Alkali metal chlorides in DMSO–methanol binary mixtures: insights into the structural properties through molecular dynamics simulations

Ion diffusion captures composition-dependent anomalies in water-DMSO binary mixtures

Aqueous dimethyl sulfoxide (Aq-DMSO) binary mixture exhibits many fascinating composition-dependent anomalies that are explained by using the peculiarities of the water-DMSO hydrogen bond. Ions can couple strongly to these composition-dependent anomalies to produce exotic dynamics of their own. We carry out theoretical studies using computer simulations to understand the structural and dynamical aspects of rigid monovalent cations (Li+, Na+, K+, Rb+, and Cs+) in aqueous DMSO solutions, with chloride as the counterion. We uncover a number of composition-dependent ion diffusion anomalies, which can be traced back to the interplay between the size-dependent charge density of the ion and the resulting difference in interactions of the ion with water and DMSO molecules. Size and composition dependence of the diffusion coefficients of the five ions exhibit fascinating variations that can be explained partially.

A theoretical investigation into the effects of functionalized graphene nanosheets on dimethyl sulfoxide separation

The potential of carbon-based nanosheet membranes with functionalized pores is great as water treatment membranes. Using the molecular dynamic simulation technique, the dimethyl sulfoxide (DMSO) separation from the water/DMSO binary solution is investigated, and the functionalized graphene nanosheets are used as a membrane. This membrane was functionalized by -F (fluorine) and -H (hydrogen) functional groups. For the separation of DMSO, external hydrostatic pressures up to 100 MPa were applied to the considered systems. The separation mechanism was based on molecular size. Multiple analyses were done to study the capability of considered membranes for the separation of DMSO molecules from water. The simulation results have indicated that the graphene membrane with various functional groups was impervious to DMSO molecules, and the water molecules were able to permeate across the membrane's pore with high penetrability. In this regard, the water permeability in 100 MPa was obtained at 3915.5 and 3715.3 L m^-2. h^-1. bar^-1 for fluorinated and hydrogenated pore membranes, respectively. These functionalized graphene membranes have high efficiency, and they can be considered effective modules for water/DMSO binary mixture separations.