柚皮果胶超滤的凝胶-衰减模型

Gel-attenuation model of ultrafiltration for shaddock peel pectin extracts

采用陶瓷膜对柚皮果胶提取液进行超滤浓缩,考察并分析了膜通量与跨膜压力的关系,建立了描述柚皮果胶提取液超滤过程膜污染的凝胶-衰减模型:当跨膜压力ΔP<最佳跨膜压力ΔPopt时,超滤行为遵循凝胶极化模型,通量随跨膜压力的增加而上升,当达到稳定态时有J=Kln(cG/cB),此时凝胶层中溶质果胶的浓度cG为20·53mg·mL-1;当ΔP≥ΔPopt时,超滤行为遵循衰减模型,其衰减方程为:J=5·464×1010(ΔP)-3·026,膜通量按指数形式衰减。该模型较合理地解释了膜通量与跨膜压力之间呈现钟形关系的原因,有助于指导柚皮果胶提取液的超滤工艺。

Shaddock-peel pectin extracts were concentrated by ceramic membrane ultrafiltration.The relations among fluxes and transmembrane pressures were investigated and analyzed.A gel-attenuation model was set up to describe membrane pollution behavior during the ultrafiltration processes of shaddock peel pectin extracts.When transmembrane pressure △P is less than the optimal transmembrane pressure △Popt, the ultrafiltration of pectin extracts follows gel-polarization model, flux J increases with the transmemberane pressure and the equation J = Kln（cG/cB）is tenable when the stable state is achieved.Pectin concentration of the gel layer at this moment is 20.53mg·mL^-1.However, when △P is higher than △Popt, the ultrafiltration behavior follows attenuation modeI.J decreases exponentially with the attenuation equation J = 5.464 × 10^10（△P）^-3.026.The bell-shape relations between transmembrane pressures and membrane fluxes can be feasibly explained with this gel-attenuation model and the model will be helpful to guide the ultrafiltration of shaddock peel pectin extracts.