Extrapolation Of Kinetic Data Research Articles

Fast devolatilization characteristics of ‘low cost’ biomass fuels, wood and reed. Potential feedstock for gasification

Fast devolatilization of woody (mixture of softwoods) and herbaceous (reed) biomasses has been studied in a heated foil reactor coupled to an FTIR spectrophotometer. Biomass fuels were chosen based on their potential for contributing to power generation on an industrial scale through gasification in The Netherlands. Heating rate (600°C/s) and holding time (10s) at peak pyrolysis temperature were chosen to correspond to conditions encountered in industrial processes. The effect of peak pyrolysis temperature on pyrolysis products was investigated. Particular emphasis was given to tar collection, and subsequent gravimetric quantification. The results indicated a strong total weight loss increase with temperature, to reach an asymptote char yield of 16.7wt.% at 800°C and of 32.4wt.% at 700°C for wood and reed, respectively. Reed primary devolatilization reactions ceased at lower temperatures compared to wood. The latter was confirmed by the lower activation energy of reed (32.1kJ/mol) compared with that of wood (38.4kJ/mol) during extrapolation of kinetic data from the fast devolatilization experiments. CO2 dominated the gaseous products released at lower temperatures (<700°C) while CO became predominant at higher pyrolysis temperatures (>700°C) reaching a maximum of 19.1wt.% and 18wt.% for wood and reed, respectively, at 1000°C. Maximum tar yields of 38.8wt.% (d.b.) of dry wood and 23.3wt.% (d.b.)of dry reed were able to be recovered at 600°C. An overall mass balance of approximately 90wt.% (d.b.) for both biomass fuels was obtained at high (900–1000°C) pyrolysis peak temperatures.

Stability Studies of Topical Carbonic Anhydrase Inhibitor 6-Hydroxyethoxy-2-Benzothiazole Sulfonamide

A new carbonic anhydrase inhibitor, 6-hydroxyethoxy-2-benzothiazole sulfonamide (6-hydroxyethoxyzolamide), was studied to determine its stability in aqueous solution from pH 2.9 to 9.2 at a constant ionic strength of 0.15M. This newly synthesized derivative of ethoxyzolamide has demonstrated clinical efficacy for use as an ophthalmic drug to lower intraocular pressure. Drug solution in sealed ampules was placed in a constant temperature oven either at two temperatures (75 and 85 ± 0.2 °C) or four temperatures (75, 80, 85, and 90 ± 0.2 °C). Samples were analyzed by known HPLC methods. The results indicated that 6-hydroxyethoxyzolamide is most stable at pH 4 to 5.5. The aqueous drug solutions at pH 7.0 and 8.0 were, nevertheless, sufficiently stable, based on extrapolation of kinetic data at high temperatures using the experimentally determined Arrhenius equation. The degradation compound was identified by spectral analysis to have a hydroxyl group substituting for the original −SO2NH2 group.

A LABORATORY MICROWAVE STERILIZER AND ITS POSSIBLE APPLICATION TOWARD IMPROVING TEXTURE OF STERILIZED VEGETABLES

A microwave-permeable chamber was constructed for high temperature sterilization of foods in glass containers at overpressures up to 50 psig. Temperatures could be monitored satisfactorily in the microwave field using stainless steel shielded type T thermocouples if the metal sheat were grounded. Percent fracturability did not differ between potato samples sterilized by microwave energy (1000 W output) and stem. Extrapolation of kinetic data indicated that although fracturability retention is quite low at temperatures below 150°C ( 60%). Verification of this will require a higher microwave output (>1000 W) than was available in these experiments.