推导出大面积扩散渗析总传质系数K的计算式,该计算式由两部分组成,其中,Kc表示在溶液体积不发生变化时,仅由溶质浓度梯度引起的传质;Kw表示由水反渗导致的溶液体积变化引起的传质.除此之外,还通过卷式循环扩散渗析实验,定性的研究了流量对两种扩散渗析传质及总传质系数的影响.结果表明,扩散过程中Kc,基本占主导地位;随着流量的增加(100~300mL/min),Kc逐渐减小,而Kw却不断增大;导致总传质系数K先略有增大,后逐渐减小;其中,流速为200mL/min时,总传质系数最大.
A new equation is derived to calculate overall mass transfer coefficient, K of diffusion dialysis with large membrane areas. The equation consists of two parts, Kc, and Kw. Kc is the mass transfer coefficient, owing to solute concentration gradient without solution volume change caused by water osmosis, and Kw, is the mass transfer coefficient, owing to solution volume change caused by water osmosis. Besides, effect of flow rate,Q on two kinds of mass transfer coefficient, Kc, Kw and overall mass transfer coefficient K, is also qualitatively investigated in continuous spring wound diffusion dialysis with large membrane areas. The results show that Kc is the key factor of mass transfer during diffusion dialysis, however, Kc gradually decreases, and Kw gradually increases, so that overall mass transfer coefficient, K firstly increases and then decreases, within the flow rate,Q range of 100-300 mL/mim reaches is the maximum when flow rate, Q is 200 mL/min.