Disposable Zirconium trisulfide-Reduced graphene oxide modified conducting thread based electrochemical biosensor for lung cancer diagnosis

Flexible technology in sensors have received much attention in monitoring of human health through various physiological indicators. Thus, it drawn a lot of interest in the development of flexible substrate for the diagnosis of various diseases via analysis of analytes. Present work focusses on the development of ecofriendly, portable, flexible, conducting thread (Th) and used as smart substrate for fabrication of biosensor towards ultrasensitive detection of the lung cancer biomarker (cytoskeleton-associated protein 4; CKAP4). The zirconium trisulfide-reduced graphene oxide nanocomposite and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) modified cotton thread based biosensor was fabricated via dip coating method. Next, successive immobilization of monoclonal antibodies of CKAP4 (anti-CKAP4) and bovine serum albumin (BSA) was performed via drop cast approach using fabricated electrode [nZrS3@rGO/PEDOT:PSS/Th]. The response of fabricated electrode (BSA/anti-CKAP4/ZrS3@rGO/PEDOT:PSS/Th) was recorded electrochemically versus CKAP4 concentration via chronoamperometry (CA). The results showed wider linear detection range of 6.25-800 pg mL-1, excellent sensitivity of 85.2 µA[log(pg mL-1)]-1cm-2 with good stability up to 42 days. The response of fabricated biosensor was supported by investigating response of CKAP4 biomarker present in patients of lung cancer (concentration as determined through enzyme-linked immunosorbent assay) and obtained results exhibited excellent correlation with that of standard samples.

Highly Selective Nitrogen-Doped Graphene Quantum Dots/Eriochrome Cyanine Composite Photocatalyst for NADH Regeneration and Coupling of Benzylamine in Aerobic Condition under Solar Light

Photocatalysis is an ecofriendly and sustainable pathway for utilizing solar energy to convert organic molecules. In this context, using solar light responsive graphene-based materials for C–N bond activation and coenzyme regeneration (nicotinamide adenine dinucleotide hydrogen; NADH) is one of the utmost important and challenging tasks in this century. Herein, we report the synthesis of nitrogen-doped graphene quantum dots (NGQDs)-eriochrome cyanine (EC) solar light active highly efficient “NGQDs@EC” composite photocatalyst for the conversion of 4-chloro benzylamine into 4-chloro benzylamine, accompanied by the regeneration of NADH from NAD+, respectively. The NGQDs@EC composite photocatalyst system is utilized in a highly efficient and stereospecific solar light responsive manner, leading to the conversion of imine (98.5%) and NADH regeneration (55%) in comparison to NGQDs. The present research work highlights the improvements in the use of NGQDs@EC composite photocatalyst for stereospecific NADH regeneration and conversion of imine under solar light.

Experimental and first-principle computational exploration on biomass cellulose/magnesium hydroxide composite: Local structure, interfacial interaction and antibacterial property

The specification of the local structure and clarification of interfacial interactions of biomass composites is of tremendous significance in synthesizing novel materials and advancing their performance in various demanding applications. However, it remains challenging due to the limitations of experimental techniques, particularly for the manner that biomass composites commonly have hydrogen bonds involved in the vicinity of active sites and interfaces. Herein, the cellulose/Mg(OH)₂ nanocomposite has been synthesized via a simple hydrothermal approach and examined by density functional theory (DFT) calculations. The composite exhibits a layered morphology; Mg(OH)₂ flakes are around 50 nm in size and well-dispersed. They either anchor onto the cellulose surface or intercalate between layers. The specific composite structure was confirmed theoretically, in line with XRD, SEM and TEM observations. The interfacial interactions were found to be hydrogen bonding. The average adsorption energy per hydroxyl group was computed to be within -0.47 and -0.26 eV for a composite model comprising three cellulose chains and a two-layered Mg(OH)₂ cluster. The combined computational/experimental results allow to postulate the antibacterial mechanism of the nanocomposite.

