Defect free hollow fiber reverse osmosis membranes by combining layer-by-layer and interfacial polymerization

• Published in: Journal of membrane science 2020-09, Vol.610, p.118277, Article 118277
• Main Authors: Ormanci-Acar, Türkan, Mohammadifakhr, Mehrdad, Benes, Nieck E., de Vos, Wiebe M.
• Format: Article
• Language: English
• Subjects: Defect free membranes; Hollow fiber; Interfacial polymerization; Layer by layer coating; Low pressure-reverse osmosis; Micropollutant removal; Polyelectrolytes
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2020.118277

Hollow fibre RO membranes would be desired for many applications, but are notoriously difficult to fabricate. Here we demonstrate that combining layer-by-layer and interfacial polymerization (IP) allows straightforeward production of defect-free hollow fiber RO membranes. A polyelectrolyte multilayer (PEM) is used to fill the pores of a support membrane, to provide a controlled and smooth surface that can nevertheless act as an IP monomer reservoir. This approach is first demonstrated on a model surface, with IP layers being successfully applied on both poly(diallyldimethylammonium chloride) (PDADMAC)/poly(4-styrene sulfonate) (PSS) and poly(ethyleneimine) (PEI)/PSS PEMs. On plain hollow fiber support membranes, IP coating was found to have a success rate as low as 40%. However, by application of a PEM interlayer the success rate increases to 72% for PDADMAC/PSS and 90% for PEI/PSS. Also the separation performance of the successfully prepared IP membranes was significantly better when a PEM interlayer was applied, with higher NaCl retentions (from 94% to 97%), and better removal of organic micro-pollutants (from 96% to 98%), with just a small decrease in permeability (from 0.9 L/m2hbar to 0.7 L/m2hbar). Combining layer-by-layer and IP approaches can thus lead to the fabrication of defect free RO membranes with improved separation performance. [Display omitted] •We present a straigthforeward method to produce defect free hollow fiber RO membranes.•To achieve this we combine LbL and IP approaches.•A PEM interlayer prevents defect formation during IP and acts as a gutter layer.•Using this approach high (90%) succes rates are achieved.•Resulting membranes have higher selectivities at a small cost to permeability.