Amount Of Graphene Oxide Nanosheets Research Articles

Ultrasensitive QCM sensor development for monitoring of methyl orange dye in aqueous phase based on novel cross-linked chitosan/PVA/GO/Ce-ZnO nanocomposite film

In this study, chitosan/polyvinyl alcohol (CS/PVA) nanocomposite hydrogels were produced using the solution casting method due to their non-toxic and biocompatible nature. The best composition was chosen and cross-linked with glutaraldehyde, after which a certain amount of graphene oxide nanosheets (GO NS) and cerium doped zinc oxide nanoparticles (Ce-ZnO NPs) were added to develop nanocomposite hydrogel films (NCs). X-ray diffractometer (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), N2 adsorption–desorption isotherm, Raman spectroscopy, and thermogravimetric analyzer (TGA/DTG) were used to characterize the films. The synthesized composites were also evaluated for sensitivity towards methyl orange (MO) dye based on the quartz crystal microbalance (QCM) technique at different pH of MO solution. XRD results revealed that all films whether CS film or the blend CS/PVA/GO and CS/PVA/GO/Ce-ZnO films exhibited good crystallinity. The SEM images depicted the surface morphology of films, which clarified the adding effect of GO NS and Ce-ZnO NPs on the surface morphology of CS/PVA films. While the EDS analysis demonstrated the elemental composition of CS/PVA/GO/Ce-ZnO film. In the same context, the TEM images emphasized the results obtained by the SEM examination and showed no phase separation of the polymers. Whereas AFM showed an increase in surface roughness with adding of GO NS, while was decreased in the case of Ce-ZnO NPs addition. Surface area and pore size distribution results revealed significant differences due to the addition of GO NS and Ce-ZnO NPs to the CS/PVA matrix. The chemical structure of all films was investigated using the Raman shift and their thermal behaviours were also analysed. Finally, the results of QCM sensor-based prepared films showed that the inclusion of GO NS and Ce-ZnO NPs boosted the monitoring performance of sensor films towards MO dye. Furthermore, the sensors-based nanocomposite films presented the same monitoring attitude for MO at different pH.

Surface modification of commercial reverse osmosis membranes using both hydrophilic polymer and graphene oxide to improve desalination efficiency.

Various methods have been applied to modify the surface of reverse osmosis (RO) membranes to modify the membrane performance to enhance the flux, rejection, and resistance to various factors of fouling. Hence, the main objective of the current study is to modify the surface of commercial RO membranes using the synergistic effect of the hydrophilic polymer and graphene oxide (GO). GO nanosheets were firstly synthesized by the modified hummer method, then characterized by FTIR, XRD, and SEM analyses. Then, the polyacrylic acid (PAA) was grafted on the membrane surface for membrane fabrication. Furthermore, effective factors of grafting such as monomer concentration, time, and temperature of polymerization were optimized. After that, different amounts of GO nanosheets were loaded in PAA optimized layer. Then, the effect of GO loading on the RO membrane structure and performance was investigated. The outcomes of membrane characterization demonstrated that modified RO membranes had a smoother surface, more negative surface charge, a little better hydrophilicity, and more thickness. Moreover, the results of PAA and GO optimization were shown that grafting 1.5mM of PAA and loading 0.1wt% of GO nanosheets give the best membrane performance. This membrane (GO 0.1@1.5M PAA/RO) between all modified membranes has the most water flux (37.1L/m2h), the highest NaCl rejection (98%), and the best antifouling efficiency. Ultimately, it was concluded that the grafting of GO@PAA on the surface of a commercial RO membrane is an efficient approach for the enhancement of desalination and antifouling performance of this kind of membrane.

