热活化过硫酸盐氧化降解水体中泛影酸钠的研究

Thermally activated persulfate oxidation process was applied to degrade sodium diatrizoate in the aqueous solution. The impact factors, such as temperature, the initial concentrations of K₂S₂O₈ and substrate, the initial solution pH and water matrix were investigated. The results show that diatrizoate degradation by thermally activated persulfate oxidation was fitted well with pseudo-first-order mode and Arrhenius equation. The apparent activation energy for this reaction was estimated as 105.57 kJ•mol^-1. Increasing initial persulfate concentration or temperature and reducing initial substrate concentration significantly increased the apparent rate constant (k) of diatrizoate degradation (k=0.0062×[K₂S₂O₈]₀, R²=0.98, [K₂S₂O₈]₀=2~8 mmol•L^-1; lnk=-12698×1/T+34.91, R²=0.98, T=325~345 K; k=-1.54×[diatrizoate]₀+ 0.064, R²=0.98), while k was less affected by the initial pH of the solution. The presence of Cl^-, HCO₃ ^- and HA in the solution inhibited the degradation of diatrizoate. The low TOC removal rate and formation of organic by-products indicate that the degradation of diatrizoate was incomplete and only its side chain was destructed. The transformation pathways of diatrizoate in the heat-activated persulfate system mainly included amide bond cleavage, amino oxidation and decarboxylation-hydroxylation.