times that of the MCM-41/O₃ process. The experimental results of initial solution pH and hydroxyl radical capture showed that Ti–MCM-41 had the highest catalytic activity near the zero-charge point, and hydroxyl radicals were active oxygen species. Ti–MCM-41 catalytic ozonation of DMP had synergistic effects and is a promising environmental catalytic material.