甲酸乙酯改性聚酰胺正渗透复合膜的制备及表征

针对正渗透膜本身存在较低水通量以及较高反向盐通量的问题,以筛网为支撑的聚砜膜作为底膜,间苯二胺(MPD)和均苯三甲酰氯(TMC)作为水相和有机相单体,不同含量的甲酸乙酯添加在有机相中作为共溶剂,通过界面聚合法制备了高通量的聚酰胺正渗透复合膜。以2 mol/L Na Cl和1 mol/L的MgCl_2作为汲取液,去离子水作为原料液,对所得正渗透膜进行水通量以及反向盐通量的测试。结果表明,在有机相中添加少量甲酸乙酯作为共溶剂时,可以提高膜的通量和效率。通过改变甲酸乙酯的添加量,可以改变膜性能以及形貌。当甲酸乙酯的添加质量分数为4%时,正渗透的水通量能达到未改性膜的2.6倍,同时J_--s/J_v仍维持在较低的水平。     

高性能PAN-MWCNTs/PEI复合正渗透膜的制备

本研究设计并制备了一种新型复合正渗透膜，在致密聚酰胺层(PA)和静电纺丝聚丙烯腈(PAN)多孔支撑层之间敷设酸化多壁碳纳米管与聚乙烯亚胺(MWCNTs-PEI)交联的中间层。中间层的存在缩小了支撑层的孔径，为PA层的生长提供了更好的平台，有助于抑制汲取溶质的反向扩散。PEI的加入不仅可以将MWCNTs牢固地结合在支撑层上提高中间层稳定性，而且可以与TMC部分结合使得PA层更加稳定。结果表明，当中间层负载量为0.849 g/m，纯水为原料液，1 mol/L NaCl为汲取液时，FO和PRO模式下水通量分别为36.23±1.81、42.06±2.10 L/(m²·h)，反向盐扩散通量分别为11.66±0.58、12.20±0.43 g/(m²·h)。良好的整体性能表明，酸化多壁碳纳米管与聚乙烯亚胺交联形成的稳定中间层为研究和制备高性能正渗透膜提供了一条可行的途径。     

PA/PEG交联共聚反渗透膜的制备及耐污染性能

以聚丙烯腈（PAN）超滤膜为基底,在均苯三甲酰氯（TMC）和间苯二胺（MPD）界面聚合反应过程中引入聚乙二醇（PEG）,制备聚酰胺（PA）/PEG反渗透复合膜。利用傅里叶红外光谱（FTIR）、X射线光电子能谱（XPS）、场发射扫描电镜（FE-SEM）和原子力显微镜（AFM）等对膜的结构和物化性质进行了表征。考察了PEG分子量、PEG加入量、热处理温度及时间对膜反渗透性能的影响,并系统考察了膜对十二烷基硫酸钠（SDS）、十二烷基三甲基溴化铵（DTAB）以及牛血清蛋白（BSA）三种不同荷电性典型污染物的耐受性能。实验结果表明,相比于未改性的PA反渗透膜,PEG交联共聚反渗透膜的盐截留率和通量恢复率均有所提高。其中PA/PEG1000-0.1膜渗透通量为3.96kg/(m²?h),NaCl表观截留率为97.5%,并且对于SDS、DTAB和BSA都表现出较高的耐污染性,其中,SDS污染清洗后膜的通量恢复率可达89.4%。     

KAUST-8膜的制备及其对乙醇/水体系的渗透汽化分离性能的研究

为实现乙醇作为燃料的高效利用,采用二次生长法制备出亲水性KAUST-8膜并将其对乙醇水溶液进行渗透汽化分离研究。利用扫描电子显微镜（SEM）、X射线衍射仪（XRD）、比表面及孔隙度分析仪（BET）和热重等分析手段对KAUST-8晶体和膜材料的形貌、结构和性能进行表征,考察了不同操作温度和进料质量分数下,KAUST-8膜对乙醇水溶液分离效果的影响。结果表明,升高渗透汽化的操作温度,总渗透通量从281.44 g/（m²·h）增加至929.16 g/（m²·h）,分离因子从17.2降低至6.1。在同一渗透汽化温度（25℃）下,增大进料液中水的质量分数,水通量从124.2 g/（m²·h）增加到302 g/（m²·h）,总通量逐渐升高至359.2 g/（m²·h）,分离因子逐步从17.2提高至30.2。     

