含氧化石墨烯混合基质反渗透复合膜的制备及性能研究

以间苯二胺(MPD)为水相单体、均苯三甲酰氯(TMC)为油相单体,氧化石墨烯(GO)作为水相添加物,采用界面聚合法,制备了GO-PA(聚酰胺)/PSF(聚砜)混合基质反渗透复合膜。采用扫描电子显微镜表征了膜形貌,考察了该膜对氯化钠的截留性能及耐氯性。结果表明,聚酰胺反渗透膜填充氧化石墨烯后,其分离性能优于聚酰胺膜,且具有较好的耐氯性。随着氧化石墨烯含量的增加,膜的通量增大,当添加量为0.005%时,膜具有最大通量,为63 L/(m2.h)。     

界面聚合反渗透复合膜材料及其表面修饰

针对我国反渗透复合膜材料研究领域存在的膜材料品种单一、膜性能相对较差、膜产品缺乏核心竞争力等现状,重点开展了界面聚合反渗透复合膜材料及其表面修饰方面的研究工作.从功能单体与制备工艺入手,研究开发高性能反渗透复合膜材料;采用表面改性技术,对界面聚合反渗透复合膜材料进行表面功能化修饰,研究开发界面聚合反渗透复合膜材料的表面改性实用技术;以期为我国反渗透复合膜材料及其产业的发展提供核心材料和先进制备技术.     

用于分离重金属离子的聚苯胺改性氧化石墨烯复合膜

近年来,氧化石墨烯(GO)由于其独特的物理化学性质在水处理领域受到了广泛的关注.然而,单纯的GO层层自组装膜对二价阳离子的过滤效率较低,在实际应用中受到了限制.本工作通过在GO膜上接枝聚苯胺(PANI)制备了PANI/GO复合膜,并对GO膜和PANI/GO复合膜的性能进行了研究和比较.结果表明,复合膜具有较高的渗透通量和截留率,GO的负载量对复合膜的过滤性能具有重要作用,当GO负载量为150 mg·m-2时,复合膜的渗透通量为214.5 L·m-2·h-1·MPa-1;在重金属离子去除方面,复合膜对CuCl2、ZnCl2、BaCl2、CdCl2、NiCl2的截留率均超过90％,分离效果良好,其对离子的排斥依赖于唐南效应和尺寸排斥.因此,PANI/GO复合膜在废水处理领域具有良好的应用前景.     

基于低温等离子体基膜改性的高脱盐性反渗透复合膜的制备

为了改善反渗透聚砜(PS)基膜的亲水性,增加基膜与皮层间的结合力,提高反渗透复合膜脱盐性,本研究采用丙烯酸(AA)为接枝单体,对PS膜进行低温等离子体引发接枝聚合改性,将改性后的基膜通过界面聚合制备反渗透复合膜.通过均匀试验方法研究改性条件并利用SPSS软件对反渗透复合膜截留率进行回归分析,建立显著性回归方程.根据截留率高低对回归方程进行寻优处理,得出最优改性参数并进行试验验证.得到优化改性参数为:放电电流4 A,放电时间7 min,接枝液体积分数70%,接枝时间180 min,验证结果表明,基膜改性后制备的反渗透复合膜截留率达到95.83%,较未改性基膜制备的复合膜截留率提高了36.24%.     

氧化石墨烯/海藻酸钙复合膜的制备与性能

以海洋生物多糖海藻酸钠为基质,氧化石墨烯(GO)为改性添加剂,乙二醇双(2-氨基乙醚)四乙酸钙(EGTA-Ca)为交联剂,制备了网络结构均匀的氧化石墨烯/海藻酸钙复合膜。分别利用红外光谱、扫描电子显微镜、电子拉力机考察了复合膜的结构、表面形貌、力学性能和溶胀性能。结果表明,GO均匀分散在海藻酸盐基体中,GO的加入对于海藻酸钙膜的力学性能具有显著影响,当GO添加量为海藻钠原料质量的1%时,复合膜的断裂强度和断裂伸长率均达到最大,比未添加氧化石墨烯膜分别增加了~82%和~265%,适量乙二醇的加入对于复合膜具有很好的增塑作用。GO的加入对复合膜的溶胀性能影响不大。     