CuS assembled rGO heterojunctions for superior photooxidation of atrazine under visible light

The development of transition metal chalcogenide (TMC) colloidal photocatalysts has become crucial for applications in ecological remediation. Atrazine (AZ) is recognized as a potentially toxic herbicide used in many agricultural and food industries. In this paper, we introduce a facile solution route to prepare hexagonal CuS nanoparticles by a one-step sol-gel method. Then, these CuS nanoparticles are assembled on various amounts of graphene oxide nanosheets to produce colloidal CuS@rGO photocatalysts. Investigations of numerous structural, optical, and optoelectrical properties of CuS reveal the importance of adding rGO. Adding 7.0 wt% rGO to CuS enhances light absorption and decreases the bandgap from 2.36 to 1.97 eV. In addition, the optimized CuS@rGO (at 7% rGO) displays superior photooxidation of AZ (as a common pollutant) in just 20 min at a dose of only 0.8 gL−1, with outstanding stability. The increased photocatalytic ability is ascribed to the improved surface properties of the obtained CuS and photogenerated carrier recombination suppression by introducing rGO. This study realizes the importance of applying rGO-supported TMCs for the elimination of herbicides in water.

The fabrication of a high performance enzymatic hybrid membrane reactor (EHMR) containing immobilized Candida rugosa lipase (CRL) onto graphene oxide nanosheets-blended polyethersulfone membrane

Recently, membrane-immobilized enzyme as an affordable bioreactor has been explored in various fields such as biodiesel production and biosensing because of the reusability of the biocatalyst, increasing its stability and being a low-cost separating unit for producing pure products. Usually, membrane modification could affect the surface morphology and hydrophilicity to make them appropriate for enzyme immobilization. In this context, the modified nanocomposite membranes of polyethersulfone (PES) with various percentages (x: 0.00, 0.25, 0.50, 1.00, 2.00, 3.00) of the graphene oxide nanosheets (GON) named (PGx) are synthesized through the phase inversion technique. The enzymatic hybrid membrane reactors (EHMRs) are provided through the Candida rugosa lipase (CRL) immobilization on the synthesized hybrid membranes. The structure and surface functionalities of the synthesized GON and hybrid membrane are characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and attenuated total reflection (ATR), respectively. The effect of the GON incorporation and CRL immobilization on the morphology of the membrane are explored through field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), contact angle goniometry, and surface free energy analysis. After measuring the porosity of the hybrid membranes with different amounts of GON, their performance, before and after CRL immobilization, are studied through pure water flux. The effective parameters on the activity and performance of EHMR such as GON percentages, CRL initial concentration, immobilization time, and storage condition are accurately optimized. The examination of the relative activity, reusability, and product permeability display that EHMR with 1.00% of GON (EHMR1) is the most efficient between EHMRs with different percentages of GON. Moreover, EHMR1 exhibits the enhancement in pH and thermal stability compared with free CRL and even the immobilized CRL on GON. While the storage stability of the wet- EHMR1 is higher than that of the dry-EHMR1, the stored wet- EHMR1 at 4 °C is more stable than room temperature. Because of these advantages, it is recommended that this bioactive membrane could be a passable candidate for application in the environmental, analytical, and industrial processes.

Significantly improved high-rate partial-state-of-charge performance of lead-acid batteries induced by trace amount of graphene oxide nanosheets

• Trace amount of GONs is incorporated into the NAMs of LABs through a novel and simple way. • The NAMs containing 2 ppm GONs presents a spongy-like structure composed of porous Pb sticks. • Sulfation is suppressed due to the acceleration of the redox reaction between Pb and PbSO 4 . • The HRPSoC cycling life of the simulated cell increased by more than 1.4 times to 29,971 cycles. • The hydrogen generation almost has not any improvement because of the trace GONs content. In this work, trace amount of graphene oxide nanosheets (GONs) is incorporated into the negative active materials (NAMs) of lead-acid batteries (LABs) using an innovative and simple way. The effect of GONs on the morphologies, structures and compositions of the synthesized GONs-containing NAMs are investigated. It is observed that after formation, the NAMs containing 2 ppm GONs presents a spongy-like structure comprised of one-dimensional (1D) porous Pb sticks. Such a 1D structure of Pb sticks provides fast electron transport channel, while the pores on Pb sticks and the voids among Pb sticks facilitate electrolyte transportation. Therefore, accumulation of PbSO 4 crystals is greatly suppressed. Several electrochemical methods such as cyclic voltammetry and electrochemical impedance spectroscopy are used to understand the enhancement mechanism. It is found that the high-rate partial-state-of-charge (HRPSoC) cycling life of the simulated cell is increased by more than 1.4 times from 21,305 to 29,971 cycles. Although the electrochemical performance of NAMs is significantly improved, the hydrogen generation does not have any promotion because of the trace GONs content. The results demonstrate that our method is of great convenient and ultra-low cost with feasibility in large-scale application in LABs industry. Significantly improvement on the electrochemical performance of NAMs by incorporation of trace amount of GONs.

