Graphene Oxide Aqueous Solution Research Articles

The absorption effect and mechanism of graphene oxide removal from aqueous solution by basalt stone power

Graphene oxide (GO) is a novel carbon material utilized extensively for diverse industrial applications. When exposed to environmental elements like sunlight and chlorination, GO can undergo a series of physical and chemical transformations, and its presence in water and the environment can endanger ecosystems. Therefore there is a need for methods that can effectively remove GO from water. Accordingly, we delve into the efficacy of basalt stone powder (BSP) as an adsorption medium for purifying aqueous solutions of GO. We examine the impact of various experimental parameters—namely pH, initial solution concentration, adsorbent mass, contact duration, and ambient temperature—on GO adsorption, employing the method of controlled variables. The adsorption efficacy is notably influenced by the pH level. At an acidic pH of 3, an initial GO concentration of 80 mg/L, an adsorbent dosage of 50 mg, and a temperature of 303 K (approximately 30 °C), the adsorption removal efficiency reaches an impressive 99 %, boasting a maximum adsorption capacity of 112 mg/g. Dynamically, the adsorption kinetics align most closely with a pseudo-first-order model, achieving equilibrium after 24 h. Thermodynamic analyses reveal that the Langmuir isotherm model most accurately describes the adsorption behavior, indicating an enhancement in BSP's adsorption capacity for GO as temperature rises. Based on thermodynamic equations, the adsorption of GO onto BSP is deduced to be a spontaneous process. Our findings illustrate BSP's considerable potential in the treatment and removal of GO from water, and therefore it may prove useful in environmental remediation efforts.

Preparing high-performance microspheres based on the chitosan-assisted dispersion of reduced graphene oxide in aqueous solution for bilirubin removal

The removal of excess bilirubin from blood is of great clinical importance. Reduced graphene oxide (rGO) is often used to efficiently remove bilirubin. However, thin rGO pieces tend to aggregate in the aqueous phase because they are hydrophobic. In this context, we propose an effective strategy based on the chitosan-assisted (CS-assisted) dispersion of rGO to produce high-performance bilirubin-adsorbing microspheres. CS possesses a hydrophobic CH structure, which offers strong hydrophobic interactions with rGO that assist its dispersion, and the large number of hydrophilic sites of CS increases the hydrophilicity of rGO. CS serves as a dispersant in a surfactant-like manner to achieve a homogeneous and stable CS/rGO dispersion by simply and gently stirring CS and rGO in a LiOH/KOH/urea/H2O system. Subsequently, CS/rGO hybrid microspheres were prepared by emulsification. CS ensures blood compatibility as a base material, and the entrapped rGO contributes to mechanical strength and a high adsorption capacity. The CS/rGO microspheres exhibited a high bilirubin adsorption capacity (215.56 mg/g), which is significantly higher than those of the rGO and CS microspheres. The determined mass-transfer factors revealed that the rich pores of the CS/rGO microspheres promote mass transfer during bilirubin adsorption (equilibrium is almost achieved within 30 min). The CS/rGO microspheres are promising candidates for bilirubin removal owing to a combination of high strength, blood compatibility, and high adsorption capacity.

Principles determining the aggregation of graphene oxide in aqueous solutions: The effect of heterogeneous distribution of oxygen-containing groups

Molecular dynamics (MD) simulations were conducted to investigate the effects of heterogeneous distribution of oxygen-containing groups on the aggregation modes of graphene oxide (GO) flakes in aqueous solution. The results show that the aggregation of GO flakes can be divided into Brownian motion, adsorption, and adjustment steps, where the adsorption step further can be classified as point-falling-line-squeezing-plane (PFLSP) mode and bridge adsorption of confined water molecules mode. When the aggregation happens at the non-oxidized region, the successful aggregation is always accompanied by the PFLSP mode. In contrast, at the oxidized region, the bridge adsorption of CWMs mode is preferred.

