Bunshi Fugetsu

Graphene oxide adsorption enhanced by in situ reduction with sodium hydrosulfite to remove acridine orange from aqueous solution

Graphene oxide (GO) is a highly effective adsorbent, and its absorbing capability is further enhanced through its in situ reduction with sodium hydrosulfite as the reductant. Acridine orange is the selected target to eliminate with GO as the adsorbent. Under identical conditions, GO without the in situ reduction showed a maximum adsorption capacity of 1.4 g g(-1), and GO with the in situ reduction provided a maximum adsorption capacity of 3.3 g g(-1). Sodium hydrosulfite converts carbonyl groups on GO into hydroxyl groups, which function as the key sites for the adsorption enhancement.

Studies on toxicity of multi-walled carbon nanotubes on Arabidopsis T87 suspension cells.

The possible toxicities of agglomerates of multi-walled carbon nanotubes (MWCNTs) toward plant cells were evaluated. Arabidopsis T87 suspension cells were used as the model cells and decreases in values of cell dry weights, cell viabilities, cell chlorophyll contents, and superoxide dismutase (SOD) activities were seen for the cells cultured in media containing the agglomerates of MWCNTs, indicating the agglomerates of MWCNTs are toxic to the Arabidopsis T87 suspension cells. Moreover, the toxicities increased sharply as the diameters of the agglomerates of the MWCNTs became smaller. A concept based on the hypersensitive response is suggested to explain the possible toxic mechanism induced by the MWCNTs.

Prussian blue caged in alginate/calcium beads as adsorbents for removal of cesium ions from contaminated water

Prussian blue encapsulated in alginate beads reinforced with highly dispersed carbon nanotubes were prepared for the safe removal of cesium ions from aqueous solutions. Equilibrium and kinetic studies were conducted using different models and the goodness of mathematical fitting of the experimental data on the adsorption isotherms was in the order Langmuir>Freundlich, and that of the kinetic models were in the order of pseudo second order>pseudo first order. Fixed bed adsorption column analysis indicated that the beads can be used for large scale treatment of cesium contaminated water.

Tunable Fabrication of Molybdenum Disulfide Quantum Dots for Intracellular MicroRNA Detection and Multiphoton Bioimaging

Molybdenum disulfide (MoS2 ) quantum dots (QDs) (size <10 nm) possess attractive new properties due to the quantum confinement and edge effects as graphene QDs. However, the synthesis and application of MoS2 QDs has not been investigated in great detail. Here, a facile and efficient approach for synthesis of controllable-size MoS2 QDs with excellent photoluminescence (PL) by using a sulfuric acid-assisted ultrasonic route is developed for this investigation. Various MoS2 structures including monolayer MoS2 flake, nanoporous MoS2 , and MoS2 QDs can be yielded by simply controlling the ultrasonic durations. Comprehensive microscopic and spectroscopic tools demonstrate that the MoS2 QDs have uniform lateral size and possess excellent excitation-independent blue PL. The as-generated MoS2 QDs show high quantum yield of 9.65%, long fluorescence lifetime of 4.66 ns, and good fluorescent stability over broad pH values from 4 to 10. Given the good intrinsic optical properties and large surface area combined with excellent physiological stability and biocompatibility, a MoS2 QDs-based intracellular microRNA imaging analysis system is successfully constructed. Importantly, the MoS2 QDs show good performance as multiphoton bioimaging labeling. The proposed synthesis strategy paves a new way for facile and efficient preparing MoS2 QDs with tunable-size for biomedical imaging and optoelectronic devices application.

A novel adsorbent obtained by inserting carbon nanotubes into cavities of diatomite and applications for organic dye elimination from contaminated water.

A novel approach is described for establishing adsorbents for elimination of water-soluble organic dyes by using multi-walled carbon nanotubes (MWCNTs) as the adsorptive sites. Agglomerates of MWCNTs were dispersed into individual tubes (dispersed-MWCNTs) using sodium n-dodecyl itaconate mixed with 3-(N,N-dimethylmyristylammonio)-propanesulfonate as the dispersants. The resultant dispersed-MWCNTs were inserted into cavities of diatomite to form composites of diatomite/MWCNTs. These composites were finally immobilized onto the cell walls of flexible polyurethane foams (PUF) through an in situ PUF formation process to produce the foam-like CNT-based adsorbent. Ethidium bromide, acridine orange, methylene blue, eosin B, and eosin Y were chosen to represent typical water-soluble organic dyes for studying the adsorptive capabilities of the foam-like CNT-based adsorbent. For comparisons, adsorptive experiments were also carried out by using agglomerates of the sole MWCNTs as adsorbents. The foam-like CNT-based adsorbents were found to have higher adsorptive capacities than the CNT agglomerates for all five dyes; in addition, they are macro-sized, durable, flexible, hydrophilic and easy to use. Adsorption isotherms plotted based on the Langmuir equation gave linear results, suggesting that the foam-like CNT-based adsorbent functioned in the Langmuir adsorption manner. The foam-like CNT-based adsorbents are reusable after regeneration with aqueous ethanol solution.

