Fabrication of black TiO_2−x /NiFe₂O₄ supported on diatomaceous earth with enhanced sonocatalytic activity for ibuprofen mitigation

Abstract

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 further enhanced mitigation efficiency due to the synergy between adsorption and sonocatalysis. About 96.7% of 10 mg l−1 IBP was removed in 100 min using 0.7 g l−1 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.