Thermodynamic analysis on the mineralization of trace organic contaminants with oxidants in advanced oxidation processes

There is a growing demand for the efficient treatment of organic polluted wastewaters by advanced oxidation processes (AOPs) which calls for the determination of the mineralization order of ease for the organic contaminants with oxidants. The mineralization abilities of organic contaminants in AOPs are investigated in this work. Photocatalytic experiments for three representative organic contaminants are carried out, and their corresponding reaction rates are determined experimentally. Meanwhile, molar Gibbs free energy changes Δ_rG_m^°for the reactions of 31 organic contaminants (10 chlorinated hydrocarbons, four brominated hydrocarbons, 11 aromatic hydrocarbons and their derivatives, three chloroacetic acid, and three chloroacetyl chloride) with oxidants of ·OH, H₂O₂, ·O^-, O₃, and O₂ are calculated, and the mineralization order of ease is determined theoretically on the basis of Δ_rG_m^°. The agreement of the theoretical and experimental mineralization abilities for most of the organic contaminants investigated implies the reliability of the determination of the mineralization ability from the magnitude of G_m^°for the mineralization of trace organic contaminants. Results also show that for most of the organic contaminants studied, the mineralization abilities are ·OH > H₂O₂ > ·O^- > O₃ > O₂, and the mineralization ability of the organic contaminants depends on not only the oxidants but also the structure and properties of the organic contaminants themselves, and the degradation reaction products.