Graphene Oxide Particles Research Articles

Art and Science of Reinforcing Ceramics with Graphene via Ultrasonication Mixing.

This work presents an interdisciplinary approach combining materials science, ultrasonication, artistic expression, and curatorial practice to develop and investigate novel composites. The focus of the approach is incorporating graphene oxide (GO) into kaolin and exploring its effects on material properties. The composites were prepared with varying GO concentrations and sonication times, and their mechanical, thermal, and morphological characteristics were evaluated. The results reveal that the addition of 0.5 wt % GO, combined with a sonication time of 10 min, leads to the highest storage modulus and improved thermal stability. Ultrasonication proved to be an effective method for dispersing and distributing GO particles within the kaolin matrix, resulting in an enhanced material performance. Furthermore, the application of novel composites provided by Prvački adds a unique dimension to the study. Through the artistic interpretation, the tactile qualities and aesthetic potential of the composites are explored, shedding light on the transformative power of materials and cultural significance organized as part of an artist-in-residence commission, introduced in conjunction with the NUS Public Art Initiative. This interdisciplinary collaboration accompanied by an exhibition at the NUS Museum demonstrates the value of merging scientific research, technological advancements, and artistic exploration.

Influence of pegylated graphene oxide nanoparticles on the respiratory burst and phagocytic activity of human neutrophils

Scientific and technological progress contributes to the discovery and production of innovative materials. The emergence of graphene is a clear example of this. Graphene is considered a promising material for use in nanobiomedicine and nanobiotechnology. It is therefore important to understand how it affects human immune cells. In a study, the effects of 5 and 25 μg/mL graphene oxide nanoparticles with lateral sizes of 100-200 nm and 1-5 μm, modified with linear and branched polyethylene glycol, on human neutrophils were investigated. The formation of reactive oxygen species was evaluated with a lucigenin as a chemiluminescence activator.Inaddition, we investigated theeffect of a 60-minute incubation of neutrophils with pegylated graphene oxide nanoparticles on the viability of these cells by staining with trypan blue and a 30-minute incubation on the uptake of fluorescein isocyanate-labelled E. coli. The percentage of neutrophils which engulfed E. coli and the uptake index were determined. Samples without added nanoparticles served as controls.A decrease in lucigenin-enhanced chemiluminescence of neutrophils was observed under the influence of two types of graphene oxide nanoparticles: 1-5 μm in size coated with linear polyethylene glycol, and 100-200 nm in size coated with branched polyethylene glycol, at a concentration of 25 μg/mL in the zymosan-stimulated version of the assay. No dependence of the effect on the particle size and the type of polyethylene glycol was observed. The indicators for spontaneous chemiluminescence of neutrophils did not change with the addition of PEGylated graphene oxide nanoparticles.A thirty-minute incubation of human neutrophils at 37 °C with PEGylated graphene oxide nanoparticles with lateral dimensions of 100-200 nm and 1-5 μm had no effect on the viability of these cells and on the percentage of neutrophils that engulfed E. coli. However, 1-5 μm graphene oxide modified with linear polyethylene glycol at a concentration of 25 μg/mL increased the amount of E. coli engulfed by neutrophils per cell.Thus, in the absence of cytotoxicity, PEGylated graphene oxide particles have multidirectional immunomodulatory effects on neutrophils. In this case, their concentration is decisive and not the size of the graphene oxide particles and the type of polyethylene glycol.

Selective Voltammetric Determination of Paracetamol and Acyclovir on an Electrode Modified with Reduced Graphene Oxide and Gold Particles

Selective Voltammetric Determination of Paracetamol and Acyclovir on an Electrode Modified with Reduced Graphene Oxide and Gold Particles

