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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Kinetics and Mechanism for the Sonochemical Degradation of a Nonionic Surfactant
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Kinetics and Mechanism for the Sonochemical Degradation of a Nonionic Surfactant

机译：非离子表面活性剂声化学降解的动力学及机理

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摘要

The sonolytic degradation of the nonionic surfactant, octaethylene glycol monododecyl ether (C_(12)E_8), hasbeen studied at various initial concentrations below and above its critical micelle concentration (CMC). Ithas been observed that the degradation rate increases with an increase in the initial concentration of thesurfactant until the CMC is reached. Above the CMC an almost constant degradation rate is observed, suggestingthat the surfactant in its monomer form is involved in the degradation process. The degradation process ofC_(12)E_8involves two distinct primary processes occurring at the bubble/solution interface: (a) hydroxylation/oxidation of the surfactant and (b) pyrolytic fragmentation of the surfactant. The oxidative cleavage of ethyleneoxide units provides evidence for OH radical attack. Hydroxylation of the ethoxy chain gives rise to variousshort-chain carboxyalkyl-polyethylene glycol intermediates. The polyethylene glycol chain formed, due tothe scission of the C_(12)E_8molecule, undergoes rapid hydroxylation/oxidation to yield simple compounds thathave the potential to undergo further degradation. The detection of multiple intermediates indicates that severalprocesses affect the complete degradation pathways of the surfactant molecule. TOC analysis, however, indicatesthat the sonolytic mineralization of the surfactant is difficult to achieve at reasonable rates due to the relativelylow surface activity of the degradation products formed during sonolysis.
机译：已经在低于和高于临界胶束浓度（CMC）的各种初始浓度下研究了非离子型表面活性剂八乙二醇单十二烷基醚（C_（12）E_8）的声降解。已经观察到，降解速率随着表面活性剂初始浓度的增加而增加，直至达到CMC。在CMC上方，观察到几乎恒定的降解速率，这表明表面活性剂以单体形式参与了降解过程。 C_（12）E_8的降解过程涉及在气泡/溶液界面发生的两个不同的主要过程：（a）表面活性剂的羟基化/氧化和（b）表面活性剂的热解碎裂。环氧乙烷单元的氧化裂解为OH自由基攻击提供了证据。乙氧基链的羟基化产生各种短链羧烷基-聚乙二醇中间体。由于C_（12）E_8分子的断裂，形成的聚乙二醇链经历了快速的羟基化/氧化反应，从而生成了具有可能进一步降解的简单化合物。多种中间体的检测表明，几种过程会影响表面活性剂分子的完整降解途径。但是，TOC分析表明，由于在声分解过程中形成的降解产物的表面活性相对较低，因此难以以合理的速率实现表面活性剂的声分解矿化作用。

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