Study On Preparation Of Green Absorbents And Selective Absorption Of Sulfur Dioxide

Currently,the emission of acidic gas sulfur dioxide（SO₂）leads to an environmental pollution problem,which would pose a serious threat to public health.The industrial gas mixture containing SO₂ usually contains competitive CO₂.It is difficult for traditional absorbents to achieve high capacity and selectivity for absorption of SO₂ from CO₂.Therefore,it is of great significance to research and develop new green and efficient absorbents to realize efficient separation of SO₂/CO₂and recovery of SO₂ resource.The content of this thesis is shown below:（1）Four ionic liquids[P₄₄₄₈][Pen],[P₄₄₄₈][Mho],[P₄₄₄₈][Ido]and[P₄₄₄₈][Dib]were designed and synthesized.The structures of these carbanion-based ionic liquids were determined and confirmed by NMR.The values of viscosity and density were measured,as well as the effect of temperature on viscosity and density was also obtained.The experimental results showed that the solubility of SO₂ in[P₄₄₄₈][Pen]was as high as 4.70 mol·mol^-1 at 293.2 K and 1.0 bar,and the absorption equilibrium time only needed 2.5 minutes.Howeve,the absorption selectivity of SO₂/CO₂ is only 23.（2）Three matrine-based deep eutectic solvents（DESs）were prepared through mixing of matrine and amide with different molar ratios.The solubility of SO₂ and the selectivity of SO₂/CO₂ in these matrine-based DESs were then studied.The results showed that the solubility of SO₂ in the DES Mat-MFA（1:2）was as high as 0.81 g·g^-1at 298.2 K and 1.0 bar,and the equilibrium time reduced to 1.5 min.The absorption selectivity of SO₂/CO₂ was up to 256.Moreover,the thermodynamic analysis results further indicated that the enthalpy of SO₂ absorption by the DES Mat-MFA（1:2）was only-13.6 k J·mol^-1.This means that this absorption process is mainly physical absorption,SO₂ can be easily desorbed from the DES Mat-MFA（1:2）.As combined with the infrared spectrum results and recycle performance of SO₂ absorption,the DES Mat-MFA（1:2）was considered to have good reusability and cycle stability.In summary,two kinds of green SO₂ absorbents were successfully prepared in this thesis,and high capacity,high selectivity and rapid absorption of SO₂ from CO₂ was achieved.This thesis is able to provide theoretical research and reference for the separation and recovery of SO₂ in the actual industrial mixture gas.