【作者】 李晨曦；

【导师】 曾向东；

【作者基本信息】 昆明理工大学 ， 环境工程， 2008， 硕士

【摘要】 活性炭具有高度发达的孔隙结构和极大的比表面积,对分子具有极强的吸附能力,是一种优良的吸附剂。到20世纪70年代,颗粒状活性炭处理工业废水和废气的工艺开始得到广泛应用。此后,无论是在技术上,还是在应用范围及处理规模上,活性炭吸附法处理工业废水和废气工艺都取得了很大发展。与此同时,活性炭的消耗量也迅速增加。由此产生大量吸附饱和的废炭,如不进行再生处理和回收利用,不仅会造成资源的浪费,还会对环境带来二次污染。由于微波加热具有即时性、穿透能力强以及加热均匀等特点,国内外学者已将微波加热技术应用于活性炭再生工艺并就此展开了大量研究。但目前对微波再生活性炭的研究均以氮气作为载气,对以干燥空气作为载气的条件进行微波再生活性炭的研究较少,本实验对此进行了较为系统的研究。本实验以载甲苯活性炭为研究对象,以微波辐照为再生手段,以干燥空气为载气,主要从活性炭的升温行为和损耗率、甲苯的脱附率、载甲苯活性炭再生前后的吸附性能的变化等方面,考察了微波再生对活性炭性能的影响和微波辐照再生效果,并以此分析评价了微波再生工艺的优劣。活性炭的升温行为和损耗率实验结果表明:在微波场中改性活性炭升温速率要大于新鲜活性炭的升温速率;活性炭在微波场中的升温受微波功率、载气含氧量、载气流量等因素的影响;在相同的操作条件下改性活性炭的损耗率要高于新鲜活性炭的损耗率。因此,改性活性炭不宜在本实验条件下作为吸附剂。甲苯的脱附率实验结果表明:载气中含氧量的变化对甲苯的脱附率有一定的影响。相同操作条件下,当载气中含氧量为0时,甲苯的脱附率为78.74%,当载气含氧量为21%时,甲苯的脱附率为24.3%。正交实验的结果表明,本实验中微波功率、含氧量、载气流量、辐照时间这4个所考察的因素中对脱附率影响大小依次为载气流量、辐照时间、微波功率、氧含量。若以脱附率为衡量指标,则在本实验条件下的最佳工艺参数是:载气流量800mL/min、氧含量6%、辐照时间3min、微波功率231W。载甲苯活性炭再生前后的吸附性能实验表明:微波辐照再生过程中,载气中含氧量的变化对再生活性炭吸附甲苯的性能产生了影响。经过一定次数的再生后,活性炭对甲苯的平衡吸附量增加,再生过程中氧气的存在有利于再生活性炭对甲苯的吸附。在本实验的操作条件下,各影响因素重要性依次为微波功率、载气流量、含氧量、辐照时间,最佳工艺参数是:微波功率231W、含氧量10%、载气流量500mL/L、辐照时间3min。通过X射线衍射发现,微波辐照对活性炭的晶体结构具有一定影响;氮气吸附实验的结果表明,微波再生后活性炭的比表面积比新鲜活性炭比表面积大,因而提高了活性炭的吸附性能;经分形理论分析得出,微波辐照后活性炭的表面比新鲜活性炭表面粗糙,这有利于活性炭的吸附。更多还原

【Abstract】 Activated carbon has good opening structure and huge surface area, it has excellent absorption capacity and had got wide application in industry. Since the first application of grain AC in industrial waste water treatment and waste air treatment in 1970s, AC has got great development in terms of technique and has been employed for different purposes. Meanwhile, a lot of waste saturated adsorbing AC have been produced in the process of its application, it not only wastes resources, but pollutes the environment if it were not reclaimed and disposed correctly.As microwave heating takes advantages of instantaneous heating, good penetrate ability etc, a lot of researches have been carried out regarding the application of microwave in AC regeneration both at home and abroad. But all the researches which use microwave to regenerate AC use N₂ as carrier gas. Using the dry air as the carrier gas in the experiments is little, so this research will use the dry air as the carrier gas.In the experiment, the object is the AC which loading the toluene, the regenerating method is microwave radiation, the carrier gas is dry air . The research will survey the wastage and temperature increasing behaviour of AC, the toluene desorption, the changment of absorption capacity of AC which loading the toluene, etc. The research will also survey the microwave’s effect on the AC, the effect of microwave regeneration, and evaluate the technology of the microwave regeneration.The experiments on AC wastage and temperature increasing character show that: the temperature increasing velocity of modified activated carbon is higher than AC; the temperature increasing performance of AC was influenced by the microwave power, the oxygen content in the carrier gas, the velocity of carrier gas, ect. On the same condition the wastage of modified activated carbon is higher than AC. So, the the modified activated carbon is not suitable for the research.The experiment on toluene desorption shows that: the alteration of oxygen content will effect on the desorping rate. Under the same condition, the desorping rate of toluene is 78.74% when oxygen’s content is 0%, the desorping rate of toluene is 24.3% when oxygen’s content is 21%. Based on orthogonal experiment, among the four factors: microwave power, oxygen content, the velocity of carrier gas and the time of radiation, to the effect on the desorping rate, the significance sort is the velocity of carrier gas, the time of radiation, microwave power and oxygen content. The best technology condition for AC regeneration is obtained as follows: the velocity of carrier gas is 800mL/min, oxygen content is 6%, the time of radiation is 3 min , and the microwave power is 231W.The experiment of absorption capacity on AC which loading the toluene shows that: in the process of microwave radiation, the alteration of oxygen content will have effect on the adsorbing ability of regenerated AC to the toluene. After several regenerations the adsorption quantity of AC to the toluene is augmentation. So in the process of regeneration the existent of oxygen has advantage on the adsorbing ability of AC. In the condition of this experiment, the significance sort is the microwave power, the velocity of carrier gas, the oxygen content and the time of radiation. The best technology condition for adsorption of regenerated AC: the microwave power is 231W, the oxygen content is 10%, the velocity of carrier gas is 500mL/min and the time of radiation is 3 min.The result of XRD shows that: the crystal structure of AC has changed after the microwave radiation. The result of N2 adsorption shows that: the specific area of regenerated AC is higher than the fresh AC, so the microwave radiation can enhance the adsorbing ability of AC. After the fractal theory analysis, the result shows that: the microwave radiation has advantage on the adsorption of AC, for the face of regenerated AC is rougher than that of AC.更多还原