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3D re-crosslinking of an acid-resistant layer on NaA tubular membrane for application in acidic feed

Li, Jie, Li, Chong, Li, Xiaoqing, Wang, Naixin, Ji, Shulan, An, Quan-Fu
Journal of membrane science 2019 v.589 pp. 117259
acid tolerance, artificial membranes, biomass, calcium, calcium chloride, crosslinking, fermentation, industry, pH, pervaporation, sodium alginate, water content
NaA membranes are recognized as one of the most promising materials for fabrication of high-performance pervaporation membrane for dehydration, which has been widely employed in dehydration industry. However, the chemical structure breakage of NaA in acidic conditions severely hampered the application of NaA membrane in purification of biomass fermentation. In order to overcome this bottleneck, we proposed construction of a protective acid-resistant skin on the 3D surface of NaA tube. The protective layer was prepared by self-assembly of sodium alginate (SA) and CaCl2, which formed the ‘egg-box’ network via crosslinking SA with Ca2+. The effect of cross-linking, SA concentration, layer numbers and operation pH on the membrane performance was investigated. When applied for pervaporation at acidic feed, the protective skin was partly broken, but it can be re-crosslinked again by simple ionic exchange to form a solid acid-resistant skin. After the re-crosslinking treatment, the performance of membrane can be recovered (the water content in the permeate and the flux were 99.6 wt% and 860 g/(m2.h), respectively) with operation condition at pH = 2. Notably, the membrane can be continuously operated in acid feed for 100 h and showed no obvious performance degradation.