氧化石墨烯分离膜的制备及其水处理领域的应用进展

氧化石墨烯优越的物理化学性能和膜技术的广泛应用使氧化石墨烯分离膜成为解决水环境污染和水资源短缺问题最具潜力的手段之一。本文简要介绍了氧化石墨烯分离膜的概念、分类和制备方法,在氧化石墨烯分离膜的制备方法中,表面改性的氧化石墨烯膜和氧化石墨烯杂化复合膜的相关研究报道比较多;梳理了最近几年氧化石墨烯分离膜在水处理领域的应用研究,主要包括重金属的去除、脱盐、抗菌、油水分离、染料脱色以及天然有机物的去除。详细介绍了氧化石墨烯分离膜的独特分离性能和分离机理,氧化石墨烯能够改善原有聚合物膜的某些性能,比如提高水通量、污染物截留率、膜的机械强度和抗污染性等,分离机理主要为尺寸筛分机制和电荷效应。最后,展望了氧化石墨烯分离膜在水处理领域未来的发展和面临的挑战。     

交联型氧化石墨烯复合膜在水处理中的应用研究进展

近年来,氧化石墨烯基纳米材料作为一种新型的膜材料,以其优异的机械强度、良好的物理化学稳定性和独特的二维结构,在水处理方面表现出优异的分离性能。本文综述了氧化石墨烯基膜的制备方法,介绍了交联型氧化石墨烯复合膜在纯水渗透通量、无机盐截留性能、膜稳定性方面的性能特点以及在超滤、纳滤和反渗透领域的研究进展,并对其在水处理领域的应用前景进行了展望。     

氧化石墨烯水处理材料的研究进展

污水的净化及海水淡化作为解决水资源短缺的有效手段具有广阔的发展空间。氧化石墨烯作为一种新型水处理碳材料,由于其特殊的二维纳米结构和丰富的含氧官能团,具有优异的物理化学性能,引起了研究者们的兴趣。综述了氧化石墨烯分离膜、吸附气凝胶及太阳能水蒸发材料等氧化石墨烯水处理材料的研究进展,并对其未来的前景进行了展望。     

氧化石墨烯膜在浓盐水分离领域的应用研究

随着工业废水资源化利用的发展，膜分离技术由于其分离效率高、占地面积小以及易于操作管理等优点，成为废水资源化利用过程中不可或缺的工艺技术。而氧化石墨烯作为石墨烯的衍生物，具有超高的水通量、可控的层间距以及优异的分离性能，广泛应用于海水淡化和污水处理等领域。为探究氧化石墨烯膜对工业实际浓盐水的分离效果，对氧化石墨烯膜的制备及分离效果进行了探究。实验结果表明，以13.81 mg/m2制备氧化石墨烯膜为最佳，制备的氧化石墨烯膜对0.6 mol/L的氯化钠溶液具有20.43%的截留率，对0.2 mol/L的硫酸钠溶液具有25.49%的截留率，对实际工业浓盐水SO42-和Cl-分别具有17.98%～19.83%和21.23%～23.33%的截留率。制备的氧化石墨烯膜，在较低的压力作用下，能够展现出较好的分离能力，是一种具有良好应用前景的水处理膜材料。     

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。     

基于层层自组装技术的抗污染膜研究进展

膜分离技术已经广泛应用于污水处理领域，但膜污染是制约其进一步发展的主要障碍，开发抗污染膜材料实现节能降耗是目前膜法污水处理领域的研究热点之一。层层自组装作为一种膜表面改性技术，具有组装材料丰富、适用场景广泛、制备条件温和、分子水平结构可控等特点，已被应用于抗污染膜材料的研制中。本文综述了近年来基于层层自组装技术的水处理用抗污染膜的研究进展，在阐释层层自组装技术应用于膜污染控制机制的基础上，重点总结了基膜的选择和处理、抗污染组装单元的种类和复合方式、组装层数、制备方法对膜抗污染性能的影响，并对未来该技术实现膜污染控制的构筑设计和发展方向，如组装过程机制挖掘、制膜工艺优化、制膜成本降低、长期稳定性提升等方面进行了展望。     

纤维素基分离膜材料的应用研究进展

膜是具有选择性分离功能的材料,在某种推动力作用下,利用膜的选择性分离可实现不同组分的分离、纯化、浓缩目的。膜技术在水处理、生化制药、食品制造、石油化工、医疗卫生等领域占据着不可替代的地位。纤维素是自然界中分布最广、储量最为丰富的一类可再生资源,其特殊的分子结构赋予了材料优异的性能,是一种很好的膜材料。文章介绍了分离膜技术的特点,阐述了纤维素在膜领域的高值化利用,同时对近年来国内外关于纤维素基膜材料的制备、性能进行了总结,综述了其在水处理、气体分离、生物医用、手性拆分、电池隔膜等领域的应用研究进展,并对进一步值得研究的重点方向进行了展望。     

