Performance Of Graphene Oxide Membranes Research Articles

The performance of a graphene oxide thin film composite membrane for sweet whey ultrafiltration

Membranes manufactured from graphene oxide (GO) have received significant attention for desalination and nanofiltration applications due to their exceptional mechanical strength, chemical stability and high selectivity. However, the performance of GO membranes in food processing applications is less well understood. In this work, the performance of a GO membrane, advertised as being of 1 kDa molecular weight cutoff, is compared to that of two commercial polymeric membranes of different molecular weight cut-off (advertised as 10 kDa and 1 kDa) for the ultrafiltration of sweet whey from the dairy industry. At bench scale, the GO membrane had comparable rejection for both total solids and protein to the 10 kDa polymeric membrane, but with more than double the flux, provided by a much lower intrinsic membrane resistance. Analysis of the membrane fouling process suggested that the GO membrane fouled more slowly than the 1 kDa polymeric membrane, but the fouling process was not significantly different to that reported in the literature for polymeric membranes in this application. Pilot scale trials conducted using a commercial spiral wound module of 1.2 m2 area of the GO membrane confirmed that the membrane retained a higher flux. This flux was, however, reduced from the bench scale value.

Layered graphene oxide membrane for heavy metal separation via molecular dynamics simulation

Layered graphene oxide membrane for heavy metal separation via molecular dynamics simulation

Effect of Addition Amount of Ethylenediamine on Interlayer Nanochannels and the Separation Performance of Graphene Oxide Membranes.

In recent years, graphene oxide (GO)-based two-dimensional (2D) laminar membranes have attracted considerable attention because of their unique well-defined nanochannels and deliver a wide range of molecular separation properties and fundamentals. However, the practical application of 2D GO layered membranes suffers from instability in aqueous solutions as the interlayer d-spacing of GO membranes is prone to expansion caused by the hydration effect. In this study, the effects of the ethylenediamine (EDA) addition amount on the structure, crosslinking mechanism and separation performance of GO membranes were investigated systematically, and membrane performance was evaluated using water permeability and dye/salt rejection tests. The experimental results show that the amine groups of EDA chemically bond with the hydroxyl functional group (O=C-OH) of GO after intercalation, as evident from Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). By further controlling the amount of the intercalated EDA, the as-prepared GO composite membranes show nanoscale-tuned d-spacing promising for downstream applications. In the demonstrated dye/salt nanofiltration scenario, the EDA intercalated and crosslinked GO membrane has enhanced permeability by over five times and a better dye rejection rate of over 96% compared with pure GO membranes. These findings highlight a facile strategy for controlling nanochannels by tuning the amounts of reactive intercalants.

Enhanced Separation Performance of Graphene Oxide Membrane through Modification with Graphitic Carbon Nitride

The treatment of tritiated nuclear wastewater is facing greater challenges with the continuous expansion of the nuclear industry. The key to solving the issue of detritium in low-abundance tritium water lies in developing highly efficient and cost-effective hydrogen isotope separation technology. Graphene oxide (GO) membrane separation method exhibits greater potential compared to other existing energy-intensive technologies for the challenging task of hydrogen isotope separation in nuclear wastewater. In recent years, researchers have explored few strategies to enhance the performance of graphene oxide (GO) membranes in hydrogen isotope water treatment, recognizing the current limitations in separation efficiency. In this study, the GO/g-C3N4 composite membrane has been successfully employed for the first time in the separation of hydrogen isotopes in water. A series of GO membranes were prepared and their performances were tested by a self-made experimental device. As a result, the separation performance of the GO membrane was enhanced by the modification with graphitic carbon nitride (g-C3N4). The permeation rate of the GO/g-C3N4 membrane was higher than that of the GO membrane, while maintaining a high separation factor. Our study also demonstrated that this phenomenon can be attributed to the changes in membrane structure at the microscopic scale. The H/D separation factor and the permeate flux of the composite membrane containing g-C3N4 of 6.7% by mass were 1.10 and 7.2 × 10−5 g·min−1·cm−2 are both higher than that of the GO membrane under the same experimental conditions, which is promising for the isotope treatment.

