Highly Efficient Cu-Biocl Catalysts for Continuous Microwave-Assisted Water Treatment

Abstract

The accelerated impacts of climate change have led to increased variability in raw water quality, which compromises the efficiency of conventional water treatment facilities and poses challenges in meeting regulatory water quality standards. Microwave (MW) assisted advanced oxidation processes (AOPs) present a promising approach by accelerating reaction rates and improving treatment efficiency, allowing effective adaptation to variable water quality conditions. To achieve this potential, it is important to develop catalysts that combine strong MW absorption with high catalytic activity. In parallel, the establishment of practical strategies for catalyst separation or immobilization is critical to facilitate their application in continuous processes. In this study, we synthesized a highly active Cu-BiOCl catalyst exhibiting a needle and sheet morphology for application in MW-assisted Fenton-like reactions. The synthesized Cu-BiOCl exhibited excellent performance across a broad pH range (3 to 8), with particularly high degradation efficiency observed under neutral to mildly alkaline conditions (pH 7 and 8). Remarkably, the catalyst maintained its structural and chemical integrity without requiring intermediate washing steps and showed negligible loss in degradation efficiency over 10 consecutive reaction cycles, confirming its high stability and reusability. To facilitate the practical application of the catalyst, a MW-assisted continuous flow system was adopted in which the catalyst was immobilized by coating it onto inert beads. The degradation efficiency in the flow system increased linearly with the number of Cu-BiOCl coated beads, highlighting the scalability and practical applicability of MW-assisted continuous flow processes for large scale water treatment.

Keywords: oxidation, Hydroxyl radical, defect, Flow system