Antifouling Membrane Surfaces Research Articles

Fabrication of antifouling membrane surface by poly(sulfobetaine methacrylate)/polydopamine co-deposition

Poly(sulfobetaine methacrylate) (PSBMA) has been widely employed for the surface modification of membranes due to its excellent antifouling property. However, challenges still remain to simplify the modification processes and to increase the utilization efficiency of PSBMA (or sulfobetaine methacrylate, SBMA). In this paper, a simple one-step co-deposition process is introduced to fabricate antifouling surfaces for microporous polypropylene membranes (MPPMs) based on the self-polymerization and high adhesion properties of dopamine with the hydrophilicity of PSBMA. Meanwhile, the effect of PSBMA concentration on the membrane surfaces was studied in detail by ATR/FT-IR, XPS, and FESEM. Significant improvement is demonstrated for the surface hydrophilicity by results of water contact angle and pure water flux. Dynamic protein filtration experiments confirm the excellent antifouling property of the resulted membranes. Furthermore, the utilization efficiency reaches 9.13wt% for PSBMA, 10 times higher than that of SBMA for UV-induced grafting on MPPM. In conclusion, the one-step modification method provides a simple and effective approach to construct antifouling surfaces for membranes.

Engineering amphiphilic membrane surfaces based on PEO and PDMS segments for improved antifouling performances

Antifouling membrane surfaces capable of reducing biofouling are highly desirable in a broad range of applications. In this study, amphiphilic membrane surfaces, derived from block copolymers bearing hydrophilic poly(ethylene oxide) (PEO) and low surface energy polydimethylsiloxane (PDMS) segments, have been constructed via surface segregation during the standard phase inversion process. The surface chemical features of the membranes are confirmed by contact angle measurement, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and surface energy analysis. The PEO segments are utilized to prevent biofoulant adsorption (fouling-resistance) whereas the PDMS segments are utilized to drive away the adsorbed biofoulants (fouling-release). The resultant surfaces exhibit better antifouling properties compared with the control polyethersulfone (PES) membrane when using bovine serum albumin (BSA), sodium alginate (SA) and yeast as three model biofoulants (proteins, polysaccharides and microorganisms). During the filtration of model biofoulant aqueous solutions, both irreversible and reversible flux declines are remarkably decreased and the flux recovery is retained completely after simple hydraulic washing. Static and dynamic biofoulants adsorption experiments reveal the synergistic effect of the PEO and PDMS segments on biofouling-resistance and biofouling-release. It is also found that the biofouling can be significantly reduced by the coexistence of optimized hydrophilic microdomains, low surface energy microdomains, and shear flow near membrane surfaces. Hopefully, the demonstrated attempt of membrane surface construction is favorable to prepare a wide spectrum of environmentally benign antifouling membranes.

Efficient Wastewater Treatment by Membranes through Constructing Tunable Antifouling Membrane Surfaces

In the present study, a facile in situ approach for constructing tunable amphiphilic or hydrophilic antifouling membrane surfaces was demonstrated by exquisitely manipulating the microphase separation and surface segregation behavior of the tailor-made ternary amphiphilic block copolymers during the commonly utilized wet phase inversion membrane-formation process. Under dead-end filtration for oily wastewater treatment, the membrane with amphiphilic surface exhibited over 99.5% retention ratio of chemical oxygen demand (COD) without appreciable membrane fouling: the water permeation flux was slightly decreased during operation (total flux decline was 6.8%) and almost completely recovered to the initial value (flux recovery ratio was more than 99.0%) after simple hydraulic washing. While for the proteins-containing wastewater treatment, the membrane with hydrophilic surface exhibited about 52.6% COD retention ratio and superior antifouling performance: only 17.0% total flux decline and also more than 99.0% flux recovery ratio. Hopefully, the present approach can be developed as a competitive platform technology for the preparation of robust and versatile antifouling membrane, leading to the high process efficiency of wastewater treatments.