Vancomycin removal using TiO2-clinoptilolite/UV in aqueous media and optimisation using response surface methodology

Investigations have shown the traces of antibiotics in surface water, groundwater, wastewater treatment plants, and drinking water. However, conventional wastewater treatment is not entirely effective for vancomycin degradation. Advanced oxidation is one of the most widespread methods of antibiotic degradation in aqueous media. Vancomycin was quantified by high-performance liquid chromatography. The Response Surface Methodology (RSM) based on Central Composite Design (CCD) was used to explore and optimise the effect of the independent variables on vancomycin degradation. Independent variables were as follows: pH (3-11), vancomycin concentration (15-75 mg/L), TiO2-clinoptilolite (25-125 mg in 250 mL reactor volume), the temperature (25-45 degrees C), and the reaction time (15-75 min). The validity and adequacy of the model were confirmed by the corresponding statistics (F-value = 111.5, correlation coefficient R-2 = 0.98, adjusted R-2 = 0.97, and prediction R-2 = 0.95). The vancomycin degradation efficiency was 97% under optimal conditions (pH = 5, vancomycin concentration = 30 mg/L, TiO2-clinoptilolite content = 50.2 mg in a 250 mL reactor volume, temperature = 32.24 degrees C, and reaction time = 50.9 min). This process followed the zero-order reaction kinetics model (R-2 = 0.98), and the removal rate of Total Organic Carbon (TOC) under optimal conditions was 56%. The results indicated that supporting TiO2 on clinoptilolite particles could increase the photocatalytic properties.