The main purposes of this project are to assess and to optimize the solubility of carbon dioxide (CO2) in an aqueous 30 wt% monoethanolamine-tetrabutylphosphonium methanesulfonate (MEA-[TBP][MeSO3]) new hybrid solvent. In this study, the viscosity and density of aqueous MEA-[TBP][MeSO3] hybrid solvents containing different amounts of [TBP][MeSO4] were determined. Meanwhile, Fourier Transform-Infrared (FT-IR) Spectroscopy was used to determine the presence of carbamate in aqueous MEA-[TBP][MeSO3] to prove that CO2 was absorbed by aqueous MEA-[TBP][MeSO3]. Response Surface Methodology (RSM) based on central composite design (CCD) was used to design the experiments and explore the effects of three independent parameters on the solubility of CO2 in aqueous MEA-[TBP][MeSO3]. The three independent parameters are concentration of [TBP][MeSO3] (2–20 wt.%), temperature (30–60 °C) and pressure of CO2 (2–30 bar). The experimental data was found to fit a quadratic equation using multiple regressions and analyzed using analysis of variance (ANOVA). The final empirical equation in terms of actual factors was deducted as mol fraction = 0.5316 − (2.76 × 10−4)A − (8.8 × 10−4)B + (8.48 × 10−3)C + (2.9 × 10−5)AB + (2.976 × 10−6)AC + (5.5 × 10−5)BC − (8.4 × 10−5)A2 − (3.3 × 10−5)B2 − (1.19 × 10−4)C2, whereby A = ionic liquid ([TBP][MeSO3]) concentration, B = temperature and C = CO2 pressure. An attempt was made to perform the experiments for solubility of CO2 in aqueous MEA-[TBP][MeSO3] to validate the removal of CO2 predicted by RSM. Based on a validation study, the experimental data showed a percentage error between 0.6% and 2.11% as compared to the predicted value of CO2 removal by RSM.
Ni/Al-layered double hydroxides (Ni-LDHs) and Ni/Al-sodium dodecyl sulfonate layered double hydroxide nanocomposites (Ni-SDS-LDHs) with a molar ratio of Ni:Al (4:1) have been prepared by a co-precipitation (or salt-base) method. Their structures were determined using Powder X-Ray Diffractometer (PXRD) and the spectra showed that basal spacings for Ni-LDHs and Ni-SDS-LDHs synthesised were around 8.1 Å and 34.8 Å , respectively. Lipase from Candida rugosa was immobilised onto these advanced materials, by physical adsorption. The activity of immobilised lipase was investigated through esterification of palmitic acid and isopropyl alcohol in hexane. The effects of reaction temperature, thermostability, stability in organic solvent, operational stability, leaching and storage studies of the immobilised lipase were investigated. These biocatalysts exhibited higher activities than the native lipase with an optimum temperature of 408C. Immobilised lipases showed higher storage stability than native lipase (up to 60 days) and during operational studies at 308C for 5 h, more than 50% of its activity was retained. Leaching studies showed that physical adsorption is suitable for the attachment of enzymes onto LDHs.
This paper investigated the solubility of carbon dioxide (CO2) in an aqueous solution of monoethanolamine (MEA) and 1-butyl-3-methylimidazolium dibutylphosphate ((BMIM)(DBP)) ionic liquid (IL) hybrid solvents. Aqueous solutions of MEA-(BMIM)(DBP) hybrid solvents containing different concentrations of (BMIM)(DBP) were prepared to exploit the amine’s reactive nature, combined with the IL’s non-volatile nature for CO2 absorption. Response surface methodology (RSM) based on central composite design (CCD) was used to design the CO2 solubility experiments and to investigate the effects of three independent factors on the solubility of CO2 in the aqueous MEA-(BMIM)(DBP) hybrid solvent. The three independent factors were the concentration of (BMIM)(DBP) (0–20 wt.%), temperature (30 °C–60 °C) and pressure of CO2 (2–30 bar). The experimental data were fitted to a quadratic model with a coefficient of determination (R2) value of 0.9791. The accuracy of the developed model was confirmed through additional experiments where the experimental values were found to be within the 95% confidence interval. From the RSM-generated model, the optimum conditions for CO2 absorption in aqueous 30 wt% MEA-(BMIM)(DBP) were 20 wt% of (BMIM)(DBP), a temperature of 41.1 °C and a pressure of 30 bar.
Asphaltene is a component of crude oil that has remained relatively unexplored for organic electronic applications. In this study, we report on its extraction technique from crude oil tank bottom sludge (COTBS) and its thin-film characteristics when 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) ionic liquid (IL) was introduced as dopants. The extraction technique yielded asphaltene with more than 80% carbon content. The IL resulted in asphaltene thin films with a typical root-mean-square surface roughness of 4 nm, suitable for organic electronic applications. The thin films each showed an optical band gap of 3.8 eV and a sheet resistance as low as 105 Ω/□. When the film was used as a conductive layer in organic field-effect transistors (OFET), it exhibited hole and electron conduction with hole (µh) and electron (µe) mobilities in the order of 10−8 and 10−6 cm2/Vs, respectively. These characteristics are just preliminary in nature. With the right IL, asphaltene thin films may become a good alternative for a transport layer in organic electronic applications.
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