Advanced Materials Research Vols. 391-392

Abstract: It still remains challenging for effective hydrolysis of chitosan into chitosan oligomers. In this work, a pretreatment was conducted on chitosan by an ionic liquid 1-butyl-3-methylimidazolium chloride ([C4mim]Cl), aiming at improving enzymatic depolymerization of chitosan. X-ray diffraction analysis indicated that the inter- and intra-molecular hydrogen bonds within chitosan molecules were broken by [C4mim]Cl and the crystalline was destroyed. The oligo-chitosan hydrolyzed from IL-pretreated chitosan, coded as COS-IL, showed a DP of 3~5, in contrast to DP 5~8 with oligo-chitosan obtained from untreated chitosan(coded as COS-UN). COS-IL was more effective than COS-UN in inhibiting intestinal spoilage bacterials growth and it has positive effect on the growth of intestinal probiotic bacterials.

Abstract: By using Palygorskite as matrix and introducing the surface ion-imprinting concept to the synthesis process, a Palygorskite-supported organic–inorganic hybrid polymer for selective separation of Pb²⁺ from aqueous solutio was prepared. The prepared polymer was characterized with techniques of SEM, XRD and FT-IR. The effects of contact time, pH value and temperature of the initial solution on the adsorption characters of Pb²⁺ were investigated. Under the optimum conditions, the ions-imprinted polymer offered a fast kinetics for the adsorption of Pb²⁺ and the maximum capacity was 4.51 mg/g. And the pseudo-second order model bestly described the kinetics of adsorption of Pb²⁺ onto the as-prepared materials.

Abstract: Excessive intake of fat will damage human health seriously, and it can also cause obesity, high blood pressure, atherosclerosis and coronary heart disease. So low fat foods gradually become highly widespread. As a result, fat substitutes are focused, which have the same physical and sensory properties as fat, and can be used in place of fat in many cases. In this work, fat substitute was prepared by acid-alcohol treated hydrolysis of corn starch with and without ultrasound. Some factors affecting the DE of starch hydrolysate were investigated by experiments with and without ultrasound, including reaction temperature, time, ethanol concentration, and hydrochloric acid concentration. Enhancements of the hydrolysis by ultrasound was observed.The results showed that the DE increased with the rise of reaction temperature, time and hydrochloric acid concentration. However, it decreased as the increase of alcohol concentration. Ultrasound can accelerate the hydrolysis evidently, and increased the DE by at least 22.22%.

Abstract: Titania nanotubes were synthesized after the protonation and calcination of titanate precursors prepared at different hydrothermal temperatures. Calcination of the titanate precursors at various temperature, governs the TiO₂ nanotubes formation. It was observed that sample prepared at 130°C and calcination at 500°C forms only anatase, but at 800°C, both anatase and rutile formed. The as-prepared titania nanotubes were used as photocatalyst in order to degrade organic contaminant, oxalic acid from aqueous solution by UV irradiation. 78 % oxalic acid was removed from the aqueous media at the nanotubes dose of 2 g L^-1, in 120 min.

Abstract: The hydrothermal technique is introduced into the synthesis of glutathione-stabilized ZnCdSe QDs. By incorporating cadmium ions into the pre-prepared ZnSe QDs, with continuously heating, the preparation of alloyed ZnCdSe QDs was realized. The bandgap emission dominated the emission spectra in 15 minutes.

Abstract: The corrosion behavior of reinforcing steel HRB335 in structure in simulated concrete solution (0.5 wt.% NaCl solution) was investigated, and its tensile mechanical properties were tested before and after corrosion. The results show that, with the increase of corrosion time from 240h to 720h, the corrosion rate increases and the corrosion becomes heavier and heavier, and the composition amounts of corrosion scale are not familiar. After 720h, the yield strength is decreased by about 3%, and the tensile strength and the elongation are decreased by more than 4%.

Abstract: The ammonia-nitrogen wastewater was purified by using electrodialysis (ED) device in this paper. The NH₄Cl solution was used as the artificial ammonia-nitrogen wastewater. Various unsteady factors in the experiment may cause the concentration polarization phenomenon, which may have negative effect on ED cell performance and its lifetime. The limiting voltage was confirmed as 12V in this study. At steady-state operation condition of ED, the outlet concentration was measured at different operation voltages, feed concentrations, and concentrations ratio of two cells. The efficiency of ammonia-nitrogen removal was evaluated in different conditions by a factorially designed experiment. The results from the experiment indicate the best process conditions for the ED, that is, the voltage was 12V, and the concentrations ratio of two cells was 1:3. It seems that the ammonia-nitrogen removal is more effective for a higher feed concentration stream.

Abstract: This paper presented a study on the reaction kinetics of magnesium sulfite catalyzed by Catalyst TR. Used a Lib-scale Plexiglas reactor aerated by air compressors to research the oxidation process Influence by pH, catalyst concentration, aeration quantity, temperature, time, sulfate concentration. Through experiment concluded the activation energy, got the formula between reaction rate and sulfate concentration.

Abstract: Novel SO₃H-functionalized ionic liquids were successfully applied as catalysts for synthesis of xanthenediones under microwave irradiation in Aqueous. Various types of Xanthenes were provided in 90-97% yields using the catalytic system of [(HSO₃-p)₂im][CF₃SO₃]/H₂O. The products could be conveniently separated from the reaction mixture by filtration and the dissolved catalyst could be reused without any treatment, which of the separation process was performed in water without using any organic solvents. The method not only has the adventages of shrot time and simple operation, but also is environmentally friendly.

Abstract: This thesis analyzes the existence form of MgO in the gas quenching steel slag. By calculating the degree of saturation of the MgO in the gas quenching steel slag and adopting the method of electronic probe, it investigates the corrosion of the viscosity of the gas quenching steel slag to MgO crucible when measuring viscosity under a high temperature and explains why the gas quenching steel slag exerts no corrosion to the MgO crucible with the help of the metallurgy thermodynamics principle.