Bicarbonate ions promote rapid degradation of pollutants in Co(II)Fe(II)/peroxyacetic acid systems

Abstract

Peroxyacetic acid (PAA), as an oxidizing agent, has gained significant attention in the field of advanced oxidation because of its low toxicity and high degradation capacity. In this study, cobalt-iron-based Prussian blue analogs (Co-PBAs) were utilized for the first time to activate PAA for tetracycline degradation. In the Co-PBAs/PAA system, organic radicals (RO•) and high-valent metal oxides are mainly produced. TC is efficiently removed in a wide pH range (5-9) and a variety of interferences (Cl^-, SO₄^2-, bicarbonate ions (HCO₃^-), humic acid, and the actual water bodies) in water bodies due to the specificity of RO•. Interestingly, the catalytic rate of the Co-PBAs/PAA system was significantly accelerated in the presence of HCO₃^- (k_obs increasing from 0.171 min^-1 to 0.534 min^-1). This enhancement is attributed to the reaction between HCO₃^- and PAA, and carbonate radicals (•CO₃^-) and acetyl peroxyl radicals (CH₃C(O)OO•) are generated and then react with the phenolic hydroxyl group of TC. In this study, the mechanism of PAA activation by Co-PBAs was revealed, and PAA-based advanced oxidation process enhanced by HCO₃^- was provided for the removal of pollutants from wastewater.

Keywords: Advanced oxidation processes; Bicarbonate promotion; Bimetallic synergy; Oxidative organic radicals; Peroxyacetic acid activation.