Highly efficient capture of odorous sulfur-based VOCs by ionic liquids

Highlights: • Sulfur-based VOCs capture with [EMIM][Tf₂N] were systematically investigated. • The removal efficiency of both DMS and DMDS can reach more than 90 %. • Both cation and anion in [EMIM][Tf₂N] have important effects on DMS/DMDS capture. • The process design for continuously capturing sulfur-based VOCs was carried out. This study proposes the capture of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) from waste gas using an ionic liquid (IL), namely, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][Tf₂N]), and examines the process from a molecular level to the laboratory scale, which is then scaled up to the industrial level. The binding energy and weak interactions between DMS/DMDS and the anion/cation in [EMIM][Tf₂N] were investigated using quantum chemistry calculations to identify the capture mechanism at the molecular scale. A thermodynamic model (UNIFAC-Lei) was established by the vapor−liquid equilibrium data of the [EMIM][Tf₂N] + DMS/DMDS systems measured at the laboratory scale. The equilibrium and continuous absorption experiments were performed, and the results demonstrated that [EMIM][Tf₂N] exhibits a highly efficient capture performance at atmospheric conditions, particularly, absorption capacities (AC) for DMS and DMDS are 189.72 and 212.94 mg g⁻¹, respectively, and partial coefficients (PC) as more reasonable evaluation metrics for those are 0.509 × 10^-4 and 6.977 × 10^-4 mol kg⁻¹ Pa⁻¹, respectively, at the 100 % breakthrough. Finally, a mathematical model of the strict equilibrium stage was established for process simulations, and the absorption process was conceptually designed at the industrial scale, which could provide a decision-making basis for chemical engineers and designers.