Effects of graphene-oxide and nanosilica on the wear resistance and strength of self-consolidating high-strength cement mortar

ABSTRACT This paper investigates the effects of the nanosilica (NS) and graphene oxide (GO) on the mechanical properties of the self-consolidating high-strength cement mortars (SCHSCM). Ten different mortar mixes, including aqueous solutions of GO and NS, were designed to perform the experimental study. Multiple specimens are prepared for each mortar mix to be tested to determine the mean tensile, flexural and compressive strength as well as wear resistance of the SCHSCM at 28 days of curing. Different contents of GO (0.00%, 0.01%, 0.02% and 0.05% by weight of cement) and NS (0.0%, 1.5% and 3% by weight of cement) are used in the experiments. The hybrid effects of the NS and GO on the mechanical properties of the SCHSCM are also investigated. The obtained results illustrate that the simultaneous use of 0.01% of GO and up to 3% of NS can increase the flexural, tensile and compressive strength of SCHSCM up to 45%, 30% and 26%, respectively, which are higher than those obtained by using NS and GO separately. However, the hybrid use of GO and NS has negative effects on the abrasion depth while the NS additive could improve the abrasion resistance of the SCHSCM.

Exploration of the impact of graphene oxide, acetylenic gemini, and CTAT on the photophysical and aggregation properties of dipolar coumarin 153.

Advanced spectroscopic techniques have been utilized to study the interaction between the laser dye coumarin 153 (C153) and graphene oxide (GO) nanoparticles. GO was synthesized using a modified Hummers' method and characterized by UV-vis spectroscopy, Raman laser spectroscopy, FTIR-ATR spectroscopy, FESEM, HR-TEM, and XRD techniques. The GO@C153 composite was formed by mixing two aqueous solutions of GO and C153 due to their strong interaction through stacking and hydrophobic interactions. In this case, GO acts as an effective fluorescence quencher for C153 molecules, which undergo H-type aggregation in the presence of GO. The Stern-Volmer equation and time-dependent fluorescence studies were utilized to analyse the mechanism of fluorescence quenching. According to the findings, both static and dynamic quenching processes are responsible for the reduction in fluorescence intensity. The effect of surfactants (both cetyltrimethylammonium p-toluenesulfonate (CTAT) and synthesized N,N'-dihexadecyl-N,N,N',N'-tetramethyl-N,N'-but-2-ynediyl-di-ammonium chloride (16-4-16)) on the aggregation and photophysical properties of the dye was investigated using surface tensiometry, conductometry, UV-vis absorption spectroscopy, steady-state fluorescence measurements, DLS, and time-dependent fluorescence spectroscopy. Surfactants change the microenvironment of the C153 dye, leading to spectrum shifting and a higher quantum yield, which causes a rapid rise in fluorescence intensity in the micellar medium. It has been noted that in a micellar medium rather than in an aqueous one, the luminous intramolecular charge transfer (ICT) state of C153 stabilises. Lastly, we investigated the photophysical behavior of the GO-C153-micelle ternary system and discovered that, in the presence of a micellar medium, the quenched and blue-shifted (H-type aggregation) fluorescence peak of C153 (in the presence of GO) began to intensify once more. The main goal of this work is to create an effective and fairly cost powerful fluorescence sensor. Additionally, the ternary system (GO-C153-micelle) analytical idea can be employed to identify the onset of micelle formation. In wastewater treatment analysis, the GO-C153-surfactant ternary system concept can also be used to regenerate the adsorbent (in this case, GO) from dye molecules by allowing the dye molecules to exit the adsorbent and enter the micellar medium.

Separation of graphene oxides of different sizes by multi-layer dialysis and anti-friction and lubrication performance

Abstract As a 2D carbon material, graphene exhibits a unique structure and outstanding properties and has been widely applied in various fields. Because the properties of graphene are closely related to their structural parameters, graphene with different size distributions is suitable for different applications. However, current methods of fine-scale separation of graphene and its derivatives have certain limitations. In this study, graphene oxide (GO) size separation using multilayer dialysis was proposed. Multiple size separation in one step was achieved by customizing the dialysis size of each layer according to the actual requirements. In this way, GOs of different sizes were separated and large-scale synthesis can be achieved using this method. Meanwhile, the anti-friction and lubrication properties of aqueous dispersion solutions of GOs of different sizes were investigated. The results indicated significant improvements of the anti-friction and lubrication properties of GO samples prepared by the proposed method, as large-scale GOs can act as lubricants by relieving, if not preventing, friction between the two friction surfaces.

