Alginate Hydrogel Assisted Controllable Interfacial Polymerization for High-Performance Nanofiltration Membranes

Abstract

The deepening crisis of freshwater resources has been driving the further development of new types of membrane-based desalination technologies represented by nanofiltration membranes. Solving the existing trade-off limitation on enhancing the water permeance and the rejection of salts is currently one of the most concerned research interests. Here, a facile and scalable approach is proposed to tune the interfacial polymerization by constructing a calcium alginate hydrogel layer on the porous substrates. The evenly coated thin hydrogel layer can not only store amine monomers like the aqueous phase but also suppress the diffusion of amine monomers inside, as well as provide a flat and stable interface to implement the interfacial polymerization. The resultant polyamide nanofilms have a relatively smooth morphology, negatively charged surface, and reduced thickness which facilitate a fast water permeation while maintaining rejection efficiency. As a result, the as-prepared composite membranes show improved water permeance (~30 Lm−2h−1bar−1) and comparable rejection of Na2SO4 (>97%) in practical applications. It is proved to be a feasible approach to manufacturing high-performance nanofiltration membranes with the assist of alginate hydrogel regulating interfacial polymerization.

Interfacial polymerization at unconventional interfaces: an emerging strategy to tailor thin-film composite membranes

“…This kind of structure endows liquid-gel interfaces with interesting characteristics for interfacial polymerization. [61][62][63][64][65][66] Yuan et al conducted interfacial polymerization on the surface of a nanoporous Kevlar hydrogel to create high-performance TFC nanofiltration membranes. 61 The hydrogel's high water content and a low proportion of polymer networks are similar to those observed for the free water phase used for synthesizing a freestanding membrane.…”

Surface and Interface Engineering of Polymer Membranes: Where We Are and Where to Go

“…Such a method could fabricate a nanofiltration membrane with promoted permeation and competitive rejection. In addition, the distinctive solid–liquid interface consisting of hydrogel and alkane could be integrated with the interlayer to enhance the binding between substrates and skin layers …”

“…In addition, the distinctive solid− liquid interface consisting of hydrogel and alkane could be integrated with the interlayer to enhance the binding between substrates and skin layers. 194 Beyond the solid−liquid interface, there are also some reports regarding the interfacial polymerization at the gas−liquid interface. For example, Droudian et al have reported a pinhole-free polymeric layer synthesized within a free-standing carbon nanotube buckypaper at the air−liquid interface.…”

High Flux Nanofiltration Membranes with Double-Walled Carbon Nanotube (DWCNT) as the Interlayer

“…With population growth and economic development, fresh water scarcity has become extremely serious [ 1 , 2 , 3 , 4 , 5 ], and 25% of the population currently do not have enough fresh water. Due to low energy requirements, good stability and environment compatibility, membrane separation technology has been widely applied to alleviate the shortage of water resources.…”