α-丙二醇-水相中氯代二噁英的催化加氢脱氯降解

Catalytic hydrodechlorination of chlorinated dioxins in α-propanediol-water solution

二噁英类物质由于具有亲脂性、高毒性、化学结构稳定、难生物降解而在环境中持久存在,成为持久性有机污染物的典型代表.二噁英的去除方法研究,一直是国际研究的热点.以5%钯/炭为催化剂,氢气作为氢源,以环境友好的α-丙二醇-水为溶剂,在1mol/L氢氧化钠的碱性条件下,研究了1,2,7,8-四氯代二噁英(1,2,7,8-TCDD)的催化加氢脱氯降解.探讨了反应温度、初始浓度、反应时间、催化剂用量等对1,2,7,8-TCDD去除率的影响.结果表明,在反应初期(前5min),反应速率较快;在反应温度为45℃,催化剂用量为0.5g/mL,反应时间为150min的条件下,1,2,7,8-TCDD的去除率达97.0%;初始浓度对1,2,7,8-TCDD的去除率没有影响.初步试验结果表明,催化加氢脱氯降解是去除环境中氯代二噁英的有效手段,但实际应用还有待于进一步研究.

Dioxins are persistent in the environment as a typical representative of persistent organic pollutants because of their lipophilicity,highly toxicity,stable chemical structure and antibiodegradation.The research about removal methods of dioxins has become an international research focus.Dechlorinations of polychlorinated dibenzo-p-dioxins were carried out in α-propanediol-water solution of 1 mol/L NaOH in the presence of Pd/C catalyst with using of H2.The effects of reaction temperature,initial concentration,reaction time,catalyst dosage on the removal of 1,2,7,8-TCDD were studied.It is found that the reaction rate is very fast in the beginning of the reaction （before 5 min）; the optimal reaction conditions are as follows：reaction temperature is 45 ℃,the amount of catalyst is 0.5 g/mL,reaction time is 150 min; the removal rate of 1,2,7,8-TCDD is over 97.0％ at this point; initial concentration of 1,2,7,8-TCDD has no effect on the removal rate.The preliminary test results show that catalytic hydrodechlorination is an effective means to remove chlorinated dioxins in the environment; however,further studies are necessary for its practical applications.