多功能GO/g-C3N4/Ag复合膜的制备及性能研究

采用真空辅助抽滤的方法制备了自支撑的氧化石墨烯复合膜,对其形态和结构进行表征,并以R6G溶液为目标污染物,考察了复合膜的水通量、R6G(罗丹明6G)截留率、SERS(表面增强拉曼光谱)检测性能及光催化降解性能.结果表明,g-C_3N_4(石墨相氮化碳)和Ag纳米颗粒成功嵌入GO片层之间,制备出GO/g-C_3N_4/Ag复合膜,膜厚度约为4.2μm,水通量为230.64 L/(m~2·h·MPa),R6G截留率达到91.27%;复合膜通过SERS技术能实现对R6G的快速、高灵敏度检测,检测浓度可低至10 nmol/L;复合膜光催化降解性能良好,可见光下反应2 h后R6G降解率可达97.05%.GO/g-C_3N_4/Ag复合膜具有吸附分离、SERS检测及光催化降解等多种功能,改善了GO膜的渗透通量低、不可重复利用等问题,可用于水中有机污染物的检测及降解.     

氧化石墨烯负载无纺布复合膜的制备及光热转换性能

氧化石墨烯(GO)是一种性能良好的光热转换材料,广泛用于海水淡化、光电转换和太阳能利用等领域。为了测试GO负载无纺布膜(GO膜)和聚乙烯醇-氧化石墨烯无纺布复合膜(PVA-GO复合膜)的光热水蒸发特性,通过改进Hummers方法制备GO,选取了纤维素和聚酯类型的无纺布,通过浸泡-超声法制得GO膜和PVA-GO复合膜。运用紫外-可见-近红外光谱仪分析了GO膜和PVA-GO复合膜的吸光性能,并通过电子天平测量GO膜和PVA-GO复合膜的蒸发水量。由于PVA具有亲水性,能增大膜的吸水性,因而PVA加入会使蒸发水量增大。通过SEM分析GO膜和PVA-GO复合膜表面特征,发现无添加PVA的GO膜是纤维丝状结构,且纤维清晰可见。加入PVA后,纤维被PVA包裹,说明膜对光的吸收能力增强。当加入6wt% PVA时,无纺布纤维被PVA完全包裹。当用氙灯对两种膜进行水蒸发实验时,GO膜的蒸发速率达到了1.67 kg/(m2·h),PVA-GO复合膜的蒸发速率达到了1.85 kg/(m2·h)。此外,GO膜中出现GO层状结构,在紫外-可见-近红外光谱分析中表现出较好的吸光能力,在光热蒸发实验中表现出较好的光热转换能力。PVA-GO复合膜在PVA质量浓度为4wt%时有较好的光热转换性能和吸光性。      

电子受体材料功能化还原氧化石墨烯的结构和光学性能

采用Hummers法制备氧化石墨烯(GO),利用水热法对GO分别还原5 h和10 h制得两种还原氧化石墨烯(5-RGO和10-RGO),进一步用异氰酸苯酯对还原前后的氧化石墨烯材料进行改性,即得功能化氧化石墨烯和功能化还原氧化石墨烯(SPFGO、5-SPFRGO和10-SPFRGO)。以功能化还原氧化石墨烯材料为电子受体,聚3-己基噻吩(P3HT)为电子给体,制备复合膜。结果表明:GO由3-5层组成,经水热还原后样品表面仍含有—CO,—COOH等含氧官能团;功能化后石墨烯在邻二氯苯中分散性良好,与P3HT能级相匹配,满足作为聚合物太阳能电池受体材料要求;以5-SPFRGO做为受体材料与P3HT复合制备的复合膜表面规整致密,光吸收强度高,荧光光谱强度低,性能最优。     

氧化石墨烯含量对聚砜超滤膜结构和性能的影响

以氧化石墨烯和聚砜作为前体,采用浸没沉淀相转化方法制备氧化石墨烯/聚砜复合超滤膜.通过扫描电镜、傅里叶变换红外光谱仪、接触角测量仪分别对复合膜的断面结构、官能团及膜表面的接触角进行表征和测定;使用超滤杯测定复合膜的水通量及通量恢复率;同时测试了复合膜的抗菌性.结果表明:当氧化石墨烯含量为2%时,复合膜的指状孔结构明显而且较粗,水通量达到峰值242.43L/(m2·h);此时复合膜的亲水性和抗污染性显著提高,复合膜的抗菌性能也得到改善.     