NaOH-assisted hydrothermal reduction of graphene oxide

The influence of the pH of the reaction medium on the structural characteristics of hydrothermally reduced graphene oxide, synthesized by the Tour method, has been investigated. Varying the pH of the reaction medium within the range of 8.0, 10.0 and 12.0
(adjusted with NaOH) has revealed distinct effects on the morphology and properties of the resulting reduced graphene oxide. At a pH of 8.0 the hydrothermal treatment yielded reduced graphene oxide comprising of two particle fractions with a thickness equivalent to 4-5 graphitic layers each. In contrast, pH of 10.0 resulted in two particle fractions corresponding to 2-3 and 4 layers, respectively, while pH of 12.0 produced a single fraction with a particle thickness of 0.70 nm, encompassing 3 graphitic layers. Increasing the pH led to a decrease in the average lateral size of reduced graphene oxide particles to about 8 nm. All rGOs had micro- and mesopores with a specific surface area up to 226 m2/g, showing a proportional increase in mesopores with increasing pH. Analysis of slit-like micropores revealed a minimum fractal dimension (D = 2.18) at pH = 8.0. The obtained results provide valuable insights into tailoring the structural properties of hydrothermally reduced graphene oxide by controlling the pH of the reaction medium, offering potential applications in various fields, including nanotechnology and materials science.&#xD.

Investigate the influence of GO as an additive in the silica-based polyethylene glycol shear thickening fluid on the rheological properties

Abstract Shear thickening fluids (STF) represent stabilized and concentrated colloidal suspensions, wherein hard nanoparticles are dispersed within a liquid medium (polymer). Under the influence of impact forces, they exhibit non-Newtonian behavior, effectively dissipating energy through shear thickening. The optimization of the dispersion medium’s viscosity is critical, as it not only fosters shear thickening but also facilitates proper particle dispersion. This study investigates the impact of graphene oxide (GO) as an additive in STFs, analyzing both static and dynamic rheological properties. STFs were formulated using colloidal silica particles (600 nm) and polyethylene glycol (PEG-200), with varied concentrations of GO particles (0.12–0.5 % w/W). The systems underwent comprehensive analysis concerning steady-state and dynamic-state rheological behavior under diverse conditions. The findings reveal that the inclusion of GO augments both static and dynamic rheological properties, reaching an apex at an optimal concentration of 0.36 % w/W. GO functions as a network builder within the STF, interacting with the existing particle network to create a more robust and interconnected structure. These enhanced properties underscore the potential of the synthesized STF for applications requiring impact resistance.

(Invited) Graphene Oxide As an Additive for Ni-Fe Electrodeposition

In contrast to graphene, graphene oxide (GO) is readily disperse in aqueous electrolytes and can be reduced along with nickel and iron metal ions. While others had incorporated graphene in Ni-Fe deposits, no previous studies have addressed the role of GO particles on metal deposition. Ni-Fe is characterized by the anomalous codeposition behavior where there is a tendency of more Fe to be deposited than Ni even though there is an excess of Ni ions in the electrolyte. This behavior has been modeled assuming adsorbed intermediates. Here, the influence of GO on the deposit composition, structure and anomalous codeposition effect is investigated. The deposits were galvanostatically electrodeposited from a boric acid-sulfamate electrolyte at pH 2 containing commercial graphene oxide platelets. Two different cell configurations were examined:1) a rotating cylinder electrode (RCE) and 2) a copper mesh. The rotating cylinder as a working electrode was used in order to investigate mass transport. The copper mesh working electrode was placed in close contact to a flat bottom pH probe in order to examine the local pH change. The addition of GO to the electrolyte had an effect on the deposit composition and the local pH change (Fig 1). The deposit composition had either more Ni or remained the same compared to an electrolyte without GO on the RCE electrode at electrode rotation rates of 372 and 1000 rpm (Fig 1 (a) and (b)). The larger Ni content in the deposit was due to an enhanced Ni partial current density in the presence of GO. The local pH during the deposition on the mesh electrode with vigorous electrolyte stirring increased the local pH (Fig 1(c)). The composition behavior is similar to the results from the RCEs, with higher Ni content in the presence of GO. The local pH increase when GO was present is considered a factor that drives the enhanced Ni content, that may be a consequence of changes in adsorbed hydrogen. GO was not incorporated into the deposit; however, it had a dramatic effect on the morphology. There was less micro-cracks when GO was present in the electrolyte suggesting less adsorbed hydrogen. Thus, GO influenced the adsorbed intermediates making the electrodeposition less anomalous and having less cracks. Acknowledgement: This work was supported in part by the AESF Foundation. Figure 1. The influence of GO in the electrolyte during Ni-Fe electrodeposition (a) composition on a RCE, rotating rate (a) 372, (b)1000 rpm and (c) local pH measurements on a mesh electrode under vigorous stirring, 30 mA/cm2. Figure 1

