非碳基吸附剂高温捕集氯化铅蒸气

Experimental study on high temperature adsorption of lead chloride by non-carbon adsorbents

垃圾焚烧技术的局限在于其产生的二次污染会给人类、环境带来危害,焚烧烟气中的铅是污染的源头之一,非碳基吸附剂捕集技术是这一领域的研究热点。本文结合我国垃圾成分中水含量大的特点,利用双温区水平管式炉系统考察4种非碳基吸附剂(高岭土、沸石、氧化钙、二氧化硅)在有水蒸气和无水蒸气条件下对氯化铅蒸气的吸附性能,重点探究了高岭土对氯化铅蒸气的吸附规律及机理。结果表明:在氧气无水蒸气氛围下,4种吸附剂的铅吸附能力依次为高岭土>氧化钙>沸石>二氧化硅,吸附剂的化学组成和结构共同决定其吸附性能;在氧气有水蒸气氛围下,高岭土的吸附能力显著提高,而水对其他3种吸附剂的吸附能力影响不大;对于高岭土而言,利用X射线衍射(XRD)表征发现,两种氛围下的吸附产物均为PbAl_2Si_2O_8;通过对比高岭土吸附前后的扫描电子显微镜及X射线能谱仪(SEM-EDS)图谱,发现有水氛围下样品的整个表面都呈熔融状,与原始高岭土、无水氛围下高岭土的表面形成强烈对比,是水分的影响在其微观形貌上的体现;水分对高岭土铅吸附能力的促进作用可能在于:(1)水能参与吸附反应,(2)水的存在促进了高岭土表面共晶融化,使得吸附增强。700~900℃时,在两种氛围中温度升高均有利于吸附,氧气无水氛围中的高岭土吸附效率在20%~40%,氧气有水氛围中的高岭土吸附效率在75%~85%。

The limitation of waste incineration technology is that the secondary pollution it caused will bring harm to human beings and environment.As lead in flue gas is one of the pollution sources,the study of non carbon based adsorbent arises concern in this field.Since the moisture rate of waste is high in China,fixed bed reactor was used to investigate the lead chloride adsorption properties of kaolin,zeolite,calcium oxide and silica in the atmosphere with and without moisture.Then the adsorption behavior of kaolin was further discussed.The results showed that kaolin has the highest adsorption capacity,followed by calcium oxide,zeolite and silicon dioxide in pure oxygen without moisture.Both chemical composition and structure determine the adsorption efficiency.In the atmosphere of oxygen and moisture,the capacity of kaolin is improved significantly.Moisture has great effects on kaolin,but has little effects on the other three adsorbents.The X-ray diffraction(XRD)results of kaolin showed that the adsorption products in two kinds of atmosphere were both PbAl2Si2O8.By comparing the scanning electron microscope and energy dispersive spectrometer(SEM-EDS)results of kaolin,it was found that the whole surface of the kaolin after adsorption is in a molten state at the atmosphere of oxygen and moisture,which is in sharp contrast to the surface of kaolin in another atmosphere.The role moisture plays in the adsorption of kaolin could be explained as follows:①moisture can participate in the adsorption reaction;②moisture promotes the melting of kaolin,which makes adsorption easier.When the temperature at700-900℃,higher temperature is beneficial to kaolin adsorption,the efficiency ranges from20%to40%in oxygen atmosphere without moisture,and ranges from70%to85%in oxygen atmosphere with moisture.