Experimental and theoretical study of CO2 absorption by Water-Ionic liquid-Piperazine solution using the method of Constrained Mixture Design

Separation of carbon dioxide, as a main environmental pollutant, from natural gas using amine mixture is one of the most common methods. In this research, the optimal composition of the amine mixture was determined using the method of designing limit vertices. The amine mixture used in this research included water, piperazine and 1-butyl-3-methylimidazolium hydrogen sulfate. In order to measure the solubility of carbon dioxide in amine solution, an equilibrium cell (autoclave) was used. According to the analysis of variance, explanation coefficient (R2) has a high value (R2=99.79%). The analysis of the results was conducted at the 95% confidence level in a block with 9 tests and Ludinig's definition as the response variable. The optimization results showed that the combination consisting of 24.811 ml of water, 188 ml of amine and 0.76 ml of ionic liquid had the best efficiency and, in this case, the maximum loading of 1.702 was obtained.