Photocatalytic degradation of ciprofloxacin in water using BiOCl/Bi2S3 composite: Experimental and model-predicted kinetic evaluation

Pharmaceutical contaminants in wastewater pose a significant environmental and public health risks. The conventional treatment methods often used suffer from incomplete degradation, high costs, and limited applicability. To address these shortcomings, this study developed an efficient visible-light-driven photocatalytic degradation of pharmaceutical contaminants particularly antibiotics which contributes significantly to environmental pollution. A novel BiOCl/Bi2S3 photocatalyst was synthesized through a facile one-step method to enhance charge separation and suppress electron-hole recombination. The research used ciprofloxacin antibiotic as a model pollutant. The innovative aspect of this work lies in tuning the BiOCl: Bi2S3 mole ratios (3:1, 5:1, 7:1) to identify the optimal configuration for maximum degradation efficiency under visible light and found that 5:1 BiOCl/Bi2S3 achieved 94% of ciprofloxacin (CIP) degradation within 50 min under 300 W visible irradiation. Systematic optimization of pH, catalyst dosage, and initial concentration was also studied. The degradation pathway was elucidated through intermediate analysis, while kinetic studies using both linear and nonlinear Langmuir-Hinshelwood models confirmed the enhanced reactivity. This study also integrates computational kinetic modeling with experimental data using polynomial fit and showed the nonlinear relationship of predicted and experimental kinetic constants with different initial concentration of CIP.