Photocatalytic Removal of Cefotaxime Using Mn–ZnO Materials

Cefotaxime residues in environments can contribute to the selection and dissemination of antimicrobial resistance, which motivates advanced treatment processes. In this study, undoped ZnO and Mn-doped ZnO samples containing 2 and 5 wt.% Mn were synthesized via a citrate-assisted sol–gel route and subsequently calcined at 500°C for 3 h. The materials were examined by FTIR spectroscopy, while their photocatalytic activity was evaluated using 25 mg·L-1 cefotaxime solutions at pH 5.59 and a catalyst dose of 0.05 g·L-1. Under UV irradiation at an incident flux of 0.21 mW·cm-2, 2% Mn-ZnO achieved 96.2% removal after 90 min, compared with 91.5% for 5%Mn-ZnO and 81.4% for ZnO. The apparent first-order constant reached 0.0421 min-1. Only 4.2% removal was obtained under visible light. The results identify 2% Mn as the most effective composition under the investigated conditions and show that excessive doping reduces the photocatalytic benefit.