An efficient ternary photocatalyst Ag/ZnO/g-C3N4 for degradation of RhB and MG under solar radiation

Abstract

Industrial dyes are the crucial reason for water contamination. Due to their recalcitrant nature, these toxic dyes represent a significant risk to aquatic creatures as well as carcinogens to human beings. The common methods used for the removal of dyes for example electro-coagulation, reverse-osmosis, and ultra-filtration are cumbersome, expensive, and non-repeatable. In this study, a cost-effective, environmentally benign, and recyclable nano-composite material for effective solar photodegradation of Rhodamine B (RhB) and Malachite green (MG) was discussed. Silver doped ZnO nanoparticle modified g-C3N4 was fabricated by chemical precipitation procedure where melamine was taken as a precursor. The results showed that the modification of g-C3N4 with Ag/ZnO has increased activity under visible light and is suitable for photodegradation when compared to the neat g-C3N4. The percentage of dye degradation increased with an increase in agitation time. The efficiency was almost 97% for RhB in 30 ​min and 91% for MG with Ag/ZnO/g-C3N4 in 60 ​min. The deprivation of dye by the photocatalytic nanocomposite was studied using first-order kinetics. The First-order rate constant (K) determined by using ternary nanocomposite Ag/ZnO/g-C3N4 had a greater reactivity than the pure g-C3N4. The most important reactive species in the photocatalytic reaction over Ag/ZnO/g-C3N4 are detected as superoxide radicals (O2−•) and hydroxyl radical (OH•) by using the quenching test. Several sophisticated techniques like powder XRD, SEM, EDAX, FTIR, and UV–Vis DRS were used for the characterization of synthesized nanocomposites. Doping of Ag nanoparticles has increased the response towards visible light for g-C3N4 and also an increase in the rate of photogenerated electrons thereby reducing electron-hole recombination.