Publication

Abstract : In this study, photocatalytic degradation of synthetic hospital wastewater containing two pharmaceutical contaminants, namely amoxicillin trihydrate (a commonly used antibiotic) and metformin HCl (a widely used diabetic medicine), was carried out using a laboratory-scale photoreactor (200nbsp;mL), TiO2 as photocatalyst, and 125nbsp;W low-pressure mercury vapour lamp emitting UV rays at 365nbsp;nm. The response surface methodology based on face-centred central composite design was used to optimize the independent variables, namely the initial concentrations of contaminants (10–50nbsp;mg/L), TiO2 dosage (250–1250nbsp;mg/L), initial pH (3–11), and reaction time (30–150nbsp;min). Results showed that both amoxicillin and metformin removals were influenced by all the four variables individually and also by the interaction between these variables. Response surface and overlaid contour plots were used to evaluate the optimum conditions. It was found that the maximum removal of amoxicillin (90%) and metformin (98%) could occur when the pH is 7.6, TiO2 dosage is 563nbsp;mg/L, and reaction time is 150nbsp;min for an initial concentration of the contaminants at 10nbsp;mg/L. Further experiments were conducted to evaluate the characteristics of photocatalytic degradation. Low adsorption of contaminants on TiO2 surface and negligible degradation of contaminants using acetonitrile as solvent suggest that hydroxyl radical attack could be the predominant pathway in the removal process. The COD and TOC analyses of the samples confirmed the mineralization of the compounds to more than 60%. © 2018, Islamic Azad University (IAU).