Papers by Keyword: Preparation

Abstract: Compared with inorganic phosphonates, organic phosphonates have better chemical stability in water treatment, and are not easy to hydrolyze in higher temperature and wider pH range. In this paper, a one-step synthesis method of ethylene diamine tetra (methylene phosphonic acid) sodium (EDTMPS) and methylene phosphonic acid (DTPMPA) were studied. A new phosphate scale inhibitor was prepared and its scale inhibition performance was evaluated. The results showed that the scale inhibition rate increased with the increase of the concentration of synthetic products (EDTMPS, DTPMPA). At the same concentration, compared with DTPMPA, EDTMPS has better scale inhibition performance, and the maximum scale inhibition rate can reach 96.85%. The scale inhibition performance of composite scale inhibitor is better than that of single scale inhibitor, and the scale inhibition rate of the synthesized products can reach more than 90% after compounding. And inhibitory mechanism has been proposed: Because phosphonates effectively control the rate of nucleation. In addition, polyphosphonates can chelate Ca²⁺, Mg²⁺ plasma to form monocyclic or bicyclic chelates. This will destroy the normal growth process of calcium carbonate and other crystals, thus preventing the formation of calcium carbonate scale.

Abstract: Due to the developed pore structure ,high specific surface area, low cost, accessible raw materials and stable physical and chemical properties, activated carbon has caused high attention of society. Nowadays activated carbon has been widely used in capacitor electrode production, water pollution treatment, medicine and other fields. We review the various preparation methods of activated carbon and analyze the advantages and disadvantages of them in this paper. The characteristics of activated carbon regeneration technology are also discussed from the perspective of improving the utilization rate of activated carbon. With the development of China's green economy and the increasing awareness of people's environmental protection, the research on the preparation and regeneration of activated carbon will surely have a broader development prospect.

Abstract: Using magnesium nitrate, nickel nitrate and aluminum nitrate as raw materials and urea as precipitant, magnesium nickel aluminum ternary hydrotalcites with large specific surface area were prepared by hydrothermal method. The prepared samples were characterized by SEM、XRD、BET and EDS etc., respectively. The adsorption properties of MgNiAl-LDHs, MgAl-LDHs and their calcined products (MgNiAl-LDOs, MgAl-LDOs) for chloride ions in solution were investigated. The results show that MgNiAl-LDHs are cubic with rod-like structure, with a specific surface area of 197.62 m²/g, which is much larger than that of MgAl-LDHs (102.82 m²/g). Under the same adsorption conditions, the saturated adsorption capacities of MgNiAl-LDHs and MgAl-LDHs for chloride ions are 130.06mg/g and 110.02 mg/g respectively. MgNiAl-LDOs showed better adsorption ability for chloride ions. By simulating the adsorption data, the results show that the adsorption kinetics and the adsorption isotherm are in accordance with the quasi-second-order kinetic model and the Langmuir isotherm model, respectively.

Abstract: Because of its superior surface properties, nanocalcium carbonate can be applied to the adsorption of heavy metals in wastewater. However, because of the easy aggregation of nanocalcium carbonate, high surface energy and poor dispersibility in water, it is not conducive to the process of adsorption. Therefore, surface modification of nanocalcium carbonate is needed. In this paper, nanocalcium carbonate was prepared by liquid phase method. And the nanocalcium carbonate was surface modified by sodium dodecyl sulfate. The effects of modifier amount, modification temperature, and modification time on the activation and absorbance of nanocalcium carbonate were investigated. And the morphology and particle size of modified nanocalcium carbonate were tested by SEM and XRD patterns.The results show that the dispersion and surface activity of the modified nanocalcium carbonate have been improved remarkably. Moreover, the Cu²⁺ was adsorbed by sodium dodecyl sulfate modified nanocalcium carbonate and unmodified nanocalcium carbonate under the optimum modification conditions. And the effects of nanocalcium carbonate initial concentration on the adsorption performance were studied. The results show that the adsorption performance of modified calcium carbonate is better than that of the unmodified. Moreover, the adsorption process is studied by adsorption isotherm. By drawing the adsorption isotherms lines and by comparing the fitting result of the experimental data based on the Langmuir model and that of Freundlich model, it is found that the adsorption of Cu²⁺ by modified nanocalcium carbonate meets the Langmuir model.

Abstract: Transparent glass ceramics containing Na_3.6Y_1.8(PO₄)₃ crystals were successfully synthesized using high temperature melting quenching and subsequent heat treatment of the precursor glass with a composition 15Na₂CO₃-3Y₂O₃-45SiO₂-31H₃BO₃- 5.4P₂O₅-0.6Sb₂O₃ (mol%). The impact of heat treatment is investigated in detail. The glass sample was tested by differential scanning calorimetry analysis to determine the heat treatment system. The ideal heat-treated condition is at 650°C for 2 h. The structure and morphology properties were systematically analyzed by recording X-ray diffraction patterns and scanning electron microscopy images, which indicate that Na_3.6Y_1.8(PO₄)₃ crystal were precipitated homogeneously among the glass matrix. The microstructural of precursor glass and glass ceramic were compared by analyzing FTIR spectra, indicating the formation of phosphate groups in glass ceramic. The refractive index of glass ceramics samples were measured. In the visible region, the transmittance of glass ceramics is up to 85%. Moreover, the relationship between the refractive index of the sample and the transmittance is discussed.

