Modelling of cefixime (CFIX) removal using photocatalyst/UV/polyurethane by response surface methodology (RSM): optimisation and kinetic study

The present study investigated the cefixime removal from aqueous solution using TiO2 and ZnO photocatalyst immobilised at polyurethane (PU) as well-asoptimized the effective parameters using response surface methodology (RSM). In this study, firstly, the polyurethane was synthesised and then photocatalysts were incorporated into the polyurethane. The experimental design was used to first determine the concentration of effective variables (pH, initial cefixime, catalyst dosage, and reaction time) and then optimize the independent variables based on the response (cefixime removal efficiency). The characteristics of photocatalyst were determined through scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The optimum variables for cefixime removal efficiency were pH of 4.80, catalyst dosage of 2.60 g/m(2); initial cefixime concentration of 25.90 mg/L, and reaction time of 85 min for TiO2/ultraviolet (UV)/polyurethane (TiO2/UV/PU) process. In addition, the optimum conditions for the ZnO/ultraviolet/polyurethane (ZnO/UV/PU) process for pH of the solution, the dosage of ZnO, CFIX concentration, and reaction time were found to be6.70, 2.40 g/m(2), 25 mg/L, and 89 min, respectively. The results of the kinetic model showed that experimental values were best fitted with the first-order model. Also, the results of a scavenger study represented that degradation of antibiotics and the generation of free radicals of hydroxide play an important role in the cefixime removal. Therefore, it is demonstrated that the CFIX antibiotic should significantly be removed from the aqueous solution using a photocatalyst/ultraviolet/polyurethane process.

Automated summary

The present study investigated the removal of cefixime antibiotic from aqueous solution using TiO2 and ZnO photocatalyst immobilized at polyurethane. The optimal conditions for the TiO2/UV/PU process were found to be pH of 4.80, catalyst dosage of 2.60 g/m(2), initial cefixime concentration of 25.90 mg/L, and reaction time of 85 min. For the ZnO/UV/PU process, the optimum conditions were determined as pH of 6.70, ZnO dosage of 2.40 g/m(2), CFIX concentration of 25 mg/L, and reaction time of 89 min. The results suggest that the photocatalyst/UV/PU process is effective for the removal of cefixime antibiotic from aqueous solution.