乙醇-水体系渗透汽化分离过程的影响因素

Effects of Variables on the Pervaporation Performance of Water-ethanol Mixtures

为了考察乙醇-水体系渗透汽化实验中影响因素对亲水性PAA-Al2O3复合膜分离性能的影响,采用中心组合旋转设计方法设计实验,以渗透通量和选择性为实验响应,建立了以接枝丙烯酸单体浓度、操作温度和料液浓度为变量的回归模型方程。通过回归模型的分析,发现在乙醇-水渗透汽化脱水实验过程中,对渗透通量影响最明显的是操作温度,其次是料液浓度;对选择性影响最明显的则是操作温度与料液浓度间的交互作用,其次是接枝丙烯酸单体浓度。为了对乙醇-水体系的渗透通量和选择性进行优化,运用满意度函数方法分析了回归模型方程。结果表明,料液浓度为95%(wt)的乙醇-水共沸混合物的优化条件为接枝丙烯酸单体浓度为8%(wt)和操作温度为55.9℃,其总体满意度函数值为0.50,优化结果是令人满意的。

In order to investigate the effects of the variables on the pervaporation（PV） performance of the hydrophilic PAA-Al2O3 composite membrane for the ethanol-water mixture,the central composite rotatable design（CCRD） was used,and the permeate flux and selectivity were chosen as the experimental responses.Regression models were developed as the functions of the graft concentration of acrylic acid,the operating temperature,and the inlet ethanol concentration.From the regression analysis of the pervaporation of ethanol-water mixture,the permeate flux was found to be significantly influenced by operating temperature and then ethanol concentration.Meanwhile,the selectivity was significantly influenced by the interaction of temperature and ethanol concentration,followed by the graft concentration of acrylic acid.In order to optimize the flux and selectivity of ethanol-water azeotropic mixtures,the desirability function approach was applied to analyze the regression model equations.For the 95%（wt） ethanol-water azeotropic mixture,the optimum graft concentration of acrylic acid and temperature were found to be 8%（wt）and 55.9 ℃,respectively;and the value of overall desirability was 0.50,which indicated that the results of optimization for the separation of ethanol-water azeotropic mixture are acceptable.