Radical-/non-radical-mediated catalyst activation of peroxymonosulfate for efficient atrazine degradation

Abstract

Efficient degradation technologies are urgent to be developed to avoid the ecological and healthy hazards brought from atrazine (ATZ). LaCoO3-δ/peroxymonosulfate (PMS) system was proved to have strong degradation capabilities to contaminants. In this work, we intended to investigate the effect of the synthesis method on LaCoO3−δ. However, the hydrothermal method yielded a new material (H–Co) with better catalytic performance than LaCoO3−δ, which showed stable catalytic ability at pH 3.0–9.0 and 5 consecutive cycles. The coexistence of inorganic Cl−, SO42−, NO3−, H2PO4−, HCO3− and organic humic acids exerted little influences on the H–Co/PMS system. In addition, the actual livestock and poultry breeding wastewater could be well degraded and mineralized by the H–Co/PMS system. Free radical burst experiments and EPR characterization were performed to verify the synergistic effects of free radicals and non-free radicals during ATZ degradation. Based on SEM, XRD, O2-TPD, FTIR, XPS, and electrochemistry characterizations, the efficient catalytic ability of H–Co could be attributed to the abundant oxygen vacancies, surface hydroxyl groups, zero-valent cobalt sites and high electronic conductivity. The degradation pathways were proposed based on the detection of degradation intermediates of ATZ by UPLC-MS. Moreover, the toxic of ATZ during the oxidation was evaluated by TEXT and E. coli inhibition assay. This work comprehensively analyzed the catalytic reaction mechanism of the H–Co/PMS system and provided a feasible pathway for the treatment of the actual livestock and poultry breeding wastewater.