Analytical evaluation and mechanistic elucidation of the Co3O4/biochar composite-activated peroxymonosulfate system for efficient tetracycline degradation

Abstract

Tetracycline (TC), an extensively utilized antibiotic, can cause significant environmental and health problems owing to its exceptional chemical permanence and resistance to traditional effluent alleviation techniques. To tackle these concerns, the implementation of peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs), accomplished through catalyst activation, may be an alternative solution. The objective of this study was to develop a highly efficient biochar-supported Co₃O₄ (Co₃O₄/BC) composite catalyst and assess its synergistic performance in conjunction with PMS for the effective degradation of TC antibiotics. Several advanced techniques, including XRD, FTIR spectroscopy, SEM, XPS, and EPR, were utilized to meticulously analyze the Co₃O₄/BC(9 : 1) composite developed using co-precipitation and calcination methods. The Co₃O₄/BC(9 : 1)/PMS system exhibited remarkable catalytic potential, achieving complete degradation with a rate constant of 0.0937 min⁻¹, which was 1.76 and 6.89 times higher than those of Co₃O₄/PMS (0.0533 min⁻¹) and Co₃O₄/BC(9 : 1) (0.0138 min⁻¹). Additionally, the catalyst loading, PMS and pollutant concentrations, and pH were systematically optimized. The Co₃O₄/BC(9 : 1)/PMS system demonstrated remarkable environmental adaptability when exposed to common anions, humic acid, various water matrices, and multiple antibiotics. The Co₃O₄/BC(9 : 1)/PMS system primarily depends on the SO₄˙⁻ and ˙OH radicals, followed by the non-radical ¹O₂, as the principal active species liable for TC elimination, as confirmed by quenching experiments. The system demonstrated exceptional cycling stability over four consecutive runs and maintained a degradation rate of 87.73%. Finally, this study demonstrates substantial practical potential by offering new strategies for the development of PMS-activating catalysts that are environmentally benign, low-cost, stable, and efficient.