Electrocatalysis degradation of tetracycline in a three-dimensional electrocatalysis reactor (3DER) with MnO2/Pd(OAC)2@CA particle electrodes: Influencing factors, degradation pathway and toxicity assessment

Abstract

The extensive use of antibiotics poses a significant risk to human health, and electrocatalysis has demonstrated effectiveness in treating antibiotic contamination. This study details the synthesis of MnO₂/Pd(OAC)₂@CA particle electrodes using a straightforward one-step sol–gel method and the development of a three-dimensional electrocatalytic reactor (3DER) to remove antibiotics from water. Under optimal conditions (1.5 g/L MnO₂/0.3%Pd(OAC)₂, pH 3 and 2.0 V), a degradation of 97.8% of tetracycline hydrochloride (TCH) at a concentration of 15 mg/L is achieved within 80 min. The rate constant in the 3DER (k = 0.0389) is 9.26 times greater than that in a two-dimensional electrocatalytic reactor (2DER) (k = 0.0043). After ten cycles of treatment, the degradation rate of TCH remains at 86.4%. Furthermore, under optimal conditions, the energy consumption of the 3DER is significantly lower than that reported in other studies, with an EEO value of only 0.033 kWh/m³. Radical scavenger experiments and electron paramagnetic resonance (EPR) studies identify the free radicals involved, including •OH, SO₄•^–, H*, and •O₂^–. Theoretical calculations and toxicity assessment reveal a general reduction in the toxicity of the intermediate products formed during the electrocatalytic degradation of TCH. In summary, the MnO₂/Pd(OAC)₂@CA particle electrodes exhibit high electrocatalytic degradation efficiency, excellent recyclability and reusability. The 3DER constructed using particle electrodes demonstrates broad applicability and environmental friendliness, providing a novel solution for remediating antibiotic-contaminated water.