Facile Preparation of Graphene Oxide-MIL-101(Fe) Composite for the Efficient Capture of Uranium

Graphene oxide (GO)-MIL-101(Fe) (Fe-based metal-organic frameworks (MOFs) with Fe(III) as the metal anode and 2-aminobenzene-1,4-dicarboxylic acid as a ligand) sandwich composites are designed and fabricated through a facile in situ growth method. By modulating the addition amount of GO nanosheets, composites containing MIL-101(Fe) octahedrons with a tunable dimension and density are achieved. The optimized ratio between individual components is determined through adsorption experiments. Adsorption isotherms reveal an enhanced adsorption efficiency and improved adsorption capacity of GO15-MIL-101(Fe) (GO dosage is 15 mg) in comparison with raw MIL-101(Fe) nanocrystals. Experimental evidence indicates that the removal of U(VI) by the composite is based on inner-sphere surface complexation and electrostatic interaction. The improved adsorption performance originates from the optimized synergistic effects of GO and MIL-101(Fe) octahedrons. In summary, this work offers a facile synthetic method to achieve cost-effective composites towards the U(VI) capture. It also lays the foundation for the design of novel adsorbents with the full play of component’s functionality.

Aqueous Nanocoating Approach to Strong Natural Microfibers with Tunable Electrical Conductivity for Wearable Electronic Textiles

Electronically conductive and mechanically strong natural fibers with desirable durability, flexibility, and environmental compatibility are in great need for manufacturing multifunctional textiles. Here we reveal a facile yet effective nanocoating approach to immobilization of few-layer graphene oxide (GO) nanosheets at ramie fiber by hydrogen-bond-driven self-assembly process under all-aqueous and additive-free condition. The surface morphology and chemistry of GO-functionalized ramie fiber (GOFR) were significantly altered with the homogeneous decoration of trace amount of GO nanosheets, readying remarkable property improvements and functionality realization. The tensile strength of GOFR (553 MPa) witnessed an increase of over 25% compared to pristine ramie, as accompanied by moderate promotion of extensibility with the assistance of robust GO nanosheets. It is worth noting that exceptionally high electrical conductivity was achieved for thermally reduced GOFR (rGOFR), with values as high as 83.2 S/cm ...

A simple vortex-assisted graphene oxide nanosheets dispersive micro-solid phase extraction combined with high-performance liquid chromatography for UV-Vis detection of tramadol in biological samples

ABSTRACTThis study developed a simple, rapid and sensitive method that utilizes vortex-assisted graphene oxide nanosheets dispersive micro-solid phase extraction of tramadol hydrochloride from biological samples. The data obtained from scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy confirmed the characteristics of graphene oxide nanosheets (GONSs). In order to increase the extraction efficiency, a vortex was applied in the extraction process. In this study, parameters affecting the extraction efficiency were identified and discussed. The optimal experimental parameters were as follows: pH, amount of GONSs, type and volume of desorption solvent, vortexing time, and addition of NaCl. Under optimized conditions, this method allowed the determination of tramadol in the range of 5–300 µg l−1 and the limit of detection was 0.16 µg l−1. The intra-day and inter-day precisions obtained were 2.4% and 3.8%, respectively. This method can be used as an analytical technique for the determination of tramadol in biological samples.

