A di-azo dye, Congo Red (CR) was used as a model compound to investigate the degradation mechanism in hot compressed water (HCW). The unique properties of HCW facilitated the degradation efficiency without addition of any organic solvent. The influences of reaction time, temperature, initial dye concentration and amount of hydrogen peroxide (H2O2) on the degradation of CR and the removal of total organic carbon (TOC) from the product solution were investigated. The presence of H2O2 was found to enhance the degradation of CR. The results showed that the degradation yield could reach 99.0% with a solution of 100 ppm CR and 50 mM H2O2 at 150°C at the end of 60 min. Maximum conversion of the total organic carbon was recorded as 62.2%. Moreover, the effect of the presence of several co-existing negative ions such as SO4 2-, Cl-, CO32- were investigated. It was found that the presence of SO42- accelerated evidently the degradation of CR. The other chosen anions (CO32- and Cl-) had an inhibitory effect on the decolorization of CR. Finally, kinetic study was carried out and the order of the reaction was calculated as 0.37.
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机译：以重氮染料刚果红（CR）为模型化合物，研究了热压缩水（HCW）中的降解机理。 HCW的独特性能可促进降解效率，而无需添加任何有机溶剂。研究了反应时间，温度，初始染料浓度和过氧化氢（H2O2）的量对CR降解和从产物溶液中去除总有机碳（TOC）的影响。发现过氧化氢的存在增强了CR的降解。结果表明，在60分钟后，在150°C下使用100 ppm CR和50 mM H2O2的溶液，降解率可以达到99.0％。总有机碳的最大转化率记录为62.2％。此外，研究了几种共存负离子（例如SO4 2-，Cl-，CO32-）的存在的影响。发现SO42-的存在明显加速了CR的降解。其他选择的阴离子（CO32和Cl-）对CR的脱色具有抑制作用。最后，进行了动力学研究，反应顺序被计算为0.37。
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