光催化分离膜的制备及其在水处理中的应用

光催化分离膜将膜分离与光催化结合在同一处理单元中,可发挥膜分离作用,同时也可以利用光催化剂高效降解水中的有毒有害污染物,提高膜的抗污染性能和水处理效率。因此是水处理领域的研究热点,并显示出巨大的应用潜力。本文综述了基于二氧化钛（TiO₂）、氧化锌（ZnO）、石墨相氮化碳（g-C₃N₄）和氧化钨（WO₃）四种常用催化剂的光催化分离膜的研究概况,重点对光催化分离膜的制备方法和性能进行了总结,光催化分离膜具有良好的发展前景,制备高效、稳定的可见光响应光催化分离膜是未来的发展趋势。     

氧化石墨烯分离膜的性能调控及其传质机理研究进展

氧化石墨烯（GO）作为理想的膜构筑材料,因其蜂窝状的结构特点及表面分布大量含氧基团的特性,被广泛用于水处理分离膜的构筑。GO膜具有良好的物理特性、优异的化学稳定性和独特的二维层状结构,在污水处理、脱盐和离子筛分等水处理领域备受关注。在水处理中,GO膜对有机物和离子有较好的截留效果,但也存在水通量低、稳定性差等问题。本文分析了近年来GO膜在水处理领域的研究新进展;简单总结了GO膜的制备方法和水处理应用;重点阐述了GO水处理膜分离性能优化的方法和传质机理的研究进展;最后总结并展望了GO膜在结构调控和性能提升方面的发展方向。本文为设计和制备高性能GO水处理膜提供参考。     

Cu(Qc)2强化Pebax混合基质膜分离CO2

为了提高Pebax-1657的CO₂分离性能,本文制备了对CO₂有吸附作用的金属有机骨架Cu(Qc)₂,将其加入到Pebax-1657基质中,制备混合基质膜,用于CO₂的气体分离。通过扫描电子显微镜、热重分析、红外光谱和X射线衍射对溶液浇铸法制备的膜进行表征,通过膜的气体渗透性能测试考察填料含量、操作压力和混合气对膜气体渗透性能的影响。结果表明,Cu(Qc)₂在Pebax基质中随机有效地堆叠形成了高选择性的气体传输通道,极大地提高了CO₂/N₂的选择性。随着Cu(Qc)₂填充量的增加,CO₂渗透系数和CO₂/N₂选择性均呈现先上升后下降的趋势。当Cu(Qc)₂的质量分数为3%时,呈现最佳的CO₂/N₂分离性能,CO₂ 渗透系数和CO₂/N₂选择性分别为102Barrer和84,与Pebax-1657膜相比,分别提高了45.7%和40.0%,突破了Robeson分离上限,表明该混合基质膜在CO₂的分离应用上具有潜力。     

Fe2C和氮共掺杂的具有有序孔道结构碳膜用于锂硫电池正极

利用定向冷冻-碳化法制备了Fe₂C、氮共掺杂的碳膜（Fe₂C/N-C）作为一体化电极用于锂硫电池。由于其兼具规则的导电网络和连通的离子扩散通道,可有效缓解活性物质硫及放电终端产物导电性差的问题,且孔道结构亦可有效缓冲充放电过程活性物质的体积膨胀效应。该膜结构有利于电子传递和锂离子扩散,掺杂的Fe₂C纳米颗粒对多硫化锂具有较强的吸附作用以及向放电终端产物转化的催化作用,有效抑制了多硫化物的“穿梭效应”,提高硫利用率,显著提升电池的综合性能和循环稳定性。Fe₂C/N-C电极在载流量1.1 mg·cm^-2、1.0 C电流密度下循环100圈后得到833.0 mA·h·g^-1的比容量、99.3%的库仑效率、每圈容量衰减率低至0.02%,在较高载硫量3.8 mg·cm^-2时,0.2 C下循环100圈仍能取得714.3 mA·h·g^-1的比容量。     

