This work aims to screen out absorbents with excellent performance to control toluene pollution. Based on density functional theory (DFT), this article calculated the binding energy between toluene and organic solvents molecules with specific functional groups, and comprehensively examined the physical and chemical properties of the solvents to screen out suitable toluene absorbents. The computational binding energy and the experimental absorption efficiency have the same change tendency, that is, the value of the binding energy determines the ability of the solvents to absorb toluene. Pentaethylene glycol dimethyl ether (PGDE), 1-methyl-2-pyrrolidinone (NMP), dioctyl phthalate (DOP) and sulfolane (SUL) were initially selected as toluene absorbents. Atoms in molecules (AIM) analysis, reduced density gradient (RDG) analysis and symmetry-adapted perturbation theory (SAPT) analysis were used to explore the microscopic mechanism of toluene absorption by four organic solvents. The results show that the interactions between organic solvents and toluene are weak interactions dominated by dispersion attraction. The experiment used polyethylene glycol dimethyl ether (NHD) with very low volatility as the main solvent, which is a polymer containing the main component PGDE, and compounded it with NMP, DOP, and SUL respectively. The absorption experiment investigated the efficiency of compound solvents with different mass fractions of compound components on toluene under the conditions of normal pressure, liquid-to-gas ratio 2.5 L/m3, gas flow rate 4 L/min, temperature 30°C, inlet concentration approximately 6000 mg/m3, and packing height 60 cm. The results show that the toluene absorption efficiency of the three compound solvents is more than 91%. Considering the absorption performance, consumption and stability of the solvent, NHD-SUL solvent (20 wt.% SUL) was finally selected as the new compound solvent. The new compound solvent regenerated lean solution still maintains a good absorption efficiency of 90% after 13 desorption cycles. Theoretical and experimental research are of great significance for the future treatment of exhaust gas pollution.
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