Bandgap engineering approach for synthesising photoactive novel Ag/ HAp/SnS2 for removing toxic anti-fungal pharmaceutical from aqueous environment

The present work shed light on synthesising a novel ternary Z-scheme Ag/HAp/SnS2 (AHS) nano photocatalyst to degrade metronidazole (MTZ) in wastewater through H2O2-assisted AOP under natural sunlight. HAp extracted from the fish scales of rohu fish through alkaline treatment was decorated with Ag nanoparticles using ascorbic acid as a bio-reductant. Tin disulphide (SnS2) was anchored over Ag/HAp to prevent agglomeration and enhance photocatalytic activity by delaying the electron-hole recombination rate. After 45 min of irradiation, a degradation efficiency of 98.85 +/- 1.86% for 15 ppm MTZ could be achieved. The performance of the prepared photocatalyst in real wastewater was investigated by introducing several metal cations and anions in the pho-todegradation process. The degradation products were identified by HRLCMS analysis, and the breakdown mechanism of MTZ was proposed. The present study enlightens the importance of SnS2-based photocatalysts for organic pollutant degradation under natural sunlight through an advanced oxidation process. The characterization results showed that the enhanced photodegradation efficiency of AHS is attributed to the formation of an all-solid-state Z-scheme heterojunction with Ag nanoparticles acting as charge transfer medium and as electron accumulators helping in delaying charge recombination.

Automated summary

This study presents the synthesis of a novel ternary Z-scheme Ag/HAp/SnS2 nano photocatalyst for the degradation of metronidazole in wastewater under natural sunlight. The photocatalyst demonstrated a high degradation efficiency and showed potential for organic pollutant degradation in real wastewater. The incorporation of SnS2 enhanced the photocatalytic activity by delaying electron-hole recombination.