Latest ArticlesThis paper mainly investigated a relationship between clay mineral type/clay powder content in crushed dust and methylene blue (MB) value, and analyzed the effect of the adsorption properties of clay minerals on the MB value. The results show that the MB value gradually increases, but is far less than 1.00 with the increase of crushed dust content. Clay powder and mixed clay powders both have an influence on the MB value, showing a linear relationship. Montmorillonite and montmorillonite-based mixed clay powders can affect the MB value, i.e., 8.00 and 4.20, respectively. The maximum MB values of kaolin and illite are 1.75 and 1.05. The maximum MB value of two mixed mud powders with its main components is 2.10 and 1.95. Mixed clay powders with different clay minerals can affect the MB value rather than single clay powder. The methylene blue value is more sensitive to clay mineral type, and the sensitivity in an order is montmorillonite>kaolin>illite. That is, montmorillonite has a greater adsorption capacity.
The Berkovich indenter was used to conduct nanoindentation tests on the (100) and (010) crystal planes of gallium oxide by a constant load method, and the creep stress index of the gallium oxide crystal was obtained by data fitting. The creep stress index of single crystal gallium oxide crystal face (100) ranges from 15.5 to 27.8, and the creep stress index of crystal face (010) ranges from 46.1 to 63.4. The nanoindentation method can effectively determine the creep deformation of gallium oxide. The two crystal planes of gallium oxide show two stages of initial creep and steady-state creep. Among them, the crystal plane (100) has an obvious initial creep. The initial creep phase of the crystal plane (010) is not obvious. The holding load is positively correlated to the creep displacement and equivalent indentation stress of gallium oxide, and has no significant effect on the creep stress index. The creep stress index of different crystal planes of gallium oxide is different. The crystal plane (010) has a larger creep stress index rather than the crystal plane (100), which has a more intense creep resistance and is more suitable for precision machining.
Homogeneous cellulose and hetergenous oak leaves with montmorillonite as a catalyst were used as a biomass to investigate bio-gas and bio-oil. The results show that the loading of montmorillonite promotes the conversion of cellulose pyrolysis to β-elimination pathways, leading to an increase in activation energy and DTG peak temperature, but has little effect on the pyrolysis characteristics of oak leaves. Montmorillonite can catalyze the secondary cracking of biomass pyrolysis liquid products, which reduces the liquid yield and increases the gas yield, but has little effect on the solid product yield. Pyrolysis gases are mainly H2, CH4 and CO2. The surface and layers of montmorillonite contain the Lewis and Brønsted acid sites, which can catalyze the decarboxylation reaction of carboxylic acids in situ and degrade their yield, and has a promoting effect on the furfural and levoglucosenone enrichment of bio-oil.
Zeolite is a kind of aluminosilicate crystal with a regular pore structure, which is widely used in gas adsorption separation, industrial catalysis, and heavy metal ion pollution treatment. The hydrothermal synthesis of zeolite often uses silicon and aluminum-containing chemical products and organic template as raw materials, which is expensive and pollutes the environment. It is thus important to develop green synthetic zeolite using natural clay minerals as a raw material. This review represented recent studies on clay-based zeolite from the aspects of the activation and depolymerization process natural clay, clay-based zeolite of green synthesis process and mechanisms and some application on clay-based zeolite as solid acid catalyst, gas adsorption separation and heavy metal adsorption. In addition, the future work on clay-based zeolite was also given.
A high-purity quartz sand was prepared by a mixed acid leaching method with quartz sand in Donghai County as a raw material, hydrochloric acid, oxalic acid and citric acid as leaching agents. The influences of acid concentration, liquid-solid mass ratio, acid leaching temperature and acid leaching time on the phase structure and leaching efficiency of quartz sand were investigated, and the kinetic model of leaching quartz sand with mixed hydrochloric acid, oxalic acid and citric acid was deduced. The results show that the acid concentration, liquid-solid mass ratio, acid leaching temperature and acid leaching time all have an effect on the efficiency of acid leaching. The mixed acid leaching process follows a diffusion control model, and Ea is 13.22 kJ/mol. Fe content in quartz sand decreases from 342.62 mg/kg to 90.21 mg/kg, and the iron removal rate is 73.67% a after leaching at a hydrochloric acid concentration of 4.5 mol/L, an oxalic acid concentration of 0.05 mol/L and a citric acid concentration of 0.01 mol/L under normal pressure at 80℃ for 6 h. In this case, the total impurity content decreases from 523.79 mg/kg to 194.39 mg/kg, the impurity removal rate is 62.89%, and the purity of SiO2 is 99.97%, which meets the requirements for the use of crystalline glass.