Graphene-Based Hybrid Functional Materials

Graphene is a 2D material combining numerous outstanding physical properties, including high flexibility and strength, extremely high thermal conductivity and electron mobility, transparency, etc., which make it a unique testbed to explore fundamental physical phenomena. Such physical properties can be further tuned by combining graphene with other nanomaterials or (macro)molecules to form hybrid functional materials, which by design can display not only the properties of the individual components but also exhibit new properties and enhanced characteristics arising from the synergic interaction of the components. The implementation of the hybrid approach to graphene also allows boosting the performances in a multitude of technological applications. This review reports the hybrids formed by graphene combined with other low-dimensional nanomaterials of diverse dimensionality (0D, 1D, and 2D) and (macro)molecules, with emphasis on the synthetic methods. The most important applications of these hybrids in the fields of sensing, water purification, energy storage, biomedical, (photo)catalysis, and opto(electronics) are also reviewed, with a special focus on the superior performances of these hybrids compared to the individual, nonhybridized components.

Enhanced photocatalytic activity of Ag-coated ZnO nanorods for the degradation of methylene blue

Worldwide water pollution is a serious issue, which needs special attention. Among these pollutants, methylene blue (MB) is dangerous for aquatic life as well as for human beings. Researchers are trying their best to degrade the various pollutants found in water. In the present work, we synthesized ZnO nanorods (NRDs) by one-step hydrothermal method. The synthesized samples were then characterized with the help of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). ZnO nanostructures were composed of rod-shaped NRDs with flat edges and were highly crystalline with hexagonal shaped morphology. UV/Visible spectroscopy was carried out to investigate the optical properties, which shows the absorption in UV range and highly transmittance in the visible range. Finally, the photocatalytic activity was performed for the degradation of MB. The results show that MB was not fully degraded by bare ZnO NRDs. After all, we coated Ag NPs on the surfaces of ZnO NRDs through the simple solution-based method. The UV/Visible data reveal absorption in the UV as well as in the visible range due to the surface plasmonic effect of Ag NPs. Hybrid Ag-coated ZnO NRDs successfully degraded MB within 60 min. Therefore, we found that Ag-coated ZnO NRDs show good photocatalytic properties as compared to uncoated ZnO NRDs.

Deep Eutectic Solvent Micro-Functionalized Graphene Assisted Dispersive Micro Solid-Phase Extraction of Pyrethroid Insecticides in Natural Products

Deep eutectic solvent micro-functionalized graphene (DES-G) was synthesized and first applied as the adsorbent of dispersive micro solid-phase extraction (DMSPE) to extract five pyrethroid insecticides. In DMSPE, the target analytes were absorbed by DES-G and then desorbed by trace eluent, next, the treated samples were quantified via ultra-high performance liquid chromatography equipped with diode-array detection. A scanning electron microscope, transmission electron microscopy and Fourier transform infrared spectrometer were used to characterize the prepared DES-G. Furthermore, this method was verified under the selected conditions with the precision for retention times ranging from 0.43 to 0.57%, and repeatability ranged from 0.04 to 2.41% for peak areas. The developed method was successfully applied to determine pyrethroid insecticides residues in beebread, Curcuma wenyujin and Dendrobium officinale with the recoveries in the range of 80.9–114.1%.

Three-dimensional graphene-based adsorbents in sewage disposal: a review

A kind of graphene functional materials based on three-dimensional (3D) porous structure is a new star for environmental application in the past decades because it not only inherits the perfect carbon crystal structure of two-dimensional (2D) graphene sheets but also exhibits several advantages such as extremely low density, high porosity, and big surface area, all which enable diverse contaminants to easily access and diffuse into 3D networks, and make these materials ideal adsorbents with superior adsorptivity and recyclability. This review aims to summarize the recent progress in constructing 3D graphene-based adsorbents (3DGBAs) with two hybrid systems such as graphene/polymers and graphene/inorganic nanomaterials, and to provide a fundamental understanding of synthetic methods for interconnecting these nanostructures, structure-property relationships, and extensive applications in environmental protection towards adsorption of heavy metals, dyes, oils, and organic pollutants. Furthermore, we make a forecast on the future development opportunities and technical challenges, which is hoped to make an inspiration for the researchers to exploit a new family of graphene-based adsorption materials. Graphical abstract ᅟ.