Enhancing mechanical and corrosion properties of GO and Al2O3 reinforced Cu composite coatings

Despite their significant functions and properties, the performance characteristics of Al2O3 ceramic particles and graphene oxide (GO) within hybrid copper composite coatings have been seldom investigated. This study successfully fabricated a Cu-GO- Al2O3 composite coating featuring fine particulate spherical network-like structures on St37 low carbon steel using an ultrasonic-electroless coating method. The effects of Al2O3-decorated graphene oxide hybrid reinforcement on the texture and nanomechanical properties of the copper matrix were examined. The tribological performance of the Cu-GO- Al2O3 composite coating under dry sliding conditions was evaluated, and the wear mechanism was investigated in detail. Results demonstrate that the Cu-GO- Al2O3 composite coating effectively reduces the wear rate and friction of the GO/ Al2O3 hybrid reinforced composite coating. Potentiodynamic polarization tests indicated that the Cu-GO- Al2O3 composite coating exhibits higher corrosion resistance compared to the copper matrix. The enhanced mechanical, tribological, and corrosion properties of the Cu-GO- Al2O3 composite coating are primarily attributed to: (i) the fine particulate spherical network-like structure; (ii) the synergistic effect of the GO and ceramic particle hybrid with a decorated structure; (iii) the formation of graphene oxide/ Al2O3 nanorolls in tribofilms and the excellent self-lubrication properties of graphene oxide. The Cu-GO- Al2O3 composite coating significantly improves the frictional and electrochemical properties of the copper matrix, offering new perspectives for next-generation electrical contacts and nanoelectromechanical systems.

Synergistic Evolution of Alloy Nanoparticles and Carbon in Solid-State Lithium Metal Anode Composites at Low Stack Pressure.

Solid-state batteries with Li metal anodes can offer increased energy density compared to Li-ion batteries. However, the performance of pure Li anodes has been limited by morphological instabilities at the interface between Li and the solid-state electrolyte (SSE). Composites of Li metal with other materials such as carbon and Li alloys have exhibited improved cycling stability, but the mechanisms associated with this enhanced performance are not clear, especially at the low stack pressures needed for practical viability. Here, we investigate the structural evolution and correlated electrochemical behavior of Li metal composites containing reduced graphene oxide (rGO) and Li-Ag alloy particles. The nanoscale carbon scaffold maintains homogeneous contact with the SSE during stripping and facilitates Li transport to the interface; these effects largely prevent interfacial disconnection even at low stack pressure. The Li-Ag is needed to ensure cyclic refilling of the rGO scaffold with Li during plating, and the solid-solution character of Li-Ag improves cycling stability compared to other materials that form intermetallic compounds. Full cells with sulfur cathodes were tested at relatively low stack pressure, achieving 100 stable cycles with 79% capacity retention.

Enhancement of controllable circular actuator using graphene oxide particles

ABSTRACT This work aims to study the responsive expansion of graphene oxide- acrylic elastomer (GO-Acry ER elastomer) under applied electric field. The GO was synthesized from graphite (GP) by using Hummer’s method based on various the ratios of GP to oxidizing agent namely potassium permanganate. GO-Acry ER elastomer was prepared by painted GO as the polarized particle on circular Acry ER as elastomer matrix. The optimum condition of synthesized GO was 1:2 ratios of GP: oxidizing agent which provided a more crystallinity, smaller particle size, and higher pore volume. The circular actuation response of GO-Acry ER elastomer was stimulated by applying external stimuli under various electric field strengths and GO characteristics. The expansion of the GO-Acry ER elastomer increased with an increasing external electric field strength. The GO-Acry ER elastomer under adding GO of 1:2 ratios was the largest expansion with 50% strain under applied electric field of 300 kV/mm. When the electric field strength was > 300 kV/mm, the ER elastomer shrank owing to electrical breakdown. Thus, GO is a suitable choice due to its ease of preparation and fast electro-responsive properties.