双选择层复合正渗透膜制备及其表征

以聚丙烯腈制备基膜,聚氮杂环丙烷、聚-4-苯乙烯磺酸钠为聚阳阴电解质,间苯二胺、均苯酰氯为水相和油相单体,依次用层层自组装(Lb L)和界面聚合制备双选择层正渗透膜,研究Lb L和界面聚合影响膜性能的典型因素。结果表明,优化条件,PEI和PSS的质量浓度均为1.0 g/L,Na Cl浓度为1.0 mol/L,Cu~(2+)浓度为0.20 mol/L,聚电解质单层沉积时间为10.0 min,MPD、TMC的质量浓度分别为20.0、0.25 g/L,单体反应时间均为2.0 min,Lb L3个聚电解质双层,界面聚合1次。在此优化条件下,所得正渗透膜水通量为42.40 L/(m~2·h),反向盐通量为10.86 g/(m~2·h)。结合石英晶体微天平说明Lb L中聚电解质层最为密实,其性能对膜影响较大。这种新的制备方法为提高正渗透工艺展现了一种新途径。     

含甲基纤维素的NaA沸石膜的制备和表征

NaA沸石膜具有规则的孔道结构,利于分子传输,在有机物脱水领域有一定的应用。为使沸石膜生长更连续均匀,提高渗透汽化性能,本文以甲基纤维素作为空间限制剂加入合成液,探究碱度、晶化温度以及晶化时间对膜的影响,按最优条件制备合成液,并依据质量比m(MC)∶m(H₂O)=1∶100添加甲基纤维素,制备NaA沸石膜。表征方法采用XRD、SEM和渗透汽化3种方式,结果表明添加甲基纤维素的沸石膜表面结构完整,生长致密且性能优良,在75℃下对0.6mol/L的NaCl水溶液做渗透汽化测试时,通量达8.33kg/(m²·h),盐离子截留率为99.95%。在0.6mol/L的NaCl的水溶液中测试72h,结果表明添加甲基纤维素的NaA沸石膜时间依存性更好,通量保持在8.30kg/(m²·h)左右,离子截留率稳定在99.90%。渗透汽化分离ω(C₂H₆O)=90%乙醇的水溶液,随着温度从60℃升高到75℃,沸石膜的通量由1.55kg/(m²·h)升高到2.56kg/(m²·h),渗透侧水含量保持在99.90%左右。     

新型复合膜制备工艺研究

以间苯二胺(MPD)为水相单体，均苯三甲酰氯(TMC)为油相单体，采用低温界面聚合方法在聚砜超滤底膜表面制备聚酰胺反渗透膜，无需传统烘箱热处理，考察了界面聚合过程中反应温度、水浴温度及时间对膜性能的影响。结果表明，水相温度为35℃、油相温度为50℃，90℃条件下水浴后处理1 min制备得到的膜性能最佳。该复合膜在25℃、1.05 MPa条件下，以1 500 mg/L的NaCl溶液为进料液进行性能测试，截留率为99.5%，水通量为70 L/(m²·h)，获得良好的分离效果。本研究提供低温界面聚合制备反渗透膜工艺的探索，可运用于海水淡化等领域。     

氧化高银/聚酰胺复合膜的制备及性能研究

采用液相氧化沉淀法制备了氧化高银,间苯二胺(MPD)、均苯三甲酰氯(TMC)分别为水相和油相反应活性单体,通过界面聚合法制备了氧化高银/聚酰胺复合膜。研究了氧化高银质量分数对膜分离性能和抗菌性能的影响。利用扫描电子显微镜(SEM)、膜性能评价仪、接触角测量仪等对膜表面形貌、分离性能、亲水性进行表征,通过抑菌圈法对膜的抗菌性能进行测试。结果表明:当氧化高银质量分数为0.3%时,聚酰胺复合膜的分离性能最佳,水通量达161.48 L/(m~2·h~(-1)),截留率为88.5%,且具有抗菌性。     

