Carbon-silica mesoporous composite in situ prepared from coal gasification fine slag by acid leaching method and its application in nitrate removing.

Coal gasification fine slag (CGFS) was produced in the coal gasification process which was classified as an industrial solid waste. It was featured with naturally formed amorphous structures and an abundance of silicon, carbon and metal oxides. In this study, on the basis of the composition and structure characteristics of CGFS, a simple hydrochloric acid (HCl) leaching technology was applied to in situ prepare carbon-silica mesoporous composites (CSMCs) from CGFS by fully considering the value of the residual carbon. Special focus was put on the novel mechanism of pore formation in amorphous silica glass microspheres (SGM) during acid leaching. Experimental evidences showed that the metal oxides were uniformly distributed in SGM thus the dissolution of the metal oxides were starting from the surface of SGM, then gradually extending to the interior, and finally leading to form "tree branch" mesoporous channels. In addition, a response surface method was used to predict the optimal reaction conditions and the optimal sample (named as CGFS-O) was successfully prepared. CGFS-O possessed a prominent specific surface area (SSA) (337.51 m2/g) as well as an excellent pore volume (0.341 cm3/g). CGFS-O also exhibited a desirable capacity for NO3- removing and the adsorption process was studied detailed by changing different adsorption conditions. Adsorption results proved that CSMCs have the potential to purify wastewater in an economically and environmentally way. Therefore, combined with a proof-of-concept adsorption performance experiment, our study has not only provided a cost-effective strategy to industrially prepare CSMCs, reutilizing CGFS in an environmentally friendly way, but also contributed to the future applications of CSMCs with valuable insights into the pore formation mechanism in SGM during acid leaching process.

Using chemical experiments and plant uptake to prove the feasibility and stability of coal gasification fine slag as silicon fertilizer.

Coal gasification fine slag (CGFS) is a kind of industrial waste that is generated from entrained-flow coal gasification with a high content of 0.5 M hydrochloric acid (HCl)-extractable silicon (Si). Si fertilizer has been widely used in agriculture to enhance the mechanical properties and yield of crops. An evaluation was actualized by analyzing HCl-extractable Si fractions and X-Ray diffraction (XRD) of different treatments (acid, alkali, salt, grind, calcination, temperature, and time) for CGFS samples and other Si source materials. The results showed that CGFS had stable HCl-extractable Si concentrations of 60 ± 2 g/kg except in the calcination treatment, which decreased the content of extractable Si by 28.2%. Furthermore, under the same processing conditions, CGFS showed a higher content of extractable Si than other Si source samples. Moreover, a rice growth experiment was carried out for 120 days in a different mass incorporation of CGFS in the greenhouse. The strength index and total Si content of the stem proved that using CGFS at 5 wt.% markedly promoted the growth of rice. The study indicated that an appropriate application of CGFS as a Si resource to an agricultural field could be considered as a viable option for safe disposal of this industrial waste.

Surface functional groups of carbon-based adsorbents and their roles in the removal of heavy metals from aqueous solutions: A critical review.

Carbon-based adsorbents such as graphene and its derivatives, carbon nanotubes, activated carbon, and biochar are often used to remove heavy metals from aqueous solutions. One of the important aspects of effective carbon adsorbents for heavy metals is their tunable surface functional groups. To promote the applications of functionalized carbon adsorbents in heavy metal removal, a systematic documentation of their syntheses and interactions with metals in aqueous solution is crucial. This work provides a comprehensive review of recent research on various carbon adsorbents in terms of their surface functional groups and the associated removal behaviors and performances to heavy metals in aqueous solutions. The governing removal mechanisms of carbon adsorbents to aqueous heavy metals are first outlined with a special focus on the roles of surface functional groups. It then summarizes and categorizes various synthesis methods that are commonly used to introduce heteroatoms, primarily oxygen, nitrogen, and sulfur, onto carbon surfaces for enhanced surface functionalities and sorptive properties to heavy metals in aqueous solutions. After that, the effects of various functional groups on adsorption behaviors of heavy metals onto the functionalized carbon adsorbents are elucidated. A perspective of future work on functional carbon adsorbents for heavy metal removal as well as other potential applications is also presented at the end.

Opal promotes hydrothermal carbonization of hydroxypropyl methyl cellulose and formation of carbon nanospheres.

Hydrothermal carbon nanospheres were prepared by introducing opal into the hydrothermal carbonization system of hydroxypropyl methyl cellulose (HPMC). Then the effects of opal on hydrothermal carbonization of HPMC were investigated after different reaction durations (105-240 min). The reaction products were characterized by elemental analysis, gas chromatography-mass spectrometry (GC-MS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and N2 adsorption-desorption. Results of elemental analysis indicated that the H (hydrogen) and O (oxygen) content of HPMC decreased through dehydration, demethylation, decarbonylation and hydrolysis reactions, forming hydrochar with higher carbon content. The addition of opal was confirmed to accelerate the hydrolysis of HPMC. N2 adsorption-desorption tests and SEM analysis showed that opal with a large specific surface area adsorbed HPMC hydrolysis products, such as furans, and facilitated furan cyclodehydration on its surfaces to form cross-linked carbons, which contributed to the quick formation of hydrochar. Moreover, the adsorption by opal also inhibited hydrochar aggregation, so the final hydrothermal carbon spheres had sizes of 20-100 nm.

