• 关键词：十氯联苯  亚临界水  超临界水  氧化  去除率  降解

• 基金项目：国家自然科学基金(No.51276168)

• 张晓林
• 浙江大学能源清洁利用国家重点实验室, 杭州 310027

• 邹道安
• 浙江省电力设计院, 杭州 310012

• 池涌
• 浙江大学能源清洁利用国家重点实验室, 杭州 310027

• 摘要：以多氯联苯(Polychlorinated biphenyls, PCBs)中氯代饱和度最高的十氯联苯(Deca-chlorobiphenyl, D10CB)为对象,考察了反应温度、供氧量、停留时间和NaOH对十氯联苯降解效果和PCBs产物分布的影响,并通过产物的GC-MS检测结果,推测了D10CB的降解机理.实验表明,在供氧量50 mL条件下反应10 min,350~450 ℃时,D10CB去除率均高于96%,总PCBs的去除率为77.2%~81.2%.供氧量的增加有助于提高PCBs去除率,450 ℃时,供氧量200 mL比无氧条件下提高了10.5%.NaOH的加入不仅明显提高了D10CB和总PCBs的去除率,而且使产物不同氯代水平PCBs含量分布趋于均匀.结合产物中其他小分子有机组分推测,D10CB超(亚)临界水降解首先发生脱氯反应,继而发生苯环开环、小分子基团去除及氧化分解等复杂反应.

• Abstract：Deca-chlorobiphenyl (D10CB) was selected to explore the effects of temperature, oxygen amount, retention time and NaOH on its degradation in subcritical and supercritical water (SCW), as highest chlorinated polychlorinated biphenyl (PCB). The degradation mechanism was envisaged, according to the reaction products established by GC-MS. A series of orthogonal experiments were carried out at different temperature (350~450 ℃), oxygen amount (0~200 mL) and retention time (10 and 20 min) with or without addition of sodium hydroxide. The results showed that after 10 min retention time at 350~450 ℃ with 50 mL oxygen, the D10CB removal efficiency exceeded 96% and the total PCBs removal efficiency attained 77.2%~81.2%. This PCBs removal efficiency rose with increasing oxygen amount. Also a longer retention time could enhance the PCBs removal efficiency, especially in subcritical water. The presence of sodium hydroxide not only improved the PCBs removal efficiency, but also contributed to a more even distribution of the different chlorinated PCB isomer groups. Generally, the percentage of low chlorinated PCBs increased when reaction conditions (temperature, oxygen amount and retention time) became more severe. Moreover, some other organic compounds, including 3-methyl pentane, toluene, ethylbenzene, phenol, benzyl alcohol and benzaldehyde, were detected by GC-MS. According to the PCBs distribution and the presence of other organics after treatment, we postulated that the D10CB degradation in subcritical and supercritical water was initially dominated by dechlorination and then a series of complicated reactions, such as opening of the benzene ring, removal of methyl or ethyl group, oxygenolysis, etc., occurred.

• Key words：deca-chlorobiphenyl  subcritical water  supercritical water  oxidation  removal efficiency  degradation

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