Impact of water chemistry on surface charge and aggregation of polystyrene microspheres suspensions

The discharge of microplastics into aquatic environment poses the potential threat to the hydrocoles and human health. The fate and transport of microplastics in aqueous solutions are significantly influenced by water chemistry. In this study, the effect of water chemistry (i.e., pH, foreign salts and humic acid) on the surface charge and aggregation of polystyrene microsphere in aqueous solutions was conducted by batch, zeta potentials, hydrodynamic diameters, FT-IR and XPS analysis. Compared to Na⁺ and K⁺, the lower negative zeta potentials and larger hydrodynamic diameters of polystyrene microspheres after introduction of Mg²⁺ were observed within a wide range of pH (2.0-11.0) and ionic strength (IS, 0.01-500mmol/L). No effect of Cl^-, HCO₃^- and SO₄^2- on the zeta potentials and hydrodynamic diameters of polystyrene microspheres was observed at low IS concentrations (<5mmol/L), whereas the zeta potentials and hydrodynamic diameters of polystyrene microspheres after addition of SO₄^2- were higher than that of Cl^- and HCO₃^- at high IS concentrations (>10mmol/L). The zeta potentials of polystyrene microspheres after HA addition were decreased at pH2.0-11.0, whereas the lower hydrodynamic diameters were observed at pH<4.0. According to FT-IR and XPS analysis, the change in surface properties of polystyrene microspheres after addition of hydrated Mg²⁺ and HA was attributed to surface electrostatic and/or steric repulsions. These investigations are crucial for understanding the effect of water chemistry on colloidal stability of microplastics in aquatic environment.

Carbon Cloth Supported Nano-Mg(OH)2 for the Enrichment and Recovery of Rare Earth Element Eu(III) From Aqueous Solution

Nano-Mg(OH)₂ is attracting great attention as adsorbent for pre-concentration and recovery of rare earth elements (REEs) from low-concentration solution, due to its superior removal efficiency for REEs and environmental friendliness. However, the nanoparticles also cause some severe problems during application, including aggregation, blockage in fixed-bed column, as well as the difficulties in separation and reuse. Herein, in order to avoid the mentioned problems, a carbon cloth (CC) supported nano-Mg(OH)₂ (nano-Mg(OH)₂@CC) was synthesized by electrodeposition. The X-ray diffraction and scanning electron microscopy analysis demonstrated that the interlaced nano-sheet of Mg(OH)₂ grew firmly and uniformly on the surface of carbon cloth fibers. Batch adsorption experiments of Eu(III) indicated that the nano-Mg(OH)₂@CC composite maintained the excellent adsorption performance of nano-Mg(OH)₂ toward Eu(III). After adsorption, the Eu containing composite was calcined under nitrogen atmosphere. The content of Eu₂O₃ in the calcined material was as high as 99.66%. Fixed-bed column experiments indicated that no blockage for Mg(OH)₂@CC composite was observed during the treatment, while the complete blockage of occurred to nano-Mg(OH)₂ at an effluent volume of 240 mL. Moreover, the removal efficiency of Mg(OH)₂@CC was still higher than 90% until 4,200 mL of effluent volume. This work provides a promising method for feasible application of nanoadsorbents in fixed-bed process to recycle low-concentration REEs from wastewater.

In Situ Mg/MgO-Embedded Mesoporous Carbon Derived from Magnesium 1,4-Benzenedicarboxylate Metal Organic Framework as Sustainable Li-S Battery Cathode Support

Development of advanced carbon cathode support with the ability to accommodate high sulfur (S) content as well as effective confinement of the sulfur species during charge-discharge is of great importance for sustenance of Li-S battery. A facile poly(vinylpyrrolidone)-assisted solvothermal method is reported here to prepare Mg-1,4-benzenedicarboxylate metal organic framework (MOF) from which mesoporous carbon is derived by thermal treatment, where the hexagonal sheetlike morphology of the parent MOF is retained. Existence of abundant pores of size 4 and 9 nm extended in three dimensions with zigzag mazelike channels helps trapping of S in the carbon matrix through capillary effect, resulting in high S loading. When tested as a cathode for lithium-sulfur battery, a reversible specific capacity of 1184 mAh g^-1 could be achieved at 0.02 C. As evidenced by X-ray photoelectron spectroscopy, in situ generated Mg in the carbon structure enhances the conductivity, whereas MgO provides support to S immobilization through chemical interactions between Mg and sulfur species for surface polarity compensation, restricting the dissolution of polysulfide into the electrolyte, the main cause for the "shuttle phenomenon" and consequent capacity fading. The developed cathode shows good electrochemical stability with reversible capacities of 602 and 328 mAh g^-1 at 0.5 and 1.0 C, respectively, with retentions of 64 and 67% after 200 cycles. The simple MOF-derived strategy adopted here would help design new carbon materials for Li-S cathode support.

