Ultrafiltration (UF) is an effective approach for the separation and purification of organic components dissolved in lignocellulosic pre-hydrolysis liquor (PHL). However, flux decline has been a problem that restricts UF industrial applications. Here, the main impact factors for flux decline on UF processing of PHL are examined. Flux decline curves for four UF membranes having different molecular weight cut-offs (MWCOs) indicated that the largest MWCO UF membrane had a faster flux decline rate because of its better ability to concentrate PHL. Using a 10-kDa UF membrane, the normal UF procedure was modified three different ways to study the independent factors affecting flux, including retentate concentration, charge density, and membrane fouling. The results indicated that membrane fouling was a main impact factor causing flux decline in the early stages of UF, and then charge and concentration effects gradually intervened. Relative to the latter factors, membrane fouling displayed a more regular behavior, with a good linear relationship between flux and operating time. Micro-computed tomography, scanning electron microscopy, and atomic force microscopy were used to characterize fouled membranes. It was revealed that surface contamination plays a more dominant role in flux decline than does internal contamination.

超滤（UF）是分离和纯化溶解在木质纤维素预水解液（PHL）中的有机成分的有效方法。但是，通量下降一直是限制超滤工业应用的问题。在此，考察了通量下降对PHL UF处理的主要影响因素。四种具有不同分子量截留值（MWCO）的UF膜的通量下降曲线表明，最大的MWCO UF膜具有更快的通量下降速率，因为它具有更好的浓缩PHL的能力。使用10 kDa的超滤膜，对正常的超滤程序进行了三种不同的修改，以研究影响通量的独立因素，包括滞留物浓度，电荷密度和膜污染。结果表明，膜结垢是造成超滤早期通量下降的主要影响因素，然后逐渐干预了电荷和浓度效应。相对于后一个因素，膜结垢表现出更规则的行为，并且通量和工作时间之间具有良好的线性关系。微计算机断层扫描，扫描电子显微镜和原子力显微镜被用来表征污损的膜。结果表明，表面污染在通量下降中比内部污染起更主要的作用。扫描电子显微镜和原子力显微镜用于表征污染的膜。结果表明，表面污染物在通量下降中的作用比内部污染物更重要。扫描电子显微镜和原子力显微镜用于表征污染的膜。结果表明，表面污染物在通量下降中的作用比内部污染物更重要。