Transformation of Rusty Stainless-Steel Meshes into Stable, Low-Cost, and Binder-Free Cathodes for High-Performance Potassium-Ion Batteries.

To recycle rusty stainless-steel meshes (RSSM) and meet the urgent requirement of developing high-performance cathodes for potassium-ion batteries (KIB), we demonstrate a new strategy to fabricate flexible binder-free KIB electrodes via transformation of the corrosion layer of RSSM into compact stack-layers of Prussian blue (PB) nanocubes (PB@SSM). When further coated with reduced graphite oxide (RGO) to enhance electric conductivity and structural stability, the low-cost, stable, and binder-free RGO@PB@SSM cathode exhibits excellent electrochemical performances for KIB, including high capacity (96.8 mAh g-1 ), high discharge voltage (3.3 V), high rate capability (1000 mA g-1 ; 42 % capacity retention), and outstanding cycle stability (305 cycles; 75.1 % capacity retention).

Flexible and Foldable Li-O2 Battery Based on Paper-Ink Cathode.

A flexible freestanding air cathode inspired by traditional Chinese calligraphy art is built. When this novel electrode is employed as both a new concept cathode and current collector, to replace conventional rigid and bulky counterparts, a highly flexible and foldable Li-O2 battery with excellent mechanical strength and superior electrochemical performance is obtained.

Artificial Protection Film on Lithium Metal Anode toward Long-Cycle-Life Lithium-Oxygen Batteries.

An artificial while very stable solid electrolyte interphase film is formed on lithium metal using an electrochemical strategy. When this protected Li anode is first used in a Li-O2 battery, the film formed on the anode can effectively suppress the parasitic reactions on the Li anode/electrolyte interface and significantly enhance the cycling stability of the Li-O2 battery.

Photocatalytic degradation of an azo dye using N-doped NaTaO3 synthesized by one-step hydrothermal process.

N-doped NaTaO(3) compounds (NaTaO(3-)(x)N(x)) with nano-cubic morphology were successfully synthesized by one-step hydrothermal method and Methyl Orange (MO) was used as a model dye to evaluate their photocatalytic efficiency under visible-light irradiation. The as-prepared NaTaO(3-)(x)N(x) samples were characterized by various techniques, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra and GC-MS. The results indicate that NaTaO(3-)(x)N(x) displays a pure perovskite structure when the synthesis temperature is higher than 180°C. Moreover, as observed by SEM images, the particles of resultant NaTaO(3-)(x)N(x) show cubic morphology with the edge length of 200-500nm, which can be easily removed by filtration after photocatalytic reaction. Doping of N increases the photocatalytic activity of NaTaO(3), and NaTaO(2.953)N(0.047) shows the highest visible-light photocatalytic activity for the degradation of MO. Based on the experiment results, a possible mechanism of the photocatalysis over NaTaO(3-)(x)N(x) and the photodegradation pathway of MO were proposed.

Synthesis and photocatalytic activity of N-doped NaTaO3 compounds calcined at low temperature.

N-doped NaTaO(3) compounds (NaTaO(3-x)N(x)) were successfully synthesized using NaTaO(3) prepared at low calcination temperature as starting material and melamine (C(3)H(6)N(6)) as nitrogen source. The as-prepared NaTaO(3-x)N(x) samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra. The XRD results indicate that the crystallization temperature of NaTaO(3) is up to 700 degrees C and the doping of N does not lead to significant structural changes. Moreover, as observed by SEM images, the particle sizes of resultant NaTaO(3-x)N(x) are in the range of 100-150 nm, which are much smaller than NaTaO(3) particles synthesized by traditional solid state reaction method. The photocatalytic activities of NaTaO(3-x)N(x) were examined by methylene blue (MB) aqueous solution under UV light. It is found that the photocatalytic activity of NaTaO(3-x)N(x) depend strongly on the doping content of N, and sample NaTaO(2.961)N(0.039) shows the highest photocatalytic activity for the degradation of MB. Furthermore, it is also found that NaTaO(3-x)N(x) catalysts display super structural stabilities during photocatalytic degradation, and could recover their photocatalytic activity after calcination at 500 degrees C, suggesting a promising utilization of such photocatalyst.

A high-stability silica-clay composite: synthesis, characterization and combination with TiO2 as a novel photocatalyst for Azo dye.

