Modified Graphene Oxide Research Articles

Regulating the thickness of nanofiltration membranes for efficient water purification.

Fabrication of an organic polymer nanofiltration membrane with both high water permeability and high salt rejection is still a big challenge. Herein, phytic acid (PhA)-modified graphene oxide (GO) was used as the membrane thickness modifier, which was introduced into the thin-film nanoparticle composite (TFN) membrane via in situ interfacial polymerization (IP) on a porous substrate. The water flux of the optimally tuned TFN-GP-0.2 composite membrane is 48.9 L m-2 h-1, which is 1.3 times that of the pristine thin-film composite (TFC) nanofiltration membrane (37.9 L m-2 h-1) (GP represents the PhA modified GO composite). The rejection rate of 2000 ppm MgSO4 for TFN-GP-0.2 membranes was maintained at 97.5%. The increased water flux of the TFN-GP composite membrane compared to that of the TFN nanofiltration membrane was mainly attributed to enhanced hydrophilicity and reduced thickness of the polyamide (PA) layer. Molecular dynamics (MD) simulations confirm that the diffusion rate of amine monomers is reduced by the presence of a GP complex in the IP process, which facilitates the formation of PA layer with thinner thickness. In addition, the TFN-GP-0.2 composite membrane also showed good long-term stability; after 12 h of continuous operation, the water flux only decreased by 0.1%. This study sheds new light on the development of GO-based nanofiltration for potential implementation, as well as a unique concept for manufacturing high-performance nanofiltration membranes.

Study on the Hydration and Physical Properties of Cement by M18 Polycarboxylate Superplasticizer Modified Graphene Oxide

Graphene oxide (GO) as a new nano-enhancer in cement-based materials has gained wide attention. However, GO is easy to aggregate in alkaline cement mortar with poor dispersibility. This hinders its application in practical infrastructure construction. In this work, GO-M18 polycarboxylate compound superplasticizer (GM) were obtained by compounding the M18 polycarboxylate superplasticizer with GO solution at different mass ratios. The dispersion of GM in alkaline solution was systematically studied. The phases and functional groups of GM were characterized by XRD and FTIR. The effects of GM on the cement mortar hydration and the formation of microstructure were investigated by measuring the heat of hydration, MIP, TG/DSC, and SEM. The results show that the long-chain structure of the M18 polycarboxylate superplasticizer can increase the interlayer spacing of GO and weaken the force between GO sheets. The modified GO can be uniformly dispersed in the cement slurry. GM can accelerate the early hydration process of cement, which can increase the content of Ca(OH)2 and decrease the grain size. It can optimize the pore size distribution of cement-based materials, increase the density of harmless and less harmful pores, thereby improving mechanical properties. Such methods can transform traditional cement-based materials into stronger, more durable composites, which prolong the life of cement-based materials and reduce the amount of cement used for later maintenance. This provides an idea for achieving sustainability goals in civil engineering.

Harnessing graphene oxide nanocarriers for siRNA delivery in a 3D spheroid model of lung cancer.

Gene therapy has been recently proposed as an effective strategy for cancer treatment. A significant body of literature proved the effectiveness of nanocarriers to deliver therapeutic agents to 2D tumour models, which are simple but not always representative of the in vivo reality. In this study, we analyze the efficiency of 3D spheroids combined with a minimally modified graphene oxide (GO)-based nanocarrier for siRNA delivery as a new system for cell transfection. Small interfering RNA (siRNA) targeting cluster of differentiation 47 (CD47; CD47_siRNA) was used as an anti-tumour therapeutic agent to silence the genes expressing CD47. This is a surface marker able to send a "don't eat me" signal to macrophages to prevent their phagocytosis. Also, we report the analysis of different GO formulations, in terms of size (small: about 100 nm; large: >650 nm) and functionalization (unmodified or modified with polyethylene glycol (PEG) and the dendrimer PAMAM), aiming to establish the efficiency of unmodified GO as a nanocarrier for the transfection of A549 lung cancer spheroids. Small modified GO (smGO) showed the highest transfection efficiency values (>90%) in 3D models. Interestingly, small unmodified GO (sGO) was found to be promising for transfection, with efficiency values >80% using a higher siRNA ratio (i.e., 3 : 1). These results demonstrated the higher efficiency of spheroids compared to 2D models for transfection, and the high potential of unmodified GO to carry siRNA, providing a promising new in vitro model system for the analysis of anticancer gene therapies.