Influence of graphene oxide nanosheets on the stability and thermal conductivity of nanofluids

Many theoretical and experimental studies on heat transfer and flow behavior of nanofluids have been conducted, and the results show that nanofluids significantly enhance heat transfer. However, less attention has been paid to obtain the thermal conductivity of nanofluids and their stability using molecular simulations which are applied by investigators to explain the molecular mechanisms of nanoscale phenomena. In this work, the stability of water–ethylene glycol-based graphene oxide (GO) nanofluids was investigated by classical molecular dynamics simulations in which the kinetic energy, radial distribution function and intensity diagrams were obtained. The obtained results confirmed the stability of nanofluids. Also, the thermal conductivity of nanofluids was studied by reverse non-equilibrium molecular dynamics method at different ratios of water–ethylene glycol as base fluids and various amounts of graphene oxide as nanoparticles. The results show that the thermal conductivity of nanofluids increases with the amount of graphene oxide nanosheets. For example, the thermal conductivity of water–ethylene glycol (75/25%)-based nanofluid containing 3, 4 and 5% of GO nanosheets was increased by 24, 28 and 33%, respectively, at 46.7 °C. Finally, the theoretical models on heat transfer and flow behavior of nanofluids were employed to validate the molecular simulation results. The obtained thermal conductivity results are in good agreement with theoretical models.

Mechanically strong and pH-responsive carboxymethyl chitosan/graphene oxide/polyacrylamide nanocomposite hydrogels with fast recoverability

The biocompatible, quickly recoverable, mechanically strong and tough polymer hydrogels have great potential for biomedical applications. A novel carboxymethyl chitosan (CMCTs)/graphene oxide (GO)/polyacrylamide (PAM) nanocomposite (NC) hydrogel with excellent mechanical performance was synthesized through a facile, one-pot free radical polymerization, using GO nanosheets as the crosslink centers instead of toxic organic molecules. The content of GO nanosheets and CMCTs has great influence on the mechanical properties of CMCTs/GO/PAM NC hydrogels. When the amount of GO nanosheets is 0.118 wt % and CMCTs is 1.5 wt % (to the total weight of CMCTs and acrylamide), CMCTs/GO/PAM hydrogel displays a compressive stress as high as 5.8 MPa at the breaking deformation of 87.5% and a tensile strength of 223.6 kPa at the failure strain of 631%. Besides, with nearly complete recovery in 1 min at the room temperature after unloading, the CMCTs/GO/PAM hydrogels exhibit excellent fast recoverability. Additionally, the CMCTs/GO/PAM hydrogels also have an obvious pH-responsive property.

Biodegradable graphene oxide nanosheets/poly-(butylene adipate-co-terephthalate) nanocomposite film with enhanced gas and water vapor barrier properties

Poly-(butylene adipate-co-terephthalate) (PBAT) has captured significant interest by dint of its biodegradability, superb ductility, promising processing properties and good final properties, but the insufficient barrier performance limits its application, especially in packaging field. In the present work, improved barrier properties of PBAT films were obtained by introducing an extremely low amount of graphene oxide nanosheets (GONS). O2 and water vapor permeability coefficients were decreased by more than 70% and 36% at the GONS loading of 0.35 vol%, respectively. The enhanced barrier performance was ascribed to the outstanding impermeability and well dispersion of GONS as well as the strong interfacial adhesion between GONS and PBAT matrix. Furthermore, tensile strength and Young's modulus of GONS/PBAT nanocomposite rise up to 27.8 MPa and 72.2 MPa from 24.6 MPa to 58.5 MPa of neat PBAT, respectively, showing a prominent increase of mechanical properties compared to neat PBAT. The incorporation of GONS also endowed PBAT matrix with an excellent thermal stability. These findings provide a significant guidance for fabricating high barrier films on a large scale.

