Preparation Of Glycolic Acid Eutectic Ionic Liquid And Its Application In Ammonia Capture And Separation

As a new kind of green solvents,EILs（Eutectic Ionic Liquids）have similar properties to ionic liquids.In this paper,a new type of EILs for NH₃ absorption and separation were prepared and studied by summarizing and analyzing the current status and progress of NH₃ capture.Five EILs were prepared at 363.15K,and their chemical structures were characterized by FT-IR and ¹H NMR spectra.The low eutectic points,water contents,densities,viscosities,electrical conductivities and surface tensions at different temperatures were measured.The properties of EILs were fitted and the fitting precisions R²>99%.Five EILs were screened for NH₃ absorption.The results showed that GA-XYL EILs could achieve high capacity absorption while maintaining uniformity and stability,and the absorption capacity increased first and then decreased with the increase of the molar fraction of carboxylic acid;When the molar fraction of GA is 0.75,the absorption capacity is the best and better than the existing ionic liquids,which can reach 0.22 g NH₃·（g EIL）^-1,and can be recycled at 333.15K and 0.13k Pa.The water contents,densities,viscosities,conductivities and surface tensions were measured and fitted at 303.15K～343.15K,The results show that GA-XYL（3:1）has higher E_ηand E_σ,which is conducive to mass transfer and diffusion of NH₃;The FT-IR and ¹H NMR spectra of GA-XYL（3:1）before and after NH₃ absorption were also characterized,and the potential mechanism was analyzed.The molecular interaction mechanism,reduced density gradient function,electrostatic potential,density change,?H_vap,?H_sub and free energy of dissolution were simulated.The results show that NH₃ is more easily attracted to the secondary alcohol of xylitol than to the primary alcohol,and the carboxyl H in GA tends to lose one electron and be averaged by COO and NH₃,which belongs to strong H-bond interaction.Compared with pure carboxylic acid,GA-XYL is difficult to evaporate and sublimate due to its higher density,and its solubility in water is similar to that of ethylenediamine.Aspen Plus was used to simulate the selective separation of NH₃ in gas mixture,and the selective separation coefficient of NH₃/CO₂ was 184.