Predicting ciprofloxacin and levofloxacin decomposition utilizing ozone micro-nano bubbles through the central composite design method

Antibiotics have several negative effects on aquatic ecosystems and are difficult to degrade using traditional water/wastewater treatment methods. As a result, new treatment techniques must be employed to eliminate these contaminants from aquatic environments. Research on the relationship between the decomposing process of antibiotics and different factors by new technologies is scarce. This research focuses on the capability of ozone micro-nano bubbles (OzMNBs) to eliminate the antibiotics ciprofloxacin (CIPR) and levofloxacin (LEVO) in aqueous solutions. We studied the CIPR and LEVO decomposition to different variables through the central composite design method. The main variables included pH, ozonation time, and initial antibiotic concentration. The correlation coefficients of the quadratic model obtained by using the software, Design Expert version 13.0.1. Analysis of variances proved the significance of models and main factors. Verification tests also confirmed that the final optimum conditions of the antibiotics decomposition were: pH 9, ozonation for 40 min and, initial antibiotic concentration of 5 mg/L. In optimum conditions, removal rate of about 97% and 100% was obtained for CIPR and LEVO, respectively. The order of influence of various factors on CIPR and LEVO decomposition were obtained and the interactions between the main factors were also investigated. At the last stage of the research, the efficiency of OzMNBs in the removal of total organic carbon and mineralization of the solutions containing CIPR and LEVO under optimum conditions was examined.