Magnetically separable quaternary g-C₃N₄/Fe₃O₄/AgBr/rGO nanocomposite for enhanced photocatalytic degradation of ofloxacin in water under visible light irradiation

Novel photocatalytic-magnetic hybrid quaternary nanocomposite (g-C₃N₄/Fe₃O₄/AgBr/rGO) was successfully synthesized for the first time via ultrasonication-assisted wet chemistry technique. The nanocomposite was characterized using various advanced characterization techniques and its visible light photocatalytic performance was analyzed by using ofloxacin (OFL) as target pollutant. The photocatalytic degradation efficiency was 100 % under conditions (pH 6.65, 0.1 g/L nanocomposite and 10 mg/L OFL) in 5 h. The pseudo-first-order kinetic constant of g-C₃N₄/Fe₃O₄/AgBr/rGO was as high as 1.1832 h⁻¹. Evaluation of different catalysts, catalyst dosage, initial concentrations of OFL and initial solution pH have been studied. Based on the scavenging tests, benzoquinone (BQ) significantly decreased the removal efficiency of OFL to 41.4 %, indicating that ^[rad]O₂⁻ served as the dominant radical involved in the reaction. More importantly, after undergoing five cycles, the g-C₃N₄/Fe₃O₄/AgBr/rGO nanocomposite demonstrated robust stability and was effectively separated from the solution through magnetic means. The remarkable performance of g-C₃N₄/Fe₃O₄/AgBr/rGO is linked to substantial utilization of visible light and facilitation of Z-scheme heterojunctions, thereby facilitating charge separation. The quaternary nanocomposite can be expected to have tremendous potential for the degradation of emerging organic pollutants. Thus, it is favorable for practical application in water and wastewater treatment.