Construction of Cnts/calcined Zn-Co-LDHs hydrid to enhanced photocatalytic for ofloxacin decomposition: mechanism, degradation pathway, and toxicity assessment

Abstract

This work successfully synthesized the Cnts/calcined Zn-Co-LDHs (xCnts@ZnC) hybrid material using the Zn-Co-LDHs precursor. Using the co-precipitation method, we synthesized Zn-Co-LDHs onto Cnts ranging in mass from 0 to 80 mg. These were subsequently calcined at 550 °C to yield xCnts@ZnC (x = 2, 4, 6, 8). Based on the results, ZnC is found on the surface of Cnts in two phases: ZnO and ZnCo₂O₄. The photocatalytic activity of xCnts@ZnC is demonstrated by its capacity to degrade ofloxacin antibiotics (OFL) in the visible region; 6Cnts@ZnC (85.8%; k = 0.0099 min⁻¹), shows the best decomposition rate constant, increasing by three times when compared to ZnC (53.3%; k = 0.0048 min⁻¹). The h⁺, O₂˙⁻, radicals are the main factors that determine of the decomposition process in the identified OFL decomposition mechanism of 6Cnts@ZnC, in which Cnts have the role of transporting and collecting electrons, minimizing the recombination between photogenerated electrons and holes. The OFL degradation pathways of 6Cnts@ZnC were also investigated and identified by the HPLC-MS spectrum and suggested the new degradation mechanism to small molecules that have nontoxic of small molecules to environment site by ADMET model. The OFL degradation obtained 96.44% and set equivalent of degradation after completing 300 min.