Design of dual-functional sensor and co-catalyst nanomaterial for photodegradation of metronidazole based on biomass carbon dots derived from pine bark

Abstract

The health risk posed by metronidazole antibiotic in the environment necessitates a sustainable approach for its detection and degradation. A benign microwave pyrolysis approach was adapted for the fabrication of fluorescent biomass carbon dots (BCDs) from pine bark (PB) agro-waste, highlighting its dual functionality for metronidazole (MNZ) detection, and as a co-catalyst with CoTiO3 (CTO) in MNZ degradation. The results demonstrated that the BCDs with diverse functional groups, was an effective fluorescent probe for MNZ detection, with fluorescence quenching at an emission of 430 nm under 330 nm excitation. The linear range for detection of MNZ was 0–25 μM with a detection limit as low as 0.014 μM. Additionally, rationally modifying BCDs on CTO resulted in the design of highly active BCDs/CTO photocatalysts, and the experimental results were modeled through a central composite design (CCD) under the response surface methodology (RSM) to predict and optimize MNZ photodegradation. At optimal operational conditions (pH = 9, MNZ = 64.17 mg/L, and 5.5 wt % catalyst loading), 99.81 % of MNZ was degraded within the 60 min irradiation time. The degradation rate constant of 5.5 wt% BCDs-CTO (0.0786 min􀀀 1) surpasses that of CTO (0.0192 min􀀀 1) and BCDs (0.0131 min􀀀 1) by 4.1 and 6 times, respectively. The reusability of 5.5 wt% BCDs/CTO was assessed in five consecutive series, thus providing evidence of high stability and superior interaction of the BCDs, and CTO. The BCDs nanomaterial significantly contributes to the simultaneous sensing and degradation of MNZ, offering a promising solution to mitigate pharmaceutical pollution in aquatic environments.