二氧化钛/聚酰胺正渗透复合膜的制备与表征

以钛酸四丁酯为原料,在水/丁醇界面区进行水解,制备了锐钛矿型二氧化钛。将TiO2分别分散在水相(MPD溶液)和油相(TMC溶液)中,以界面聚合方法制备了TiO2/聚酰胺正渗透复合膜,初步研究了TiO2分散在油相和水相中制备的二氧化钛/聚酰胺复合膜的结构及其在正渗透过程中分离性能。SEM图谱结果表明,TiO2添加到水相中时,其主要存在于聚砜基膜的指状孔道中;当TiO2添加到油相中时,其主要分布在复合膜表面。膜分离性能的研究结果表明,TiO2添加在水相和油相中都能显著提高膜的水通量和截盐率;TiO2添加在油相中对膜的分离性能改进更大,膜的水通量为未添加TiO2聚酰胺复合膜的两倍,截盐率可达99.9%。     

CS@CAU-10复合膜的制备及其对乙醇/水的分离性能

利用原位生长法在氧化铝载体上制备金属有机骨架CAU-10膜，并在其表面覆盖一层壳聚糖(CS)得到CS@CAU-10复合膜。考察了CAU-10膜合成液浓度、CS醋酸水溶液浓度以及操作温度对膜层的结构和性能的影响。结果表明，在合成液浓度为0.06 mol/L、CS质量分数为3%时获得的膜层性能最好；升高温度，该膜通量增大、分离因子下降；在30℃时，原料的水质量分数从5%增大到20%,总通量由91 g/(m²·h)增加至450 g/(m²·h),分离因子从497降低至92。该膜与其他乙醇脱水膜相比具有一定的优势。     

Forward-osmosis strategy and chemical cleaning of seawater desalination reverse osmosis membranes

In order to settle the membrane fouling of reverse osmosis membranes in seawater desalination process, this study reported a novel strategy based on forward-osmosis process and discussed the effects of different factors like different cleaning combination among reverse osmosis product, simulated reverse osmosis concentrate and simulated seawater, as well as cleaning time on the membrane permeate flux and salt rejection. For irreversible fouling, the effects of different chemical cleaning agents, immersion time and concentration were also investigated in this study. The results exhibited that the cleaning combination between diluted water and simulated reverse osmosis concentrate possessed the best cleaning performance in the process of forward-osmosis cleaning. Such approach also enhanced normalized flux from 9.48 L/(m²·h·MPa) to 13.6 L/(m²·h·MPa) and enhanced NaCl rejection from 80.59% to 92.80%. Furthermore, the normalized flux was enhanced from 9.48 L/(m²·h·MPa) to 14.3 L/(m²·h·MPa) and NaCl rejection was also enhanced from 80.59% to 96.27% after soaking in 2%(mass) citric acid solution for 2h, soaking with 1%(mass) ethylenediamine tetra-acetic acid tetrasodium salt and 0.3%(mass) sodium tripolyphosphate solution for 1.5 h. According to the result of SEM images and AFM images, the forward-osmosis cleaning strategy could not cause the damage of selective layer of membrane surface and caused the drop of inorganic and organic fouling on the membrane surface. Hence, cleaning fouled RO membranes by such approach could prolong the chemical cleaning cycle and reduce the amount of chemical cleaning agent, which has certain industrial application perspectives.     

