Synthesis of coal fly ash-based heterogeneous Fenton catalyst for bisphenol a removal: Performances and proposed mechanism

Abstract

In this work, coal fly ash (CFA) was first converted to fly ash-derived zeolite (FAZ), then CuO particles were prepared and loaded onto FAZ to build a heterogeneous Fenton catalyst (CuO-FAZ) for bisphenol a (BPA) removal. The characterization results demonstrated that CFA was changed into a mesoporous structure with a higher specific surface area after FAZ conversion, and CuO showed granularity and was well distributed on the surface of FAZ. Under optimal experimental conditions ([BPA] = 50 mg/L, [catalyst] = 1.0 g/L, [H2O2] = 140 mM, and temperature = 25 °C), over 85% of BPA was degraded within 60 min. After five consecutive cycles, BPA removal remained more than 70%, indicating that CuO-FAZ had excellent catalytic capability as well as superior stability. Furthermore, compared to other reactive radicals generated in the process, OH∙(sur) radicals were found to play a major role in the removal, with a contribution of nearly 50%. A ligand complex could develop between CuO-FAZ and BPA, thereby enhancing the OH∙(sur) radicals generation. Results further showed that CuO-FAZ can be employed to effectively and economically treat actual industrial wastewater containing phenolic compounds. This work introduces a method of preparing coal fly ash-based heterogeneous Fenton catalyst, which provides a novel idea for high-value coal fly ash reuse.