Papers by Keyword: Dissolution

Abstract: Pyromorphite was synthesized by precipitation and characterized by various techniques. The batch dissolution experiment was conducted at 25°C and different initial pHs (2, 4 and 6). The solid phase showed no obvious change before and after dissolution. The aqueous phosphate concentration decreased quickly from 0.22 to 0.01mmol/L and then increased very slowly with time. After 2160h dissolution, it reached a steady-state value of about 0.13mmol/L. The aqueous lead concentration increased initially and reached a peak value after 72h dissolution.

Abstract: Cellulose, the most abundant materials in the plant resources, has been paid more attention. The updated technology of cellulose dissolution and the application of cellulose functional material were reviewed, especially the compounds of cellulose/inorganic (or organic) substance. The review is of benefit to the research in familiarizing with cellulose dissolution and its application.

Abstract: It took long time for reed leaf cellulose to dissolve in ionic liquid (1-butyl-3-methylimidazolium chloride), and part of the cellulose was degraded and the fiber strength reduced greatly. In order to decrease its dissolution time, the ultrasonic wave pretreatment was applied in this article. Results were showed through polarizing microscopy, SEM, FT-IR and XRD. By comparing the original fiber with the regenerated cellulose, it can be concluded that Ultrasonic wave pretreatment significantly increased the crystallinity of the fiber, weakened the fibrillation on fiber surface obviously, which proved the process was a physical change and did not affect the cellulose structure.

Abstract: Dissolution plays a dominant controlling role on reservoir properties in delta sandstone of the Permian He 8 Formation, Sulige gasfield. Dissolution forms intergranular dissolved pore and intragranular dissolved pore. Areas with high percentages of dissolved pores occur along delta-plain distributary channel and delta-front underwater distributary channel deposits. Due to dissolution, the porosity increased to 10-17% with permeability as high as 10md. Wells drilled through He 8 sandstones have high daily gas production of 4~6×10⁴m³/d.

Abstract: Abatract. The enthalpies of dissolution for nitroguanidine (NQ) in dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) were measured using a RD496-2000 Calvet microcalorimeter at 298.15 K. Empirical formula for the calculation of the enthalpies of dissolution (Δ_dissH) was obtained from the experimental data of the dissolution processes of NQ in DMSO and DMF. The corresponding kinetic equations describing the dissolution processes were dα/dt=10^-1.49(1-α)^0.94 for the dissolution of NQ in DMSO and dα/dt=10^-1.59(1-α)^0.90 for the dissolution of NQ in DMF.

Abstract: Waste silk fibers were dissolved in calcium chloride aqueous solution. Effect of calcium chloride concentration on silk solubility was studied. Dialysis method was used to purify the dissolved silk fibroin. The purified silk fibroin was characterized by FTIR and thermoanalysis technique. Results showed that the purified silk fibroin mainly had irregular curly conformation. The glass transition temperature of the regenerated silk fibroin reached 90.6°C-135°C, higher than 78.9°C-135°C before purification. Thermal weight loss temperature by 50% was 490.3°C differing from 429.7°C before purification.

Abstract: Porous metals that have open pores structure with low density and light weight properties are suitable to be used in many engineering applications. In this work, the porous aluminum was fabricated via sintering dissolution process (SDP). Aluminum and sodium chloride (20, 40, 50 wt. %) powders were mixed together to produce a homogeneous mixture. The mixture was compressed at 200 MPa followed by sintering at 500 °C, 550 °C and 600 °C for 2 hours. The sintered samples were placed under a warm running water stream for 45 min to dissolve the sodium chloride that embedded in the aluminum. From the result, the sodium chloride content controlled the total porosity between 20% and 40% of the sintered aluminum. Porosity increased and compressive strength decreased as the content of NaCl increased. It was also observed, the porosity increased with increasing sintering temperature for the sample with 40 wt. % of NaCl.

Abstract: In this investigation, the bioleaching of potassium, silicon and aluminum from natural illite by three strains of Paenibacillus polymyxa , Agrobacterium tumefaciens and Penicillium heteromorphum purchased from China General Microbiological Culture Collection Center was studied. Chemical analyzing investigation indicated that K₂O , SiO₂ and Al₂O₃ were major chemical components. Bioleaching tests were performed in an orbital shaker with 250mL conical flasks at 30°C and 200 r/min agitation. The results show that, In the whole bioleaching process, the maximum extracts of K₂O , SiO₂ and Al₂O₃ are 1.96, 7.96 and 4.57 g/L respectively with Paenibacillus polymyxa, 1.73, 6.9 and 4.19 g/L with Agrobacterium tumefaciens, and 1.68, 6.23 and 7.12 g/L with Penicillium heteromorphum. Paenibacillus polymyxa is the most efficient of releasing K and Si, the most efficient of releasing Al is the strain of Penicillium heteromorphum.

Abstract: Holistic tin-plating on the outer conductor is one of the key processes in the manufacture of semi-flexible coaxial cable. In this study, a tin-based solder alloy was developed for this special tin-plating process. For this new solder alloy, the molten solder's antioxidant performance, the morphology of inter-metallic compounds (IMCs) at the solder/copper interface and the dissolution rate of outer conductor during tin-plating process were studied. The results indicate that when the addition of P element in the pure tin solder up to 35ppm, the static oxidation rate of pure tin decreased to 12.1g/m² from 26.5g/m², while the dynamic oxidation rate decreased from 8.9g/m² to 5.6g/m², which can significantly reduce the amounts of the oxidized slag from tinned tank during the continuous operating; By adding 0.1%Co, 0.05%Ni, the morphology of IMCs changed from scallop-shape to a uniform plate-shape, which can improve the interfacial bonding strength and flexibility; Adding 0.7%Cu can reduce the dissolution of the outer copper conductor during tin-plating process.

Abstract: s: A research study has been undertaken to develop the fundamentals of a method for the direct dissolution of platinum group metals (PGMs). At room temperature and pressures, the reaction between sodium cyanide and platinum group metals (PGMs) does not occur because of poor kinetics. However, at elevated temperatures between 120-180 °C, PGMs can be leached by sodium cyanide like the reaction of gold. In this work, the dissolution of Palladium and Platinum powder were measured in pressure clear cyanide solution. The cyanide leaching reaction mechanism is also discussed.The data at different cyanide concentrations, different temperature and different oxygen pressure are obtained. The dissolution rate off metal Palladium and Platinum powder were found to be a function of the cyanide and oxygen level.