基于硅烷化石墨烯掺杂硅橡胶的聚合物电致动器

以有机锡为催化剂、异佛尔酮二异氰酸酯(IPDI)为偶联剂,将端羟基-聚二甲基硅氧烷(HO-PDMS)接枝到氧化石墨烯(GO)的表面,制备了硅烷化氧化石墨烯(SGO)。红外光谱、拉曼光谱和X射线光电子能谱结果证明了HO-PDMS的成功接枝。通过扫描电子显微镜观测到SGO均匀分散在硅橡胶(PDMS)基体中,由此得介电常数和力学性能提升的SGO/PDMS复合膜。当添加10 phr SGO后,复合膜的相对介电常数达到3.076,较纯PDMS膜增加了40.7%。在复合膜两侧涂覆柔性PDMS/炭黑电极,制备了SGO/PDMS膜介电弹性体电致动器(DEP)。该致动器在4.71 V/μm(2 Hz)的低压电场下发生面外弯曲振动,中心偏转位移达到0.654 mm,折合膜形变率为5.42%,在文献已报道的同类产品中处于较高水平。     

中空纤维反渗透复合膜的制备及分离性能研究

通过间苯二胺水溶液和均苯三甲酰氯的正己烷溶液的界面缩聚反应,以聚砜中空纤维超滤膜为基膜,制备了聚芳香酰胺反渗透复合膜.用扫描电镜对复合膜的表面及断面进行表征,探索了复合膜在不同操作条件以及进液性质下的分离性能.研究结果表明:中空纤维反渗透复合膜具有良好的耐压密性和稳定性,在0.7MPa下具有良好的分离性能.此复合膜对NaCl、KCl、CaCl2、MgCl2、MgSO4、Na2SO4等无机盐水溶液的脱盐率不低于93.5%,通量大于21L/(m2·h);对天津市大港、小站两地的苦成水具有优异的淡化性能;对天津市自来水中的盐分也有良好的去除率.     

Tip and inner walls modification of single-walled carbon nanotubes (3.5 nm diameter) and preparation of polyamide/modified CNT nanocomposite reverse osmosis membrane

To enhance the water flux and salt rejection of reverse osmosis membranes, thin film nanocomposite reverse osmosis membranes were prepared by incorporating functionalised single-walled carbon nanotubes (SWNTs). The functionalised SWNTs were obtained by chemical process such as mixed acid oxidation and substitution reaction. The SWNTs were characterised by HRTEM, FTIR, TGA, Raman spectra, UV-Vis and XPS, etc. The surface morphology and structure of membrane were characterised by SEM and contact angle measurement, respectively. The results showed that carboxyl, acyl, amide and amine were successfully grafted on the tip and inner wall of the single-walled carbon nanotubes. The dispersity of the functionalised SWNTs in water was tested, indicating a good hydrophilic property. The polyamide/modified CNT nanocomposite reverse osmosis membrane was prepared. Compared with the bare polyamide membrane, the SWNT-polyamide thin film nanocomposite membranes showed higher property in hydrophilic surface and its water flux, as along with salt rejection, improved dramatically. The experimental results revealed that the modified SWNTs (especially those containing hydrophilic groups such as carboxyl groups and amino groups) well dispersed in the polyamide thin film layer, and hence improved the water permeation, and the salt rejection.     

海水淡化反渗透耐氯膜材料的研究与制备进展

反渗透是重要的海水淡化技术,本文针对反渗透膜易被水中活性氯破坏导致性能下降的问题,介绍了聚酰胺反渗透膜氯化降解理论,并深入探讨了国内外对耐氯反渗透膜材料的研究与开发现状,讨论了耐氯反渗透膜的研究方向和发展前景。     

Antibiofouling thin-film composite membranes (TFC) by in situ formation of Cu-(<Emphasis Type="Italic">m</Emphasis>-phenylenediamine) oligomer complex

In situ formation of a Cu-(m-phenylenediamine) (Cu-mPD) oligomer complex from copper chloride during the interfacial polymerization process was successfully employed to produce modified thin-film composite reverse osmosis membranes (TFC-RO) with antibiofouling properties. Membranes were characterized by field emission scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy, and contact angle measurements. Antibiofouling properties were studied using a colony-forming unit test with Escherichia coli. Moreover, an antiadhesion test was developed using fluorescence microscopy. Membrane performance using a cross-flow cell was evaluated, and copper concentration in permeate water was measured. FTIR, XPS and XRD results confirmed the formation of a Cu-mPD oligomer complex and its incorporation into the polyamide layer. A mechanism for formation of the oligomer within the membrane was proposed based on the interaction between the oxygen of the carbonyl group of the polyamide layer and copper ion of the Cu-mPD oligomer complex. The modified membrane showed a slight decrease in hydrophilicity and higher surface roughness. However, excellent antibacterial and antiadhesion effects were observed, attributed to copper toxicity as a result of Cu²⁺ ions release from the membrane surface. Release of copper ions in the permeate water was determined, and the maximum value observed was considered negligible according to the World Health Organization. The desalination performance of modified membrane showed an important salt rejection with stable water flux. In conclusion, a novel chemical method for the incorporation of Cu-mPD oligomer complex into the polyamide layer of TFC-RO membranes to improve their antibiofouling properties and desalination performance was achieved.     

