Biological sequestration of carbon dioxide (CO2) in geological formations is one of the proposed methods to
reduce the carbon dioxide released into the atmosphere. In this method, an enzyme is used to enhance the
hydration and subsequent precipitation of CO2. In the present work, the effect of bovine carbonic anhydrase
on the hydration of CO2, and its precipitation in the form of calcium carbonate, was studied. The enzyme
enhanced the hydration reaction. The rate of hydration reaction increased with both the enzyme concentration
and temperature. The precipitation of calcium carbonate was promoted in the presence of the enzyme. The
concentration of the enzyme did not affect the precipitation; however, temperature impacted the precipitation
of calcium carbonate. At higher temperatures, less calcium carbonate was formed. Also, in the presence of
the enzyme, calcium carbonate settled more quickly. The enzyme activity was not influenced by the pH of
the reaction mixture. In contrast, the formation of calcium carbonate was affected by the pH of the solution.
A kinetic analysis was performed for the bovine carbonic anhydrase. Based on the experimental results, the
activation energy and catalytic rate constant are estimated as 700.91 cal/mol and 0.65 s-1, respectively.
The main objective of this work was to examine the influence of pyrolysis pressure on product yield from wheat straw pyrolysis. The experiments were performed in a tubular reactor at different pressures (10, 20, 30, and 40 psi) with a constant flow rate of nitrogen (50 cc/min) at a temperature of 500 °C. During pyrolysis, the products obtained are oil, gas, and char. The maximum oil yield was 37.6%, obtained at high pressure (40 psi). Liquid product was analyzed using gas chromatography/mass spectrometry (GC-MS). The percentage of bio-oil compounds increased as operating pressure increased. The major components present in the bio-oil were phenols, methoxyphenols, and substituted methoxyphenols such as eugenol and vanillin. The gas products were mainly CO, H 2 , CO 2 , CH 4 , C 2 H 4 , C 2 H 6 , C 4 H 10 , and C 3 's. Char characteristics were measured using scanning electron microscopy (SEM) and ultimate analysis. Van Krevelen diagram shows that the chars obtained from wheat straw pyrolysis have very less H: C and O: C ratios than the raw wheat straw. On the basis of the results of this study, it may be concluded that, within the pressure range studied, 20 psi is the optimum pressure for the pyrolysis of the wheat straw in a tubular reactor with respect to products (char, bio-oil, and gas) yield.
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