石墨烯基材料在CO2分离膜领域的研究进展

节能高效的CO₂分离技术的开发具有重要的现实及长远意义,膜法CO₂分离在该领域备受关注,具有优异传质特性的新型分离膜材料对膜分离过程有决定性的影响。近年来,石墨烯及其衍生材料因独特的单原子层厚度、亚纳米级别的孔道结构以及优异的机械、化学和热稳定性,成为气体分离膜领域的研究热点,膜的加工难度、技术成本、大面积制备、工作稳定性等问题是限制其实际应用的关键因素。石墨烯基CO₂分离膜主要有三种形式：纳米孔石墨烯膜、层状结构氧化石墨烯膜、基于石墨烯及其衍生材料的混合基质膜。本文综述了石墨烯基CO₂分离膜领域的突破性研究进展,重点介绍了气体的跨膜传质机理和膜的构性关系,总结了膜性能的优化思路和原理,梳理了石墨烯基CO₂分离膜发展面临的挑战,提出了潜在的研究方向。分析表明,进行系统的理论研究,采用先进的表征手段,以建立膜构性关系的理论模型,指导膜结构设计是未来研究的重点。此外,进一步降低膜加工成本,充分研究膜在实际工作环境中的稳定性也至关重要。     

电活性MXene膜电极构造原理与水质净化应用研究进展

电活性膜净水技术可借助电化学反应和膜分离的耦合协同作用实现对污染物的短流程高效去除，具有传质效率高、能耗低、抗污染、适应性强等优势，在水处理中展现出巨大的应用潜力。为深入研究电化学水处理技术机理，围绕电活性MXene(E-MXene)膜电极的构造原理与水质净化应用，以典型的MXene及其复合膜电极材料为例，对E-MXene膜电极的构筑原理、策略及其在水质净化领域中的应用研究进行了综述，之后对E-MXene膜电极在重金属去除、油水分离、脱盐及耦合处理技术等领域的研究进展进行了系统性回顾，并对E-MXene膜技术在水处理领域的未来发展趋势进行了展望。     

氧化石墨烯改性复合纳滤膜的研究进展

氧化石墨烯(GO)掺杂到膜表面制备的GO-复合纳滤膜具有抗污染能力强、污染物截留率高的特点,是目前研究解决复合纳滤膜污染问题的热点。本文综述了GO-复合纳滤膜的材料选择和主要制备方法,并讨论了GO对GO-复合纳滤膜抗污染性能的影响,为进一步提高GO-复合纳滤膜抗污染性能的研究提供了理论依据和建议。     

Multifunctional fly ash-based GO/geopolymer composite membrane for efficient oil-water separation and dye degradation

Membrane fouling and separation materials with low cost and high efficiency are challenges for membrane separation technology in wastewater treatment. Superhydrophilic and underwater superoleophobic membranes show broad application prospects in oily wastewater treatment because of their high permeability, selectivity, and antifouling performance; however, they are generally ineffective for organic pollutant molecules. In this study, a novel graphene oxide (GO)/geopolymer composite membrane with superhydrophilic and underwater superoleophobic characteristics was prepared by dipping a mixed slurry of GO and fly ash-based geopolymer onto a stainless steel mesh via a facile self-assembly process. The results show that GO could adjust the hydrophilicity and water flux of composite membranes. The composite membrane containing 0.4 wt% GO (4GO/GCM) had the best hydrophilic, water flux of 1363 kg/(m²·h), and high separation efficiencies (≥98.2%) for oil-water mixtures and oil-in-water emulsions under gravity-driven. In addition, the 4GO/GCM sample exhibited excellent stability under harsh conditions, including hot water and strong acid, alkali, and salt solutions. Importantly, the sample derived from fly ash exhibited unique photocatalytic degradation performance for organic dye molecules under simulated solar-light irradiation. Thus, it is believed to this strategy has substantial potential for high-value utilization of fly ash and the sustainable treatment of oily and dye wastewater.     

Theoretical study on Janus graphene oxide membrane for water transport

Graphene oxide (GO) membranes have received considerable attention owing to their outstanding water-permeation properties; however, the effect of the membrane’s microstructures (such as the distribution of oxidized and pristine regions) on the transport mechanism remains unclear. In this study, we performed molecular simulations to explore the permeation of a water–ethanol mixture using a new type of Janus GO membranes with different orientations of oxidized and pristine surfaces. The results indicate that the oxidized upper surface endows the GO membrane with considerable water-capture capability and the in-built oxidized interlayer promotes the effective vertical diffusion of water molecules. Consequently, using the optimized Janus GO membrane, infinite water selectivity and outstanding water flux (~40.9 kg⋅m⁻²⋅h⁻¹) were achieved. This study contributes to explaining the role of oxidized regions in water permeation via GO membranes and suggests that Janus GO membranes could be used as potential candidates for water–ethanol separation.     

