膜蒸馏

Abstract(#br)Superhydrophobic membranes with nanostructure for membrane distillation are fabricated via spraying a mixture of polydimethylsiloxane (PDMS) and hydrophobic SiO 2 nanoparticles on poly (vinylidene fluoride) (PVDF) flat sheet membranes.

Abstract(#br)Considerable efforts have been devoted to finding economic and simple preparation methods for polydimethylsiloxane (PDMS) superhydrophobic membrane in past decades. This study provides a simple method to electrospin PDMS membrane using poly (methyl methacrylate) (PMMA) as carrier polymer. Effects of PMMA concentration, PDMS/PMMA mass ratio and main parameters of electrospinning process (voltage and injection rate) were investigated to obtain superhydrophobic membrane with high water contact angle (WCA).

Abstract(#br)Superhydrophobic electrospun nanofibrous membranes (ENMs) with a fully interconnected porous web structure and high void volume fraction have been proposed for membrane distillation (MD). This study describes a novel and facile design strategy for the fabrication of superhydrophobic and self-cleaning polysulfone-polydimethylsiloxane (PSU-PDMS) ENMs for direct contact membrane distillation (DCMD) via electrospinning PSU nanofibers followed by PDMS coating and cold-press post-treatment.

Abstract(#br)The further advance of membrane distillation (MD) is hampered due to inadequate membrane durability challenged by wetting-induced performance deterioration. The current study presents a novel approach to fabrication of superhydrophobic polyvinylidene fluoride (PVDF) membranes via construction of hierarchical textures on membrane surfaces based on a nanocasting strategy. Two types of PVDF membranes with different surface textures were prepared, separately using a stainless-steel mesh (SSM) or its negative polydimethylsiloxane (PDMS) template as a fabrication substrate.

Abstract(#br)Porous SiOC ceramic membranes (PSCM), with a narrow pore size distribution, were prepared by a casting method, using a polymer liquid (polydimethylsiloxane, PDMS), as a pore-forming agent, and a pre-ceramic liquid (polysiloxane, PSO), followed by pyrolysis at 1200 °C in flowing Ar gas. Pore size, porosity, and N 2 and water permeation increased with increasing PDMS content in the mixture of the precursors. An oil-in-water emulsion, with an average oil diameter of 0.83 μm, was effectively separated (95% rejection rate) with membranes which had an average pore size of 0.59 μm.

文摘( # br )具有层次结构的膜由于在其纳米微区提供了更多的气囊，因而具有更高的水接触角，进而被称为更疏水。但是，如在真空膜蒸馏( VMD )过程中，口袋中的空气已经耗尽后，疏水性可能会消失。这里提出了一种本征疏水的电纺纳米纤维膜( ENM )，其疏水性完全取决于这些材料的表面能，在不借助任何分级结构的情况下，促进其抗润湿性能。以聚偏氟乙烯( PVDF )为基体材料制备了新型复合ENMs，并通过简单的浸渍提拉法在其表面包复了低表面能的聚二甲基硅氧烷( PDMS )。复合ENMs中纳米纤维的扫描电镜( SEM )图像几乎不存在分层结构，而理论上认为分层结构是为了降低水接触角。然而，随着纳米纤维表面能的降低，复合ENMs表现出更高的亲水性。因此，复合ENMs在整个MD过程中不能被冷凝蒸汽所润湿，较薄的膜在连续真空MD测试中表现出优异的耐久性。结果表明，对于本征疏水性的ENMs材料而言，低的表面能是VMD过程中表现出强而持久的抗润湿能力的必备品质，这是传统的在膜表面构建层次结构难以实现的。