One-step synthesis of Ag2O@Mg(OH)2 nanocomposite as an efficient scavenger for iodine and uranium

Ag₂O nanoparticles anchored on the Mg(OH)₂ nanoplates (Ag₂O@Mg(OH)₂) were successfully prepared by a facile one-step method, which combined the Mg(OH)₂ formation with Ag₂O deposition. The synthesized products were characterized by a wide range of techniques including powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and nitrogen physisorption analysis. It was found that Ag₂O nanoparticles anchored on the Mg(OH)₂ nanoplates show good dispersion and less aggregation relative to the single Ag₂O nanoaggregates. In addition, iodide (I^-) removal by the Ag₂O@Mg(OH)₂ nanocomposite was studied systematically. Batch experiments reveal that the nanocomposite exhibits extremely high I^- removal rate (<10min), and I^- removal capacity is barely affected by the concurrent anions, such as Cl^-, SO₄^2-, CO₃^2- and NO₃^-. Furthermore, I^- and UO₂²⁺ could be simultaneously removed by the nanocomposite with high efficiency. Due to the simple synthetic procedure, the excellent removal performances for iodine and uranium, and the easy separation from water, the Ag₂O@Mg(OH)₂ nanocomposite has real potential for application in radioactive wastewater treatment, especially during episodic environmental crisis.

Nanoscale zero-valent metals: a review of synthesis, characterization, and applications to environmental remediation

Engineered nanoscale zero-valent metals (NZVMs) representing the forefront of technologies have been considered as promising materials for environmental remediation and antimicrobial effect, due to their high reducibility and strong adsorption capability. This review is focused on the methodology for synthesis of bare NZVMs, supported NZVMs, modified NZVMs, and bimetallic systems with both traditional and green methods. Recent studies have demonstrated that self-assembly methods can play an important role for obtaining ordered, controllable, and tunable NZVMs. In addition to common characterization methods, the state-of-the-art methods have been developed to obtain the properties of NZVMs (e.g., granularity, size distribution, specific surface area, shape, crystal form, and chemical bond) with the resolution down to subnanometer scale. These methods include spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM), electron energy-loss spectroscopy (EELS), and near edge X-ray absorption fine structure (NEXAFS). A growing body of experimental data has proven that nanoscale zero-valent iron (NZVI) is highly effective and versatile. This article discusses the applications of NZVMs to treatment of heavy metals, halogenated organic compounds, polycyclic aromatic hydrocarbons, nutrients, radioelements, and microorganisms, using both ex situ and in situ methods. Furthermore, this paper briefly describes the ecotoxicological effects for NZVMs and the research prospects related to their synthesis, modification, characterization, and applications.

The Application of Graphene and Its Derivatives to Energy Conversion, Storage, and Environmental and Biosensing Devices

Graphene (GR) and its derivatives are promising materials on the horizon of nanotechnology and material science and have attracted a tremendous amount of research interest in recent years. The unique atom-thick 2D structure with sp(2) hybridization and large specific surface area, high thermal conductivity, superior electron mobility, and chemical stability have made GR and its derivatives extremely attractive components for composite materials for solar energy conversion, energy storage, environmental purification, and biosensor applications. This review gives a brief introduction of GR's unique structure, band structure engineering, physical and chemical properties, and recent energy-related progress of GR-based materials in the fields of energy conversion (e.g., photocatalysis, photoelectrochemical water splitting, CO2 reduction, dye-sensitized and organic solar cells, and photosensitizers in photovoltaic devices) and energy storage (batteries, fuel cells, and supercapacitors). The vast coverage of advancements in environmental applications of GR-based materials for photocatalytic degradation of organic pollutants, gas sensing, and removal of heavy-metal ions is presented. Additionally, the use of graphene composites in the biosensing field is discussed. We conclude the review with remarks on the challenges, prospects, and further development of GR-based materials in the exciting fields of energy, environment, and bioscience.

Novel Fe3O4/HNT@rGO composite via a facile co-precipitation method for the removal of contaminants from aqueous system

Fe₃O₄/HNT@rGO composite (FHGC) was fabricated via a facile co-precipitation process, followed by heat treatment. For RhB and As⁵⁺removal, the high performance and easy separation of FHGC highlight its potential application in water treatment.

A graphene–melamine-sponge for efficient and recyclable dye adsorption

The submersible graphene–melamine-sponges present fast and highly efficient adsorption for water soluble dyes.