Poly(vinylidene fluoride) hollow‐fiber membranes containing silver/graphene oxide dope with excellent filtration performance

In this study, an antifouling poly(vinylidene fluoride) (PVDF) hollow‐fiber membrane was fabricated by blending with silver‐loaded graphene oxide via phase inversion through a dry‐jet, wet‐spinning technique. The presence of graphene oxide endowed the blended membrane with a high antifouling ability for organic fouling. The permeation fluxes of the blended membrane was 3.3 and 2.9 times higher than those of a pristine PVDF membrane for filtering feed water containing protein and normal organic matter, respectively. On the other hand, the presence of silver improved the antibiofouling capability of the blended membrane. For the treatment of Escherichia coli suspension, the permeation flux of the blended membranes was 8.2 times as high as that of the pristine PVDF membrane. Additionally, the presented blended membrane improved the hydrophilicity and mechanical strength compared to those of the pristine PVDF membrane, with the water contact angle decreasing from 86.1 to 62.5° and the tensile strength increasing from 1.94 to 2.13 MPa. This study opens an avenue for the fabrication of membranes with high permeabilities and antifouling abilities through the blending of graphene‐based materials for water treatment. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44713.     

Review on structural control and modification of graphene oxide-based membranes in water treatment: From separation performance to robust operation

Membrane separation has become an important technology to deal with the global water crisis. The polymerbased membrane technology is currently in the forefront of water purification and desalination but is plagued with some bottlenecks. Laminated graphene oxide(GO) membranes exhibit excellent advantages in water purification and desalination due to the single atomic layer structure, hydrophilic property, rich oxygen-containing groups for modification, mechanical and chemical robust, anti-fouling properties, facile and large-scale production, etc. Thus the GO-based membrane technology is believed to offer huge opportunities for efficient and practical water treatment. This review systematically summarizes the current progress on the water flux and selectivity intensification, stability improvement, anti-fouling and anti-biofouling ability enhancement by structural control and modification. To improve the performance of the laminated GO membrane, interlayer spacing tunability and surface modification are mainly used to enhance its water flux and selectivity. It is found that the stability and biofouling also block the service life of the GO membrane. The crosslinking method is found to effectively solve the stability of GO membrane in aqueous environment. Introducing nanoparticles is a widely used method to improve the membrane biofouling ability. Overall, we believe that this review could provide benefit to researchers in the area of GO-based membrane technology for water treatment.     

Transport properties of graphene oxide nanofiltration membranes: Electrokinetic modeling and experimental validation

There is a need for developing reliable models for water and solute transport in graphene oxide (GO) membranes for advancing their emerging industrial water processing applications. In this direction, we develop predictive transport models for GO and reduced-GO (rGO) membranes over a wide solute concentration range (0.01–0.5 M) and compositions, based on the extended Nernst–Planck transport equations, Donnan equilibrium condition, and solute adsorption models. Some model parameters are obtained by fitting experimental permeation data for water and unary (single-component) aqueous solutions. The model is validated by predicting experimental permeation behavior in binary solutions, which display very different characteristics. Sensitivity analysis of salt rejections as a function of membrane design parameters (pore size and membrane charge density) allows us to infer design targets to achieve high salt rejections. Such models will be useful in accelerating structure-separation property relationships of GO membranes and for separation process design and optimization.     

A high flux graphene oxide nanoparticles embedded in PAN nanofiber microfiltration membrane for water treatment applications with improved anti-fouling performance

A high flux and anti-fouling graphene oxide (GO) nanoparticles embedded in polyacrylonitrile (PAN) nanofiber microfiltration membranes (PANGMs) were fabricated through the facile electrospinning method and were characterized by water treatment applications. The synthesized GO nanoparticles and GO nanoparticles embedded in PAN nanofiber membranes were characterized by FESEM, FTIR, and EDS. SEM images showed that the PANGMs possessed randomly overlaid fibers with a network-like highly porous structure similar to the pristine PAN nanofiber membrane, while agglomeration of GO nanoparticles was observed at high GO concentration. The introduction of GO nanoparticles into the PAN polymeric matrix significantly increased the permeation flux of the resulting membrane in both dead-end and cross-flow filtration systems. A high flux recovery ratio of 96.6% and a low irreversible fouling ratio of 3.4% were obtained at 2% (wt.) GO nanoparticles. More importantly, a high flux recovery ratio of GO nanoparticles embedded in PAN nanofiber membrane was retained after 20 repeated cycles of activated sludge suspension filtration. Therefore, it can speculate that the incorporation of GO nanoparticles into the PAN nanofibers could efficiently improve the anti-fouling ability of membranes which had opened up an alternative for the preparation of high flux and anti-fouling microfiltration membranes in practical water treatment applications such as membrane bioreactors.

