Heterogeneous catalytic ozonation of oxalic acid with an effective catalyst based on copper oxide modified g-C3N4

Abstract

Various amounts of copper oxide (CuO) modified graphitic carbon nitride (g-C3N4) denoted as CuO-CNx composites were successfully fabricated via a reflux condensation method and used as efficient ozonation catalysts for oxalic acid (OA) degradation in aqueous solution. The BET, FT-IR, HRSEM, TEM, XPS, etc. characterizations revealed the chemical composition, bond structure and morphologies of as-prepared CuO-CNx composites. The results indicated that the introduction of CuO into g-C3N4 relying on the chemical interaction rather than simple physical mixture. Moreover, the increased active sites and the intense chemical bonds could play important roles in improving the catalytic ozonation performances of CuO-CNx composites. In this study, the practical applications of catalysts at different conditions were also investigated. When the mass ratio of CuO/g-C3N4 was 10, the CuO-CN10 composite exhibited superior catalytic ozonation activity with 97.9% OA removal efficiency after 30 min at pH 5.0. Meanwhile, the CuO-CN10 showed excellent stability and reusability for contaminant degradation during multiple consecutive cycles. Furthermore, hydroxyl radical and superoxide radical as the major reactive radicals were identified and the catalytic mechanism for OA degradation improvement was also elucidated. Overall, this work would provide an efficient and eco-friendly catalyst for water treatment as well as a new idea for future environmental purification.