蛭石层状膜的制备及有机溶剂纳滤性能

受全球能源形势与环境问题影响,新型膜分离技术尤其是二维层状膜在分离领域展现出广阔的应用前景。然而,目前使用的二维纳米材料化学环境相对复杂,且膜制备成本高昂,限制了其工业化推广。天然蛭石廉价易得,剥离简单,表面只含有硅羟基且其含量易于调控,可精确调控所制备层状膜层间亲疏水性,实现有机溶剂的高效渗透和极性与非极性溶剂的高效分离。研究发现：蛭石层状膜展现出优异的极性溶剂分子传递能力,而非极性溶剂则相对较低,其中乙腈分子渗透性高达1650L/（m²·h·bar)（1bar=0.1MPa）,甲苯分子渗透性仅为37.8L/（m²·h·bar),乙腈与甲苯的分离因子高达43.6,展现出优异的分子分离性能。本文所制备蛭石层状膜具有1.36nm的规则平直层间传递通道,对分子动力学直径大于层间距的结晶紫（1.5nm）、亮蓝（1.6nm）、酸性黄14（1.9nm）等染料分子的截留率均大于90%,截留性能优良。同时,蛭石层状膜具有良好的压力循环稳定性及抗污染能力, 展现出巨大的分离应用潜力。     

Zn-BTC/MoS2复合二维膜构筑及有机溶剂纳滤性能研究

尽管最近兴起的二维膜材料相较于传统的聚合物基膜材料呈现出明显提升的分离性能。但是二维膜中分子传质需要经过层层堆积的二维通道,传输路径较长,限制了二维膜渗透通量的进一步提升。提出用一维金属有机框架纳米线来调控二维膜实现通量提升,同时不降低分离能力。该策略的实现是通过Zn-BTC纳米线插层MoS₂层级膜,制备了Zn-BTC/MoS₂复合膜。该复合膜的有机溶剂通量比MoS₂二维膜提高了2~6倍,丙酮渗透通量高达3562 L·m^-2·h^-1·bar^-1。同时该复合膜保持了与MoS₂膜同等优异的筛分能力,对于尺寸大于0.42 nm的染料分子,可以实现100%截留。     

g-C3N4同型异质结复合光催化剂的制备及性能研究

石墨相氮化碳(g-C_3N_4)由于其合适的带隙和较高的物理化学稳定性等,被认为是一种有应用前景的光催化材料。然而,纯相g-C_3N_4的光催化性能和应用受到光生电子空穴易复合和比表面积相对较低等原因的限制。本文使用两种合适的前驱体(三聚硫氰酸与硫脲)共聚合有望优化高温煅烧过程中的缩聚过程,抑制团聚的发生,提高比表面积,同时形成的同型异质结能有效抑制光生载流子的再复合。在可见光照射下,形成的g-C_3N_4同型异质结复合光催化剂的活性明显高于单一的g-C_3N_4样品。显著增强的光催化活性主要归因于比表面积增大、活性位点增多和光生载流子再复合的有效抑制。     

雷诺数及流道结构对纳滤膜分离性能的影响

采用自制的平板式纳滤膜分离系统进行膜分离实验,考察雷诺数和流道结构对膜分离性能的影响。研究结果表明,雷诺数对膜通量的影响不明显,但对Mg2＋的截留率的影响显著,雷诺数越大,离子截留率越大;流道结构对膜通量的影响不明显,但对Mg2＋的截留率的影响显著,且螺旋形流道和蛇形流道的离子截留率差别不大,但均大于无绕流板流道对Mg...     

高性能纳滤膜的制备及性能研究

本文以磺化聚醚砜（SPES）为涂层材料,以聚砜（PSF）超滤膜为支撑层,采用涂覆法制备SPES/PSF纳滤脱色膜,研究了有机溶剂,无机、有机添加剂等因素对纳滤脱色膜性能的影响,并通过SEM表征纳滤脱色膜的表面和断面形貌。结果表明,SPES/PSF纳滤脱色膜对甲基蓝的截留率可以达到90%以上,硫酸钠的截留率低于20%,水通量可以达到70 L/（m2·h）以上,实现了低分子染料和无机盐高选择性分离。     

有机溶剂纳滤膜的润湿性对渗透和分离性能的影响

有机溶剂纳滤是一种绿色、高效、节能的新型膜分离技术,在回收和处理有机溶剂中具有广泛的应用前景。本文采用浸渍法分别将聚合物聚二甲基硅氧烷（PDMS）、嵌段聚醚酰胺（PEBAX2533）和聚乙烯醇（PVA）与聚砜（PS）超滤基膜复合,制备了3种不同润湿性的聚合物耐溶剂纳滤膜,研究了PDMS/PS、PEBAX/PS和PVA/PS复合膜对甲醇、乙醇、异丙醇、正己烷、正庚烷的渗透性能,考察了3种聚合物膜对伊文思蓝/甲醇溶液的有机溶剂纳滤性能。结果表明,有机溶剂在不同润湿性复合膜的渗透和传递性能与溶剂本身的溶度参数、分子量、黏度和极性等有很密切的相关性,溶剂的分子量、黏度、分子动力学直径越小,在同一极性复合膜中渗透通量越大;对伊文思蓝/甲醇溶液的有机溶剂纳滤分离表明,PDMS/PS和PEBAX/PS复合膜的截留率均可达90%以上,通量分别为 58.0L/(m²·h·MPa)和72.2L/(m²·h·MPa);PVA/PS复合膜的截留率为85.1%左右,通量为57.5L/(m²·h·MPa)。     

