邻苯二甲酸二丁酯降解过程的单体同位素分析

研究对比了邻苯二甲酸二丁酯（DBP）在不同降解过程（水解、UV/H₂O₂光解、直接光解、过硫酸钾光氧化）中的碳、氢同位素组成变化、分馏特征及二维同位素（Δδ²H-Δδ¹³C）的相关性.水解反应中DBP分子产生了显著的碳同位素分馏，未发现氢同位素分馏，而且碳同位素富集因子ε_C为（-2.7±0.4）‰，表明DBP水解时发生C-O键断裂，氢原子不参与反应.而UV/H₂O₂光解和直接光解反应（pH值分别为2、7和10）中，DBP分子呈现了相似的二维同位素相关性Λ值（9±2）~（11±2）]，推测经历了相同的反应过程.过硫酸钾光氧化降解时，明显偏大的Λ值（31±3）说明反应可能发生C-H键断裂.结果表明：二维单体同位素分析（2D-CSIA）技术可以有效区分DBP的水解、光解、光氧化3种不同类型的降解过程，有助于分析其降解路径.

Compound specific isotope analysis of dibutyl phthalate during degradation processes

A systematic investigation on carbon and hydrogen isotopic compositions, isotope fractionations and dual isotope correlations (Δδ²H-Δδ¹³C) during different degradation processes (hydrolysis, UV/H₂O₂, direct photolysis and UV-activated persulfate oxidation) of dibutyl phthalate (DBP) was performed in this study. Significant carbon isotope enrichment and no hydrogen isotope fractionation were observed during hydrolysis. The carbon isotope enrichment factor (ε_C) was determined as (-2.7±0.4)‰. The difference between carbon and hydrogen isotope patterns indicated the C-O bond cleavage in the hydrolytic reaction without H atoms involvement. During photodegradation of DBP induced by UV/H₂O₂ and direct photolysis at different pH values (pH 2, 7 and 10), correlation Λ values of dual isotope were observed in a similar range of(9±2)~(11±2)] and indicated similar reaction mechanism. UV-activated persulfate oxidation yielded the distinct Λ value of (31±3), which was likely associated with the C-H bond cleavage. Therefore, two-dimensional compound specific isotope analysis (2D-CSIA) highlighted the potential to discriminate three types of degradation processes (hydrolysis, photolysis and UV-activated persulfate oxidation) of DBP and to deduce degradation pathways.