Linear maltodextrin polymer–folic acid modified graphene oxide nanoparticles for targeted delivery and pH/photothermal sensitive release of hydrophobic anticancer drugs in tumor cells

GO@LM-SP-FA was constructed by connecting linear maltodextrin polymer and folic acid to the surface of graphene oxide nanoparticles. Doxorubicin hydrochloride was loaded into GO@LM-SP-FA to form GO@LM-SP-FA/DOX, and controlled release of anticancer drugs was realized.

Design of a new polyethersulfone nanofiltration membrane with anti-fouling properties using supported protic ionic liquid modification for dye/salt removal.

Facile techniques to fabricate the nanofiltration membranes with ideal molecular sieving is one of the most interesting subjects in membrane separation technology. In this study, the application of modified graphene oxide (GO) with triethylenetetramine (TETA), CuFe2 O4 , and acetic acid (AC) (supported GO-TETA-CuFe2 O4 @AC) as a supported protic ionic liquid (PIL) modifier for polyethersulfone (PES) membrane was evaluated to approve the improvement of anti-fouling properties and wastewater rejection of the fabricated membranes. To enhance the key properties of graphene oxide, it was modified by hydrophilic nanomaterials (TETA-CuFe2 O4 ). High flux and promising flux recovery ratio (up to 95% compared to the unmodified membrane) can be observed in the modified membranes. The modified membranes by GO-TETA-CuFe2 O4 @AC were studied at optimum concentrations (0.5 wt.%) for salt rejection and different dyes. The obtained data indicated that the modified membranes by GO-TETA-CuFe2 O4 @AC indicated higher salt removal (up to 97% for BaCl2 than the unmodified membrane), which was related to the efficient modification. The obtained pure water flux (PWF) for bare and optimal modified membrane from 13.11 to 27.87 kg/m2 ·h, respectively. To exact evaluate the effect of membrane modification on performance examination, the modified membranes were evaluated for chlorine resistance testing. This study aimed to develop cost-effective nanofiltration (NF) membranes with high anti-fouling properties and to determine the maximum filtration capacity of in-time dyes and salts in effluents. PRACTITIONER POINTS: A GO-TETA-CuFe2O4 mixed matrix membrane was prepared for removal of salts and dyes. The effect of GO-TETA-CuFe2O4 enhanced the hydrophilicity and porosity. The membrane exhibited superior antifouling properties and ions rejection.

An overview of the application of graphene-based materials in anticorrosive coatings

• Anti-corrosion performance of graphene and graphene based material coatings is reviewed. • Chemically modified graphene oxide emerged as new class of corrosion inhibitors. • Future development directions for graphene anti-corrosive coatings are anticipated. Graphene-based materials (GBMs) have an extensive range of potential uses, but over past ten years, interest in their usage as barrier layer or as reinforcements in coatings for corrosion prevention has developed. This review compiles the most recent information and seeks to provide authors with a broad synopsis of the most contemporary progresses in the application of GBMs in various anti-corrosion techniques.

Amino acid-driven adsorption of emerging contaminants in water by modified graphene oxide nanosheets

Amino acid modified graphene nanosheets adsorb emerging contaminants from tap water outperforming unmodified precursors and activated carbon for carbamazepine, bisphenol A and benzophenone 4. Structure–adsorption relationships are unraveled.

A Review of Graphene Oxide Crosslinking as Enhanced Corrosion Shield Application

Nowadays, corrosion is not only undesirable, but it also has a significant influence on the industrial sectors and technical innovations that have demand for metals. The global economic damage is expected to reach $2.5 trillion, equivalent to more than 3.4% of the world’s GDP in 2013. It is linked with significant financial harm, manufacturing pollution, and safety issues. An electrochemical process primarily induces metal corrosion at the metalelectrolyte interface region, caused by steel oxidation and the reduction of oxygen, protons, and water. Therefore, organic and epoxy coatings can be applied as protective coatings. Additionally, it can prevent metal corrosion in various fields due to its unique properties, like the ability to manage its curing process over a long period. This review paper focuses on improving the physicomechanical properties of modified graphene oxide (GO) coating by attaching a polymer, epoxy resin (EP). Moreover, we reviewed recent achievements for different methods in minimizing a corrosion phenomenon. Further, we considered the modification of epoxy resin using the curing agent as a bridge to the polymer to strengthen the functionalization of nanocomposites during the reaction. Afterward, we discussed the relationship between the modified GO/EP anticorrosive coating and physicomechanical properties since it is currently being questioned and remains unresolved. As a result, extensive studies on the mechanism of synthesis of the modified GO/EP anticorrosive coating were highlighted.

