CO ₂  Diffusivity in Non‐Aqueous Mononethanolamine‐Electrolyte Solution

BACKGROUND Integrated carbon capture and conversion (ICCC) relies on efficient CO 2 transport within absorbent–electrolyte systems, yet diffusivity data for non‐aqueous amine–electrolyte solutions remain limited. This study investigated the diffusivities of CO 2 and N 2 O in a non‐aqueous monoethanolamine (MEA)– lithium chloride (LiCl)– dimethyl sulfoxide (DMSO) over MEA concentrations of 2–4 M, LiCl concentrations of 0.1–0.5 M, and temperatures of 303–323K using a pressure decay method, with viscosity measurements performed to elucidate mass transport behaviour. RESULTS The measured solution viscosities ranged from 1.084 to 4.427 mPa·s, while the estimated CO 2 diffusivities in MEA–LiCl–DMSO solutions ranged from 5.52 × 10 −9 to 18.50 × 10 −9 m 2 .s −1 . Increasing LiCl concentration from 0 to 0.5 M reduced CO 2 diffusivity by up to 24% due to the corresponding increase in solution viscosity, whereas increasing temperature from 298 to 323K enhanced diffusivity by more than twofold. Similar trends were observed for N 2 O and MEA diffusion coefficients, confirming the strong influence of viscosity on molecular transport. CONCLUSION An inverse relationship between viscosity and diffusivity was established for the MEA–LiCl–DMSO system, highlighting the importance of balancing electrolyte concentration and mass transport performance in carbon capture applications. The diffusivity and viscosity data reported in this work provide fundamental insights and a useful basis for the rational design of non‐aqueous absorbent–electrolyte systems for integrated carbon capture and conversion processes.