Mixed-matrix membranes comprising graphene-oxide nanosheets for CO2/CH4 separation: A comparison between glassy and rubbery polymer matrices

The effect of graphene oxide (GO) nanosheets on the CO2/CH4 separation performance of a rubbery (poly(dimethylsiloxane), PDMS) as well as a glassy (polyetherimide, PEI) polymer is studied. Interfacial interactions between the nanosheets and both polymers are revealed by FTIR and SEM. The results of gas permeation through the membranes demonstrate that GO nanosheets enhance CO2/CH4 diffusivityselectivity of PEI and CO2/CH4 solubility-selectivities of the PEI and PDMS polymers, while diminish CO2/CH4 diffusivity-selectivity of PDMS. Furthermore, the possibility of overcoming the common tradeoff between CO2 permeability and CO2/CH4 selectivity of rubbery and glassy polymers by incorporating very low amounts of graphene oxide nanosheets is addressed. In other words, at 0.25 wt % GO loading, the PEI membrane shows simultaneous enhancement of CO2 permeability (16%) and CO2/CH4 selectivity (59%). Also, for the PDMS membrane simultaneous enhancement of CO2 permeability (29%) and CO2/CH4 selectivity (112%) is occurred at 0.5 wt % GO loading. Finally, the capability of the well known Nielsen model to predict the gas permeability behavior of the nanocomposites is investigated.

Cobalt promoted TiO2/GO for the photocatalytic degradation of oxytetracycline and Congo Red

A family of titania derived nanocomposites synthesized via sol-gel and hydrothermal routes exhibit excellent performance for the photocatalytic degradation of two important exemplar water pollutants, oxytetracycline and Congo Red. Low loadings of Co3O4 nanoparticles dispersed over the surfaces of anatase TiO2 confer visible light photoactivity for the aqueous phase decomposition of organics through the resulting heterojunction and reduced band gap. Subsequent modification of these Co3O4/TiO2 composites by trace amounts of graphene oxide nanosheets in the presence of a diamine linker further promotes both oxytetracycline and Congo Red photodegradation under simulated solar and visible irradiation, through a combination of enhanced photoresponse and consequent radical generation. Radical quenching and fluorescence experiments implicate holes and hydroxyl radicals as the respective primary and secondary active species responsible for oxidative photodegradation of pollutants.

Assembly of graphene oxide on nonconductive nonwovens by the synergistic effect of interception and electrophoresis

Electrophoretic deposition has always been an attractive method to deposit nanoparticles on conductive materials, while most fiber-based materials have poor conductivity which limits the application of electrophoretic deposition in assembling nanoparticles onto fiber-based materials. A new approach to assemble graphene oxide (GO) nanosheets on nonconductive nonwovens via the synergistic effect of electrophoresis and fiber interception was reported in this study. To improve surface wettability, polypropylene (PP) nonwovens were modified by acrylic acid and subsequent N2 plasma treatment. Then GO nanosheets were anchored onto modified nonwovens by electrophoresis process and nonwoven interception. The results of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) manifested that etching and grafting simultaneously occurred on the surface of modified PP nonwovens, resulting in a great improvement of nonwoven hydrophily, which corresponded to the results of water contact angle. Furthermore, the results of X-ray diffraction, energy dispersive X-ray, SEM, and FTIR indicated that different amounts of GO nanosheets were successfully assembled onto modified PP nonwovens. This method provides a new avenue for incorporating carbon nanoparticles with nonconductive fiber-based materials, and modified PP nonwovens assembled with GO nanosheets show good air filtration performance for sodium chloride aerosol with a filtration efficiency of 87.9 % and a pressure drop of 36.4 mmH2O, and the reduced GO/PP composite nonwovens exhibit enhanced conductivity.

Assessment of graphene oxide/epoxy nanocomposite as corrosion resistance coating on carbon steel

Graphene and its derivatives are new materials with unique properties. In recent years, various studies about the nanocomposites based on graphene oxide (GO) have been carried out. However, the electrochemical properties of nanocomposite coatings based on GO materials have not been widely studied. In this study, GO/epoxy nanocomposite coatings were prepared by incorporation of different amounts of GO nanosheets into the epoxy matrix via mechanical agitation and sonication process. The dispersion of GO nanosheets in matrix was analysed by optical microscopy, transmission electron microscopy and Fourier transform infrared. The anticorrosive properties of these nanocomposite coatings were investigated by electrochemical impedance spectroscopy tests. Results showed that the corrosion protection of coatings was improved by addition of GO into the coatings material. Furthermore, the best corrosion resistance was achieved in 0·25 wt-%GO/epoxy nanocomposite coatings.