Research progress on graphene oxide modification of titanium surface

Research progress on graphene oxide modification of titanium surface

Hydrophobic metal-organic framework@graphene oxide membrane with enhanced water transport for desalination

As a new generation of high-performance alternative, graphene-based membranes have shown great prospect in water purification. Among them, numerous efforts are concentrated on designing hydrophilic membranes while less attention is paid to hydrophobic membranes, which limit the potential application of graphene-based membranes, such as desalination via membrane distillation (MD) process. Anisotropic heat transfer and easy hydrophobic modification of graphene oxide (GO) make it suitable for MD membrane fabrication. Herein, we developed a novel porous and hydrophobic MOF-801@GO-PDMS membrane with enhanced water vapor transport for water desalination via direct contact membrane distillation (DCMD). MOF-801 nanoparticles were in-situ grown within GO interlayer followed with vacuum filtration to fabricate MOF-801@GO membrane which was subsequently modified with polydimethylsiloxane (PDMS) to fabricate the MOF-801@GO-PDMS membrane. The water-stable porous MOF-801 nanoparticle was introduced to increase the porosity of GO laminate and provide extra water vapor transport channels. PDMS was employed to ensure the membrane hydrophobic stability by utilizing its intrinsic hydrophobicity and segment entanglement. The optimum MOF-801@GO membrane exhibited water flux of 29.24 kg m−2 h−1 and NaCl rejection of over 99.99%, as well as robust stability during continuous DCMD desalination test. This work not only gives a promising candidate for water desalination, but also provides a method to design hydrophobic and porous graphene-based nanostructures for other potential applications.

Layer-by-layer assembly of calixarene modified GO and LDH nanostructures on flame retardancy, smoke suppression, and dye adsorption behavior of flexible polyurethane foams

In this study, the effect of LbL coatings based on layered double hydroxide (LDH), graphene oxide (GO), and sodium p-sulfonatocalix[4]arene (SC4A) modified graphene oxide (GOSC4A) on the fire properties and dye adsorption behavior of flexible polyurethane foam was investigated. For this purpose, samples including neat PU foam and modified PU foams with 3, 6, and 9 bilayers of LDH-GO and LDH-GOSC4A coatings were prepared. SEM micrographs of the prepared foams confirmed the presence of LDH-GO and LDH-GOSC4A coatings on the foam surface and showed that the LDH-GOSC4A layers form a denser and more uniform coating on the PUF surface. Combustion studies of prepared foams using CCT and horizontal burning test demonstrated that at the same number of bilayers, foams including LDH-GOSC4A coatings showed better flame retardancy than LDH-GO coated foams. Therefore, the PUF/LDH-GOSC4A 9BL foam showed the best fire properties, and its PHRR, THR, and TSP values ​​were reduced by 28.8, 11.8, and 36.3%, respectively, compared to uncoated PUF. Methylene blue (MB) adsorption studies revealed that adsorption of MB onto PUF/LDH-GOSC4A 9BL is well consistent with the pseudo-second-order kinetic model and its maximum adsorption capacity is 38.46 mg/g based on the Langmuir isotherm equation.

Corrosion behaviour of zinc coated with composite silica layers incorporating poly(amidoamine)-modified graphene oxide

Corrosion behaviour of zinc coated with composite silica layers incorporating poly(amidoamine)-modified graphene oxide

Mechanical and Recyclable Properties of Polyimine Enhanced by Biomimetic Modification of Graphene Oxide Sheets/Silicon Carbide Nano-Whiskers.

