Synthesis and Application of Kaolin-Based Catalyst for the Degradation of Ciprofloxacin in Catalytic Ozonation

Abstract

In this study, kaolin-based catalysts were used in the catalytic ozonation process to degrade ciprofloxacin (CIP), a common antibiotic found in wastewater. The kaolin (KL) was calcined and converted into the amorphous aluminum silicate structure of calcined kaolin (CKL). CKL has more active sites, which enhances the oxidation and mineralization of CIP. Iron (Fe), Biochar (BC), and Iron-loaded biochar (Fe@BC) were loaded into CKL to enhance its active sites. The CKL, CKL+6%Fe, CKL+6%BC, and CKL+8%Fe@BC degraded 94.72%, 95.98%, 96.25%, and 98.46% of CIP after 30 minutes of catalytic ozonation, respectively, whereas single ozonation degraded 90.4% of CIP. Compared to other catalysts, the CKL+8%Fe@BC showed the highest catalytic activity. After confirming the effectiveness of CKL+8%Fe@BC for CIP degradation, the latter was used to degrade Tetracycline hydrochloride (TCH), P-nitrophenol (PNP), Chlortetracycline hydrochloride (CTH), and Norfloxacin (NOR). CKL+8%Fe@BC degraded 96.4%, 93.13%, 99.2%, and 94.6% of these molecules, respectively. The contribution of reactive oxygen species (ROS) to the catalytic ozonation was determined using a scavenger test. Three pathways have been proposed for CIP degradation based on the intermediates identified during the degradation. This study reports the synthesis of a novel kaolin-based catalyst, which can be successfully integrated into the catalytic ozonation process for the degradation of various antibiotics.

Keywords: Kaolin-based catalyst, Wastewater treatment, ciprofloxacin, Catalytic ozonation