Dissolution is an important part of silk fibroin (SF) reprocessing, and it is the only way to process it into films, gels, porous scaffold materials, and electrostatic spinning silk fibers. There are a variety of dissolution systems used to dissolve SF. However, few studies have focused on the differences between these different solvent systems. The dissolution of SF with different solvent systems was investigated in this study. Regenerated silk fibroin (RSF) solutions and films were characterized by dynamic light scattering, Fourier transform infrared spectroscopy, differential scanning calorimetry, X‐ray diffraction, and scanning electron microscopy. The results show that the RSF film structures changed with the solvent system, especially LiBr–H2O. The characterization proved that the random coil did not change into a β‐sheet structure during film formation, and this indicated that its crystal structure and thermal stability was different from others. Interestingly, the differences in the morphologies of all of the RSF films prepared with different solvents were outstanding. Because the mechanism and force of the ion in the solvent systems were different, the SF molecule was hydrolyzed differently in individual solvent systems and produced different hydrolyzed SF molecular chains. These chains had different self‐assembly processes and would lead to RSF products with different microstructures and properties. This suggests that a suitable solvent should be chosen for different uses. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41959.
This purification process may be described by the unreacted shrink core model with solid resultant (inert material) and fixed particle size, which is carried out by the action of nitric acid solution on the precipitated silica obtained from yellow phosphorus slag which was leached with phosphoric acid. The study results indicate that the purification process is a chemical reaction controlling step and its apparent activation energy E a is 30.354 kJ/mol, with reaction order 0.6746.Le présent procédé de purification peutêtre décrit par le modèle du noyau rétrécissant non réagi avec la résultante solide (matériau inerte) et la taille de particule fixe. Ce procédé est obtenu par l'action d'une solution d'acide nitrique sur une silice précipitée obtenueà partir des scories de phosphore lavéesà l'acide phosphorique. Les résultats de l'étude montrent que le procédé de purification est uneétape de contrôle de la réaction chimique, dont l'énergie d'activation apparente Ea est de 30,2354 kJ/mol, avec un ordre de réaction de 0,6746.
The four factors such as alcium silicon proportion, coke dosage, burned time and the addition of solubilizer are studied in poorer oxidative atmosphere at 1200 °C. The grade-analysis and visual preferred plan of orthogonal table are reappeared.The results show the indexs of visual preferred plan of orthogonal table are perfecter,therefore,the plan is used as preferred plan.The product is separated and characterized by infrared.The infrared map shows the product is potassium sulfate . The XRD inflection of samples is studied, waste residue is also effective ingredient besides potassium slufate.It is used again to avoid secondary pollution.
The calcium arsenate waste, containing amounts of arsenic (7.62 wt%), was treated using solidification/stabilization technology (S/S) with geopolymer. In order to optimize the procedure for S/S, 9 different S/S samples, differing in amount of the geopolymer materials were prepared. On these samples, extraction tests were performed, showing that the arsenic concentration in the leachate was less than the China countermeasure standard (5 mg/l) after 28 days of curing when a geopolymer (GP) dosages more than 30 wt%. Furthermore, the samples showed substantially decreasing leachability with curing times. But there was no appreciable change in leachability under various time and pH conditions.
The thermal decomposition process of K-feldspar-CaSO4-CaO system was studied by X-ray diffraction (XRD) analysis of the product which calcined at 1473K. The results show that KAlSi3O8 firstly is decomposed into KAlSi2O6 and released the SiO2, then has a complex reaction between KAlSi2O6 and CaO, which generated intermediates-K2SiO3 under the operating conditions. K2SiO3 is unstable and reacted with calcium sulfate to generate K2SO4. When the CaO amount is insufficient, the main products are KAlSi2O6 and 2CaOAl2O3SiO2, the potassium existed as K2S2O8; when n (CaO) / n (KAS6) 12:1, the products will further transfer into CaOSiO2 and 2CaO SiO2 and the potassium existed as K2SO4.
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