Three-dimensional Nitrogen-Doped Graphene Supported Molybdenum Disulfide Nanoparticles as an Advanced Catalyst for Hydrogen Evolution Reaction

An efficient three-dimensional (3D) hybrid material of nitrogen-doped graphene sheets (N-RGO) supporting molybdenum disulfide (MoS2) nanoparticles with high-performance electrocatalytic activity for hydrogen evolution reaction (HER) is fabricated by using a facile hydrothermal route. Comprehensive microscopic and spectroscopic characterizations confirm the resulting hybrid material possesses a 3D crumpled few-layered graphene network structure decorated with MoS2 nanoparticles. Electrochemical characterization analysis reveals that the resulting hybrid material exhibits efficient electrocatalytic activity toward HER under acidic conditions with a low onset potential of 112 mV and a small Tafel slope of 44 mV per decade. The enhanced mechanism of electrocatalytic activity has been investigated in detail by controlling the elemental composition, electrical conductance and surface morphology of the 3D hybrid as well as Density Functional Theory (DFT) calculations. This demonstrates that the abundance of exposed active sulfur edge sites in the MoS2 and nitrogen active functional moieties in N-RGO are synergistically responsible for the catalytic activity, whilst the distinguished and coherent interface in MoS2/N-RGO facilitates the electron transfer during electrocatalysis. Our study gives insights into the physical/chemical mechanism of enhanced HER performance in MoS2/N-RGO hybrids and illustrates how to design and construct a 3D hybrid to maximize the catalytic efficiency.

Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium

We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent.

Osteoconductivity and biodegradability of collagen scaffold coated with nano-β-TCP and fibroblast growth factor 2

Nanoparticle bioceramics have become anticipated for biomedical applications. Highly bioactive and biodegradable scaffoldswould be developed using nanoparticles of β-tricalcium phosphate (β-TCP).We prepared collagen scaffolds coated by nano-β-TCP and fibroblast growth factor 2 (FGF2) and evaluated the effects on new bone augmentation and biodegradation. The collagen sponge was coated with the nano-TCP dispersion and freeze-dried. Scaffold was characterized by SEM, TEM, XRD, compressive testing and cell seeding. Subsequently, the nano-β-TCP/collagen scaffold, collagen sponge, and each material loaded with FGF2 were implanted on rat cranial bone. As a control, no implantation was performed. Nano-TCP particles were found to be attached to the fibers of the collagen sponge by SEM and TEM observations. Scaffold coated with nano-TCP showed higher compressive strength and cytocompatibility. In histological evaluations at 10 days, inflammatory cells were rarely seen around the residual scaffold, suggesting that the nano-TCPmaterial possesses good tissue compatibility. At 35 days, bone augmentation and scaffold degradation in histological samples receiving nano-β-TCP scaffold were significantly greater than those in the control. By loading of FGF2, advanced bone formation is facilitated, indicating that a combination with FGF2 would be effective for bone tissue engineering.

Affinity-based elimination of aromatic VOCs by highly crystalline multi-walled carbon nanotubes.

Carbon nanotubes (CNTs) are capable of adsorbing pollutant chemicals. Their adsorptive capacities and adsorbing mechanisms, however, are not fully understood. As-grown CNTs often contain both crystalline and amorphous carbon, and the ratio of carbon types can affect adsorption. In this study, highly crystalline multi-walled carbon nanotubes (HC-MWCNTs) were used as the adsorbent for volatile organic compounds (VOCs) in contaminated air samples. Air containing 23 added VOCs (1,1-dichloroethylene, dichloromethane, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, chloroform, 1,1,1-trichloroethane, carbon tetrachloride, 1,2-dichloroethane, benzene, trichloroethylene, 1,2-dichloropropane, bromodichloromethane, cis-1,3-dichloropropene, toluene, trans-1,3-dichloropropene, 1,1,2-trichloroethane, tetrachloroethylene, dibromochloromethane, m-xylene, p-xylene, o-xylene, bromoform, and p-dichlorobenzene) was used for model samples. Adsorptive experiments were carried out by passing the air samples through a cartridge packed with HC-MWCNTs. Initial results showing high selectivity and high affinity for adsorbing aromatic VOCs (benzene, toluene, m-xylene, p-xylene, o-xylene, and p-dichlorobenzene) have provided new insight into the adsorption mechanisms. Data suggest that the HC-MWCNTs, unlike conventional carbon materials, adsorb aromatic compounds according to Fukuis frontier theory, which is based on the interactions between the HOMO and LUMO of the aromatic VOCs and those of the HC-MWCNTs.

Graphene oxide captured for green use: Influence on the structures of calcium alginate and macroporous alginic beads and their application to aqueous removal of acridine orange

Environmentally-benign high-performance graphene oxide (GO)/alginate-based absorbents were prepared to eliminate acridine orange selected as a typical dye. Characterizations demonstrated GO well encapsulated and its promotion of pore formation on structure. Kinetic studies exhibited that the addition of GO shortened the adsorption equilibrium time, raised the initial rate and the adsorption capacity. Isotherm studies indicated the adsorptive behavior followed Langmuir type, and higher maximum capacity was obtained in the presence of GO. The adsorption positively responded to pH increased from acidic to weakly alkaline. At low pH, GO would contribute dominantly to the adsorption, whereas alginate component was inhibited.