Improved photocatalytic activity of rGO modified Mn(VO3)2 nanorods for the degradation of rifampicin: Insight into mechanism, pathway and by-product toxicity evaluation

Background

The discharge of rifampicin into surface and groundwaters leads to the emergence of antibiotic resistant bacteria which could possess a detrimental threat to human health and aquatic life.

Methods

In this work, rod shaped Mn(VO₃)₂ was synthesised by simple co-precipitation method and it was deposited over rGO to enhance the photocatalytic degradation of rifampicin under visible light irradiation.

Findings

The study highlighted the enhanced photocatalytic degradation of rifampicin (RFP) by rGO/Mn(VO₃)₂ nanocomposites (NCs) and it was 99.2 % at pH 7 and the photocatalyst was stable even after 6th cycle. The total organic carbon removal was determined to be 97.1 %. To achieve this, rod shaped Mn(VO₃)₂ was prepared and deposited over rGO and it was confirmed by SEM and TEM analysis. While XRD studies confirmed the purity of the synthesized materials, XPS and Raman spectroscopy validated their chemical states and bonding nature respectively. BET and BHJ revealed the enhanced surface area and mesoporous nature of the NCs. Further, PL studies indicated the reduced charge carrier recombination in the NCs. The dominant radicals involved in the degradation was identified to be O₂^•− and ^•OH. The degraded intermediates were identified and the possible degradation pathway was proposed by using GC–MS/MS analysis. The by-product toxicity was assessed by ECOSAR program and were found to be non-toxic to algae, Daphnia and fish. The study demonstrates the promising potential of rGO/Mn(VO₃)₂ NCs with improved behaviour and stability for environmental application.