     

Ultrafast water-selective permeation through graphene oxide membrane with water transport promoters

Graphene oxide (GO), as a representative two-dimensional material, has shown great prospect in developing high-performance separation membranes via forming ordered and tunable nanochannels. However, for aqueous molecular separations, the implementation of an excellent separation performance remains a critical challenge due to the membrane swelling phenomenon and the trade-off effect between permeation flux and separation factor. Herein, a facile and tunable approach is presented for introducing water transport promoters into GO interlayer channels to construct water transport highways. The combination of covalently cross-linked channel structure, facilitated water-selective sorption, and expedited water-preferential diffusion overcome the trade-off effect, achieving a superior performance from an ultrathin GO membrane with a flux of 5.94 kg/m²∙h and a water/butanol separation factor of 3,965, which exceeds the performance of state-of-the-art membranes for water/butanol separation. The strategy proposed here is straightforward, holding great potential to produce high-efficiency GO and other two-dimensional (2D)-material membranes for precise aqueous molecular separations.     

Development of a novel graphene oxide-blended polysulfone mixed matrix membrane with improved hydrophilicity and evaluation of nitrate removal from aqueous solutions

In this study, four types of mixed matrix membranes were fabricated using polysulfone (as the base polymer) and different contents of graphene oxide (GO) nanosheets (as modifier) through wet phase inversion method. Based on the amounts of GO (0, 0.5, 1, and 2?wt%), the synthesized membranes named as M1, M2, M3, and M4, respectively. The membranes characteristics were evaluated using FE-SEM, FT-IR, and water contact angle measurements. In addition, the performance of the prepared membranes was investigated in terms of basic parameters: filtrate water flux, nitrate removal efficiency, and antifouling properties. Results showed significant improvements of the characteristics of modified membranes with GO. Accordingly, the permeability and hydrophilicity were enhanced and water flux was considerably improved. At operating pressure of 4?bar and nitrate concentration of 110?mg/L, the removal efficiency for unmodified membrane (M1) was 15.5% and for modified M2, M3, and M4 membranes were 22.78%, 39.12%, and 41.37%, respectively. In addition, the results of flux recovery ratio (FRR) showed that the anti-fouling properties of the GO modified membranes were improved due to the increase in membrane surface hydrophilicity.     

A graphene oxide membrane with self-regulated nanochannels for the exceptionally stable bio-oil dehydration

The transport behaviors and nanochannel structures of a graphene oxide (GO) membrane were studied for pervaporation dehydration of bio-oil with a high acidity and a complex composition. The GO membrane showed an unprecedentedly stable water flux of approximately 0.43 kg m⁻² hr⁻¹, with a water content of 97 wt% in the permeate throughout 70 hr of pervaporation testing at 30°C. Both the calculated activation energy for water permeation and X-ray diffraction characterization results confirmed that the nanochannel structures of the GO membrane were temperature- and liquid media-responsive. The molecular intercalation-induced self-regulation of the size of laminar nanochannels in the GO membrane was suggested to be primarily responsible for the significantly reduced membrane fouling and the exceptionally stable pervaporation performance for the GO membrane. The mechanistic insights into the nanochannel structures and antifouling properties would provide important inspiration for the design of novel highly fouling-resistant membrane materials for practical applications.     

Cellulose acetate ultrafiltration membranes customized with copper oxide nanoparticles for efficient separation with antifouling behavior

Cellulose acetate (CA) nanocomposite ultrafiltration membranes are fabricated with copper oxide (CuO) nanoparticles with the aim of improving efficient protein separation and antifouling performance. CuO nanoparticles are synthesized from cupric nitrate using a wet precipitation method and characterized by FTIR and XRD. CA/CuO nanocomposite membranes fabricated using 0.5, 1.0, and 1.5 wt% of CuO nanoparticles individually by simple phase inversion technique. The CA nanocomposite membrane with 0.5 wt% of hydrophilic CuO exhibited enhanced PWF of 118.6 Lm⁻² h⁻¹ due to the improvement in porosity and water uptake. This is in good agreement with the enhanced hydrophilicity of the CA/CuO nanocomposite membranes results observed in surface contact angle and morphological investigations. Further, 95.5% of BSA separation and 94.7% of flux recovery ratio (FRR) indicates its superior antifouling potential caused due to the presence of the hydration layer at the CA/CuO membrane surface. Among all the fabricated membranes, the CA-0.5 nanocomposite membrane with 0.5 wt% of CuO exhibited superiorly improved hydrophilicity, water permeation, BSA separation, and antifouling performance indicates its potential use in water and wastewater treatment applications.