Heavy oil sorption and recovery by using carbon fiber felts

On fibrous carbon materials, including activated carbon fibers, sorption capacity for heavy oils. less viscous A-grade and more viscous C-grade, was determined. Sorption capacity depended strongly on their bulk density the correlation was the same as that found previously on exfoliated graphite and carbonized fir fibers. On carbon fiber felts, excellent recycling performance was observed. though sorption capacity was not so high as on exfoliated graphite and carbonized fir fibers. By filtration under suction, about 90% of sorbed A-grade heavy oil could be recovered and no decrease in sorption capacity was detected even after eight cycles. By washing with solvents, n-hexane for A- and C-grade oils and A-grade oil for C-grade oil, almost 100% recovery with no marked reduction in sorption capacity was found for each cycle. For the felts of PAN-based carbon fibers, rather severe operations for oil recovery, centrifugation and squeezing with twisting, could be applied without pronounced decreases in sorption capacity and recovery ratio. (C) 2002 Elsevier Science Ltd. All rights reserved.