木聚糖溶液超滤透过率的研究

A STUDY ON ULTRAFILTRATION FLUX OF XYLAN

研究了玉米芯碱抽提所得木聚糖溶液不同的超滤膜超滤时溶剂透过率与主要操作参数间的关系。研究发现 ,增加操作压力 ,通过PLGC、PLCC两种超滤膜的溶剂透过率随之增加 ,但对PLGC超滤膜而言 ,适宜的操作压力不应超过 80kPa ;进料速度对PLGC超滤膜的溶剂透过率影响较大 ,J∝u0 .63b ,而对PLCC超滤膜的溶剂透过率影响较小 ,J∝u0 .0 9b ;料液浓度与溶剂透过率间关系符合膜模型 ,膜面上溶质浓度与膜截留分子量和操作条件有关。用均匀设计考察操作参数对透过率的影响 ,结果表明 ,对截留分子量大的超滤膜 (PLGC)而言 ,进料速度是控制溶剂透过率的最关键因素 ;而对截留分子量小的超滤膜 (PLCC) ,操作压力是控制溶剂透过率的最关键因素。同时 ,对各操作参数与溶剂透过率间的关系进行了关联 ,各模型预测值与实验值吻合较好 ,相对误差小于 7%

Experimental study was carried out on ultrafiltration flux of xylan solution derived from alkali extraction of corncob through different membranes. It was shown that solvent flux was increased with the enchanced operating pressure through PLGC and PLCC membrane, but the proper operating pressure should not exceed 100 kPa with PLGC membrane. Feed velocity has more pronounced effect on solvent flux through PLGC membrane than through PLCC.Relations between feed concentration and solvent flux followed the membrane model. Solute concentration on membrane was affected by operating conditions and membrane cutoff molecular weight. The influence of operating parameters on flux was investigated by means of uniform design test, and results showed that feed velocity is the most critical factor to control flux with membrane of high molecular weight cutoff(PLGC), and operating pressure is the most critical factor to control flux with membrane of low molecular weight cutoff (PLCC). Meanwhile, relations between solvent flux through two kinds of membrane and operation parameters were correlated, and the values calculated from the two sets of correlation were in good agreement with those obtained from experiment at relative error 7%.