【作者】 贾美欣；

【导师】 高军； 王忠卫；

【作者基本信息】 山东科技大学 ， 化学工艺， 2008， 硕士

【摘要】 从低浓度醋酸水溶液中回收醋酸,是目前化工企业尚待解决的一项难题。据统计,在工业上所消耗或生成的醋酸有相当的数量随废水排出。例如,在糠醛生产中,全国每年被排放掉的醋酸量约有1万吨左右,这不仅损失了大量的有用资源,而且还污染了环境。因此,从稀醋酸水溶液中回收醋酸,不仅有着重大的经济效益,而且也是环境保护所必需。本课题研究的是醋酸稀溶液的萃取,在综述了络合萃取技术在处理有机羧酸及其水溶液方面的研究进展的基础上,系统地研究了醋酸稀溶液的萃取动力学。采用磷酸三丁酯（TBP）和三烷基胺(7301和N₂₃₅)为络合剂,正辛醇、加氢煤油为稀释剂,成功地筛选出三元高效混合络合萃取剂;利用恒界面池法,研究了络合萃取平衡的时间,萃取剂体积分数、醋酸初始浓度、温度、水溶液pH、搅拌速率、两相接触面积等因素对络合萃取平衡过程的影响;从萃取动力学角度,对络合萃取稀醋酸过程的级数及机理进行初步探讨,从而为提高萃取效率提供依据。实验结果表明:（1）三烷基胺（7301）对醋酸具有较好的萃取分离效果,而且在加入极性助溶剂正辛醇后其萃取能力可明显增大;（2）经过筛选,优化选出萃取剂为三烷基胺-正辛醇-加氢煤油体系,且最佳配比为3:6:1;（3）溶液的pH值较低时,平衡分配系数较大;随着溶液pH值的升高,平衡分配系数明显下降,pH值达到一定数值时,分配系数非常低。（4）采用斜率法确定了三烷基胺萃取醋酸的萃合物组成,在27℃和0.346 mol/l浓度范围内可能形成组成为1:1的萃合物。（5）分配系数随着醋酸稀溶液初始浓度、水油相比、温度的增加而下降:随着一定范围内络合剂三烷基胺(7301 N₂₃₅)浓度、两相接触面积以及搅拌速度的增加而升高。通过数据分析,三烷基胺对醋酸萃取过程的级数约为1,络合萃取醋酸过程包括三个步骤:（1）三烷基胺从有机相传递到水相或水相内界面;（2）三烷基胺于醋酸发生络合反应生成络合物;（3）络合物传递并溶解到有机相中。得到了萃取剂络合萃取醋酸稀溶液在试验范围内的平衡分配系数模型。更多还原

【Abstract】 Recycling acetic acid from the dilute aqueous solution of acetic acid is a difficult problem to chemical plant at present. Statistic data show that a considerable amount of acetic acid which is produced or consumed in industries is discharged with wastewater. For example, in the production of furfural, about 10,000 tons of acetic acid is discharged each year, which is not only losing a great deal of useful resources, but also polluting the environment. Therefore, recovering the acetic acid from the dilute aqueous solution of acetic acid can be beneficial to the economy and the environment.So the extraction of acetic acid from its dilute aqueous solution was studied in this paper. On the basis of the discussion of the complex extraction technology in the treatment of organic carboxylic acid, the extractive kinetics on acetic acid extraction from its dilute aqueous solution has been studied. The chelators are TBP and three alkyl amines (7301 and N235), the diluents are n-caprylic alcohol and hydrogenating kerosene. The efficient complex extractant was successfully examined. The complex extraction factors, the equilibrium time, extractant volume, the initial concentration of acetic acid, temperature, pH value, stirring rate and contacting area were considered by the Lews cell method. In the meantime, the kinetic order of the extraction process and the mechanism of the complex extraction process were analyzed, with which the extraction efficiency of such process can be improved.The results showed that the better effect of extraction of acetic acid were obtained with trialkylamines (7301), and the extraction capacity could be increased significantly after adding amount of n-caprylic alcohol. According to the orthogonal experiments, the better extraction system is trialkylamines +n-caprylic alcohol+ hydrogenating kerosene with the ratio of 3:6:1. The higher equilibrium distribution coefficient was obtained with the lower pH value. With increasing the pH value, the equilibrium distribution coefficient decreased significantly and the lowest distribution coefficient was measured, when pH value increased to a certain level. With the temperature of 27℃and the concentration of 0.346 mol/l, the form of the complex was likely 1:1. The distribution coefficient decreased with increasing the initial concentration of acetic acid solution, the ratio of the aqueous phase to the oil phase and the temperature. The distribution coefficient increased with the increasing the concentration of trialkylamines (7301 N235), two-phase contact area and stirring rate.With the data analysis, the kinetic order of the extraction process is nearly 1. There are three steps in the acetic acid complex extraction process, which are the transfer of trialkylamines into the aqueous phase or the interface of it, the formation of the complex of trialkylamines and acetic acid, and the transfer of the complex into the organic phase. A distribution coefficient mathematical model of the extraction process based on the above analysis was presented in the paper.更多还原