【作者】 张凯；

【导师】 李亚民；

【作者基本信息】 大连交通大学 ， 环境科学， 2011， 硕士

【摘要】 长期以来,持久性有机污染物(Persistent Organic Pollutants,以下简称POPs)的处理是环境治理中的难点,氯酚类芳香化合物是其中的典型代表。由于其具有稳定的化学性质,很难自然降解,对生态系统产生了强烈的干扰,严重危害人类安全和健康。传统降解POPs的方法由于反应条件苛刻、处理费用高、工艺流程复杂、易产生二次污染等原因使其商业化推广受到了限制。本试验用机械化学法处理POPs的典型代表五氯酚(Pentachlorophenol,以下简称PCP),在机械力的作用下,通过钢球与废物颗粒不断地碰撞,将机械能传给废物与金属粉末颗粒,使其不断变细,从而增强PCP分子中的惰性卤素原子反应活性,使其与碱性脱卤试剂发生化学反应,并转化为可溶于水的金属卤化物。具体的实验过程是：在常温常表压下,将PCP与金属氧化物及球磨介质钢球混合放入球磨机中球磨,球磨一定时间后出料,用AgNO3标准溶液滴定含氯离子的研磨产物溶出液,根据消耗AgNO3溶液的量计算氯的脱出率,以此来反映PCP的降解效果。实验结果表明：1、PCP与金属氧化物的摩尔比越大,脱氯率越高,并确定了本实验的最佳摩尔比为1:60,脱氯效果达到98%以上。2、脱氯率随球磨时间的增加而增大。随着球磨时间的延长,产物的颜色由浅变深至黑色,可能有单质碳产生。本实验中最佳的球磨时间为2.5h,有2/3左右的有机氯转化为无机氯。3、金属氧化物的种类对PCP的降解有直接的影响,本实验表明,在同等条下,CaO作为磨料对PCP的降解效果要好于MgO。4、通过价键理论证实,CaO和MgO作为脱卤试剂更容易在机械力作用下,引发PCP的化学降解反应。通过本课题的研究,机械化学法相比于传统的化学方法处理PCP,具有工艺流程简单、工作条件温和、短时间内就可以达到理想的处理效果、而且不涉及传统化工单元的操作,具有广泛的商业化应用前景。更多还原

【Abstract】 Fore a long time, the treatment of the Persistent Organic Pollutants(POPs) is difficult in environment governance, chlorophenols aromatic compounds is one of the typical. It might cause disturbance in ecosystem and threaten human being’s health because of its difficulty to be decomposed owing to the stable chemical property. Traditional methods of degradation of POPs is difficult to commercialize for they have so many disadvantages, including severe restriction on reaction condition, extortionate handing cost, complicated technological process and secondary pollution etc.We used mechanochemical method to degrade the Pentachlorophenol (PCP) that one is the typical of the POPs in this experiment. Ball and waste particles became thin and occurred continuously collision under the action of mechanical forces, consequently, the inert halogen atomic’s reactivity of PCP would be boosted up, halogen atoms removed from organic carbon chains and transform to Metal halide, through the reaction between PCP and dehalogenation reagent occurred. The specific experiment process:PCP, metallic oxide and ball-grinder medium steel beads are ground together in a ball-grinder under ordinary temperature and pressure, which is a mechanochemical way of degrading PCP. A AgNO3 standard solution was used to titrate the Cl--containing solution made from grinding product. The dechlorination rate, which can show the degradation result of PCP, was calculated through the amount of AgNO3 standard solution.The results are presented as follows:1. The bigger the Metal Oxide/PCP molar ratio was, the better the dechlorination rate was:when the molar ratio is 60:1, the dechlorination rate was almost over 98%. So, the best molar ratio is 60:1 in this experiment.2. PCP dechlorination rate increased as grinding time. With increased the ball milling time, the product showed a black hue after 2.5h’s grinding, which might be a sigh of formation of elemental carbon. In this experiment, the best ball milling time is 2.5h, and the radio of organochlorine transformed to inorganic chlorine was almost 2/3.3. Metal oxide species has a direct impact on the degradation of PCP. CaO is better than MgO as a grinding material for dechlorination in the same time.4. Confirmed by valence bond theory, CaO and MgO as a dehalogenation reagent can trigger the chemical degradation of PCP more easily under the action of mechanical forces.Due to its simple technological process, normal reaction condition, noticeable effect can get good treatment effect in short time, does not involved the operation of the traditional chemical unit, the mechano-chemical de-halogenations of halogenated organic has received attentions as a promising technology to destroy solid waste containing persistent organic pollutants.更多还原