Layered mesoporous Mg(OH)2/GO nanosheet composite for efficient removal of water contaminants

Mg(OH)₂ flakes composited on GO nanosheets as triggered by the colloidal electrostatic self-assembly in an liquid laser ablation process. The as-synthesized composite presented excellent adsorption performance for MB and heavy metal ions.

Carbon-Based Sorbents with Three-Dimensional Architectures for Water Remediation

Over the past decade, carbon-based 3D architectures have received increasing attention in science and technology due to their fascinating properties, such as a large surface area, macroscopic bulky shape, and interconnected porous structures, enabling them to be one of the most promising materials for water remediation. This review summarizes the recent development in design, preparation, and applications of carbon-based 3D architectures derived from carbon nanotubes, graphene, biomass, or synthetic polymers for water treatment. After a brief introduction of these materials and their synthetic strategies, their applications in water treatment, such as the removal of oils/organics, ions, and dyes, are summarized. Finally, future perspective directions for this promising field are also discussed.

Introduction of α-MnO2nanosheets to NH2graphene to remove Cr6+from aqueous solutions

The planar structure of the designed α-MnO₂–NH₂–RGO hybrid was prepared and characterized and used to remove hexavalent chromium ions (Cr⁶⁺) from aqueous solutions.

Anchoring superparamagnetic core–shells onto reduced graphene oxide: fabrication of Ni–carbon–rGO nanocomposite for effective adsorption and separation

The magnetic Ni nanoparticles encapsulated in carbon shells were anchored on to reduced graphene oxide. The excellent removal ability of organic dyes and enhanced separation efficiency make NGC a useful candidate for waste water treatment.

Magnesium hydroxide nanoplate/graphene oxide composites as efficient adsorbents for organic dyes

Mg(OH)₂ nanoplates/graphene oxide nanocomposites: controlled synthesis of Mg(OH)₂ nanoplates on the GO surface and the use of the resulting nanocomposites for efficient removal of dyes are presented.

Controlling the microstructure of MFI zeolites with Mg(OH)2 nanocrystals to improve their catalytic performances

The microstructure of TS-1 and S-1 were affected by Mg(OH)₂ NCs and their catalytic performance has been improved.

Synthesis of copper oxide/reduced graphene oxide nanocomposite and its enhanced catalytic activity towards reduction of 4-nitrophenol

Graphene oxide (GO) and its derivatives have attracted extensive interest in many fields, including catalytic chemistry, organic synthesis, and electrochemistry.

Applications of graphene and its derivatives as an adsorbent for heavy metal and dye removal: a systematic and comprehensive overview

Because of their persistency and toxicity, dyes and heavy metal ions discharged to water bodies have become a worrisome issue.

Graphene nanosheets as novel adsorbents in adsorption, preconcentration and removal of gases, organic compounds and metal ions

Due to their high adsorption capacities, carbon-based nanomaterials such as carbon nanotubes, activated carbons, fullerene and graphene are widely used as the currently most promising functional materials. Since its discovery in 2004, graphene has exhibited great potential in many technological fields, such as energy storage materials, supercapacitors, resonators, quantum dots, solar cells, electronics, and sensors. The large theoretical specific surface area of graphene nanosheets (2630 m(2)·g(-1)) makes them excellent candidates for adsorption technologies. Further, graphene nanosheets could be used as substrates for decorating the surfaces of nanoparticles, and the corresponding nanocomposites could be applied as novel adsorbents for the removal of low concentrated contaminants from aqueous solutions. Therefore, graphene nanosheets will challenge the current existing adsorbents, including other types of carbon-based nanomaterials.

EDTA-induced self-assembly of 3D graphene and its superior adsorption ability for paraquat using a teabag

In the past two years, three-dimensional graphene (3DG) was introduced to the environmental treatment area as a promising new material. Despite much progress in its synthesis and applications, 3DG is still limited in terms of green large-scale synthesis and practical environmental applications. In this work, a 3DG synthetic method was developed at 95 °C in an EDTA-induced self-assembly process. Because little EDTA was found to be consumed during synthesis, which might be due to its great stability and poor reducibility, 3DG with complete structure can be successively obtained by reusing the EDTA solution more than 10 times. Furthermore, 3DG was found to possess a superior adsorption capacity of 119 mg g(-1) (pH 6.0) for paraquat, a highly toxic herbicide with positive charges and a conjugated system of π bonds in its molecular structure. The adsorption capacity was much higher than those in classic paraquat adsorbents, such as clay and activated carbon. To address the problem of 3DG damage by stirring, a pyramid-shaped nylon teabag was adopted to protect the soft hydrogel during the repeated adsorption-desorption processes. After five cycles, the 3DG teabag still maintained 88% of the initial adsorption capacity. This facile method may be easily applied in other environmental treatment conditions.

