Amphiphilic Block Copolymer of Poly(dimethylsiloxane) and Methoxypolyethylene Glycols for High-Permeable Polysulfone Membrane Preparation.

Poly(dimethylsiloxane)-block-methoxypolyethylene glycols (PDMS-b-mPEG) were synthesized by Steglich esterification. The high-permeable membrane (PSf/PDMS-b-mPEG) was prepared by using PDMS-b-mPEG as additives. The successful synthesis of PDMS-b-mPEG was confirmed by nuclear magnetic resonance. Field emission scanning electron microscopy images show that the distribution of finger-like macroporous and sponge-like macroporous can be modulated by controlling the ratio of the hydrophilic/hydrophobic components of additives. The distribution of additives and membrane wettability are validated with X-ray photoelectron spectroscopy and water contact angle test. The permeability of the blended membrane, especially for the membrane PSf/PDMS-b-mPEG1900 (M3), was remarkably improved. The water permeability of M3 (239.4 L/m2·h·bar) was 6.6 times that of the unblended membrane M0 (42.5 L/m2·h·bar). The findings of protein BSA filtration show that the flux recovery ratio of M3 is 89.2% at a BSA retention rate of about 80%, which demonstrates that the polysulfone membranes blended with PDMS-b-mPEG have excellent antifouling performance and extraordinary permeability.

Integration of RAFT polymerization and click chemistry to fabricate PAMPS modified macroporous polypropylene membrane for protein fouling mitigation.

A copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC) grafting-to method was used to tether alkyne-terminated poly(2-acrylamido-2-methyl propane sulfonic acid) (alkyne-PAMPS) to the azide functionalized macroporous polypropylene membrane (MPPM-N3). Alkyne-PAMPS was synthesized by the reversible addition-fragmentation chain transfer polymerization (RAFT) of AMPS with an alkyne-terminated trithiocarbonate served as a chain transfer agent. The combination of RAFT polymerization with click chemistry to graft polymer to the surface of polypropylene membrane produced relatively high grafting density and controllable grafting chain length. The structure and composition of the modified and unmodified MPPM surfaces were analyzed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR/FT-IR), X-ray photoelectron spectroscopy (XPS); field emission scanning electron microscopy (FE-SEM) was employed to observe the morphological changes on the membrane surface. The permeation performances were tested by the filtration of protein dispersion. The experimental results show that with the grafting degree going up, the relative flux reduction decreases, while the relative flux recovery ratio increases, and the protein fouling is obviously mitigated by tethering PAMPS to the membrane surface. The modified membranes can be potentially applied for fouling reduction during the filtration of proteins.

Surface modification of polypropylene macroporous membrane to improve its antifouling characteristics in a submerged membrane-bioreactor: H(2)O plasma treatment.

To improve the antifouling characteristics of polypropylene hollow fiber macroporous membranes in a submerged membrane-bioreactor for wastewater treatment, the membranes were surface modified by H(2)O plasma treatment. Structural and morphological changes on the membrane surface were characterized by X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FE-SEM). The change of surface wettability was monitored by contact angle measurement. The static water contact angle of the modified membrane reduced obviously with the increase of plasma treatment time. The total surface free energy and its dispersive component decreased, while the polar component increased with the increase of treatment time. The relative pure water flux for the modified membranes increased gradually with the increase of plasma treatment time. The tensile strength and the tensile elongation at break for the membranes decreased after plasma treatment. After continuous operation in a submerged membrane-bioreactor for about 68 h, flux recovery after water and caustic cleaning, flux ratio after fouling were improved by 2.0, 3.6 and 22.0%, while reduction of flux was reduced by 1.1% for the 1 min H(2)O plasma treated membrane, compared to those of the unmodified membrane.

Surface modification of polypropylene microporous membrane to improve its antifouling characteristics in an SMBR: N2 plasma treatment.

Fouling is the major obstacle in membrane processes applied in water and wastewater treatment. The polypropylene hollow fiber microporous membranes (PPHFMMs) were surface modified by N(2) low-temperature plasma treatment to improve the antifouling characteristics. Morphological changes on the membrane surface were characterized by field emission scanning electron microscopy (FE-SEM). The change of surface wettability was monitored by contact angle measurements. The static water contact angle of the modified membrane reduced obviously; the relative pure water flux of the modified membranes increased with the increase of plasma treatment time. To assess the relation between plasma treatment and membrane fouling in a submerged membrane bioreactor (SMBR), filtration of activated sludge was carried out by using synthetic wastewater. After continuous operation in the SMBR for about 90 h, flux recoveries for the N(2) plasma-treated PPHFMM for 8 min were 62.9% and 67.8% higher than those of the virgin membrane after water and NaOH cleaning. The irreversible fouling resistance decreased after plasma treatment.

[Microwave-assisted route to fibre-like ternary NaFeS2 nanoparticles and its XPS].

Ternary NaFeS2 nanoparticles were obtained in aqueous solution at room temperature via microwave-assisted route. The products were fibre-like with the diameter less than 10 nm, which were characterized with X-ray diffraction (XRD) pattern, transmission electron microscope (TEM) image, selected area electron diffraction (SAED) pattern and X-ray photoelectron spectroscope (XPS) pattern. The results indicated that the composition of fibre-like ternary nanoparticles are with atomic ratio of Na:Fe:S=1:1.1:1.9. The mechanism for the formation of fibre-like NaFeS2 nanoparticles is discussed.

[Chemical modification on the surface of nano-particles of ZnO and its characterization].

After nano-particles (ZnO) had been encapsulated by a kind of water-soluble cellulose Hydoxyl-Propyl-Methyl Cellulose (HPMC), then methyl methacrylate was grafted onto the surface of them. Thus the surface of nano-ZnO had been successfully modified. FTIR, DTA and TEM were utilized to confirm the results. FTIR shows that HPMC was adsorbed onto the surface of ZnO, and PMMA was also grafted onto its surface, DTA says that the heat stability of HPMC, HPMC-g-PMMA and ZnO/HPMC-g-PMMA increased greatly, TEM photo demonstrates that polymer adhered onto the surface of nano-ZnO which was encapsulated by a layer of film-like polymer.