Predicting the compressive strength of advanced concrete structures by developed African vulture optimization algorithm-Elman neural networks

ABSTRACT: Concrete plate structures’ compressive strength and natural frequency are connected by the mechanical characteristics of the material and structural dynamics. Concrete’s elastic modulus rises along with its compressive strength, making the structure stiffer. Since the natural frequency is proportional to the square root of the stiffness over the mass, the increased stiffness raises the natural frequency. In this work, the relationship between natural frequency and compressive strength in advanced concrete constructions reinforced with graphene oxide particles is examined. Also, the structure is under applied pressure. By using a trigonometric shear deformation plate theory, we hope to improve compressive strength prediction accuracy. Navier’s technique is used as the analytical solution process in the analysis. This study contributes to the design and assessment of more durable and effective structural systems by offering a reliable framework for estimating the compressive strength of reinforced concrete structures. This paper presents a novel method by combining Elman Neural Networks (ENNs) with the developed African Vulture Optimization Algorithm (DAVOA) to estimate the frequency of the structure. With the help of this integration, researchers and engineers can now more precisely estimate the compressive strength of sophisticated concrete structures, leading to the creation of stronger and more robust structural solutions.

Evaluation of physical and mechanical properties of graphene oxide reinforced epoxy/Kevlar hybrid composites

Graphene is a miracle material with low density, excellent mechanical strength, electrical conductivity, molecular barrier properties and many other remarkable properties. Hence, recent research has been more focused on delving into various application areas of graphene. In this study, the effects of graphene oxide (GO) on the mechanical properties of composites based on epoxy resin and Kevlar fibers were investigated. The composites were fabricated by incorporating varying concentrations (1 %, 3 %, 5 %, 10 %, and 16 %) of graphene oxide (GO) into an epoxy matrix. The matrix was reinforced by two different wt.% (12.5 % and 25 %) of Kevlar fibers (KF). The hybrid composites were manufactured by hand lay-up process in a silicon mold at room temperature. Mechanical characterizations such as flexural, impact and hardness test exhibited an enhancement of the mechanical properties of the composites. Moreover, the measured density showed a significant reduction in density with increasing wt.% of GO. As a result, it was possible to fabricate a composite with a significant increase of specific flexural strength and specific flexural modulus. A microstructural analysis of the composites was performed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDX). From the SEM images, it was revealed that the interphase bonding of the GO particles with Kevlar fibers and matrix was strong, thereby resulting in improved mechanical performance. It was observed that 5 wt% GO incorporation along with 25 wt% KF showed improved flexural strength, hardness and impact strength than that of sample fabricated only with Kevlar.

Stable, Self‐Adhesive, and High‐Performance Graphene‐Oxide‐Modified Flexible Ionogel Thermoelectric Films

AbstractIonic thermoelectric materials have attracted increasing attention because of their high flexibility and high Seebeck coefficient. However, their insufficient thermoelectric performance and long‐standing processing limit their practical applications. To achieve exotic ionic thermoelectric materials, here, a graphene oxide (GO) modified acrylamide ionogel is designed with high thermoelectric performance and flexibility. Detailed structural characterizations confirm that the uniform dispersion of GO particles in the ionogel structure enables a power factor of 753.0 µW m−1 K−2 and a promising ZT value of 0.19. Additionally, the as‐prepared ionic thermoelectric thin film shows excellent flexibility, stretchability, and self‐adhesiveness. An integrated device, assembled by the as‐prepared ionogel films, can generate an optimal output power density of 1.32 mW cm−2 with a temperature difference of 20 K, indicating great potential for wearable electronics. This work provides insight for searching long‐term, high‐performance ionic thermoelectric materials.

Studying the Structure and Properties of Epoxy Composites Modified by Original and Functionalized with Hexamethylenediamine by Electrochemically Synthesized Graphene Oxide.

In this study, we used multilayer graphene oxide (GO) obtained by anodic oxidation of graphite powder in 83% sulfuric acid. The modification of GO was carried out by its interaction with hexamethylenediamine (HMDA) according to the mechanism of nucleophilic substitution between the amino group of HMDA (HMDA) and the epoxy groups of GO, accompanied by partial reduction of multilayer GO and an increase in the deformation of the carbon layers. The structure and properties of modified HMDA-GO were characterized using research methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy and Raman spectroscopy. The conducted studies show the effectiveness of using HMDA-OG for modifying epoxy composites. Functionalizing treatment of GO particles helps reduce the free surface energy at the polymer-nanofiller interface and increase adhesion, which leads to the improvement in physical and mechanical characteristics of the composite material. The results demonstrate an increase in the strength and elastic modulus in bending by 48% and 102%, respectively, an increase in the impact strength by 122%, and an increase in the strength and elastic modulus in tension by 82% and 47%, respectively, as compared to the pristine epoxy composite which did not contain GO-HMDA. It has been found that the addition of GO-HMDA into the epoxy composition initiates the polymerization process due to the participation of reactive amino groups in the polymerization reaction, and also provides an increase in the thermal stability of epoxy nanocomposites.

