Efficient electrocatalytic degradation of doxycycline hydrochloride in wastewater by Ni/MWCNTs-OH on modified Ti

The abuse of doxycycline hydrochloride (DOX) in animal husbandry and its incomplete treatment have led to serious environmental problems, especially the risk of bacterial resistance. As an efficient, simple, and non-polluting method of catalysis, electrocatalysis has many advantages, which has attracted extensive attention in the removal of antibiotic pollutants in wastewater. Hence, the Ni/MWCNTs-OH/Ti composite electrode was prepared by galvanostatic electrodeposition to electrocatalyze DOX, and then the electrode was observed and analyzed by SEM, XRD and XPS. The optimal conditions (MWCNTs-OH was 0.10 mg/L, the concentration of NiSO4 was 75 mmol/L, the degradation current was 15 mA, NaCl was present at a concentration of 0.20 mol/L, and pH value of 4) for degradation of 30 mg/L DOX within 60 min were determined by controlling variables. The degradation process of DOX followed Langmuir-Hinshelwood quasi-first-order reaction kinetics. As a result of stable the electrode, DOX removal rate was consistently above 70 % after 10 continuous uses, which showed good stability and reusability. The composite electrode electrocatalyzed DOX under the synergistic effect of cathode and anode. To identify the main intermediates involved in the electrochemical degradation of DOX, LC-MS was used. The toxicity of the intermediate products and final products was compared and analyzed by microbial culture experiment. And then Ecosar 2.2 was used to predict the biotoxicity of main intermediates to fish, daphnid, and green algae. This work provides a new material for the environmental remediation of antibiotic pollution.