正渗透策略和化学清洗海水淡化反渗透膜

为解决海水淡化过程中反渗透膜的污染问题,研究了基于正渗透策略的反渗透产水、模拟反渗透浓水、模拟海水不同的组合清洗和清洗时间对膜通量和截留率的影响。针对不可逆污染,研究了不同化学清洗药剂、浸泡时间、浓度对膜通量和截留率的影响。结果表明,正渗透策略清洗方式中,淡水/模拟反渗透浓水的组合清洗方式效果最佳,其归一化通量从9.48 L/(m²·h·MPa)提升至13.6 L/(m²·h·MPa),截留率从80.59%提升至92.80%。此外,经质量分数为2%的柠檬酸溶液浸泡2 h后,再使用质量分数为1%的乙二胺四乙酸四钠盐和0.3%的三聚磷酸钠溶液浸泡1.5 h,其归一化通量从9.48 L/(m²·h·MPa)提升至14.3 L/(m²·h·MPa),截留率从80.59%提升至96.27%。从SEM和AFM图可以看出,正渗透清洗策略并未对膜表面选择层造成损坏,且可以清洗膜表面的有机污染物和无机污染物,因此,应用这种方法对污染的反渗透膜进行清洗,可延长化学清洗周期,减少化学清洗剂用量,具有一定的工业应用前景。     

Preparation of reverse osmosis composite membrane with high flux by interfacial polymerization of MPD and TMC

In this study, reverse osmosis (RO) composite membrane with extra‐thin separation layer was prepared by the interfacial polymerization (IP) of metaphenylene diamine (MPD) with trimesoyl chloride (TMC) on the surface of polysulfone (PS) support membrane. The properties and structures of skin layer of RO composite membranes were characterized by FTIR and SEM, it was found that IP had occurred and the separation layer was formed. The effects of the monomer concentration on membrane flux and salt rejection were investigated, and the optimum concentration of MPD and TMC were 2 and 0.3% (w/v), respectively. To improve flux, the phase‐transfer catalyst was added to the water phase, and the effects were remarkable when the concentration of MPD was low, in which both salt rejection and flux increased by 20% than initial results. When some of the hydrophilic additives such as alcohols and phenols were added into water phase, the flux of the prepared membrane increased from 13.03 to 33.42 L/(m² h) without loss in salt rejection. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polyethyleneimine-Mediated Polyamide Composite Membrane with High Perm-Selectivity for Forward Osmosis

Thin-film composite (TFC) membranes comprised of a polyamide (PA) selective layer upon a porous substrate dominate the forward osmosis (FO) membrane market. However, further improvement of perm-selectivity still remains a great challenge. Herein, a polyethyleneimine (PEI) interlayer is intentionally designed prior to interfacial polymerization (IP) to tailor the PA layer, which thus improves the separation performance. The PEI interlayer not only improves the substrate hydrophilicity for adsorbing more diamine monomer and controlling its release rate, but also participates in IP reaction by crosslinking with acyl chloride (TMC). Furthermore, it can decrease the electronegativity of the substrate for decreasing reverse salt diffusion. Consequently, a denser, thinner and smoother PA layer is formed due to the uniform distribution, controllable release of diamine monomer and the extra crosslinking between PEI and TMC. Furthermore, the PA layer becomes more hydrophilic with PEI involvement. As a result, the asprepared TFC membrane exhibits a favorable water flux of 16.1 L m⁻² h⁻¹ and an extremely low reverse salt flux (1.25 g m⁻² h⁻¹). Meanwhile, it achieves an excellent perm-selectivity with a ratio of water to salt permeability coefficient of 8.25 bar⁻¹. Moreover, it exhibits an outstanding antifouling capacity. The work sheds light on fabricating high perm-selective membranes for desalination.     

