Preparation of low-pressure water softening hollow fiber membranes by polyelectrolyte deposition with two bilayers

Enhanced hollow fiber membrane performance via semi-dynamic layer-by-layer polyelectrolyte inner surface deposition for nanofiltration and forward osmosis applications

“…Yet, most of those studies were focused on the inorganic substrate or flat sheet membranes only. As for the hollow fiber membrane substrate, we have successfully demonstrated the outer surface LBL deposition by immersion method which is similar to the traditional dip-coating process and explored their applications in NF [16] and forward osmosis (FO) process [17]. Meanwhile, some research groups have also investigated the possibility of applying LBL deposition on the inner surface of hollow fiber substrate.…”

High-flux composite hollow fiber nanofiltration membranes fabricated through layer-by-layer deposition of oppositely charged crosslinked polyelectrolytes for dye removal

“…To begin with, the PP hollow fibers were immersed in a filtrated CMCNa aqueous solution containing 0.02 %w/v of surfactant sodium dodecylsulfate (SDS) for 20.0 min before air-drying at room temperature until no liquids remained on the fiber surface. CMCNa deposition takes place on PP substrate based on the hydrophobic interaction [26,29]. The CMCNa-coated hollow fibers were then immersed in a glutaraldehyde (GA) aqueous solution for 2.0 min before air-drying for 30.0 min followed by 60.0 min of rinse with de-ionzed water.…”

“…The research group also reported that the permeation properties of the multilayer film could be tailored for specific applications by using different kinds of polyelectrolytes and changing deposition conditions [19][20][21][22]. Li et al [23,24] [26] also adopted the technique of LBL deposition of oppositely charged polyelectrolytes to fabricate low-pressure water softening hollow fiber membranes. It was reported that hollow fiber NF membrane with a salt water permeability of 12.0 l/m 2 h bar and 94% Mg 2+ rejection could be obtained by depositing only two bilayers of oppositely charged polyelectrolytes of poly(styrene sulfonic acid) sodium salt (PSS)/poly(allylamine hydrochloride) (PAH) on the PES substrate.…”

A novel type of polyelectrolyte complex/MWCNT hybrid nanofiltration membranes for water softening

“…For example, Magnenet et al [31] produced a positively charged NF membrane by alternately depositing poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) on the functionalized polyethersulfone (PES) membrane with 88% Cu 2 þ rejection. Rajabzadeh et al [26] deposited two bilayers of PSS/PAH on a PES hollow fiber ultrafiltration membrane to prepare positively charged polyelectrolyte complex (PEC) NF membrane with the Mg 2 þ rejection of 94%. Although the positively charged PEC NF membranes with good NF performance have been prepared by the electrostatic LbL method, they always require a specific film substrate and it is time consuming [32].…”

“…There are many methods for preparing NF membranes, such as the phase inversion [14], photo-initiated polymerization [15], chemical cross-linking [16][17][18][19][20][21][22], interfacial polymerization [23][24][25], and electrostatic layer-by-layer (LbL) self-assembly [26][27][28][29], etc. The surface charge character of NF membranes can be divided into neutral, negatively charged, and positively charged [18].…”