Reliable treatment approach for levofloxacin and ciprofloxacin removal from aqueous medium: process modelling, kinetic and isotherm studies.

Current work aimed to optimize the electrocoagulation (EC) process for the efficient and economic removal of ciprofloxacin (CIP) and levofloxacin (LVX) from aqueous solution via response surface methodology. Four main parameters were selected for the optimisation process, including the initial pH of the solution, initial concentration of antibiotics, operation time, and current density. Subsequently, kinetic and isotherm modelling was performed to characterise the performance behaviour of the EC process at optimum conditions. Based on the results, the EC process achieved a removal efficiency of 92% and 84% for CIP and LVX, respectively, under optimum experimental conditions. The experimental results were consistent with the Langmuir isotherm model for the adsorption of both antibiotics on the iron hydroxide (Fe(OH)3) flocs based on the predicted maximum adsorption capacity of 142 and 185 mg/g, respectively. In addition, the experimental results best fitted the second-order kinetic model with a coefficient of determination (R²) value of 0.986 and 0.992 for CIP and LVX, respectively, implying the chemisorption mechanism controlling the adsorption process. The regression analysis also showed that the experimental results best fitted with the second-order polynomial model with a predicted correlation coefficient (Pred. R²), adjusted correlation coefficient (Adj. R²), and R² of 0.834, 0.941, and 0.967 for CIP; 0.723, 0.908, and 0.952 for LVX, respectively. In short, a comprehensive economic evaluation was performed and the total operational cost over a single run under optimized EC conditions was estimated at $0.490 US/m3. Under optimized EC conditions, the electrical energy consumption and electrode consumption were 3 kWh/m3 and 0.167 kg/m3, respectively, during a single run. [ABSTRACT FROM AUTHOR]