Fabrication of 3D porous polyurethane-graphene oxide scaffolds by a sequential two-step processing for non-load bearing bone defects

Bone defects as a common orthopedic disease lead to severe pains over a long period. Scaffolds are novel approaches in tissue engineering to treat bone problems and deal with their challenges. Here, 3D porous polyurethane (PU) scaffolds containing graphene oxide (GO) with different percentages (0, 0.1, 0.3, and 0.5 wt%) were developed through a combination of freeze-drying and salt etching techniques for bone tissue engineering applications. The morphologies of scaffolds, physicochemical properties, the degree of crystallinity, and hydrophilicity were evaluated by SEM, FTIR, XRD, and water contact angle assay, respectively. The porosity, degradation behavior, compressive strength, and elastic modulus of 3D porous scaffolds were also determined. To assess the scaffold bioactivity, the morphology of the deposited calcium phosphate layer on the scaffold with macro-structure was evaluated by SEM images. The viability and adhesion of MG63 osteoblast-like cells cultured on the fabricated scaffolds were examined by MTT assay and SEM images, respectively. The results show that adding GO particles not only had no effect on the interconnectivity and porosity of 3D porous macroscopic structures of neat PU but also smaller and more uniformed microscopically pores were obtained. The crystallinity, water contact angle, and weight loss of scaffolds increased as the higher GO concentrations were employed. Followed by increasing GO contents from 0 to 0.5 wt%, the compressive strength and Young’s modulus were increased by 232% and 245%, respectively. The bioactivity of scaffolds was fostered as GO concentration increased. Although, the MTT assay proved the biocompatibility of PU scaffolds containing 0.1 and 0.3 wt% GO, the samples loaded with 0.5 GO had a negative impact on the viability of MG63 cell lines. In conclusion, the present study demonstrates a high potential of PU scaffolds loaded with 0.1 and 0.3 wt% GO particles in bone tissue engineering applications.

The impact of nitrogen-doped reduced graphene oxide reinforcement on the thermal and mechanical properties of CFRP

This study used experimental methods to investigate the impact of nitrogen-doped reduced graphene oxide particles (ND-RGOP) reinforcement on thermal and mechanical properties of unidirectional carbon fiber/ epoxy composites (CFRP). In the results, storage modulus and loss modulus significantly increase with the ND-RGOP addition. Besides, glass transition temperature is enhanced with the addition of 0.4 wt% ND-RGOP. In tensile mode, when compared to the baseline (0 weight% ND-RGOP) composites, the elastic modulus in the 0° direction (E1) enhanced by 8.25 % and 11.39 % with 0.4 (0.4 weight%) and 0.8 (0.8 weight%) ND-RGOP addition, respectively. Besides, the ultimate tensile strength of the 0.4 ND-RGOP/CFRP composites significantly reduced by 16.33 % and 53.08 % in both 0° and 90° directions, respectively, as a result of the fracture mechanism changing from fiber pull out and fiber cracking to fiber breakage which was confirmed by SEM investigations. Furthermore, both the compressive modulus and the shear modulus increased with ND-RGOP reinforcement over 10 %, although the ultimate compressive strength decreases with low ND-RGOP reinforcement. In conclusion, low concentrations of ND-RGOP addition improves the thermal and mechanical properties of CFRP laminates in elastic region, although high concentrations of ND-RGOP decreases the thermal properties.