纤维和遮光剂对纳米孔粉体隔热材料性能的影响

新型高温隔热材料对工业窑炉高效节能作用显著,降低其高温辐射导热率有利于提高高温隔热性能。采用干压成型制备了添加不同种类和不同含量的纤维及遮光剂的纳米孔粉体隔热材料,分别测试了试样的常温耐压强度和不同温度下的导热系数,探讨了纤维和遮光剂对纳米孔粉体隔热材料的力学性能和隔热性能的影响,并利用SEM、EDS和FTIR对试样的微观结构和红外透射率进行了分析表征。结果表明,多晶莫来石纤维有效增强了纳米孔粉体隔热材料的耐压强度,掺杂9%(质量分数)多晶莫来石纤维试样在800 ℃的导热系数为0.047 W/(m·K),低于添加石英纤维的隔热材料;纳米SiC粉体和锆英石粉体作为遮光剂能够有效抑制辐射传热,降低高温辐射热导率,添加10%(质量分数)纳米SiC粉体遮光剂的隔热材料试样导热系数随温度的变化较小,在800 ℃仅为0.041 W/(m·K)。     

金属有机骨架混合基质水处理分离膜研究进展

金属有机骨架（MOFs）晶体由无机金属离子和有机配体通过自组装合成,具有高的孔隙率和可调节的窗口尺寸,可使MOFs混合基质膜在水处理时同步获得高通量和高截留率,有望突破传统分离膜的渗透性和选择性之间此消彼长的trade-off效应。本文综述了MOFs的典型构造、影响MOFs混合基质膜性能的关键因素、MOFs混合基质膜的制备方法、MOFs颗粒改善混合基质膜水传输和溶质分离性能的原理以及MOFs混合基质膜在水处理微滤/超滤、纳滤/反渗透和正渗透领域的最新研究进展。最后总结了MOFs混合基质膜在水处理领域的未来发展亟待解决的关键问题,主要包括高性能、低成本膜的可控制备、膜结构和性能之间定量构效关系的深入探索以及如何拓宽其应用范围等,对加快MOFs混合基质膜的产业化进程具有指导意义。     

Effect of shell phase composition on the dielectric property and energy density of core-shell structured BaTiO3 particles modified poly(vinylidene fluoride) nanocomposites

Dielectric nanocomposites have attracted much attention due to their wide applications in electronics and electrical industry. Recently, incorporating core-shell nanoparticles into polymer matrix to improve the dielectric properties of nanocomposites has been widely reported. Tailoring the interfacial region between the polymer and the nanoparticles plays a crucial role in achieving the desired dielectric and energy storage properties of nanocomposites. However, the effect of shell structure in the interface region on the dielectric and energy storage properties is rarely studied. Based on this, core-shell BaTiO₃ nanoparticles with two different shell polymers, a “hard-soft” copolymer of methyl methacrylate and butyl acrylate (P[MMA-BA]) and a “hard” homopolymer of methyl methacrylate (PMMA), were prepared in this paper. The effect of core-shell BaTiO₃ nanoparticles with different shell structures on the dielectric and energy storage properties of poly(vinylidene fluoride) (PVDF) was investigated in depth. Due to the formation of a tight interfacial region between P(MMA-BA)@BT and PVDF matrix, P(MMA-BA)@BT/PVDF nanocomposites not only have low dielectric loss but also higher energy efficiency than PMMA@BT/PVDF nanocomposites. This study suggests a potential strategy that fabricating a “hard-soft” copolymer shell on BaTiO₃ surface can obtain desirable energy storage efficiency than the single “hard” shell structure in dielectric nanocomposites.     