g-C3N4/BiOBr异质结对罗丹明B可见光催化活性研究

采用硝酸剥离的二维g-C_3N_4纳米片为基材,通过分散掺杂溴化钾(KBr)和五水合硝酸铋(Bi(NO_3)_3·5H_2O),构建了花状的g-C_3N_4/BiOBr异质结,采用x射线衍射、场发射扫描电子显微镜和傅里叶变换红外光谱等研究了制备的复合光催化剂的微观结构和形态特征。该异质结对罗丹明B为代表的一系列偶氮类化合物产生光催化降解性能。良好的结果可归结于异质结的形成可以充分捕获催化剂表面的光激化电子,同时提高了光生载流电子的转移和分离效率,催化性能,稳定性以及降解率等。     

新型荷正电纳滤膜的制备与表征

以聚砜超滤膜为基膜、聚乙烯亚胺和均苯三甲酰氯为单体,采用界面聚合方法制备荷正电复合纳滤膜.采用均匀设计实验优化制膜条件,用SPSS软件处理实验数据得到模型方程.模拟计算结果表明,膜对PEG400的截留率随界面聚合反应时间、热处理时间的增长而增大;聚乙烯亚胺浓度和表面活性剂浓度之间的交互作用比较明显.实验结果表明,随着操作压力的增加,膜的纯水通量以及膜对NaCl和PEG400的截留率均相应增大.在NaCl/PEG400/水混合体系中,随着NaCl 或PEG400浓度的增大,膜的渗透通量稍有减小,膜对NaCl-PEG400的分离因子有所降低.在0.4MPa、25℃, NaCl和PEG400浓度分别为0.01mol(L(1和500mg(L(1条件下, 膜对NaCl-PEG400的分离因子大于10.     

纳滤膜结构特征对纳滤过程分离性能的影响

以预测纳滤过程分离性能为目的,讨论了纳滤膜结构特征对分离性能的影响。采用基于扩展的Nernst-Planck方程的DSPM模型进行预测,通过计算机模拟计算,研究了纳滤膜孔径(rp)、膜内电荷密度(X)以及膜厚与孔隙率的比值(λ/Ak)对纳滤分离过程的影响,为纳滤膜的工业化应用提供借鉴。     

聚酰亚胺膜的制备及对有机物系的纳滤分离

针对以均苯四甲酸二酐(PMDA)和4,4′-二氨基二苯醚(ODA)为原料合成聚酰亚胺的过程,研究了亚胺化方法、凝胶浴组成与温度等条件对膜的结构和分离性能的影响。实验结果表明,当聚酰胺酸铸膜液质量分数为15%、凝胶浴为30%乙醇(质量)的醇水溶液时,所制得的聚酰亚胺纳滤膜具有最佳的分离性能。操作压力为2MPa下稳态操作时,该膜对酮苯脱蜡工艺后的溶剂与润滑油基础油混合物的截留率达66%,通量为4.26L/(m2.h),为有机溶剂体系的纳滤膜分离技术的工业应用提供了基础。     

Construction,structure and photocatalysis of janus nanofiber modified by g-C3N4 nanosheets heterostructure photocatalysts

The construction of photocatalyst with gradient band structure is guided by the principle of band gap engineering. Rational structural design is advanced and applied to construct a new-typed peculiarly structural and functional carbon-based [TiO₂/C]//[Bi₂WO₆/C] Janus nanofiber modified by g-C₃N₄ nanosheets heterostructure photocatalyst (denoted as TB-JgHP). The flexible carbon-based [TiO₂/C]//[Bi₂WO₆/C] Janus nanofiber with one side responding to ultraviolet light and the other capturing visible light is fabricated by conjugate electrospinning, and then g-C₃N₄ nanosheets are uniformly grown in-situ on the surface of the Janus nanofibers by using gas-solid reaction via gasification of urea. The optimized TB-JgHP possesses remarkable hydrogen evolution efficiency (17.48 mmol h⁻¹ g⁻¹) and methylene blue degradation rate (99.2%) under simulated sunlight illumination for 100 min, demonstrating prominent dual-functional characteristics. The enhanced photocatalytic performance benefits from the unique Janus structure as well as the synergistic effects among the triple heterostructures of TiO₂ and Bi₂WO₆, g-C₃N₄ and TiO₂, g-C₃N₄ and Bi₂WO₆. The formation of gradient band structure among heterostructures is more conducive to the multi-step separation of photo-induced electron-hole pairs and more effective absorption of light. Further, flexible self-standing carbon-based photocatalysts not only have outstanding electron transport performance, but also are easy to separate from solution with preeminent recyclable stability. Based on a series of characterization techniques, it is further proved that TB-JgHP has higher carrier separation efficiency than the counterpart contrast samples. The formation mechanism of TB-JgHP is proposed, and the construction technique is established. The design philosophy and construction technique presented in this work pave a new avenue for research and development of other heterostructure photocatalysts.     

