Graphene quantum dots (GQDs) decorated zeolitic imidazole framework-67 (ZIF67) electrode for the in-situ oxidation of ciprofloxacin in water

Abstract

Ciprofloxacin (CIP) is a biorecalcitrant pharmaceutical compound that is frequently found in wastewater and aquatic environment and has a wide range of detrimental effects on living organisms. In this study, graphene quantum dots doped zeolitic imidazole framework-67 ([email protected]) electrodes were prepared for the direct electrochemical degradation of CIP in NaCl supporting electrolyte. The presence of GQDs improved oxidation peak current at a lower applied potential, which enhanced the direct oxidation capacity and applicability of [email protected] electrode for CIP degradation. Under optimal conditions ([NaCl] = 0.1 M, applied potential of 1.0 V (∼0.5 A m−2), pH = 7, and temperature = 25 °C), the CIP removal and mineralization efficiency was greater than 90 and 70%, respectively, after five consecutive cycles. The [email protected] electrocatalytic system was effective over a broad range of initial pH. Scavenger test and EPR measurement showed that the RCSs, i.e., ClO• and Cl2•− were being generated in the [email protected] electrochemical system and played the main role in CIP oxidation. The intermediates of degradation were studied, and a plausible mechanism was proposed. This research developed an innovative electrocatalytic approach for treating antibiotic-contaminated water.