Efficient photocatalytic degradation of chloramphenicol from contaminated water over rGO@MoS2 nanocomposites

Abstract

Antibiotics-based effluents pose a severe threat to the natural ecosystem by acting as reservoirs for the growth of drug-resistant bacteria if untreated. Herein, a facile and scalable approach was developed to engineer photocatalysts associating reduced graphene oxide (rGO) and molybdenum disulfide (rGO@MoS₂) that were used for the degradation of chloramphenicol (CAP) from contaminated water under UV-light. The hydrothermally produced rGO@MoS₂ catalysts contain CO, COH, and COC functional groups that contribute to the binding of CAP onto their surface. The rGO surface modification with MoS₂ layers offers a high surface area for light absorption. Results show that the rGO@MoS₂ catalyst (1:1 w/w) exhibits the highest degradation efficiency (DE) of 86 % within 180 min of light exposure at neutral pH. Further, the kinetic modelling studies for CAP degradation by rGO@MoS_{2 1:1} showed high linearity with pseudo-first order kinetics (R² ∼ 0.9). The isotherm modelling studies correspond to Langmuir isotherm (R² ∼ 0.99), suggesting monolayer-type interaction of CAP with the photocatalyst surface during photodegradation. Furthermore, the mechanism of degradation elucidated using scavenging experiments showed the involvement of both holes (h⁺) and electrons (e⁻) that contribute to the degradation of CAP by generating reactive oxygen species (ROS) like OH^● and O₂^●− radicals. The applicability of the rGO@MoS₂ photocatalyst towards the degradation of CAP was tested in Ganga water, wherein a similar ∼86 % CAP removal was observed. Furthermore, the photocatalyst was found to be stable and could be reused five times. Overall, these findings demonstrate the usefulness of the rGO@MoS_{2 1:1} composite as an efficient photocatalyst that can be used for the degradation of harmful organic pollutants from water bodies to provide a safer and cleaner environment.