Inspired by the mineral bridge between hard phase layers of natural nacre, the biomimetic modified silicon carbide nano-whiskers (MSiCw)/graphene oxide sheets (MGO) reinforced polyimine (PI) composites (MSiCw-MGO-PI) were successfully prepared by heat-pressing at room temperature, which confirmed by FTIR, XPS, and XRD tests. According to the results of mechanical tests, the composites with filling weights of MSiCw and MGO, which were found to be 1% and 0.3%, presented tensile strength of 94.27 MPa, which was 32% higher than the matrix. With the additional weights amount of 1%MSiCw and 0.2%MGO, the impact strength of the composites reached 17.46 KJ/m2, which was increased by 81% compared with the matrix. In addition, the reinforcing mechanisms, such as the bridging principle and mechanism of whiskers pulling out, were investigated by analyzing the fracture surface of MSiCw-MGO-PI composites. The results showed that MSiCw and MGO can synergistically improve the mechanical properties of the composites. In addition, the recyclability of the composites valued by the mechanical properties of the composites from regrinding and heat pressing showed that three generations of MSiCw-MGO-PI composites can still maintain high mechanical properties on account of the better dispersion of the reinforcing phases in the matrix from regrinding.

Influence of modified graphene oxide on the antifouling performance of waterborne polyurethane coatings containing amphiphilic honeycomb surface

Influence of modified graphene oxide on the antifouling performance of waterborne polyurethane coatings containing amphiphilic honeycomb surface

Multilayer SnS-SnS2@GO heterostructures nanosheet as anode material for Sodium ion battery with high capacity and stability

SnS and SnS2 are two promising anode materials with excellent theoretical capacity for Sodium ion batteries. However, severe volume collapse and low electric charge conductivity dramatically affect the electrochemical performance of SnS and SnS2. As a consequence, SnS-SnS2 heterostructures are constructed to improve the conductivity of the anode material. The volume effect is prevented by compounding with Graphene Oxide (GO) to ensure cyclic stability and improve the initial coulombic efficiency of anode materials. The first-principles simulation is used to simulate SnS, SnS2, SnS-SnS2 and SnS-SnS2 @GO respectively, and the comparison is made through actual experiments. Experimental studies indicate that SnS-SnS2 @GO processes superior conductivity and cycle stability, unique nano-flake structure and the composite modification of GO can restrain the volume effect and ensure long cycle stability of the anode material (450.6 mAh·g−1 after 100 cycles). Moreover, attributing to the p-n heterostructures, the internal charges transfer and improve the electrical conductivity of SnS-SnS2 can be promoted obviously. Simultaneously, it has been detected that the multilayer SnS-SnS2 heterostructures combining GO effectively improve the conductivity and ensure good structure stability. Therefore, SnS-SnS2 @GO composites can be considered as an ideal anode material for sodium ion batteries.

Rapid incorporation of gold nanoparticles onto graphene oxide-polymer nanofiber membranes for photothermally-accelerated water purification

Abstract This work demonstrates the rapid coating of gold nanoparticles (AuNPs) onto electrospun composite polyacrylonitrile (PAN) nanofibers containing a large amount of graphene oxide (GO) and reduced graphene oxide (rGO) for photothermally-driven applications. A modification of GO with a cationic surfactant greatly improves its loading efficiency into the PAN nanofibers, and the subsequent hydrazine treatment readily converts the integrated GO into rGO. Rapid loading of AuNPs onto these membranes results in measurably higher photothermal heating characteristics than the pristine PAN, GO-PAN, and rGO-PAN membranes under a solar-simulated light source. The light-induced heating properties are then utilized in the removal of organic dyes in an aqueous solution. While the GO-PAN and rGO-PAN membranes remove the dyes via physical adsorption, the AuNP-loaded membranes show an additional catalytic decomposition process, resulting in detectably faster removal rates. The degradation of the organic dyes is accelerated under a solar simulated light source due to the light-enhanced heating and photocatalytic properties of the integrated AuNPs. The ability to maximize the dual properties of these membranes can greatly reduce toxic organic pollutants, which can lead to the development of practical water purification systems under sunlight irradiation.

