Advanced Materials Research Vols. 233-235

Abstract: The adsorption of dimethylformamide (DMF) by macroporous chitosan membranes using silica gel as porogen is studied. The morphology, porosity and DMF adsorption capacity of the macroporous chitosan membrane were measured. SEM photographs show the pores in the membrane dispersed uniformly. DMF adsorption capacity of the macroporous chitosan membranes reached 145 mg/g. Adsorption isotherm of DMF on the macroporous chitosan membranes was determined and correlated with Langmuir and Freundlich equations. The adsorption equilibrium data fitted well with Freundlich equation. The adsorption kinetics was found to follow the pseudo second-order kinetic model.

Abstract: A method for synthesizing of 2-nitrobenzaldehyde from 2-nitrobenzyl alcohol using ionic liquids (ILs) has been developed. The conversion of 2-nitrobenzyl alcohol and the selectivity of 2-nitrobenzaldehyde in the ionic liquids are higher than those in the traditional dichlorethane solvent. In addition, a reaction mechanism for the oxidation of 2-nitrobenzyl alcohol to 2-nitrobenzaldehyde is proposed.

Abstract: A mathematical model for predicting liquid flow velocity in a rectangular microchannel driven by capillary force and gravity is derived. The model takes into account the additional driving force arising from the wettability gradient on inner surface of a microchannel. The results of model prediction show that the velocity of liquid flow decreases with the length of microchannel and the wettability gradient on channel surface will accelerate the motion of the liquid when the flow-front approaches to the end of the microchannel. The analysis of driving force along the moving path matches well with the flow velocity predicted by the model.

Abstract: The styrene-acrylic emulsion modified by the ethylsiloxane as a cross-linking monomer and the hydroxyl phosphate as a flash-rust functional monomer was synthesized. The waterborne anti-corrosion coating film prepared by the styrene-acrylic emulsion exhibits a good overall performance, especially the an excellent corrosion resistance.

Abstract: Cellulose-based composites packaging films containing various amounts of modified nano-SiO₂ were prepared by utilizing hardwood pulps as natural cellulose resource through NMMO-technology to improve the mechanical properties, permeability for oxygen and water vapor etc. The tensile strength, elongation at break, thermal stability and permeability of the cellulose composites films as a function of the content of modified nano-SiO₂ were studied. The investigation suggested that the capabilities of composites films with 2 wt.% modified nano-SiO₂ added were improved largely, compared to pure cellulose films, when the diameter of particles is 30nm. The tensile strength was increased from 8.95 to 17.37 MPa and the elongation at break of the cellulose composites films was improved from 41.11% to 58.34%. The composites films with rational mechanical properties have adjustable oxygen permeability (7.90×10^-15-72.18×10^-15 cm³·cm/cm²·s·Pa) and water vapor permeability (7.12×10^-13-5.32×10^-13g·cm/cm²·s·Pa). And thermal stability of the composites films was advanced through adding modified nano-SiO₂.

Abstract: In this paper, the distribution and variation trend of temperature and velocity fields were obtained by numerical simulation of the casting process of shell die casting. According to the results of the numerical simulation, the die casting technology was optimized. The sound castings were produced. It was verified that shrinkage cavity and porosity could be reduced by increasing injected pressure and decreasing pouring and mould temperatures. The reliability of numerical simulation of die casting process was proved. In addition, the qualified products were obtained on the basis of the optimized die-casting parameters from the simulation results.

Abstract: Gram-negative bacterium, Pseudomonas delafieldii R-8 (CGMCC 0570) is capable of desulfurizing dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) to produce corresponding monohydroxydimethylbiphenyl. The immobilization of the resting cells of this strain in Ca-alginate gel effectively improved the stability of the cells and the desulfurization ability per amount of cells. 1 mmol/L of DBT and 4,6-DMDBT could be completely degraded in about 1 d. About 39 percent of the activity for 4,6-DMDBT was recovered after immobilization. The desulfurization activity was increased with the decrease of the diameter of the beads. The Ca-alginate immobilized cells could be used repeatedly for over 190 h with the addition of calcium ions to strengthen them. A thin layer of hydrophobic polyurea was coated on the surface of Ca-alginate gel using a simple method. The desulfurization activity was enhanced after the coating.

Abstract: The aim of this work is to investigate the solid concentration distribution in a DTB crystallizer under continuous operation. The effects of mixing intensity and product removal location on solid concentration distribution in the crystallizer were studied by CFD simulation with multiphase model for different sizes of particles. The results showed that the particle distribution in a crystallizer was dependent on the size of the particles and the mixing intensity. However, the product removal location did not significantly affect particle size distribution in the crystallizer under the studied conditions.

Abstract: Micromixing efficiency in the high gravity(Higee) reactor with glass bead, rasching ring and pall ring was investigated respectively by using iodide-iodate test reaction as working system. The experimental results showed that segregation index of the Higee reactor increases while increasing volumetric flow ratio, size of pall ring and decreases with the increase of rotating rate, volumetric flow rate. The Micromixing efficiency of the Higee reactor with pall ring is better than glass bead and rasching ring.

Abstract: Nano-TiO₂ particles were prepared by sol-gel method, of which the surfaces were coated by SiO₂. The coating was achieved by the hydrolysis of sodium silicate (Na₂SiO₃) in ammonium chloride (NH₄Cl). The surface bonding, phase constitution and chemical components of the samples were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy (XPS). The mechanism of the SiO₂ coating process onto TiO₂ surface was analyzed. Results show that SiO₂ particles were immobilized on the TiO₂ surface via Ti—O—Si bondings, which formed at the interface. The SiO₂ layer on TiO₂ surface was amorphous, the photocatalytic performance was decreased of the TiO₂ while its stability was enhanced after surface modification.