Unveiling the importance of surface ionization on desalination and ion-sieving performance of graphene oxide membranes

Unveiling the importance of surface ionization on desalination and ion-sieving performance of graphene oxide membranes

Modeling and optimization of Graphene Oxide (GO) membranes for nanofiltration with artificial neural networks

Modeling and optimization of Graphene Oxide (GO) membranes for nanofiltration with artificial neural networks

Nitrile derivative functionalized graphene oxide membranes for efficient separation of strontium from aqueous waste

Nitrile derivative functionalized graphene oxide membranes for efficient separation of strontium from aqueous waste

Improvement of water filtration performance of graphene oxide membranes on Nylon support by UV-assisted reduction treatment: Control of molecular weight cut-off

Improvement of water filtration performance of graphene oxide membranes on Nylon support by UV-assisted reduction treatment: Control of molecular weight cut-off

Graphene oxide nanofiltration membranes with confined Na+ in two-dimensional nanochannels

Graphene oxide nanofiltration membranes with confined Na+ in two-dimensional nanochannels

The role of driving force directions of preparation in microstructure and performance of graphene oxide membranes

The role of driving force directions of preparation in microstructure and performance of graphene oxide membranes

The role of oxidation level in mass-transport properties and dehumidification performance of graphene oxide membranes

The role of oxidation level in mass-transport properties and dehumidification performance of graphene oxide membranes

2D Heterostructured Nanofluidic Channels for Enhanced Desalination Performance of Graphene Oxide Membranes.

The two-dimensional (2D) lamellar membrane assembly technique shows substantial potential for sustainable desalination applications. However, the relatively wide and size-variable channels of 2D membranes in aqueous solution result in inferior salt rejections. Here we show the establishment of nanofluidic heterostructured channels in graphene oxide (GO) membranes by adding g-C3N4 sheets into GO interlamination. Benefiting from the presence of stable and sub-nanometer wide (0.42 nm) GO/g-C3N4 channels, the GO/g-C3N4 membrane exhibits salt rejections of ∼90% with water permeances of above 30 L h-1 m-2 bar-1, while the pure GO membrane only has salt rejections of below 30% accompanied by water permeances of below 4 L h-1 m-2 bar-1. Combining experimental and theoretical investigations, size exclusion has proved to be the dominating mechanism for high rejections, and the ultralow friction water flow along g-C3N4 sheets is responsible for permeation enhancements. Importantly, the GO/g-C3N4 membrane shows promising long-term, antioxidation, and antipressure stability.

Improvement of Water Filtration Performance of Graphene Oxide Membranes by UV-Assisted Reduction Treatment

Improvement of Water Filtration Performance of Graphene Oxide Membranes by UV-Assisted Reduction Treatment

Mild temperature-gas separation performance of graphene oxide membranes for extended period: micropore to meso- and macropore readjustments and the fate of membranes under the influence of dynamic graphene oxide changes

Mild temperature-gas separation performance of graphene oxide membranes for extended period: micropore to meso- and macropore readjustments and the fate of membranes under the influence of dynamic graphene oxide changes

Graphene Oxide Membranes for Trace Hydrocarbon Contaminant Removal from Aqueous Solution

The aim of this paper is to shed light on the application of graphene oxide (GO) membranes for the selective removal of benzene, toluene, and xylene (BTX) from wastewater. These molecules are present in traces in the water produced from oil and gas plants and are treated now with complex filtration systems. GO membranes are obtained by a simple, fast, and scalable method. The focus of this work is to prove the possibility of employing GO membranes for the filtration of organic contaminants present in traces in oil and gas wastewater, which has never been reported. The stability of GO membranes is analyzed in water solutions with different pH and salinity. Details of the membrane preparation are provided, resulting in a crucial step to achieve a good filtration performance. Material characterization techniques such as electron microscopy, x-ray diffraction, and infrared spectroscopy are employed to study the physical and chemical structure of GO membranes, while gas chromatography, UV-visible spectroscopy, and gravimetric techniques allow the quantification of their filtration performance. An impressive rejection of about 90% was achieved for 1 ppm of toluene and other pollutants in water, demonstrating the excellent performance of GO membranes in the oil and gas field.

Relationship between Desalination Performance of Graphene Oxide Membranes and Edge Functional Groups.