Influence of Radical Scavenger on Radiation Synthesis of Graphene Oxide/TiO2 Nanotubes/Ag Nanoparticles Nanocomposites and Their Dye Photodegradation Efficiency

Aqueous solutions of graphene oxide (GO), TiO2 nanotubes (TNTs), and silver nanoparticles (AgNPs) were synthesized through a facile, single-step radiolytic method at room temperature and ambient pressure. The resulting material, referred to as GO-TNTs-AgNPs (GTA), was investigated for its potential application in the photodegradation of Rhodamine-B (RhB) dye. This synthesis process relies on the interaction of high-energy gamma rays from a 60Co source with the water in the aqueous solutions. The main objective of this study was to evaluate the effect of irradiation dose and the presence of polyethylene glycol (PEG) solution on the combination within the nanocomposite materials. The inefficiency of GTA synthesis experimentally was in agreement with the hydroxyl radical (HO•) scavenger. Then, the irradiated materials were structurally characterized using various spectroscopic methods (Fourier transform infrared (FTIR), X-ray diffraction (XRD), Raman spectroscopy, and ultraviolet-visible absorption (UV–Vis)). Scanning electron microscopy (SEM) studies reveal the variable morphology of nanocomposites. GTA samples in water exhibited significantly higher degradation efficiency on Rhodamine B dye under natural sunlight irradiation conditions.

Demonstration of cross reaction in hybrid graphene oxide/tantalum dioxide guided mode resonance sensor for selective volatile organic compound

This paper experimentally demonstrates a crossed reaction of pure and hybrid graphene oxide (GO)/tantalum dioxide (TaO2) as a volatile organic compound (VOC) absorber in a guided mode resonance (GMR) sensing platform. The proposed GMR platform has a porous TaO2 film as the main guiding layer, allowing for more molecular adsorption and enhanced sensitivity. GO is applied on top as an additional VOC absorber to increase the selectivity. The hybrid sensing mechanism is introduced by varying the concentration of the GO aqueous solution. The experimental results show that the pure TaO2-GMR has a high tendency to adsorb most of the tested VOC molecules, with the resonance wavelength shifting accordingly to the physical properties of the VOCs (molecular weight, vapor pressure, etc). The largest signal appears in the large molecule such as toluene, and its sensitivity is gradually reduced in the hybrid sensors. At the optimum GO concentration of 3 mg/mL, the hybrid GO/TaO2 -GMR is more sensitive to methanol, while the pure GO sensor coated with GO at 5 mg/mL is highly selective to ammonia. The sensing mechanisms are verified using the Density Functional Theory (DFT) to simulate the molecular absorption, along with the measured functional groups measured on the sensor surface by the Fourier transform infrared spectroscopy (FTIR). The crossed reaction of these sensors is further analyzed by means of machine learning, specifically the principal component analysis (PCA) method and decision tree algorithm. The results show that this sensor is a promising candidate for quantitative and qualitative VOCs detection in sensor array platform.

Fast response humidity sensor based on chitosan/graphene oxide/tin dioxide composite

In this paper, Chitosan(CS)/graphene oxide(GO)/SnO2 composite is proposed as the sensing material of an impedance-type humidity sensor. The composite was synthesized via a facile solution mixing method. And it was formed by adding CS and SnO2 to GO aqueous solution. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometer (FT-IR) were executed to characterize the structure and morphology of the composite. At room temperature, the CS/GO/SnO2 composite shows more favorable humidity-sensing properties compared with the CS, CS/GO, and CS/SnO2 material. The resulted sensor exhibits high response (72683%), high sensitivity (402.5 kΩ/%RH), rapid response and recovery time (8 s/8 s). Moreover, small humidity hysteresis value (<7%) under maximum impedance difference, good repeatability and long-term stability are demonstrated. Therefore, the CS/GO/SnO2 composite is a promising candidate for humidity sensing.

3D Graphene Oxide-Polyethylenimine Scaffolds for Cardiac Tissue Engineering.

