Insights into kinetics of photocatalytic degradation of neurotoxic carbamazepine using magnetically separable mesoporous Fe3O4 modified Al-doped ZnO: Delineating the degradation pathway, toxicity analysis and application in real hospital wastewater

Abstract

Rapid recombination of photogenerated electron-holes and difficulty in separating the photocatalysts from the aqueous medium severely limits the application of photocatalysis. In this context, a hybrid iron modified aluminum-doped ZnO-based microporous photocatalyst (Al-ZnO/Fe) has been prepared. Aluminum doping helped prevent electron-hole recombination, and iron modification facilitated easier separation. The degradation of carbamazepine was studied using the developed photocatalyst. At optimum conditions and natural pH (UV-A light intensity: 33 W/m2; photocatalyst dose: 0.5 g/L) CBZ concentration: 1000 μg/L, more than 99% of CBZ was degraded in 60 mins at a rate of 0.079 min−1. Furthermore, the photocatalyst could be activated under solar irradiation. The scavenger study revealed that superoxide radicals played the most significant role in CBZ degradation, followed by hydroxyl radicals. The Al-ZnO/Fe photocatalyst could provide more than 90% CBZ degradation up to ten cycles. A kinetic model has been implemented to predict the CBZ removal and degradation rate at different pH, light intensity, and CBZ concentrations. The photocatalyst could also remove up to 71% CBZ from hospital wastewater. The fast degradation kinetics and ease of separation of the prepared photocatalyst may open new avenues for the degradation of persistent organic contaminants.