High desalination efficiency in principle could be achieved by layer-by-layer graphene oxide (GO) membranes, which benefits from their entrance-functionalized channels assembled by edge-functionalized GO nanosheets. The effects of these edge functional groups on desalination, however, are not fully understood yet. To study the isolated influence of three typical edge functional groups, namely, carboxyl (-COOH), hydroxyl (-OH), and hydrogen (-H), molecular dynamics simulation was used in this work. The results revealed that the edge volumetric blockage effect, resulting in ion permeability at G-H > G-OH > G-COOH membranes, was the dominant mechanistic effect inside the GO membranes with 7 Å interlayer channels. The OH edge has the same effect as the H edge in NaCl/water selectivity because of a unique "ion pulling" effect. Moreover, the OH and H edge-functionalized membranes with 7 Å interlayer channels showed preferential Na+ and Cl- rejections, respectively. This kind of preference leads to a cycle of charging and neutralization in the penetrant reservoir throughout the filtration process. The results from this work suggested that it would be strategic to keep the COOH and H edge functional groups, to maintain the size of interlayer channels in order to stimulate the effects of edge functional groups, and to increase the membrane porosity for designing higher desalination efficiency GO membranes.

The application feasibility of graphene oxide membranes for pressure-driven desalination in a dead-end flow system

The application feasibility of graphene oxide membranes for pressure-driven desalination in a dead-end flow system

Selective molecular separation of lignin model compounds by reduced graphene oxide membranes from solvent-water mixture

Selective molecular separation of lignin model compounds by reduced graphene oxide membranes from solvent-water mixture

The Variations of Structure and Water Flux Performance of Porous Alumina Supported Graphene Oxide Membrane During Heat Treatment Process

Graphene oxide membrane was fabricated based on a silane-modified Al2O3 ceramic substrate via a parallel dip-coating method. The effect of thermal treatment on the structure and performance of graphene oxide membranes was mainly studied in this paper. The thermal behaviours of graphene oxide powder and membranes were analysed by thermogravimetry (TG) and differential scanning calorimetry (DSC). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied for micro-morphology analysis. The category and content of chemical bonds were studied by fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS), and the interplanar spacing was investigated by X-ray diffraction (XRD). It was found that the thermal treatment temperature should not exceed 350 °C in order to ensure the integrity of the graphene oxide basic structure. The content of functional groups in graphene oxide was altered along with various temperatures, which led to changes in the contact angle and hydrophilicity. The pure water flux reached 15 L m–2 h –1 under 0.2 MPa pressure when the ceramic substrate was coated with 0.5 mg/mL graphene oxide dispersion and treated at 190 °C. The study indicates that the performance of the graphene oxide/ceramic composite membranes can be optimized by heat treatment.

In Silico Design and Characterizationof Graphene Oxide Membranes with Variable Water Content and FlakeOxygen Content

Grapheneoxide (GO) membranes offer exceptional promise for certainaqueous separation challenges, such as desalination. Central to unlockingthis promise and optimizing performance for a given separation isthe establishment of a detailed molecular-level understanding of howthe membrane’s composition affects its structural and transportproperties. This understanding is currently lacking, in part due tothe fact that, until recently, molecular models with a realistic distributionof oxygen functionalities and interlayer flake structure were unavailable.To understand the effect of composition on the properties of GO membranes,models with water contents and oxygen contents, varying between 0%and 40% by weight, were prepared in this work using classical moleculardynamics simulations. The change in membrane interlayer distance distribution,water connectivity, and water diffusivity with water and oxygen contentwas quantified. Interlayer distance distribution analysis showed thatthe swelling of GO membranes could be controlled by separately tuningboth the flake oxygen content and the membrane water content. Water-moleculecluster analysis showed that a continuous and fully connected networkof water nanopores is not formed until the water content reaches ∼20%.The diffusivity of water in the membrane was also found to stronglydepend on both the water and the oxygen content. These insights helpunderstand the structure and transport properties of GO membraneswith sub-nanometer interlayer distances and could be exploited toenhance the performance of GO membranes for aqueous separation applications.More broadly, the high-throughput in silico approachadopted could be applied to other nanomaterials with intrinsic non-stoichiometryand structural heterogeneity.