Supercritical water oxidation of ion exchange resins: Degradation mechanisms

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• 作者：A. Leybros ; A. Roubaud ; P. Guichardon ; O. Boutin
• 关键词：Supercritical water oxidation ; Ion exchange resins ; Polymer ; Aromatic compounds ; Reaction mechanisms
• 刊名：Process Safety and Environmental Protection
• 出版年：2010
• 出版时间：May 2010
• 年：2010
• 卷：88
• 期：3
• 页码：213-222
• 全文大小：979 K

文摘

Spent ion exchange resins are radioactive process wastes for which there is no satisfactory industrial treatment. Supercritical water oxidation could offer a viable treatment alternative to destroy the organic structure of resins and contain radioactivity. IER degradation experiments were carried out in a continuous supercritical water reactor. Total organic carbon degradation rates in the range of 95–98 % were obtained depending on operating conditions. GC–MS chromatography analyses were carried out to determine intermediate products formed during the reaction. Around 50 species were identified for cationic and anionic resins. Degradation of polystyrenic structure leads to the formation of low molecular weight compounds. Benzoic acid, phenol and acetic acid are the main compounds. However, other products are detected in appreciable yields such as phenolic species or heterocycles, for anionic IERs degradation. Intermediates produced by intramolecular rearrangements are also obtained. A radical degradation mechanism is proposed for each resin. In this overall mechanism, several hypotheses are foreseen, according to HOO radical attack sites.