大豆乳清蛋白的超滤分离及膜污染分析

Ultrafiltration and membrane fouling analysis for the separation of soybean whey protein

本文以大豆乳清蛋白为研究对象,采用孔径为5 nm的陶瓷膜对大豆乳清废水进行超滤实验,考察不同操作条件对超滤过程分离性能的影响,并结合Cake-complete模型对膜污染机理进行分析研究。实验结果表明:在0.15 MPa压力下,最大渗透通量为6.85 L·m^-2·h^-1;当压力由0.15 MPa增大到0.20 MPa时,浓差极化占主导因素,有效推动力降低,此时压差的增大对膜通量的影响不再显著。同时,乳清蛋白的截留率可通过料液p H进行调节,在p H为6左右时,截留率最高可达73.3%。此外,采用组合模型对实验数据的拟合效果最佳,拟合度达到0.99以上,说明膜污染过程并非由单一机理控制,而是由多种污染类型共同造成的。以上结果为进一步的工业应用奠定了基础。

In this work,soybean whey proteins＇ removal experiments were conducted using a ceramic ultrafiltration （UF） membrane with the average pore size of ca.5 nm,and effects of different operating conditions on separation performance were investigated.Additionally,the cake-complete model was employed to explain the ultrafiltration fouling mechanism. Results showed that the maximal permeation flux of 6.85 L. m-2. h-1 was achieved under 0.15 MPa. When the pressure were increased from 0.15 to 0.20 MPa, the concentration polarization dominated, resulting in the diminishment of effective driving force and thus the flux were not increased significantly with increasing pressure.Besides,the rejection rate of whey protein could be adjusted by pH of solution and be up to 73.3% at pH6.Moreover,the best fitting result was obtained by using the cake-complete model,the fitting degree calculated was above 0.99,which suggested that the membrane fouling process was not controlled by individual mechanism and resulted from combined effects of diverse fouling types.Therefore, these results may provide a significant inside into the industrial separation of whey proteins.