环糊精因其具有包合增溶特性，单独或与高级氧化技术（如Fenton氧化）耦合可应用于有机污染物的土壤污染修复，然而环糊精的稳定性不清楚．本研究考察了环糊精在Fenton体系中的降解动力学及转化产物，评估了环糊精的稳定性．结果表明，β－环糊精（β?CD）在Fenton体系中反应速率随着过氧化氢浓度的升高而线性增加，符合二级动力学过程．环糊精与羟基自由基反应的绝对速率常数在酸性条件下（ pH＝3）分别为3．9×109 L·（mol·s）－1（β?CD和甲基β环糊精），6．5×109 L·（mol·s）－1（羟丙基β环糊精），7．2×109 L·（mol·s）－1（γ?环糊精），中性条件下（pH＝7）为2．9×109 L·（mol·s）－1（β?CD），3．1×109 L·（mol·s）－1（MCD），3．2×109 L·（mol·s）－1（HPCD），3．3×109 L·（mol·s）－1（γ?CD），显示环糊精在酸性条件下降解加快，且绝对速率常数的种类差别较大，而在中性条件下比较稳定，且种类之间差别不大．产物质谱分析表明，环糊精空腔骨架上的羟基被氧化，生成了含有醛基和羧基氧化产物；反应前后总有机碳含量无明显差别，表明环糊精及产物的空腔结构稳定，未被开环破坏．
With good inclusion and solubilization properties, cyclodextrins can be used alone or coupled with advanced oxidation technologies ( e. g., Fenton ) for soil remediation with organic pollutants. However, knowledge about cyclodextrin stability is rare. This study investigated the degradation kinetics of cyclodextrins by Fenton′s reagent as well as identified major transformation products. Results showed that the degradation rates of cyclodextrins were linearly correlated with hydrogen peroxide concentration, and the reaction followed the second?order kinetic model. The absolute rate constants of cyclodextrins were respectively 3.9×109 L·(mol·s)-1(β?CD and MCD), 6.5×109 L·(mol·s)-1(HPCD), 7.2×109 L·(mol·s)-1(γ?CD) at pH=3 and 2.9×109 L·(mol·s)-1 (β?CD), 3.1×109 L·(mol·s)-1(MCD), 3.2×109 L·(mol·s)-1(HPCD), 3.3×109 L·(mol·s)-1 (γ?CD) at pH=7, showing that cyclodextrins are stable in the neutral condition and differences between them are less varied. Mass spectrometry analysis of the two transformation products showed that several hydroxyl groups in the cavity of cyclodextrins were oxidized to aldehyde and carboxyl
groups. Furthermore, identical TOC values of the systems before and after the Fenton reaction indicated that the cavity of natural cyclodextrins and their transformation products was less destructed.
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