The development of novel three-dimensional (3D) nanomaterials combining high biocompatibility, precise mechanical characteristics, electrical conductivity, and controlled pore size to enable cell and nutrient permeation is highly sought after for cardiac tissue engineering applications including repair of damaged heart tissues following myocardial infarction and heart failure. Such unique characteristics can collectively be found in hybrid, highly porous tridimensional scaffolds based on chemically functionalized graphene oxide (GO). By exploiting the rich reactivity of the GO's basal epoxydic and edge carboxylate moieties when interacting, respectively, with NH2 and NH3+ groups of linear polyethylenimines (PEIs), 3D architectures with variable thickness and porosity can be manufactured, making use of the layer-by-layer technique through the subsequent dipping in GO and PEI aqueous solutions, thereby attaining enhanced compositional and structural control. The elasticity modulus of the hybrid material is found to depend on scaffold's thickness, with the lowest value of 13 GPa obtained in samples containing the highest number of alternating layers. Thanks to the amino-rich composition of the hybrid and the established biocompatibility of GO, the scaffolds do not exhibit cytotoxicity; they promote cardiac muscle HL-1 cell adhesion and growth without interfering with the cell morphology and increasing cardiac markers such as Connexin-43 and Nkx 2.5. Our novel strategy for scaffold preparation thus overcomes the drawbacks associated with the limited processability of pristine graphene and low GO conductivity, and it enables the production of biocompatible 3D GO scaffolds covalently functionalized with amino-based spacers, which is advantageous for cardiac tissue engineering applications. In particular, they displayed a significant increase in the number of gap junctions compared to HL-1 cultured on CTRL substrates, which render them key components for repairing damaged heart tissues as well as being used for 3D in vitro cardiac modeling investigations.

Compositing graphene oxide with carbon fibers enables improved dynamical thermomechanical behavior of papers produced at a large scale

This article discusses the morphology and thermomechanical properties of graphene oxide (GO) paper sheets and GO paper composites reinforced with carbon fibers. GO paper was fabricated using GO paste obtained by the condensation of GO aqueous solution synthesized using the Hummers' method. Carbon fibers were implemented to improve the mechanical properties of the pristine GO paper. All the investigated papers were subjected to thermal treatment to check thermo-related morphological and mechanical properties. The results presented in this study allowed for the deeper insight into morphological, structural, and mechanical volume and surface-related properties of pristine GO and GO-based composite materials reinforced with carbon fibers. We showed that there are two important factors that should be taken into consideration for the design and fabrication of GO-based papers. These factors were the concentration of the reinforcing agent and the thermal reduction of the papers. Both factors have influenced the final properties of the resulting GO-based papers. For the first time, it was revealed how the addition of the reinforcing material affects the GO paper thermal expansion coefficient.

Adsorption properties and mechanism of sepiolite to graphene oxide in aqueous solution

Graphene oxide (GO) is widely used in various fields such as improving the performance of cement-based materials and making composite materials due to its large specific surface area and abundant oxygen-containing functional groups. However, it has also caused water pollution. To remove GO in aqueous solution, sepiolite (SEP) was used to adsorb it. The effects of pH, adsorbent quality, GO concentration, temperature and adsorption time on the ability of SEP to adsorb GO were investigated. The materials were characterized by SAP and laser particle size analyzer, and the adsorption performance and mechanism of SEP for GO were further analyzed by XRD, FTIR, SEM, TEM, XPS, AFM, and Zeta potential microscopic tests. The results showed that: 1) Under the conditions of temperature 303 K, pH = 3, adsorbent mass 30 mg, and initial concentration of GO 100 mg/L, the adsorption effect was the best, and the adsorption rate reached 94.8 %. 2) The adsorption reached equilibrium at 2160 min, and the adsorption process was more in line with the pseudo-second-order adsorption kinetic equation, and the adsorption behavior was controlled by chemical effects. 3) The adsorption of SEP to GO is more consistent with the Langmuir and Temkin adsorption isotherm model, and the reaction is a spontaneous, endothermic, and entropy-increasing process. Experiments showed that SEP had a strong adsorption capacity for GO, which provides a reference for the treatment of toxic GO in aqueous solution and the realization of water ecological protection.

