Surface modification of polyamide nanofiltration membrane by grafting zwitterionic polymers to improve the antifouling property

Abstract

A simple two‐step surface modification method of polyamide nanofiltration membrane, involving the activation of amide groups by formaldehyde and the subsequent cerium [Ce (IV)]‐induced graft polymerization of zwitterionic 3‐(methacryloylamino) propyl‐dimethyl‐(3‐sulfopropyl) ammonium hydroxide) (MPDSAH) monomers, was employed to improve membrane antifouling property. The membranes before and after modification were characterized by attenuated total reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR), scanning electron microscopy, and atomic force microscopy. The changes in both surface chemical composition and morphology of membranes confirmed the successful graft polymerizations of MPDSAH onto polyamide nanofiltration membrane. The static water contact angle measurements showed that surface hydrophilicity of the modified membranes was significantly enhanced. As the MPDSAH concentration increased, the water flux of grafted membrane decreased gradually, while salt rejection increased slightly. The fouling experiments with bovine serum albumin solution demonstrated that modified membranes exhibited better resistance to protein fouling. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41144.

Photo‐induced grafting of poly(ethylene glycol) onto polyamide thin film composite membranes

“…Although the surface hydrophilicity of membranes was enhanced after grafting, the grafting layer added extra hydraulic membrane resistance . The negative impact of increased hydraulic resistance may unexpectedly overwhelm the positive impact of increased surface hydrophilicity in term of water flux change . In this work, the increase of hydraulic resistance due to PEG grafted layer may result in slightly decrease of membrane flux, for the grafting time of longer than 10 min or the PEG concentration of higher than 30 g/L, but it is still much higher than that of the unmodified membrane ( J / J o ∼ 1.5).…”

Recent Advances in the Fabrication of Membranes Containing “Ion Pairs” for Nanofiltration Processes

“…Thus, the polymer chains would likely recover from their swelling extension state, and stop the foulants from coming into contact with the membrane surface. Li et al [ 71 ] grafted poly(zwitterionic 3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide) (PolyMPDSAH) on the surface of polyamide membranes to improve their antifouling property. The polyamide membrane was first activated with formaldehyde and phosphoric acid, and then grafted to PolyMPDSAH via free radical polymerization initiated by ceric ammonium nitrate.…”

“…With a low grafting degree, the water flux of membrane decreased a little (by 20–40%) and the salt rejection did not change, yet the membrane surface become more hydrophilic and less negatively charged, thus the antimicrobial performance of the membrane was significantly improved. Recently, Li et al [ 71 ] also modified the polyamide nanofiltration membranes with formaldehyde and then used the cerium (Ce (IV)) for inducing graft polymerization of zwitterionic 3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide) (MPDSAH) monomers, and the obtained membrane exhibited enhanced antifouling propert. The polyamide membrane could also be modified with zwitterionic polymer poly(4-(2-sulfoethyl)-1-(4-vinylbenzyl) pyridinium betaine) (PSVBP) via free radical polymerization initiated by a K 2 S 2 O 8 –NaHSO 3 redox system [ 127 ].…”

“… Representative, not comprehensive, summary of surface grafting zwitterionic polymers research: the reaction process for the activation of amide groups and graft polymerization of MPDSAH on the surface of polyamide membrane; schematic illustration of the improved UV-induced polymerization of poly(sulfobetaine methacrylate) onto MPPM; ATRP graft polymerization of MPC on a polyamide membrane. Reproduced with permission from References [ 71 , 131 , 138 ]. …”

A Simplified Method of Synthesis to Obtain Zwitterionic Cellulose under Mild Conditions with Active Ionic Moieties

“…An area of interest in cellulose modification research has been to confer, for different purposes, ionic characteristics to this polysaccharide, by means of introducing cationic or anionic moieties [12][13][14][15]. On the other hand, some reports have explored the modification of cellulose using zwitterionic groups, as well as its potential uses and applications [16][17][18][19]. In this regard, investigations by some members of our group have previously proved that covalently attaching amino acids (with equimolar amount of negative and positive sites) on cellulose fibers contributes in increasing the interfiber bonding strength around 35% in wet paper sheets [20].…”