Papers by Keyword: Sulfation

Abstract: Sulfated derivatives of polysaccharides have anticoagulant, hypolipedimic and other biological activity. In this work, a complex mixed ester of galactomannan, its sulfate-citrate, was obtained for the first time. The introduction of citrate and sulfate groups was proved by FTIR spectroscopy by the appearance of corresponding absorption bands. It was shown by X-ray diffraction that the introduction of the citrate group leads to the amorphization of the galactomannan structure.

Abstract: The main failure modes of starter battery are discussed, the causes resulting in the premature failure of starter VRLA(valve-regulated lead-acid) battery are analyzed and corresponding countermeasures against failure of starter battery are presented. It proves to be of practical help.

Abstract: In this paper, the sulfation failure mechanism on negative plates of lead-acid batteries and the pulse-repairing technology are analyzed, and an online automatic maintenance device based-on the Boost converter is designed. The device uses ATmega16 microcontroller as its controller. The test results show that by adjusting the hardware devices and programs the frequency and amplitude of charge-and-discharge pulses can be changed. And when the battery voltage is too low the device can generate sound and light alarm. The device meets the design requirements.

Abstract: Sulfation performance of a Fe-Ca based sorbent prepared from iron oxide-rich metallurgical dust and lime is investigated using thermogravimetric analysis (TGA) in the temperature range of 300-550°C, and the kinetics of the sulfation reaction is analyzed using the grain model. Comparison between the model simulation results and experimental data demonstrates that the grain model can give a relatively satisfactory description of the experimental results. In detail, the overall rate of the sulfation reaction is mainly controlled by diffusion, despite by chemical kinetics at a very low degree of conversion (lower than 0.056), and that the higher diffusion activation energy (E _D, 25460J/mol) and smaller diffusion frequency factor (D _e0,4.42×10^–2 cm²/min), in relative to those of the sulfation reaction (13008J/mol for E a and 1.65 cm/min for k _s0), may account for the shift in control mechanism, the role of diffusion in the sorbent conversion, and consequently the flat-convex conversion vs. time curves obtained by TGA.

Abstract: The sulfation behavior of calcined raw meal was investigated in a laboratory fix-bed reactor under conditions typically for SO2 capture in the kiln inlet housing used in cement production. The initial period is characterized with a fast-increasing conversion, while the second period shows a slow-increasing conversion. A desirable temperature exists for sulfation of calcined raw meal. A smaller particle size favors the sulfation reaction. The initial conversion rate is significantly promoted by a higher SO2 concentration. The SEM examinations show that the sulfation process involves nucleation and growth of CaSO4 grains- the sulfation product. Increasing the temperature and extending the time result in fewer but larger CaSO4 grains in the product layer.