Heavy oil sorption using exfoliated graphite - New application of exfoliated graphite to protect heavy oil pollution

The sorption behaviors of four kinds of heavy oils into exfoliated graphites with different bulk densities were studied. The maximum sorption capacity of an exfoliated graphite with a bulk density of 6 kg/m(3) was found to be suprisingly high, 86 g of A-grade heavy oil and 76 g of crude oil per 1 g of exfoliated graphite, respectively, and also its sorption occured very rapidly, i.e. within 2 min. Sorption capacity was found to depend strongly on the bulk density and pore volume of the exfoliated graphite and the time it took to reach maximum sorption, as well as sorption capacity, as an exfoliated graphite depended strongly on the grade of heavy oil. Heavy oils sorbed into the exfoliated graphite could be recovered either by a simple compression or suction filtration with a recovery ratio of 60-80%. Recovered oils showed no difference in molecular weight and hydrocarbon constituent from the original. No increase of the water content in the recovered oils was detected, suggesting preferential sorption of heavy oil into exfoliated graphite. This result indicates clearly that the oils recovered from the exfoliated graphite can be recycled. From the present work, exfoliated graphite with low bulk density is a promising material for the sorption and recovery of spilled heavy oil. (C) 2000 Elsevier Science Ltd. All rights reserved.