The phase composition and reaction mechanism of aluminum-spinel (Al-MgAl2O4) composite were investigated after being treated at 580℃ for 8 h and 1 700℃ for 3 h in flowing high purity nitrogen. The results show that after being treated at 580℃ for 8 h, the Al-MgAl2O4 composite forms an area phenomenon with the aluminum-aluminum nitride (Al-AlN) core-shell structure in the outside area. When the temperature increases up to a critical value, the Al-AlN core-shell structure in the outside area breaks, Al(l/g) reacts with N2 to form AlN and with O2 to form Al2O(g). This process prompts formation of an MgAl2O4 spinel with stoichiometric ratio that allows decomposition into Al2O3-rich spinel and Mg(g). On the one hand, AlN reacts with Al2O3-rich spinel to form MgAlON spinel, and on the other hand, AlN is transformed into (Mg,Al)(N,O) through the solid solution reaction of Mg(g) and O2(g) into AlN. Phase composition of the inside area is different from the outside area in which MgAlON with flake crystal morphology forms via a gas-gas phase reaction: Al2O(g)+O2(g)+N2(g)+Mg(g)→MgAlON(s) or Al(g)+O2(g)+N2(g)+Mg(g)→MgAlON(s) in which Al2O3-rich spinel doesn't further form MgAlON spinel.
ZrNiSn bulk thermoelectric materials were synthesized by a self-propagating high-temperature synthesis (SHS) process. Phases and microstructure of ZrNiSn were investigated. Its thermoelectric property was tested. The results show that there are a large number of nuclei and high concentration of dislocation groups and stress fluctuation area inside the dense material, greatly enhancing the phonon scattering and reducing the phonon mean free paths, thus leading to the decreased lattice thermal conductivity of the materials. The thermoelectric properties of the material were optimized, and the ZT value is 0.54 at 873 K.
The topologic structure of filled skutterudites (SKD)-based thermoelectric device was designed via full-parameter simulation. The influences of topologic structure factors and interfacial electrical resistance on the module output performance (i.e., conversion efficiency and output power density) were investigated by numerical analysis. An 8-pair module with an optimized design was fabricated using p-type CeFe3.85Mn0.15Sb12 and n-type Yb0.3Co4Sb12 filled skutterudites. The maximum conversion efficiency and output power density are 9.8% and 1.42 W/cm2, respectively.
Cellulose acetate (CA) nanofibers were embedded with aggregated silver-nanocubes (AgNCs) by a coaxial electrospinning method. AgNCs were dispersed with CA and acetone-dimethylacetamide (DMAc) as a precursor solution, and AgNCs aggregation was induced with acetone. The nanofibers have a remarkable surface-enhanced Raman scattering (SERS) activity due to the strong plasmon coupling between neighboring AgNCs, which is 4 times of the monomeric-AgNC/CA sample. As a result, 0.1 nmol/L p-aminothiophenol (p-ATP) and 10 nmol/L methyl parathion can be identified, respectively. The nanofibers generate large-area homogeneous SERS signals with a relative signal deviation of less than 12% over 1 mm×1 mm area due to the homogeneous adsorption of target molecules. It is thus indicated that aggregated-AgNCs/CA nanofibers have a promising potential in SERS-based detection of organic pollutants in aqueous solutions.
This paper introduced the basic properties of the sub-lattice conductive network in chalcogenide diamond-like, ABX2-type diamond-like and Cu2Se thermoelectric materials. In our recent work, we developed the high-throughput screening method and electrical/thermal transport calculation methods. A novel thermoelectric material with ZT>1.0 was obtained when these methods were used to predict the thermoelectric performance of the diamond-like thermoelectric materials. Based on the data calculated by the methods, the sub-lattice conductive network is ubiquitous in the diamond-like structure system.
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