氯化聚氯乙烯复合纳滤膜的制备及其在模拟RB5染料废水处理中的应用

以氯化聚氯乙烯（CPVC）超滤膜为基膜,采用单宁酸（TA）和哌嗪（PIP）在CPVC膜表面共沉积后与交联剂均苯三甲酰氯（TMC）进行界面聚合得到PA/TA/CPVC复合纳滤膜,采用扫描电镜（SEM）、原子力显微镜（AFM）、红外光谱及接触角对PA/TA/CPVC复合纳滤膜进行了表征,并探讨了干燥时间、TA/PIP浓度比、TA+PIP总浓度、TMC浓度对PA/TA/CPVC复合纳滤膜微观结构与性能的影响。结果表明,TA/PIP浓度比最佳为7/3,TA/PIP层的最佳干燥时间为20min,PA/TA/CPVC复合纳滤膜的纯水通量随着TA+PIP总浓度的增加和TMC浓度的增加而减少,对PEG1000的截留率均在90%以上。PA/TA/CPVC复合纳滤膜纯水通量最大值为4.5L/(m² · h · bar),此时PEG1000的截留率达到95.8%。对模拟RB5染料废水的最大通量为4.3L/(m² · h · bar),此时RB5的截留率为95.4%,对模拟RB5染料废水的稳定性较好。     

PP中空纤维换热管外表面改性强化蒸汽冷凝传热

针对塑料换热管传热性能不佳的问题,采用界面聚合法,以间苯二胺(MPD)为水相单体,均苯三甲酰氯(TMC)为有机相单体,对聚丙烯(PP)中空纤维换热管疏水性外表面进行局部亲水性改性,以形成呈"孤岛"分布的亲水性聚酰胺层,从而构建蒸汽冷凝用亲-疏水性组合表面.在此基础上,研究改性PP换热管强化蒸汽冷凝传热效果.换热管改性后...     

醇类添加剂影响界面聚合反渗透复合膜性能的机理

在考察间苯二胺和均苯三甲酰氯界面聚合单体浓度对膜性能影响的基础上,研究了在水相反应溶液中添加系列小分子醇类后膜分离性能的变化,添加醇后的聚酰胺反渗透复合膜通量有明显提高,最高增加超过一倍。FTIR结果表明由于醇羟基与酰氯基团反应生成酯键终结聚酰胺分子链的增长,降低网络结构的交联度,利于分子透过。简要分析了通量的增加量与醇的种类以及溶解度各分量之间的关系,当醇与聚酰胺溶解度越接近时,醇更容易溶解透过初生态的聚酰胺膜,与酰氯接触发生反应的机会增加,链终止的可能性就会增大,通量提高得越多。最后,根据实验结果得出结论：在前面最佳制膜工艺的指导下,醇作为水相添加剂且添加量质量分数在5%～10%之间可以有效优化聚酰胺复合膜的性能,制备出高通量的反渗透复合膜。     

Unexpected new phase detected in FT30 type reverse osmosis membranes using scanning transmission X-ray microscopy

FT30 type thin film composite membranes used for reverse osmosis water purification are very difficult to analyze. With the remarkably thin polyamide layer and surface modification of the polymers now being reported, a new analytical technique is needed to determine the surface structure and chemical distribution in the active layer. In this study we show that scanning transmission X-ray microscopy (STXM) can be used to determine the spatial distribution of polyamide and polysulfone and we report on the detection of an unexpected new phase. The new phase was identified as a homopolymer of the meta-phenylene diamine (MPD) that forms in MPD solutions and can be incorporated into the discrimination layer during the interfacial reaction with the TMC to produce a mixed polyamide polyMPD layer. The detection of this second phase was only made possible by STXM. At the levels detected in membranes in this study (less than 8%) the second phase had no effect on the flux or salt passage of the membranes, however at higher levels a change in the membrane properties most likely would occur and the quantity of the polyMPD present should be eliminated or controlled.     

反渗透复合膜(Ⅰ)结构与性能

引言 反渗透被称为"21世纪的净化水技术",具有净化率高、成本低等优点,广泛应用于海水淡化、电厂水处理、纯净水制取等领域.聚酰胺含有酰胺基团(-CO-NH-),亲水性好,且其机械稳定性、热稳定性及水解稳定性均很好,是最典型的反渗透膜材料之一[1-4],与醋酸纤维素反渗透膜相比,它具有脱盐率高、通量大、操作压力要求低等优点.反渗透膜的脱盐率和通量很大程度上取决于膜的表面形态和表面化学结构.