Porous graphene materials for water remediation

Water remediation has been a critical issue over the past decades due to the expansion of wastewater discharge to the environment. Currently, a variety of functional materials have been successfully prepared for water remediation applications. Among them, graphene is an attractive candidate due to its high specific surface area, tunable surface behavior, and high strength. This Concept paper summarizes the design strategy of porous graphene materials and their applications in water remediation, such as the cleanup of oil, removal of heavy metal ions, and elimination of water soluble organic contaminants. The progress made so far will guide further development in structure design strategy of porous materials based on graphene and exploration of such materials in environmental remediation.

Significantly enhanced dye removal performance of hollow tin oxide nanoparticles via carbon coating in dark environment and study of its mechanism

Understanding the correlation between physicochemical properties and morphology of nanostructures is a prerequisite for widespread applications of nanomaterials in environmental application areas. Herein, we illustrated that the uniform-sized SnO2@C hollow nanoparticles were large-scale synthesized by a facile hydrothermal method. The size of the core-shell hollow nanoparticles was about 56 nm, and the shell was composed of a solid carbon layer with a thickness of 2 ~ 3 nm. The resulting products were characterized in terms of morphology, composition, and surface property by various analytical techniques. Moreover, the SnO2@C hollow nanoparticles are shown to be effective adsorbents for removing four different dyes from aqueous solutions, which is superior to the pure hollow SnO2 nanoparticles and commercial SnO2. The enhanced mechanism has also been discussed, which can be attributed to the high specific surface areas after carbon coating.

Surface area measurement of graphene oxide in aqueous solutions

Graphene oxide (GO) forms persistent dispersions in aqueous solutions up to concentrations of 0.2 mg mL(-1). Addition of methylene blue (MB) to these aqueous dispersion of GO gives rise to the observation in optical spectroscopy of new absorption bands that are indicative of the formation of MB/GO conjugates. Four new absorption maxima have been characterized, and their intensity varies depending on the relative concentration of MB with respect to GO. Two of these bands appearing at 677 and 757 nm correspond to individual MB molecules adsorbed on neutral or acid sites of GO, respectively. Two other bands at 615 and 580 nm are attributable to adsorbed MB molecules showing interaction with other neighbor dye molecules at incomplete (615 nm) or complete (580 nm) surface coverage. Complete coverage of GO surface by MB causes the formation of a precipitate and the separation of the MB/GO conjugate. EDS mapping of carbon and sulfur atoms of MB/GO conjugate indicates the homogeneous distribution of MB molecules coating GO sheets. A simple and reliable protocol for surface area measurement and determination of the level of aggregation for GO dispersions in water has been proposed by determining the amount of MB that leads to the maximum intensity of the 580 nm band and precipitation of the MB/GO conjugate. Specific surface area as high as 736.6 m(2) g(-1) in the range of the theoretical value for GO has been experimentally measured for diluted GO solutions, but aggregation levels of 15% were estimated for GO concentration of 50 μg mL(-1).

Recycling rare earth elements from industrial wastewater with flowerlike nano-Mg(OH)(2)

Treatment of wastewater containing low-concentration yet highly-expensive rare earth elements (REEs) is one of the vital issues in the REEs separation and refining industry. In this work, the interaction and related mechanism between self-supported flowerlike nano-Mg(OH)2 and low-concentration REEs wastewater were investigated. More than 99% REEs were successfully taken up by nano-Mg(OH)2. Further analysis revealed that the REEs could be collected on the surface of Mg(OH)2 as metal hydroxide nanoparticles (<5 nm). An ion-exchange model was proposed as a critical factor for both guaranteeing the reaction speed and maintaining the self-supported structure of the materials. In addition, a method was developed to further separate the immobilized REEs and the residual magnesium hydroxide by varying the solution pH. In a pilot-scale experiment, the REEs from practical wastewater were immobilized effectively at a high flow rate. We anticipate this work can provide a good example for the recycling of valuable REEs in practical industrial applications.

