How alginate monomers contribute to organic fouling on polyamide membrane surfaces?
How alginate monomers contribute to organic fouling on polyamide membrane surfaces?
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DOI：
10.1016/j.memsci.2021.120078
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发表时间：
2021-11
影响因子：
9.5
通讯作者：
Yuan Xiang;Rong-guang Xu;Y. Leng
中科院分区：
文献类型：
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作者：
Yuan Xiang;Rong-guang Xu;Y. Leng
通过计算机分子模拟研究了水溶液中含有藻酸盐分子的聚酰胺膜表面的有机污染。在这里，我们专注于β-d-甘露糖醛酸（M）和α-l-古罗糖醛酸（G）海藻酸盐单体在聚酰胺膜表面上的分子结合性质。自由能计算表明，M藻酸盐单体表现出显着的疏水吸引力与某些类型的苯环单元在聚酰胺链中，虽然这样的疏水相互作用是不那么强的离子桥之间的M单体和羧酸基团的聚酰胺膜表面上的结合。这与G藻酸盐单体的结垢行为相反，G藻酸盐单体不存在与膜表面的这种疏水相互作用，并且有机结垢主要归因于由二价金属离子介导的G单体和聚酰胺羧酸酯基团之间的离子桥结合。分子动力学模拟不同的藻酸盐低聚物附近的聚酰胺表面表明，含M的低聚物和聚酰胺膜表面之间的疏水相互作用的结果在一个更短的污染途径比纯G-低聚物。这些疏水相互作用，连同M单体在聚酰胺链表面上的移动性，与纯G-低聚物相比，进一步减少了含M低聚物的对接时间，从而增强了表面结垢。
Organic fouling of polyamide membrane surfaces with alginate molecules in an aqueous solution is studied through computer molecular simulations. Here, we focus on the molecular binding properties of β-d-mannuronic acid (M) and α-l-guluronic acid (G) alginate monomers on a polyamide membrane surface. Free energy calculations show that M alginate monomers exhibit significant hydrophobic attractions with certain types of benzene ring units in a polyamide chain, though such hydrophobic interactions are not as strong as the ionic bridge binding between the M monomer and the carboxylate group on a polyamide membrane surface. This is in contrast to the fouling behavior of G alginate monomers to which such hydrophobic interactions with a membrane surface do not exist, and the organic fouling is largely attributed to the ionic bridge binding between the G monomer and polyamide carboxylate groups mediated by divalent metal ions. Molecular dynamics simulations of different alginate oligomers near a polyamide surface show that hydrophobic interactions between the M-containing oligomers and polyamide membrane surface result in a much shorter pathway of fouling than that of pure G-oligomers. These hydrophobic interactions, together with the mobility of M monomers on a polyamide chain surface, further reduce the docking time of M-containing oligomers compared to pure G-oligomers, and thus enhance the surface fouling.