Experimental and Mathematical Modelling of Factors Influencing Carbon Dioxide Absorption into the Aqueous Solution of Monoethanolamine and 1-Butyl-3-methylimidazolium Dibutylphosphate Using Response Surface Methodology (RSM).

Fatin Nor Arissa Azhar,Mohd Faisal Taha,Noor Mona Md Yunus,Siti Musliha Mat Ghani,Muhammad Syafiq Hazwan Ruslan

doi:10.3390/molecules27061779

Fatin Nor Arissa Azhar, Mohd Faisal Taha + Show 3 more

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https://doi.org/10.3390/molecules27061779

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Abstract

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.

Highlights

IntroductionThe increasing amount of CO2 in the atmosphere has critically impacted the environment and human health [1]
The main objectives of this study are to investigate three independent factors (the concentration of (BMIM)(DBP), temperature and the pressure of CO2 ) affecting CO2 absorption in aqueous 30 wt% MEA-(BMIM)(DBP) hybrid solvent and to predict the optimum conditions that would lead to high CO2 absorption
The density of the density of (BMIM)(DBP) (1.04 g/cm ) [21], which is higher than that of MEA (1.015 g/cm hybrid solvent increased with an increase in the (BMIM)(DBP) concentration

Summary

Introduction

The increasing amount of CO2 in the atmosphere has critically impacted the environment and human health [1]. The commercial solvents that are being used as chemical adsorbents in CO2 capture technologies are alkanolamines such as monoethanolamine (MEA), diethanolamine (DEA) and N-methyldiethanolamine (MDEA). The use of these alkanolamines presents several disadvantages such as corrosion, thermal and oxidative degradation, leading to the loss of absorbents, limited CO2 loading and high regeneration energy and cost [3,4]. ILs possessing significant characteristics, such as negligible volatility, high thermal stability and tunable physicochemical properties, have been demonstrated to effectively absorb CO2 [5]. The combination of more stable ILs with reactive alkanolamines, known as hybrid solvents, has demonstrated better CO2 absorption and fewer absorbent losses as compared to alkanolamines alone [6]. Mixing alkanolamines with ILs would be advantageous to overcome the problems associated with the high viscosity and high cost of ILs for the industrial application of CO2 absorption

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