Quaternary composite of CdS/g-C3N4/rGO/CMC as a susceptible visible-light photocatalyst for effective abatement of ciprofloxacin: Optimization and modeling of the process by RSM and ANN

Ciprofloxacin (CIP) is an antibacterial agent extensively used to treat acute infections. This antibiotic is frequently excreted in an incompletely metabolized form and ultimately enters the environment through wastewater. This study aims to design and optimize an efficacious photocatalytic process to abate CIP from aqueous media. To this end, a novel carboxymethyl cellulose (CMC) based nanocomposite containing CdS, g-C3N4, and rGO (CdS/g-C3N4/rGO/CMC) was synthesized via a hydrothermal route and used as a visible-light-driven photocatalyst to degrade CIP. The photocatalytic process was designed and optimized through two effective approaches: response surface methodology (RSM) and artificial neural networks (ANNs). The removal efficiency of CIP and TOC achived 81.93% and 68.87%, respectively, under RSM-based optimal conditions (8 mg L-1 CIP, 0.6 g L-1 catalyst, at pH= 6.1 within 35 min). Based on the ANN analysis, the relative importance of process-influencing parameters was: catalyst dosage (34%), pH (30%), irradiation time (26%), and CIP initial concentration (10%). Evaluation of the process mechanism revealed that the principal active species in the photocatalytic degradation of CIP were hydroxyl radicals and holes. The kinetic studies demonstrated that the photocatalytic degradation of CIP through CdS/g-C3N4/rGO/CMC followed the pseudo-first-order model with a rate constant of 0.0469 min(-1). Furthermore, the catalyst's reusability was confirmed under optimal conditions. Consequently, the synthesized nanobiocomposite could render a prominent photocatalytic activity to remove stubborn pollutants from wastewater.

Automated summary

This study designed and optimized a visible-light-driven photocatalytic process using a novel nanocomposite (CdS/g-C3N4/rGO/CMC) to degrade CIP from aqueous media. The removal efficiency of CIP and TOC achieved 81.93% and 68.87%, respectively, under the optimized conditions. The kinetic studies showed that the photocatalytic degradation followed a pseudo-first-order model with a rate constant of 0.0469 min(-1). The catalyst demonstrated reusability under the optimal conditions. The synthesized nanobiocomposite showed great potential in removing persistent pollutants from wastewater.