Hydrogel-based thermosensor using peptide nucleic acid and PEGylated graphene oxide

Developing a ready-to-use miniaturized thermosensor is a great challenge due to its individual use on a large scale for daily business such as food industry and healthcare. Herein, a polyethylene glycol (PEG)-modified graphene oxide (GO)-based hydrogel thermosensor was established with a fluorescent dye-labeled peptide nucleic acid (F-PNA). The size-tunable hydrogel with high water content and sufficient solidity allowed free movement of the oligonucleotides through the pores and improved usability for handling the sensor. In the PEG-GO hydrogel, the DNA/F-PNA duplex could be denatured by increasing the temperature, followed by selective PNA capture on the PEG-GO. Using this principle, the PEG-GO hydrogel exhibited a change in the fluorescence signal of F-PNA in a temperature-dependent manner, allowing real-time visualization of temperature on a large scale. The temperature detection range of this system can be adjusted by designing the PNA strands based on the melting temperature of the DNAzyme/PNA duplex. Its sensing specificity and detection range could be increased and broadened by observing multi-color detection using PNA probes labeled with different fluorescent dyes of different lengths in a single hydrogel. In addition, the hydrogel platform is easy to store for long time periods via dehydration and can be restored with the addition of water, allowing easy transport, storage, and use of the thermosensor in everyday life.

Antioxidant modified graphene oxide for robust and highly aging resistant rubber composites

In this work, rubber antioxidant poly(1,2-dihydro-2,2,4-trimethylquinoline) (RD) was introduced as organic surface modifier of graphene oxide (GO) for the preparation of robust and highly anti-aging rubber composites. It was found that RD was chemically grafted on GO surface by C–N bond. Interestingly, the oxygen-containing groups on GO were also substantially removed after surface modification, indicating the good reducing capability of RD on GO. As RD with large molecular weight could significantly diminish the restacking of graphene sheets and form inherent π–π interaction with styrene moieties in styrene-butadiene rubber (SBR), the modified GO (G-RD) showed fine dispersion in SBR matrix and improved interfacial interaction with rubber chains, leading to much better mechanical performance and thermal conductivity of SBR/G-RD composites than those of SBR composites with hydrazine hydrate reduced GO (H-G). Moreover, thanks to the improved barrier effect of G-RD due to its good dispersion and suppressed physical loss of RD due to its chemical grafting, SBR/G-RD composites exhibited exceptionally high long-term thermal-oxidative aging resistance compared with SBR composites with H-G and ungrafted RD, indicating that G-RD can well fit the bill of long-term applications of unsaturated rubbers in some harsh service conditions.

Epoxy primer topcoat syncretic coating prepared by using modified graphene oxide incorporated with TiO2 nanoparticles

A novel epoxy primer topcoat syncretic coating with superior corrosion resistance and weathering resistance was developed by using modified graphene oxide incorporated with TiO2 nanoparticles as effective fillers. Compared with pure epoxy resin coating, the corrosion products around scratches of epoxy primer topcoat syncretic coatings were significantly reduced after salt spray testing for 300 h, and the highest wet adhesion and the minimum adhesion loss rate of it were 1.73 MPa and 36.63%, respectively. After ultraviolet-accelerated aging for 20 d, the low-frequency impedance modulus value was 7.27 × 108, which was increased about one order of magnitude than pure epoxy resin coating. In addition, the lowest self-corrosion current density was 31.705 pA·cm–2, and the lowest corrosion rate is 14.56 mpy. These interesting features could make the epoxy primer topcoat syncretic coating as a promising anti-corrosion coating for metallic long-term protection.

Efficient uranium adsorbent prepared by grafting amidoxime groups on dopamine modified graphene oxide

In this study, a novel amidoxime functionalized graphene oxide adsorbent (GO-D-AO), based on the reaction of dopamine modified graphene oxide with acrylamide diacetonitrile and on the reaction of amidoximation, was successfully designed and prepared to effectively adsorb U(VI) ions. GO-D-AO was characterized by SEM, FT-IR, XRD and XPS techniques, and then applied as the adsorbent for the U(VI) adsorption. The GO-D-AO contained more amidoximation groups after the amidoximation modification due to the use of acrylamide diacetonitrile modifier. A series of adsorption experiments were carried out to investigate the influence factors in the adsorption process, including the pH values, contact time, temperature and initial concentration of U(VI) solution. The U(VI) maximum adsorption capacity of GO-D-AO was 1823.6 mg·g -1 , which was significantly higher than that of GO because of the excellent chelating ability of amidoxime group with U(VI) ions. And the U(VI) adsorption process of GO-D-AO fitted well with the Langmuir model and the pseudo-second-order kinetic model, indicating the adsorption process was monolayer and chemical adsorption.