Experimental Evidence of Rapid Water Transport through Carbon Nanotubes Embedded in Polymeric Desalination Membranes

As water molecules permeate ultrafast through carbon nanotubes (CNTs), many studies have prepared CNTs‐based membranes for water purification as well as desalination, particularly focusing on high flux membranes. Among them, vertically aligned CNTs membranes with ultrahigh water flux have been successfully demonstrated for fundamental studies, but they lack scalability for bulk production and sufficiently high salt rejection. CNTs embedded in polymeric desalination membranes, i.e., polyamide thin‐film composite (TFC) membranes, can improve water flux without any loss of salt rejection. This improved flux is achieved by enhancing the dispersion properties of CNTs in diamine aqueous solution and also by using cap‐opened CNTs. Hydrophilic CNTs were prepared by wrapping CNT walls via bio‐inspired surface modification using dopamine solution. Cap‐opening of pristine CNTs is performed by using a thermo‐oxidative process. As a result, hydrophilic, cap‐opened CNTs‐embedded polyamide TFC membranes are successfully prepared, which show much higher water flux than pristine polyamide TFC membrane. On the other hand, less‐disperse, less cap‐opened CNTs‐embedded TFC membranes do not show any flux improvement and rather lead to lower salt rejection properties.     

5-异氰酸酯异肽酰氯/ZnO/超支化聚酰胺纳滤膜的制备及性能EI北大核心CSCD

为获得大通量抗污染纳滤膜,通过5-异氰酸酯异肽酰氯(ICIC)与超支化聚酰胺(HBPA)在聚丙烯腈(PAN)超滤膜表面的界面聚合反应,将纳米氧化锌引入聚酰胺分离层制备ICIC/ZnO/HBPA纳滤膜。扫描电镜(SEM),X射线能谱分析证实ZnO的存在;接触角测试结果显示,引入ZnO后膜表面亲水性增强,最小接触角为22.7°。与未加ZnO相比,加入ZnO的膜通量增大了约2.6倍,为102 L·m^-2·h^-1,且对NaCl,MgCl 2,Na2SO4和MgSO4的截留率提高。随着ZnO用量的增加,膜对大肠杆菌抑菌性增强。适当增大单体含量或延长界面聚合时间有利于提高膜对无机盐的截留率,但截留率顺序发生变化。当HBPA含量为0.8%(质量分数,下同)、ICIC含量为0.1%、ZnO用量为0.02 g、反应时间为10 min时,制备的纳滤膜对NaCl,MgCl2,Na2SO4和MgSO 4的截留率分别为60.8%,96.4%,95.1%,96.7%,通量分别达到53,54.7,53.7 L·m^-2·h^-1和54.7 L·m^-2·h^-1。     

反渗透复合膜技术进展和展望

简要介绍反渗透复合膜的发展现状和趋势.自1978年全芳香族聚酰胺复合膜的成功及其产业化,大大地促进了膜科技和海水淡化的发展,膜的品种不断增多,膜的性能不断提高,低压、超低压、极低压、高脱盐率、高通量、耐污染和抗氧化等一系列的各种复合膜相继进入市场.文章简述了膜材料的选择、传递机理(如:溶解扩散模型、优先吸附-毛细孔流动模型、氢键传递和水与离子通道等)、新的功能单体合成、支撑膜的改进、界面聚合的参数调控和后处理、有机-纳米无机粒子杂化、水通道和离子通道的建立和仿生等的研究进展和发展趋势.     

Water desalination across nanoporous graphene

We show that nanometer-scale pores in single-layer freestanding graphene can effectively filter NaCl salt from water. Using classical molecular dynamics, we report the desalination performance of such membranes as a function of pore size, chemical functionalization, and applied pressure. Our results indicate that the membrane's ability to prevent the salt passage depends critically on pore diameter with adequately sized pores allowing for water flow while blocking ions. Further, an investigation into the role of chemical functional groups bonded to the edges of graphene pores suggests that commonly occurring hydroxyl groups can roughly double the water flux thanks to their hydrophilic character. The increase in water flux comes at the expense of less consistent salt rejection performance, which we attribute to the ability of hydroxyl functional groups to substitute for water molecules in the hydration shell of the ions. Overall, our results indicate that the water permeability of this material is several orders of magnitude higher than conventional reverse osmosis membranes, and that nanoporous graphene may have a valuable role to play for water purification.