Hybrid hydroxyapatite/graphene oxide composites materials synthesized from eggshell for adsorption of Cr(VI) in aqueous solution

In this work, hydroxyapatite/graphene oxide hybrid composites (HAP/GO) were prepared from eggshell by solvothermal method, which was mainly used as adsorbents for Cr(VI) removal in wastewater. The effect of graphene oxide (GO) on the structure and removal efficiency of HAP/GO was discussed. The results showed that the Cr(VI) removal of HAP/GO10% can reach more than 90% within 1 h, and the adsorption conforms to the first-order kinetics. It was found that the addition of GO changed the pore size distribution of HAP/GO and improved Cr(VI) removal. It can be concluded that the swelling of GO in aqueous solution leads to an increase in the interaction between the dissociated carboxyl groups and Cr(VI), thereby improving the adsorption efficiency.

Upcycling waste mask PP microfibers in portland cement paste: Surface treatment by graphene oxide

Used face masks resulting from the COVID-19 pandemic are forming a new waste stream that poses a considerable environmental risk to the ecosystem if not properly disposed of. This work explored an environmentally friendly solution to diverting such waste to a value-added application, i.e., fabricating waste mask microfibers for use in cementitious composites. To improve the interfacial transition zone between mask fibers and cement paste matrix, the microfibers made from recycled medical masks are pre-treated in an aqueous solution of graphene oxide (GO, at 0.05 wt%). In a cement paste with the water/cement ratio of 0.40, the GO-treated mask fibers admixed at 0.1 vol% showed great potential for improving the splitting tensile strength (by 47% at 28 days), even though they slightly decreased the compressive strength of the paste (by 3% at 28 days). Microscopic investigation was also carried out to reveal the enhancement mechanism of GO-treated fibers. This study preliminarily demonstrated the feasibility to upcycle waste masks in the concrete industry and provided a new strategy for disposing of waste masks.

Effects of surfactants on dispersibility of graphene oxide dispersion and their potential application for enhanced oil recovery

As a new type of oil displacement agent, nanofluid has shown great application potential in the field of enhanced oil recovery. Good dispersion and high stability of nanofluids are the prerequisites for engineering application. In this paper, the water-based graphene oxide (GO) nanofluid was taken as the research object, and the influencing factors of dispersion stability were systematically studied. The water-based nanofluid based on GO was formulated, and its oil displacement potential was studied. The effects of ultrasonic dispersion time, GO dosage and surfactant on the dispersion stability of GO in aqueous solution were investigated by turbidity experiment and conductivity experiment. The results showed that amphoteric surfactant disodium cocoamphodiacetate (CAD) had good dispersion stability for GO. CAD/GO dispersion not only decreased the oil/water interfacial tension to 10−2 mN/m, but also had good emulsifying effect and kept the emulsion stable. In the micromodel flooding test and core flooding test, CAD/GO dispersion effectively displace the residual oil in porous media and improve crude oil recovery. In the core flooding test, the oil recovery of CAD/GO dispersion (11.8%) was higher than CAD aqueous solution (6.7%), which was attributed to its better interfacial property and emulsifying property. These results indicated that the CAD/GO dispersion was promising for application in enhanced oil recovery (EOR).

Mechanical Properties and Microstructure of High-Strength Lightweight Concrete Incorporating Graphene Oxide.

The increasing demand for high-strength lightweight concrete (HSLWC) with excellent mechanical properties has inspired the development of nanomaterials in fundamentally solving brittleness and cracking. This work investigated the effects of graphene oxide (GO) on the mechanical properties and microstructure of HSLWC, including the workability, density, compressive strength in different curing regimes, splitting tensile strength, flexural strength, modulus of elasticity and scanning electron microscopy (SEM). Six groups of mixtures were mixed with GO aqueous solution at a dosage of 0.00%, 0.02%, 0.04%, 0.05%, 0.06%, and 0.08% by weight of cement, respectively, and dispersed by ultrasound for 30 min. The test results showed that adding a low volume of GO to the specimens could slightly increase the density, rationally reduce the slump, and significantly improve the mechanical properties. The maximum increase in compressive strength, splitting tensile strength, modulus of elasticity and flexural strength of HSLWC with GO at 28 days was by 24%, 17%, 15%, 20%, respectively, as compared with HSLWC without GO. Simultaneously, the SEM results showed that GO could not only fill nano-scale pores, but also regulate the formation and growth of flower-like crystals, which was an important factor for the further improvement of properties. The research results provided a potential new pathway to improve the mechanical properties of HSLWC.

