MOF-based photocatalytic degradation of the antibiotic lincomycin enhanced by hydrogen peroxide and persulfate: Kinetics, elucidation of transformation products and toxicity assessment

The metal-organic frameworks (MOF)-based photocatalytic treatment of lincomycin employing Basolite F300 as catalyst in the presence of two oxidants (H2O2, S2O82-) was investigated. Both processes led to the elimination of lincomycin within 120 min of treatment. The oxidant's addition has an enhancing effect on the process, possibly from heterogeneous Fenton-type reactions. The concentration effect (0-300 mg/L) of the oxidants was explored, and the optimum amount achieving the highest degradation rate proved to be 100 mg/L for both oxidants. In total, 39 transformation products were identified out of which 24 are proposed for the first time, while the main transformation pathways were hydroxylation, S-oxidation, desulfurization, pyranose ring opening, and cleavage of the C-N bond. For an integrated evaluation of the process, toxicity measurements of the treated solution were performed by a bioassay using D.Magna. Toxicity was more pronounced in the first stages of treatment, implying synergistic effects between the formed intermediate transformation products (TPs), while notable toxicity reduction was achieved at the end of the process. Ecological structure-activity relationship (ECOSAR) predictions revealed the formation of many non-toxic TPs with hydroxylation being the key to the detoxification of the formed compounds.