Effective photodegradation of cefixime and carvedilol mediated by visibly active MoO3/CoMn2O4/Cu2BaSnS4 photocatalytic system: An insight on photocatalytic mechanism, degradation pathway and by-product toxicity analysis

Abstract

Photocatalytic degradation processes are promising solutions for the effective removal of organic pollutants. This study reports the design and fabrication of MoO3-CoMn2O4-Cu2BaSnS4 QDs by ultrasonication assisted co-precipitation method for degradation of divergent pharmaceutical compounds. The nanocomposite (NC) was optimally synthesized, among which MoO3-CoMn2O4-Cu2BaSnS4-1% exhibited superior catalytic activity with the largest rate constant against cefixime (k = 0.0032 min−1) and carvedilol (k = 0.0025 min−1) under visible light irradiation. Furthermore, the photocatalytic experiments were carried out with varying operational parameters including different nanoparticle concentration, drug concentration, pH and ions, and their influence in the photodegradation of cefixime and carvedilol was studied. Notably, the nanomaterial exhibited an admirable photocatalytic stability and structural integrity after six consequent cycle tests, which was verified with XPS. Furthermore, the extended photo response window of the NCs has been discussed and the dominant active radical species was found to be ⋅OH and O2⋅-, which contributed to the photodegradation of cefixime and carvedilol. The mechanism of degradation of these compounds was investigated and with the intermediates obtained from GC–MS analysis, a corresponding pathway was also suggested. This study offers a detailed insight to design effective photocatalyst by integrating the properties of individual nanoparticles and troubleshooting the shortcomings.