磷酸三丁酯/煤油支撑液膜体系中苯酚的传质分离

Mass transfer and separation of phenol in tributyl phosphate/kerosene supported liquid membrane system

研究了苯酚在以多孔聚丙烯平板膜(Celgard2500)为支撑体、磷酸三丁酯(TBP)为膜载体和煤油为膜溶剂的支撑液膜体系中的传质过程;用传统萃取法测定了TBP/煤油体系中苯酚络合物摩尔比为1∶1,同时得到25.0℃萃取平衡常数为96.72;考察了原料相pH值、初始质量浓度、膜二侧转速、载体浓度和反萃取相碱浓度对苯酚传质的影响,确定了该体系分离苯酚的最佳条件:原料相pH<9,苯酚初始质量浓度<1 000 mg/L,膜二侧转速>300 r/m in,载体浓度为0.55 mol/L,反萃取相碱浓度0.10 mol/L;根据双膜理论提出苯酚的传质动力学方程,采用直线斜率法计算了苯酚在TBP/煤油支撑液膜体系中的扩散层厚度和膜内扩散系数,计算结果表明动力学方程计算值能较好地与实验值吻合,平均相对误差在2%以内。

The mass transfer of phenol from feed phase into stripping phase （SLM） was studied by using Celgard2500 porous polypropylene fiat-sheet through supported liquid membrane membranes as supports and tributyl phosphate （TBP） dissolved in kerosene as carrier. The composition mole fraction of phenol complex in TBP/ kerosene system was 1 ： 1 through the determination of traditional extraction methods, and the value of extraction equilibrium constants was 96.72 at 25.0℃. The effects of pH value, initial mass the concentration in feed phase, stirring speed of the feed and stripping phases, the concentration of TBP in the membrane and the sodium hydroxide concentration in the stripping phase on the mass transfer rate of phenol were also investigated. The optimal conditions of separating phenol through SLM are as follows： the pH value of feed phase is below 9, the phenol initial mass concentration in feed phase is below 1 000 mg/L, the stirring speed of the feed and stripping phases is more than 300 r/min, the concentration of TBP in the membrane is 0.55 moL/L, and the sodium hydroxide concentration in the stripping phase is 0.10 mol/L. The mass transfer kinetic equation was determined in terms of double-film theory. Various parameters such as permeability coefficient, thickness of aqueous diffusion layer and diffusion coefficient of phenol through SLM were evaluated by the linear slope method. The calculated results agree well with the experimental data according to the kinetic equation and the deviation between them is within 2%.