Unveiling the prospects of Y2O3-based nanocomposites: Synthesis, characterization, and electrochemical assessment for supercapacitor and biosensor applications

Supercapacitors distinguish themselves in the realm of energy storage with their ability to discharge rapidly and their superior cycle life when compared to conventional batteries. This research is dedicated to the synthesis of graphene oxide (GO), GO-Y2O3, and GO-Y2O3 doped with Mg2+/Cr3+ through the Hummers and hydrothermal methods. The structural and electrochemical properties of the synthesized samples were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and a CH Analyzer (Electrochemical workstation). The XRD results for both pure and doped GO-based samples indicated a cubic phase and the effective doping of Mg2+ and Cr3+ ions into the yttrium oxide matrix. Transmission electron microscopy (TEM) showed GO particle sizes of approximately 35±5 nm and the encapsulation of Y2O3:Mg2+/Cr3+ within the GO matrix GO-Y2O3:Mg2+/Cr3+ nanocomposites (NCs), with an interplanar spacing of 0.1876 nm corresponding to the (440) crystal plane. Cyclic voltammetry (CV) analysis for Y2O3 and its doped variants (Y2O3:Mg2+, Y2O3:Cr3+) showed increased current responses at various scan rates, with distinct peaks and a current peak ratio of less than 1, indicative of a quasi-reversible system. The electrodes based on Y2O3 and (Y2O3:Mg2+, Y2O3:Cr3+) NCs achieved maximum specific capacitance values of 172.54 Fg⁻¹, 279.98 Fg⁻¹, and 791.59 Fg⁻¹, respectively, at a scan rate of 2 mV/s. Galvanostatic charge-discharge (GCD) profiles for these yttrium-based samples yielded capacitance values of 71.66 Fg⁻¹, 112.77 Fg⁻¹, and 370 Fg⁻¹, respectively, with the highest value observed for Mg2+ doped samples. Additionally, the Y2O3:Mg2+ samples showcased superior charge transport within the electrode material, leading to a higher energy density of 18.5 Wh/kg compared to the Y2O3:Cr3+ and pure Y2O3 samples. Electrochemical impedance spectroscopy (EIS) of the Mg2+ and Cr3+ doped yttrium samples showed a linear response in both the low and high-frequency regions, demonstrating their enhanced charge storage capability. Notably, the Y2O3:Mg2+ sample achieved the highest capacity retention of 94.25%. The combination of Y2O3 and Mg2+ led to improved capacitance retention and efficient charge storage, with a Coulombic efficiency of 91.9%, compared to the pure sample. Additionally, the sensitivity and selectivity studies of Mg2+ and Cr3+ doped Y2O3 samples suggested that these developed nanocomposite materials hold potential for biosensor applications.

Effect of Graphene Oxide and Ammonia-modified Graphene Oxide Particles on ATPase Activity of Rat Liver Mitochondria

Graphene and its derivatives have become promising materials for biomedical applications in the last decade. Before their widespread application, however, evaluating their toxicity and mechanisms underlying interactions with cellular components is imperative. Aims: Assessment of the effect of two graphene derivatives, pristine graphene oxide (GO) and ammonia-modified GO (GO-NH2) particles, on the ATPase activity of rat liver mitochondria and ROS production. Methods: Liver mitochondria were isolated from male albino rats and treated with different concentrations of GO and GO-NH2 particles (4, 10, 25, and 50 μg/ml). ATPase activity of both, intact and uncoupled by freezing/thawing mitochondria was determined by the measurement of inorganic phosphate (Pi) released from ATP. The generation of hydrogen peroxide (H2O2) after exposure of mitochondria to GO and GO-NH2 particles was determined by a DCFH-D assay. Results: GO and GO-NH2 particles applied at concentrations of 4 and 50 μg/ml did not affect the ATPase activity of intact mitochondria. In contrast, in uncoupled mitochondria, they demonstrated a stimulating effect on ATPase activity. The impact of GO-NH2 was more substantial and concentration-dependent. ROS production was also higher in GO-NH2-treated mitochondria. Conclusion: The present study demonstrated that GO and GO-NH2 particles can exert a cytotoxic effect on mitochondria even after a short-time of exposure to both types of particles.