Abstract: Aiming to produce qualified molybdenum (Mo) target for sputter deposition, Mo targets were prepared by utilizing powder metallurgy method in this research. The influences of sintering modes, press working modes and total deformation on microstructure and properties of Mo target were studied. Furthermore, magnetron sputtering test was conducted in vacuum environment by using the prepared Mo targets to deposit Mo thin films of which the surface morphologies, electrical conductivities, and crystalline properties were analyzed. The results show that vacuum presintering followed by hydrogen sintering mode can greatly decrease the impurity contents of Mo slabs. It is favorable to obtain the Mo target with fine and uniform grains on size and distribution by using forging mode or forging cogging mode and more than 70% total deformation. With the increase of sputtering currents of Mo target, the grain size and the thickness of the Mo thin films significantly rise, while FWHM of diffraction peaks of grain orientation (110), surface roughness and electrical resistivity of thin films decrease accordingly.

Abstract: Fly ash (FA), a kind of fine-powder solid waste, was utilized to prepare a novel Fe/chitosan/FA composite (Fe/CTS/FA) by the calcination and solution reaction with chitosan (CTS) and ferric iron. In combination with the adsorption for reactive turquoise blue KN-G (RTB KN-G) and direct sky blue 5B (DSB 5B) dyes, the main conditions of preparation and adsorption of Fe/CTS/FA were investigated. The composite was characterized with SEM, EDS, particle-size distribution and N₂-gas adsorption-desorption technology. The results show that: (1) Fe/CTS/FA prepared by calcining FA at 500°C and further mixing reaction with CTS and FeCl₃⋅6H₂O solution according to the mass ratio of m(FA):m(CTS):m(Fe)=10:1:0.34 has excellent adsorption properties. The amount of adsorption is mainly affected by solution pH and reaches the equilibrium in 60 min for high-concentration RTB KN-G and DSB 5B dye wastewater with adsorption capacities of 892.95 mg/g and 615.65 mg/g, which are 16.28 and 32.56 times larger than those of FA, respectively. (2) The characterization results of Fe/CTS/FA indicate that CTS and iron hydroxides have been successfully loaded on FA. The surface morphology of Fe/CTS/FA is significantly changed, and the particle-size distribution is obviously smaller than that of FA.

Abstract: The Ni-W-P/graphene composite coatings were prepared in the Ni-based electrodepositing solution and graphene oxide mixture, the effect of stirring modes (including no stirring, mechanical stirring or ultrasonic stirring) on the surface quality of the composite coatings was investigated and the optimum formula of the electrodepositing solution of the Ni-W-P/graphene composite coatings was obtained through the orthogonal experiments in 4 factors and 4 levels. It was determined that ultrasonic stirring was the optimum stirring mode during electrodeposition. The Raman spectrum and EDS have shown that there existed graphene, in addition to Ni, W and P in the Ni-W-P/graphene composite coatings. The surface of the Ni-W-P/graphene composite coatings was smooth and the structure was compact. The average microhardness of the Ni-W-P/graphene composite coatings was improved by 26.7% higher than that of the Ni-W-P coatings after the heat treatment of 600°C.

Abstract: AlB₁₂-type Al-B alloys were prepared by high temperature treatment of AlB₂-type Al-B alloy melts with different distribution morphologies of borides. The results show that when using the “immersion” method, the produced AlB₂-type Al-B alloy melt (“alloy melt 1”) contain a small amount of AlB₁₂ phase and many boride agglomerations. The AlB₂-type Al-B alloy melt produced by using the “vortex” method (“alloy melt 2”) contains no AlB₁₂ phase and exhibits a well dispersion of AlB₂ particles. During the high temperature treatment, the AlB₂ particles in close contact with each other in the alloy melts are prone to coalescence, causing the formation of relative large AlB₁₂ particles. The high-speed stirring adopted during the high temperature treatment has an effect of prohibiting the coalescence of AlB₂ particles in boride agglomerations.

Abstract: Al₂O₃-Fe based metal ceramic is a functional ceramic material prepared by high temperature sintering with Al₂O₃ as the main component, plus iron powder (binder phase) and other additives. In this paper, the composition design of Al₂O₃-Fe based metal ceramic was made, and the performance of the material was tested and studied. The change of the content of iron powder also has a great influence on the compressive strength and bending strength of the Al₂O₃ metal ceramic. Experiments also show that the Al₂O₃-Fe-based cermet has good corrosion resistance. Finally, the following conclusions were obtained through the comprehensive analysis: the best test formula is No.4 sample, and its compressive strength is 79.79MPa, bending strength is 15.90 MPa, corrosion resistance rate is 0.028 g/dm²·h.