Photocatalytic Oxidation of Carbamazepine: Application of an Experimental Design Methodology

Carbamazepine is one of the pharmaceutical compounds frequently detected in the receiving waters and water bodies. The main objective of this study was to develop a quadratic model to predict carbamazepine (CBZ) photocatalytic removal through a response surface methodology. A factorial plan (linear model; 24 experiments) was used to determine the contribution of individual factors (pH, CBZ concentration, photocatalyst concentration, and treatment time) and interactions among the factors. Pollutant concentration and treatment time were found to be the most important parameters influencing the oxidation rate, with respective contributions of 19.22 and 71.55 %. Central composite methodology was then applied to determine the optimal experimental parameters for CBZ oxidation. The highest percentage of CBZ removed was 94.67 +/- 0.51 %, recorded using a pH of 5, a minimal CBZ concentration of 10 mg/L, a photocatalyst concentration of 1.14 g/L, and a treatment time of 90 min. The effects of different anions (NO3- and SO42-) and cations (Cu2+, Cr3+, Zn2+) were also studied. Copper was found to have both catalytic and inhibitory effects on CBZ removal rate.