Chemistry

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Browsing Chemistry by Subject "1-Butyl-3-"

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    Kinetics of Adsorption/Desorption of 1-Butyl-3-Methylimidazolium Bromide Into/Out of Mordenite
    (Addis Ababa University, 2014-02-02) Chanie, Yewilsaw; Pérez, Eduardo (PhD)
    The adsorption and desorption kinetics of ionic liquid (1-butyl-3-methylimidazolimu bromide) on mordenite have been studied. Adsorption and desorption of ionic liquid into/out of calcined and uncalcined mordenite was achieved by putting ionic liquid and mordenite in contact at 100 C. Mordenite (synthetic) was pre-treated by calcinations at 550 C in order to transform the terminal ammonium groups by proton groups. The adsorption of ionic liquid into mordenite was characterized using TGA and FT-IR, and quantitatively determined using CHN elemental analysis. The proportion of ionic liquid into mordenite was obtained from the percent by mass of nitrogen (% N2) from the elemental analysis. The kinetics of adsorption and desorption was studied based on the results obtained for % N2 composition. In addition, the kinetics of adsorption was analyzed using Lagergen pseudo first and pseudo second order kinetic models. The TGA result showed a 4% weight loss between 100 – 200 C and 17% weight loss around 400 C (around the), which are attributed to the weight loss of water and thermal decomposition of pure ionic liquid, respectively. The result obtained from the CHN elemental analysis showed that much of ionic liquid adsorbed into Mordenite very fast, within an hour, and reached equilibrium at 16% of [BMIM]+ [Br]-. On the other hand, desorption occurs much slowly, in 24 hr, and only 9% of ionic liquid was desorbed at equilibrium, suggesting that the interaction of [BMIM]+ [Br]- and mordenite is significantly strong. The adsorption isotherm data fitted best with Lagergen pseudo second order kinetic model, indicating that the concentrations of both ionic liquid and mordenite are involved in the rate determining steps. The equilibrium amount of ionic liquid adsorbed into Mordenite obtained from fit, 158.2 ± 0.8 mg/g, which is very close to the value found from elemental analysis, 160.8 mg/g, further confirming the binuclear nature of the adsorption process.