Comparison of the effects of carbon-based and inorganic nanomaterials on early cement hydration

This study delves into the impact of nanomaterials on early cement hydration, aiming to elucidate their mechanism of action. Four nanomaterials were selected, including carbon-based nanomaterials (multi-walled carbon nanotubes (CNT) and graphene oxide (GO)) and inorganic nanomaterials (nano-SiO2 and nano-CaCO3). Initially, the zeta potential was employed to examine nanomaterial adsorption on relevant ions in simulated solutions. Subsequently, SEM NMR, XRD, and TGA were utilized to assess the influence of different nanomaterials on hydration product morphology, content, and structure. Utilizing the Krstulovic-Dabic model, the hydration kinetics based on the heat of hydration in cement paste containing nanomaterials was simulated. Results revealed nanomaterials exhibited stronger Ca2+ ion adsorption than cement particles, with CNT and GO particles displaying weaker adsorption relative to SO42- ions. Conversely, nano-SiO2 and nano-CaCO3 particles exhibited a stronger adsorption capacity for Ca2+ ions than SO42- ions. This robust adsorption facilitated hydration product generation, yielding fine and regular C-S-H particles in carbon-based nanomaterial-containing cement pastes, contrasting with coarse and irregular particles in inorganic nanomaterial-containing pastes. Nanomaterial introduction increased polymerization and the average chain length of hydration products. Furthermore, it heightened exothermic peak intensity and total exothermic amount, while reducing the induction period and exothermic peak length. Hydration kinetics, simulated through the Krstulovic-Dabic model, aligned with the nucleation and growth (NG)-phase boundary reaction (I)-diffusion (D) process. In the NG stage, nanomaterials accelerated hydration by reducing reaction stages (n) and increasing the rate constant (K1'). In the I stage, hindered Ca2+ ion migration led to decreased K2', slowing hydration. Stage D witnessed a rapid decline in K3'.

First-in-human controlled inhalation of thin graphene oxide nanosheets to study acute cardiorespiratory responses

Graphene oxide nanomaterials are being developed for wide-ranging applications but are associated with potential safety concerns for human health. We conducted a double-blind randomized controlled study to determine how the inhalation of graphene oxide nanosheets affects acute pulmonary and cardiovascular function. Small and ultrasmall graphene oxide nanosheets at a concentration of 200 μg m−3 or filtered air were inhaled for 2 h by 14 young healthy volunteers in repeated visits. Overall, graphene oxide nanosheet exposure was well tolerated with no adverse effects. Heart rate, blood pressure, lung function and inflammatory markers were unaffected irrespective of graphene oxide particle size. Highly enriched blood proteomics analysis revealed very few differential plasma proteins and thrombus formation was mildly increased in an ex vivo model of arterial injury. Overall, acute inhalation of highly purified and thin nanometre-sized graphene oxide nanosheets was not associated with overt detrimental effects in healthy humans. These findings demonstrate the feasibility of carefully controlled human exposures at a clinical setting for risk assessment of graphene oxide, and lay the foundations for investigating the effects of other two-dimensional nanomaterials in humans. Clinicaltrials.gov ref: NCT03659864.

PSF/GO filtering membrane fabricated by electro-spinning applied on arsenic contaminated underground water

The excess arsenic content in groundwater sources threatens more than 50 million people worldwide. Current water treatment projects use polysulfone nanofiltration membranes (NFM). However, the inherent hydrophilicity of polysulfone nanofiltration membranes causes the membrane fouling problem. This study addresses this problem by improving the hydrophilic and anti-pollution properties by doping graphene oxide (GO) particles in polysulfone(PSF) membranes. Microstructure, morphology, and hydrophilicity of PSF/GO membranes were analyzed by field emission scanning electron microscope (FEFEM), contact angle, and BET surface area analysis. X-ray diffraction (XRD), zeta potential, Energy Dispersive Spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were used to analyze the results of the phase structure and element distribution. Permeation tests and adsorption of arsenic experiments were used to study the filtration performance of PSF/GO membranes. The results showed that PSF/GO with high porosity enlarged the specific surface area significantly. The contact angle decreased by only about 7°. Still, the water flux increased from 33.26 L/m2/h to 183.62 L/m2/h, which weakened the effect caused by membrane contamination of the arsenate solution and GO doping on the arsenate adsorption rate of PSF/GO nanofiltration membrane was discussed. The results showed that solution pH was crucial in As (V) adsorption onto PSF/GO and obtaining higher adsorption capacity at higher pH. In an alkaline environment, The adsorption rate increased from 26.71% of pure PSF fiber membrane to 79.83%.