Sorption and recovery of heavy oils by using exfoliated graphite

The behavior of sorption of heavy oils into exfoliated graphite samples with different bulk density was studied by using four grades of heavy oil with different viscosity. Maximum sorption capacity of exfoliated graphite was found to be 83 g of A-grade heavy oil per I g of the exfoliated graphite and also its sorption occurs very rapidly, within 1 min. Sorption capacity depended strongly on bulk density and total pore volume of exfoliated graphite. Time to reach maximum sorption, as well as sorption capacity, of an exfoliated graphite depended strongly on grade of heavy oil; a large amount of heavy oils with low viscosity was sorbed in a short time, but oils with high viscosity needed a long time although sorbed amount was relatively small. Heavy oils sorbed into exfoliated graphite could be recovered by a simple filtration under reduced pressure with the recovery ratio of about 70% and could not be differentiated from molecular weight values and the contents of various hydrocarbons. The exfoliated graphite packed into a bag was shown to give also high sorption capacity, if the material of the bag and the way of picking up from heavy oil were properly selected. (C) 2003 Elsevier Ltd. All rights reserved.