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

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 mu g/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.

Automated summary

The hybrid iron modified aluminum-doped ZnO-based microporous photocatalyst (Al-ZnO/Fe) has been prepared to address the rapid recombination of photogenerated electron-holes and the difficulty in separating the photocatalysts from the aqueous medium. The photocatalyst showed efficient degradation of carbamazepine and could be activated under solar irradiation. The study also revealed the significant role of superoxide radicals and hydroxyl radicals in the degradation process.