Abstract The main challenge for a widespread use of nanoporous membranes in the removal of ionic contaminants lies in the adjustment of their physicochemical properties to allow adequate ion rejection and mitigate fouling based on the targeted application. Most of the commercial membranes are negatively charged and their use is thus not necessarily relevant for divalent cation rejection. The main objective for researchers is therefore to provide novel tailored membranes by developing specific synthesis or modifying available membranes. It is proposed here to tailor physicochemical properties of a commercial low molecular weight cut-off ultrafiltration membrane by electrospray deposition of polyethylenimine (PEI) and polystyrene sulfonate (PSS). In this study, it is highlighted that, with adequate conditions, it is possible to adjust the charge of the membrane surface, which can reach values from −40 to +40 mV (compared with −20 mV for pristine membrane). Surface hydrophilicity has also been increased with a contact angle decreased from 60 to 30° with a PSS surface layer. In terms of filtration performances, it is shown that the permeation flux is not reduced by the electrospray deposition of polymer and can even be slightly enhanced in specific conditions. When polymer concentration is sufficient, the deposit is able to face the shear stress induced by cross-flow filtration, probably due to viscosity effect. The positive PEI surface layer leads to a strong enhancement in the rejection of divalent cations whereas that of divalent anions is notably decreased due to electrostatic interactions between the charge of divalent ions and that of the membrane. The weaker impact of electrostatic interactions on monovalent ions allows adjustment of the separation selectivity between cations and anions as well as between mono- and divalent ions. Finally, it is also demonstrated that rejection performances are mostly governed by the surface layer, even if the underlying deposit layers and membrane also have a non-negligible impact on ion rejection.

中文翻译：

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通过聚合物的电喷雾沉积对商业超滤膜进行改性，以调整物理化学特性并提高过滤性能

摘要 广泛使用纳米多孔膜去除离子污染物的主要挑战在于调整其理化性质，以根据目标应用进行足够的离子排斥和减轻污染。大多数商用膜带负电，因此它们的使用不一定与二价阳离子排斥相关。因此，研究人员的主要目标是通过开发特定的合成或修改可用的膜来提供新的定制膜。这里建议通过聚乙烯亚胺 (PEI) 和聚苯乙烯磺酸盐 (PSS) 的电喷雾沉积来定制商业低分子量截止超滤膜的物理化学性质。在这项研究中，强调的是，在适当的条件下，可以调整膜表面的电荷，其值可以达到 -40 到 +40 mV（与原始膜的 -20 mV 相比）。表面亲水性也随着与 PSS 表面层的接触角从 60° 降低到 30° 而增加。在过滤性能方面，表明聚合物的电喷雾沉积不会降低渗透通量，在特定条件下甚至可以略微增强。当聚合物浓度足够时，沉积物能够面对错流过滤引起的剪切应力，这可能是由于粘度效应。由于二价离子电荷与膜电荷之间的静电相互作用，正 PEI 表面层导致二价阳离子的截留率显着增强，而二价阴离子的截留率显着降低。静电相互作用对一价离子的较弱影响允许调整阳离子和阴离子之间以及一价和二价离子之间的分离选择性。最后，还证明了截留性能主要受表面层控制，即使下面的沉积层和膜对离子截留也有不可忽略的影响。