Deep eutectic solvents interaction with asphaltenes: A combined experimental and molecular dynamics study

Deep eutectic solvents (DESs) are industrially promising solvents and posses numerous applications in wide areas such as metal processing, synthesis media, synthesis of nanoparticles, gas sequestration and many more. In this work, we synthesized and investigated the performance of three deep eutectic solvents (DESs) i.e., reline, glyceline and ethaline in the separation of pure asphaltene from organic solvents, i.e., toluene and n-heptane using experimental techniques and classical molecular dynamics (MD) simulations. The DESs are prepared and characterized by Fourier transform infrared (FTIR) spectroscopy and density meter analysis. The separation and aggregation of asphaltene from the organic solvent phase into the DES phase at various DES concentrations are visually observed using optical microscopy. MD simulations are used to probe the end-to-end distance and diffusion coefficient of the asphaltene molecules in DESs-organic solvent mixtures. Further, the trajectory density contours of asphaltene in three DESs-toluene/n-heptane systems are calculated to analyze asphaltene aggregation in the presence of the DESs. Our experimental-simulations synergistic study shows the superior performance of glyceline DES in toluene and reline DES in n-heptane for efficient separation of the asphaltene.