A novel micro-mesopores composite material has successfully been synthesized at basic hydrothermal conditions using natural mineral montmorillonite (MMT) and tetraethoxysilane (TEOS). Two surfactants, cetyltrimethyl ammonium bromide (CTAB) and polyethylene glycol (PEG), have been employed in order to shape the pores in the composite. The resultant silica-clay has large surface area (472m(2)/g) and high hydrothermal stability, which makes it a potentially host-material for catalyst. The molecular size of different surfactant leads to the multi-peak distribution of pore size, and the surfactant of larger size (PEG) corresponds to the formation of larger pores. Moreover, the photocatalytic results show that, comparing with pure TiO(2) particles, the loaded TiO(2) on such silica-clay shows higher photodegradation rate of methyl orange (MO) in aqueous. And another porous aluminosilicate host, zeolite, was also discussed for comparison.

Photodegradation of an azo dye using immobilized nanoparticles of TiO2 supported by natural porous mineral.

Natural mordenite, replacing the synthetic zeolites, has been employed as the support of TiO2, and its photocatalytic activity has been examined in methyl orange (MO) aqueous under UV light. AFM, TEM, XRD, FTIR and fluorescence spectra have been used to reveal the loading effects of TiO2 on mordenite. The results show that the photocatalytic degradation (PCD) reaction rates are sharply increased by natural zeolite supports. Since mordenite is photo-inert, the PCD-enhancement is mostly caused by the bonding effects of Ti-O-Si and Ti-O-Al. Moreover, another two distinct natural zeolites have been employed as the supports of TiO2, in order to check the universality of PCD-enhancement effect of natural zeolites on TiO2. And the factors of PCD reaction on TiO2-zeolite, such as pH and catalyst dose, have been investigated.

[Experimental research on the effect of nanophase ceramics on osteoblasts functions].

In order to study the cytocompatibility of nanophase hydroxyapatite ceramic in vitro, we prepared hydroxyapatite by use of the wet chemistry techniques. The grain size of hydroxyapatite of interest to the present study was determined by scanning electron microscopy and atomic force microscopy with image analysis software. Primary culture of osteoblast from rat calvaria was established. Protein content, synthesis of alkaline phosphatase and deposition of calcium-containing mineral by osteoblasts cultured on nanophase hydroxyapatite ceramics and on conventional hydroxyapatite ceramics for 7, 14, 21 and 28 days were examined. The results showed that the average surface grain size of the nanophase and that of the conventional HA compact formulations was 55 (nanophase) and 780 (conventional) nm, respectively. More importantly, compared to the synthesis of alkaline phosphatase and deposition of calcium-containing mineral by osteoblasts cultured on nanophase was significantly greater than that on conventional ceramics after 21 and 28 days. The cytocompatibility was significantly greater on nanophase HA than on conventional formulations of the same ceramic.

[Cytocompatibility of nanophase hydroxyapatite ceramics].

OBJECTIVE: To evaluate the cytocompatibility of nanophase hydroxyapatite ceramics in vitro. METHODS: Hydroxyapatite (HA) was prepared via wet method. The grain size of the hydroxyapatite in the study was determined by scanning electron microscope and atomic force microscope with image analysis software. Primary osteoblast culture was established from rat calvaria. Cell adherence and proliferation on nanophase hydroxyapatite ceramics and conventional hydroxyapatite ceramics were examined at 1, 3, 5, 7 days. Morphology of the cells was observed by microscope. RESULTS: The average grain size of the nanophase and conventional HA was 55 nm and 780 nm, respectively. Throughout 7 days period, osteoblast proliferation on the HA was similar to that on tissue culture borosilicate glass controls, osteoblasts could attach, spread and proliferate on HA. However, compared to conventional ceramics, osteoblast proliferation on nanophase HA was significantly better after 1, 3, 5 and 7 days. CONCLUSION: Cytocompatibility of nanophase HA was significantly better than conventional ceramics.

[Photocatalysis characterization of titanium dioxide supported on natural clinoplilolite].

This paper studied preparing photocatalyst supported on natural clinoplilolite, photocatalysis degrading to methyl orange solution as photocatalysis function test, solar as light resource, explored the synthesize condition and affect factors of its catalysis activity. The capability of catalyst was evaluated by decolor rate and COD removal rate. The samples was described by XRD, IR and specific surface area. Studied result showed that catalyst prepared by combination of tetrabutyl titanate and natural clinoplilolite dryed under 120 degrees C for 6 hours then calcined under 200 degrees C had the best photocatalysis activity. Degrading rate of methyl orange solution increased with the quantity of TiO2/zeolite and additional oxidant H2O2 increasing, but superfluous H2O2 can also restrain the photocatalysis activity of titanium dioxide supported on clinoplilolite. Methyl orange solution had the best degrading rate as pH value between 2 to 5.