Fabrication of basalt embedded composite fiber membrane using electrospinning method and response surface methodology

In this study, a novel basalt embedded fiber membranes was prepared by the electrospinning method. The effects of the feed rate, voltage, tip to collector distance, and the basalt content on the prepared composite fiber membranes were investigated and optimized using the response surface method. Four models were built to compare the fibers in terms of deionized water flux (DWF), activated sludge flux, chemical oxygen demand (COD) removal, and porosity of fiber membranes. All the developed models were significant and adequately precise. The maximum flux of DWF was obtained when the voltage was 17.25 kV, the tip to collector distance of 19 cm, and a basalt content in polymer of 1.25%. COD removal decreased at higher voltage values as the feed rate increased. The porosity, pore size, and the contact angle values decreased for basalt embedded fiber membrane. The increases in the basalt percentage in polymer increased the hydrophilicity of the fiber. The flux decline for the basalt embedded fiber membrane was compared with the pristine fiber membrane. The permeate fluxes of pristine and basalt embedded fiber membranes were 42.3 and 59.6 L/m²/h, respectively. The biofouling performances of pristine and basalt embedded fiber membranes were also examined. Irreversible fouling decreased from 42.9% to 8.0%, and reversible fouling increased from 56.5% to 91.1% after modification of the membrane with basalt powder. Scanning electron microscopy with energy dispersive X-ray analysis (SEM–EDX) analysis showed that basalt powder was successfully embedded into polyether sulfone polymer.     

Preparation and characterization of soy protein isolate/SiO2 nanocomposite films and their walnut oil microcapsules

In this study, nano-SiO₂/soy protein isolate composite film was prepared by casting method. The effects of (adding 0%, 1%, 3%, 5%, 7%, and 9% w/w) nano-SiO₂ on the properties of the resulting blend films were investigated. Results showed that the addition of 5% nano-SiO₂ exhibited good barrier properties. The mechanical properties including tensile strength and elongation at break of the film with 7% nano-SiO₂ is increased by 82.6% and 31.49% correspondingly. Differential scanning calorimetry indicated that the melting temperature of the composite film is increased by 56.6°C compared with the pure film. The wall material modified by nano-SiO₂ (adding 1%, 3%, 5%, 7%, and 9% w/w) was used for encapsulating walnut oil by spray drying. After accelerating oxidation test at 63°C for 12 days, we found that the encapsulation efficiency value of walnut oil microcapsules with 0%, 1%, 3%, 5%, 7%, and 9% nano-SiO₂ decreased by 64.23%, 48%, 21%, 22%, 21.00%, and 31% respectively. The results suggested that the stability of the core material was improved by adding nano-SiO₂ to the wall material.     

Multi-cation side-chain-type containing piperidinium group poly(2,6-dimethyl-1,4-phenylene oxide) alkaline anion exchange membranes

A series of alkaline anion exchange membranes (AAEMs) based on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with multi-cation side chain containing piperidinium group were fabricated via nucleophilic substitution and Menshutkin reaction. The chemical structures of the AAEMs (PPO-AMP-X) were determined by Fourier transform infrared and proton nuclear magnetic resonance spectra. The resultant PPO-AMP-X membranes with the ion exchange capacities (IECs) of 2.05–2.77 mmol g⁻¹ displayed the hydroxide conductivities in the range of 61.04–78.92 mS cm⁻¹ at 80°C. When tested at the same degree of functionalization levels, the PPO-AMP-X membranes exhibited significantly higher hydroxide conductivity and lower conductivity loss than conventional AAEMs bearing benzyltri-methylammonium group (PPO-TMA). The PPO-AMP-28 multi-cation membrane showed a hydroxide conductivity of 70.52 mS cm⁻¹ at 80°C, which was nearly two times higher than that of the PPO-TMA-28 single-cation membrane (36.74 mS cm⁻¹). Compared with PPO-TMA-28 (56.76% decrease), the hydroxide conductivity of PPO-AMP-28 merely decreased by 23.15% after soaked in 1 M KOH at 80°C for 500 h. Additionally, the PPO-AMP-X membranes displayed moderate mechanical properties and good thermal stabilities, which can meet the basic requirements for use in fuel cells. This study provides a facile method for preparing AAEMs with multi-cation side chain containing piperidinium group.