In situ synthesis of Ru/RGO nanocomposites as a highly efficient catalyst for selective hydrogenation of halonitroaromatics

A reduced graphene oxide (RGO) supported-ruthenium (Ru) catalyst was prepared through a facile hydrothermal process with reduction of Ru(3+) and GO at the same time. Small ruthenium nanoparticles were well dispersed on the surface of the RGO sheets confirmed by a set of characterizations such as SEM and TEM. XPS analysis indicated that Ru nanoparticles were in an electron-deficient state due to the electron transfer between the nanoparticles and the RGO sheets. The as-prepared catalyst was applied for the selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN), exhibiting a turnover frequency (TOF) of 1800 h(-1) and a selectivity of 99.6% at complete conversion of p-CNB. The Ru/RGO catalyst displayed excellent stability and was extremely active for the hydrogenation of a series of nitroarenes, which can be ascribed to the fine dispersity of the Ru nanoparticles on the RGO sheets and their electron-deficient state.

Preparation of graphene adsorbents and their applications in water purification

Graphene has attracted great interest for its unique structure, fantastic properties, and wide applications. Among the various applications, graphene-based materials hold great potential as adsorbents in decontaminating water because of the large surface area, diverse functionalities, ease of preparation, and low cost of treatment. Graphene and its composites have been used in treating heavy metals, dyes, pesticide, antibiotics, oils, and so on. In this paper, we reviewed the preparation methods of graphene adsorbents and their applications in water purification. The adsorption behaviors of contaminates on graphene are summarized. The interactions between graphene and contaminates are discussed, emphasizing the influence of functional groups. We also propose some guidelines in designing high-performance graphene adsorbents from the physicochemical perspective.

Graphene-based materials: fabrication, characterization and application for the decontamination of wastewater and wastegas and hydrogen storage/generation

Graphene, as an ideal two-dimensional material and single-atom layer of graphite, has attracted exploding interests in multidisciplinary research because of its unique structure and exceptional physicochemical properties. Especially, graphene-based materials offer a wide range of potentialities for environmental remediation and energy applications. This review shows an extensive overview of the main principles and the recent synthetic technologies about designing and fabricating various innovative graphene-based materials. Furthermore, an extensive list of graphene-based sorbents and catalysts from vast literature has been compiled. The adsorptive and catalytic properties of graphene-based materials for the removal of various pollutants and hydrogen storage/production as available in the literature are presented. Tremendous adsorption capacity, excellent catalytic performance and abundant availability are the significant factors making these materials suitable alternatives for environmental pollutant control and energy-related system, especially in terms of the removal of pollutants in water, gas cleanup and purification, and hydrogen generation and storage. Meanwhile, a brief discussion is also included on the influence of graphene materials on the environment, and its toxicological effects. Lastly, some unsolved subjects together with major challenges in this germinating area of research are highlighted and discussed. Conclusively, the expanding of graphene-based materials in the field of adsorption and catalysis science represents a viable and powerful tool, resulting in the superior improvement of environmental pollution control and energy development.

Environmental applications using graphene composites: water remediation and gas adsorption

This review deals with wide-ranging environmental studies of graphene-based materials on the adsorption of hazardous materials and photocatalytic degradation of pollutants for water remediation and the physisorption, chemisorption, reactive adsorption, and separation for gas storage. The environmental and biological toxicity of graphene, which is an important issue if graphene composites are to be applied in environmental remediation, is also addressed.

Synthesis of superhydrophobic silica nanofibrous membranes with robust thermal stability and flexibility via in situ polymerization

Superhydrophobic silica nanofibrous membranes exhibiting robust thermal stability and flexibility were prepared by a facile combination of electrospun silica nanofibers and a novel in situ polymerized fluorinated polybenzoxazine (F-PBZ) functional layer that incorporated SiO(2) nanoparticles (SiO(2) NPs). By using F-PBZ/SiO(2) NP modification, the pristine hydrophilic silica nanofibrous membranes were endowed with superhydrophobicity with a water contact angle (WCA) of up to 161°. Surface morphological studies have revealed that the wettability of resultant membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. Quantitative fractal dimension analysis using the N(2) adsorption method has confirmed the correlation between hierarchical roughness and WCA for the modified membranes. Furthermore, the as-prepared membranes exhibited high thermal stability (450 °C), good flexibility (0.0127 gf cm), and comparable tensile strength (2.58 MPa), suggesting their use as promising materials for a variety of potential applications in high-temperature filtration, self-cleaning coatings, catalyst carriers, etc., and also provided new insight into the design and development of functional nanofibrous membranes through F-PBZ modification.