Investigation of water-oil separation via graphene oxide membranes: A molecular dynamics study

M Foroutan and H Zahedi and E Soleimani, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 555, 201-208 (2018).

DOI: 10.1016/j.colsurfa.2018.07.002

Recently, graphene oxide has been widely used for the extraction of hydrocarbon compounds. In the present work, the separation of water from a water-oil mixture by two-layer graphene oxide has been studied using molecular dynamics simulation. Several interlayer spacing of graphene oxide layers was considered, and for each gap in each layer of graphene oxide, several sizes were considered and it was determined the efficient interlayer distance as well as gap size which gives highest water-oil separation. The simulation results unveil that as the interlayer spacing and the size of the gap is reduced, the flux and permeability of the water molecules decrease, but the amount of water molecules separating from the oil increases. To study the number of layers' impact for higher separation efficiency, a system containing a graphene oxide layer was also studied and the importance of the number of graphene layers was highlighted. Also, for the analysis of graphene oxide functional groups' effect on separation, a system containing graphene layers was also investigated and the role of functional groups was revealed in hydrogen bond formation between graphene oxide and water molecules. By calculating PMF, the effect of functional groups on the repelling oil molecules from the graphene oxide's gaps was investigated.

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