Preparation Of Deep Eutectic Solvents And Study Of Their Properties For Nitric Oxide Capture

Coal accounts for a large proportion in Chinese energy structure,and coal flue gas contains a large amount of nitrogen oxides.Nitrogen oxide is one of the major pollutants in air pollution,and it is prone to environmental problems such as acid rain and photochemical pollution.Therefore,nitrogen oxides pose a great threat to human health and living environment.Nitric oxide accounts for the largest proportion of nitrogen oxides in flue gas,thus nitric oxide was selected as the main research object.At present,there are many technologies for the removal of nitric oxide at home and abroad,but they have confronted constraints on economic and environmental issues.Due to its special physical properties,deep eutectic solvents are expected to be used in industries that remove nitric oxide.In this work,two types of deep eutectic solvents?DESs?were designed and synthesized:Deep eutectic solvent based on 1,3-dimethyl thiourea and deep eutectic solvent based on tetrazole.The FTIR and NMR spectra of these eutectic solvents were characterized,their thermal properties was studied,absorption and desorption systems were constructed,and the capacities to absorb nitric oxide were tested for various eutectic solvents,the desorption and reusability were also investigated,the mechanism of the absorption of nitric oxide by deep eutectic solvents was investigated using Gaussian simulations.Through experimental studies,it has been found that both types of eutectic solvents have good absorption effects.At atmospheric pressure,the maximum absorption of 1,3-DMTU/P₄₄₄₄Cl deep eutectic solvent can reach 4.25 mol/mol at30?,and still had a good absorption capacity after 5 cycles of testing.Tetz/P₄₄₄₄Cl deep eutectic solvent could reach 2.1 mol/mol capacity under normal pressure at 30?,and with the increasing of absorption,the viscosity was reduced.The viscosity before absorption was 40.22 cp and the viscosity after absorption was 3.15 cp.Through the comparison of the pre-and post-absorption NMR spectra and IR spectra,as well as through quantum chemical calculation using Gaussian software,the absorption mechanism of two kinds of eutectic solvents was proposed.The selectivity of the eutectic solvents for carbon dioxide was tested.Based on the experimental results,NMR and FT-IR spectroscopic investigation,the two kinds of deep eutectic solvents have high NO/CO₂ selectivity.The deep eutectic solvents,have the advantages of good absorption effect,good recycling performance,low cost,simple preparation,no pollution,etc.,which will have a positive effect on the future nitrogen oxide treatment technology.