纳滤膜分离技术及其进展

纳滤技术是一种介于超滤和反渗透之间的新型分离技术。作者介绍了纳滤膜的特性及其独特的分离特点。高分子纳滤膜的几种主要制备方法的制备原理、制备要点,国内外纳滤膜在生产研究方面的进展,以及当前已商品化的几种主要的纳滤膜的材质。最后简单介绍了纳滤膜在水处理、食品、生化、医药、染料和化工等领域的应用进展,指出今后的发展将着重于传质机理、新的膜材料及集成工艺开发等方面。     

Facial synthesis of a novel Ag4V2O7/g-C3N4 heterostructure with highly efficient photoactivity

A novel Ag₄V₂O₇/g-C₃N₄ heterostructure was synthesized by a facial etching method in ammonia solution using Ag₂VO₂PO₄/g-C₃N₄ as a self-sacrifice precursor. With the concentration of ammonia solution increasing from 0.05 to 0.2 M, phase transformation took place, described as: Ag₂VO₂PO₄/g-C₃N₄ → Ag₂VO₂PO₄/Ag₄V₂O₇/g-C₃N₄ → Ag₄V₂O₇/g-C₃N₄. Compared with pristine Ag₂VO₂PO₄/g-C₃N₄, the etched samples of Ag₄V₂O₇/g-C₃N₄ and Ag₂VO₂PO₄/Ag₄V₂O₇/g-C₃N₄ exhibited dramatically improved activity for the degradation of methylene blue (MB), methyl orange (MO) and imidacloprid under visible light irradiation. When etched with 0.15 M ammonia solution, an Ag₄V₂O₇/g-C₃N₄ heterostructure was obtained that exhibited the highest photoactivity. This photocatalyst was nearly 9.1, 3.0, and 24.3 times more efficient than pristine Ag₂VO₂PO₄/g-C₃N₄ for degradation of MB, MO and imidacloprid, respectively. The excellent photocatalytic performance can be ascribed to the as-obtained well-defined Ag₄V₂O₇/g-C₃N₄ heterojunction, which improves the separation and transfer efficiency and prolongs the lifetime of photoinduced charges. In addition, the stability and dominant radicals were investigated.     

g-C3N4/PVDF复合膜的制备及热解性能研究

以DMF为溶剂,通过急骤凝胶法制备了一种用于光催化降解有机污染物的有机-无机复合膜g-C3N4/PVDF,并利用XRD、FTIR、TG等手段对该复合膜的微观结构进行了分析。分析结果表明,复合膜中的PVDF以β相结晶存在,g-C3N4不影响PVDF结晶的结构。此外,还利用迭代法研究了复合膜的热分解动力学,研究发现,g-C3N4的加入改变了PVDF的热分解过程,使热分解分为明显的2个阶段,并推导出了2个阶段的热分解动力学方程。     

有机溶剂纳滤传递模型及最新膜材料研究进展

有机溶剂纳滤（organic solvent nanofiltration, OSN）是一种高效节能、操作简便的新型膜分离技术,在化工、制药、能源和环境等相关领域具有广阔的应用前景,因此受到了膜技术领域内研究者们的重点关注。本文首先简述了有机溶剂纳滤的应用背景,其次从有机溶剂纳滤传递模型与膜材料两个方面,总结归纳了近年来在有机溶剂纳滤领域取得的研究进展。总结了基于无机陶瓷、高分子聚合物、多孔有机聚合物、有机-无机杂化材料以及石墨烯类二维材料等用于制备新型OSN膜的研究进展,并结合传输模型讨论分析了有机溶剂分子在膜内的传输行为及膜的分离性能。最后简述了有机溶剂纳滤技术在化工及相关行业中的应用现状,并指出了这些关键有机溶剂纳滤膜材料在有机溶剂纳滤应用中存在的优势和挑战,提出了基于这些关键材料的特点进行设计和优化OSN膜性能的建议供参考,以期促进有机溶剂纳滤膜的研究和应用。     

Analysis and optimization of continuous organic solvent nanofiltration by membrane cascade for pharmaceutical separation

The major part of the production costs of pharmaceuticals can be imputed to the downstream processing, where membrane technologies have to deal with some challenges as separations involving solutes with similar sizes or solvent recovery and recycling. This work contributes to the progress in the design of continuous organic solvent nanofiltration systems for this purpose and includes the configuration of dual membrane cascades, sensitivity analysis of the operation variables, and economic optimization as innovations. Analyzed configurations include multistage cascades up to three stages, and dual membrane cascades up to five stages. The total costs (TC) were chosen as the formulated objective function to minimize in the economic optimization strategy. The treatment of the residual stream leaving the system resulted the main cost of the process (more than 85% for dual cascades), but the solvent recovery units can significantly reduce the TC (64–77% depending on the required solvent quality). © 2014 American Institute of Chemical Engineers AIChE J, 60: 931–948, 2014