Membrane Separation and Pore Diffusion of Organic Molecules Adsorbed on Controlled-porous Acidic Ceramics

以膜分离苯为目标(b.p。80.1C)和环己烷(b.p。在可控多孔玻璃膜(Cornig，No.7930)中，测定了它们的渗透系数(Q)：(1)当底物单独或混合(摩尔比为1：1)时，苯的渗透系数大于环己烷的渗透系数(测量温度范围为30-70℃)。(2)随着温度的升高，苯的渗透率增加，而环己烷的渗透率几乎不随温度变化。基于这种温度依赖关系的对比，得出结论：苯的渗透以外科流动机理为主，而表面流动和昆森流动机理与环己烷的渗透机理相互竞争。(3)用银离子修饰膜表面后，苯的Q降低到初始值的一半，而环己烷的Q几乎没有变化。因此，双电子与银离子之间的吸引相互作用选择性地控制了材料的渗透性。用脉冲场梯度核磁共振方法测量了吸附在玻璃膜孔内的苯分子和环己烷分子的自扩散常数(D)。苯的D降低，这与观察到的Q的趋势一致。由于苯与表面之间的相互作用更强，苯的表面浓度预计会比环己烷高。因此，Q(苯)和Q(环己烷)的结果将归因于在膜分离条件下苯的表面流动的有效性。

With the aim of membrane separation of benzene(b.p. 80.1 C) and cyclohexane(b.p. 80.7 C), their permeation coefficients (Q) were betermined for a controlled-porous glass membrane (cornig, No.7930): (1) Whenever substrates were fed singly or in the mixed state (1:1 mole ratio), permeabiity of benzene was higher than that of cyclohexane (measured temperature range, 30-70 C). (2)As the tempearture was elevated, the permeability of benzene was raised, while cyclohexane showed little temperature dependence. Based on this contrasted temperature dependence, it is concluded that the surgace-flow mechanism is predominant for the permeation of benzene, whereas the surface-flow and kundsen-flow mechanisms are in competition for that of cyclohexane.(3) When the membrane surface was modified with silver ions, q of benzene was reduced to one-half its initial value, ahile q of cyclohaxane scarcely changed. Thus the permiability was selectively controlled by the attractive interaction between denzene pi-electrons and the silver ion. With the pulsed field-gradient nmr method, self-diffusion constants (d) Were measured for both benzene and cyclohexane molecules absorbed in the pores of glass membranes: by the surface modification with silver ions. d of benzene was lowered, which is consistent with the tendency observed for Q. By virtue of the stronger interaction between benzene and the surface, a higher surface concentration is expectable for benzene than for cyclohexane. Hence the results of Q(benzene) > Q(cyclohexanre) would be ascribed to the effectiveness of surface flow of benzene nuder the condition of membrane separation.