超滑聚酯纤维膜及其抗污染性能

以聚对苯二甲酸乙二醇酯(PET)纤维膜为基底,利用聚多巴胺(PDA)对膜表面进行活化,通过溶胶凝胶法在膜表面构筑二氧化硅(SiO_(2))纳米粗糙结构,进一步降低其表面能并灌注润滑油,制备得到超滑聚酯纤维膜(PET-SLIPS)。在PDA作用下,SiO_(2)纳米粒子均匀分布在膜表面,并且与基底结合牢固,在超声作用或轻度物理摩擦下,表现出良好的稳定性。SiO_(2)纳米级粗糙结构特点使其具有优异的润滑油锁定能力,PET-SLIPS在受到水流剪切或物理磨损后,表面接触角基本不变,润滑层稳定性良好。这种具有流动性的润滑层可抑制与之不互溶的液体与膜基底接触,使污染物易被冲洗去除,赋予PET-SLIPS优异的疏液性;与PET原膜相比,PET-SLIPS油水分离效率和抗污染性都得到明显提升,同时表现出良好的抗生物黏附性能。这种超滑膜在膜分离等方面具有良好的应用前景。

Ba^(2+)/Ca^(2+)co-crosslinked alginate hydrogel filtration membrane with high strength,high flux and stability for dye/salt separation

Alginate is a natural polysaccharide polymer.Hydrogel filtration membranes prepared from alginate show excellent fouling resistance and controllable separation performance,but poor mechanical properties limit the use of algae hydrogels.In this study,Ba^(2+)/Ca^(2+)co-crosslinked alginate(Ba/CaAlg)hydrogel membrane was prepared by cross-linking sodium alginate with a blend aqueous solution of barium ions and calcium ions,and the membrane was applied to the separation of dyes/salts from dyeing wastewater.Compared with the CaAlg membrane,the Ba/CaAlg hydrogel membrane exhibited more stable structure,and the mechanical properties and salt tolerance of the membrane were significantly improved.The flux of Ba/CaAlg membrane for methyl blue/sodium chloride mixed solution reached 43.5 L m^(−2) h^(−1),which was significantly higher than that of CaAlg membrane.Besides,the Ba/CaAlg membrane showed higher dye rejection(>99.6%)and lower salt rejection(<8.2%).The structure of Ba/CaAlg membrane was preliminarily simulated by molecular dynamics,and the pore size and distribution of the membrane were calculated.The Ba/CaAlg membrane has a broad application prospect in dyes/salts separation.

Ultrapermeable membranes based on connected cluster of hollow polydimethylsiloxane nanoparticles for gas separation

Mixed matrix membranes(MMMs)with the performance between the matrix and the filler is a promising strategy for membranes with excellent gas permeability-selectivity.In this study,the hollow polydimethylsiloxane nanoparticles were synthesized and then incorporated with the poly(oxide ethylene)monomer and tri-functional cross-linker to form mixed matrix membranes by in situ poly-merization.The hollow nanoparticles formed the independent closed nanocavities in membranes,which enhanced the gas permeability contributed by both the improved diffusivity and solubility.At high loading,the hollow polydimethylsiloxane nanoparticle was converted into the continuous phase with the cross-linked poly(oxide ethylene)as the dispersed phase.Gases preferred to permeate through the connected cluster of hollow polydimethylsiloxane nanoparticles,finally leading to ultrahigh gas per-meabilities far going beyond the instinct values of polydimethylsiloxane and the cross-linked poly(oxide ethylene).The optimized membrane with 34 wt%hollow nanoparticles loadings exhibited ultrahigh permeabilities with the values of 44186 Barrer for CO_(2) and 11506 Barrer for O_(2),accompanied with a CO_(2)/N_(2) selectivity of 9.9 and an O_(2)/N_(2) selectivity of 2.6,which exceeded the 2008 Robeson upper bound for O_(2)/N_(2) and located at the 2008 Robeson upper bound for CO_(2)/N_(2).

Electrospinning in membrane contactor:manufacturing Elec-PVDF/SiO2 superhydrophobic surface for efficient flue gas desulphurization applications

In membrane contactors,maintaining a high SO_(2)absorption flux and an excellent wetting resistance are crucial for hazardous gas removal.In this study,we adopted an electrospinning strategy to fabricate highly robust superhydrophobic dual-layer Elec-PVDF/SiO_(2)composite membrane contactors used for flue gas desulfurization.The composite membrane contactor consisted of a durable and ultrathin three-dimensional(3D)superhydrophobic surface and a porous supporting layer,where the formulation was optimized by regulating the PVDF concentration,solvent ratio and SiO_(2)particles content in electrospinning solution.The scanning electronic microscopy(SEM),EDS-mapping,water contact angle(WCA)and surface roughness of as-prepared Elec-PVDF/SiO_(2)composite membrane contactors were conducted to explore the physical and chemical structure.The SiO_(2)nanoparticles were uniformly loaded in ElecPVDF/SiO_(2)composite membrane contactor,and constructed micro-nano dual-coarse lotus-leaf-like morphology,which noticeably elevated surface roughness(Ra).The SiO_(2)nanoparticles also functioned as hydrophobic modifiers,which boosted the WAC up to 155.The SO_(2)absorption fluxes and SO_(2)removal efficiencies were investigated.In particular,the membrane contactor doped with 20 wt%SiO_(2)nanoparticles significantly elevated the stability of desulfurization performance.Besides,the membrane mass transfer coefficient(Km)and corresponding membrane mass transfer resistance(H/Km)were explored.

Smart light-responsive hierarchical metal organic frameworks constructed mixed matrix membranes for efficient gas separation

One type of new light-responsive hierarchical metal organic framework(MOF) has been successfully prepared using Co(NO_(3))_(3)·6H_(2)O as the metal salt and 4,4’-azobenzenedicarboxylic acid as the ligand by microwave method for the first time. It is found that MOF [Co(Az DC)] exhibits a light-responsive characteristic to SO_(2)adsorption due to the presence of azo group from the ligand. The light-responsive hierarchical MOFs are incorporated into Matrimid■ 5218(PI) matrix to prepare mixed matrix membranes(MMMs) for gas separation application. The morphology, crystallinity, chain mobility and thermal stability of MMMs are explored. Results show that Co(Az DC) may elevate both the CO_(2)(SO_(2)) permeability and CO_(2)(SO_(2))/N_(2)selectivity of the MMMs. In particular,the Co(Az DC) doped MMMs exhibit the significantly improved CO_(2)(SO_(2))/N_(2)selectivity from 33(123) for PI control membrane to 78(420) for MMMs, overcoming the 2008 Robeson upper bound for CO_(2)/N_(2)system. Sizesieving effect of Co(Az DC) with pore size 0.35 nm enhances the selectivity, while the –N=N– group from Co(Az DC) shows affinity to CO_(2)molecular rather than N_(2), also elevating selectivity of MMMs. In brief, enhanced selectivity of high-performance membrane is attributed to incorporation of Co(Az DC) particles, which displays synergistic effects both in size-sieving and CO_(2)-philic interaction for CO_(2)/N_(2)separation. Smart highly selective interface is constructed in MMMs by switching the configuration of MOFs from cis to trans. The SO_(2)permeability and SO_(2)/N_(2)selectivity of MMMs are investigated under both visible light and ultraviolet light states, and the SO_(2)/N_(2)separation performance under visible light is notably improved in comparison with that under ultraviolet light state.