Fabrication of black TiO2-x/NiFe2O4 supported on diatomaceous earth with enhanced sonocatalytic activity for ibuprofen mitigation.

This study reports a facile fabrication of black TiO2-x/NiFe2O4 (Ti3+ self-doped titania coupled with nickel ferrite), an efficient sonocatalyst for ibuprofen (IBP) mitigation. Compared with TiO2-x or NiFe2O4, TiO2-x/NiFe2O4 heterojunction displayed higher sonocatalytic activity, and their immobilization onto diatomaceous earth (DE) further enhanced mitigation efficiency due to the synergy between adsorption and sonocatalysis. About 96.7% of 10 mg/L IBP was removed in 100 min using 0.7 g/L catalyst at pH=6, with the ultrasonic power of 144 W and frequency of 60 KHz. Quenching experiment results demonstrated the roles of reactive species. The intermediates during IBP sono-oxidation were determined by HPLC-MS method, and the acute toxicity was evaluated. Furthermore, the reaction mechanism was proposed. The sonocatalyst revealed excellent reusability, suggesting itself promising for wastewater treatment.