Surface modification of polyamide reverses osmosis membrane by phosphonic acid group with improved performance

Abstract

A facial method for preparing reverse osmosis polyamide (PA) membranes of excellent antifouling and separation performance was developed via covalently grafting phosphonic acid on membrane surface. First, a pristine PA layer was synthesized by interfacial polymerization between m-phenylenediamine and trimesoyl chloride. Then, a second interfacial reaction was implemented between ethylenediamine and the residual acryl chloride on the pristine PA layer, generating an active layer enriched by primary amine. Finally, the amine-rich surface treated by formaldehyde and phosphorous acid to produce a membrane surface modified by phosphonic acid groups. Surface characterization by attenuated total reflectance infrared, X-ray photoelectron spectroscopy and zeta-potential measurements illustrated the presence of phosphonic acid group. The lowest contact angle of modified membrane was 26 , demonstrating the membrane possessed an outstandingly wettable surface. The optimal separation performance was 88 L m −2 h −1 of water flux and 99.4% of salt rejection under 1.55 MPa. In addition, bovine serum albumin was used as organic foulant to measure the antifouling property of membranes. The result of dynamic fouling experiments indicated that the modified membrane exhibited better antifouling (of which the irreversible fouling degree was 7.1%) compared with commercial membrane BW30 (of which the irreversible fouling degree was 13.5%).

Preparation and properties of phosphinic acid–functionalized polyacrylonitrile hollow fiber membrane for heavy metal adsorption

“…The isoelectric point of the PPAN membrane shifted to the left as compared to the APAN membrane, and the isoelectric points of the two membranes were at pHs of 7.4 and 4.3, respectively. Grafting a signi cant number of phosphinic acid groups onto PPAN hollow ber membranes resulted in a fall in isoelectric point pH, dramatically raising opposing charges and eventually leading to a left shift of the isoelectric point (Zhao et al 2019).…”

Protein fractionation of pH‐responsive brush‐modified ethylene vinyl alcohol copolymer membranes*

“…For surface modification, functional polymer chains adhering to the membrane surface and pore walls give the membrane self-adjustable selectivity or permeability. [18,19] Brush-like grafted polymers, with their ends attached to a surface or an interface, possess sufficient chain mobility to be more responsive to external stimuli. [20,21] Polymer brushes modified membranes have been used in several scenarios involving the protein adsorption [22,23] as well as the protein resistant surfaces, [24,25] but the application in the protein separation from the mixture is rare.…”

Application of poly(vinylphosphonic acid) modified poly(amidoxime) in uptake of uranium from seawater

“…Surface modication with phosphorylated reagents is an attractive method to improve the antibiofouling property and adsorption capability of PAO based materials. 17,18 Among the reported phosphorylated organic monomers, VPA is a simple structure, has low toxicity, and is an industrially available monomer. [19][20][21] The typical radical polymerization method of PVPA usually suffers from impurities, 19,22,23 very slow reaction rate, 23 underutilization of reagents, 24 and serious chemical pollutants.…”