Green electrochemical synthesis of nitrogen- and sulfur co-doped graphene oxide as an efficient metal-free catalyst for persulfate activation in vancomycin degradation

The widespread use of antibiotics has led to their persistent presence in aquatic environments, posing risks such as antimicrobial resistance, ecological disruption, and toxicity. Vancomycin (VAN), a glycopeptide antibiotic of clinical concern, is frequently detected in wastewater due to its incomplete removal by conventional treatment systems. Advanced oxidation processes (AOPs), particularly persulfate (PDS)-based systems, offer a promising solution for degrading such persistent contaminants; however, efficient activation of PDS remains a challenge. Carbon-based materials have emerged as effective metal-free activators for PDS activation, especially when modified through heteroatom doping. Nevertheless, traditional synthesis methods for graphene oxide, such as the Hummers' method, remain complex processes that require numerous chemicals and sophisticated setups. In this study, a greener one-pot electrochemical method was developed to synthesize nitrogen- and sulfur-doped graphene oxide (NSGO). Various analytical techniques, including scanning electron microscopy (SEM), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDX), were employed to characterize the composition and structure of NSGO. The prepared NSGO was evaluated for its ability to activate persulfate in the degradation of VAN. The results showed that VAN was reduced to below detection limits (ADD) within 5 minutes under near neutral pH and room temperature (NSGO: 50 mg/L, VAN: 10 mg/L, volume: 50 mL), demonstrating superior performance compared to undoped electrochemical graphene oxide.