Corrosion behavior of Q235 steel in graphene oxide aqueous dispersion

Conductive metals can speed up the self-assembly and reduction process of graphene oxide (GO) in liquid media, but there is little available information about the effect of this process on the corrosion rate of metal substrates. The corrosion performance of Q235 steel in GO aqueous solution was studied by comparing the influence of different GO concentrations and immersion times on the corrosion rate of steel. The result found that a GO layer will be formed on the surface of steel when immersing in the GO aqueous dispersion, which has a shielding effect on the diffusion process of ions and electrons, and effectively inhibits the steel corrosion. However, this inhibition effect of GO layer will disappear with the self-reduction of GO, which increasing the defect density and conductivity of the sedimentary layer on steel and thus the corrosion rate of steel will increase with the immersion time and the GO concentration in solution.

Adsorption Properties and Mechanism of Attapulgite to Graphene Oxide in Aqueous Solution.

In order to remove toxic graphene oxide (GO) from aqueous solution, attapulgite (ATP) was used as adsorbent to recycle it by adsorption. In this paper, the effects of different pH, adsorbent mass, GO concentration, time and temperature on the adsorption of GO by attapulgite were studied, and the adsorption performance and mechanism were further explored by XRD, AFM, XPS, FTIR, TEM and SEM tests. The results show that when T = 303 K, pH = 3, and the GO concentration is 100 mg/L in 50 mL of aqueous solution, the removal rate of GO by 40 mg of attapulgite reaches 92.83%, and the partition coefficient Kd reaches 16.31. The adsorption kinetics results showed that the adsorption equilibrium was reached at 2160 min, and the adsorption process could be described by the pseudo-second-order adsorption equation, indicating that the adsorption process was accompanied by chemical adsorption and physical adsorption. The isotherm and thermodynamic parameters show that the adsorption of GO by attapulgite is more consistent with the Langmuir isotherm model, and the reaction is a spontaneous endothermic process. The analysis shows that attapulgite is a good material for removing GO, which can provide a reference for the removal of GO in an aqueous environment.

Adherable temperature sensor to a porous structure of fiber via reduced graphene oxide and poly(diallyldimethylammonium chloride) complex

We present an adherable temperature sensor on aramid fiber filament coated with reduced graphene oxide (rGO) and poly(diallyldimethylammonium chloride) (PDADMAC) complex. The PDADMAC dispersed in a graphene oxide aqueous solution was dried and reduced to an rGO-PDADMAC complex with laser irradiation. The rGO-PDADMAC sensor was characterized with a scanning electron microscope and Raman spectroscopy. The rGO-PDADMAC sensor showed a negative temperature coefficient resistance change at 40% relative humidity (RH). Furthermore, the sensor successfully detected 58% resistance variation from 25 °C to 100 °C as the pristine rGO sensor showed 61% resistance variation on a rigid surface. Also, the rGO-PDADMAC sensor demonstrated long-term reliability of 3% sensitivity for seven days in normal room conditions at 25 °C and 40% RH. Additionally, the adherable temperature sensor of the rGO-PDADMAC complex viscous to the porous structure of aramid fiber detected 55% sensitivity from 25 °C to 100 °C.

Real-time detection of methyl salicylate vapor using reduced graphene oxide and poly (diallyldimethylammonium chloride) complex

We report the detection of methyl salicylate (MeSA) vapor with reduced graphene oxide (rGO) and a poly (diallyldimethylammonium chloride) (PDADMAC) complex. The complex was based on a graphene oxide aqueous solution where PDADMAC was dispersed and dried via photo-thermal reduction through laser irradiation to form the rGO-PDADMAC complex as a sensing matrix with a higher affinity to the target analyte, MeSA vapor. The sensor based on the rGO-PDADMAC complex was used to measure the change in resistance in real time. The rGO-PDADMAC sensor detected 11% resistance variation induced by 14.5-ppmv MeSA vapor over 540 s, while the pristine rGO sensor indicated only 1.2% resistance variation.