Sorption, Recovery and Recycle of Spilled Heavy Oils Using Carbon Materials

Abstract

Sorption capacity for heavy oils was determined on different carbon materials; exfoliated graphite showed very high capacity for A-grade heavy oil as 83g/g, fir fibers carbonized up to 900°C as 78g/g and carbon fiber felt as 20g/g. Sorption capacity depended strongly on bulk density of carbon sorbents. Heavy oils sorbed into exfoliated graphite were able to be recovered by filtration under suction, but the repetition of sorption and recovery (recycling) resulted in a rapid decrease in sorption capacity. Carbonized fir fibers and carbon fiber felts were found to have a better recycling performance, even by washing with a solvent as well as filtration. Viscous C-grade heavy oil could be washed out by using less viscous A-grade oil, resulting in the recovery as B-grade oil. Carbon fiber felts were found to show excellent recycling performance; almost 100% of sorbed oil was recovered by centrifugation without marked reduction in sorption capacity. Recovered oils were confirmed to have the same chemical and physical properties as the original. Exfoliated graphite was able to pump up heavy oil from contaminated sand. The relation between grain size of sand and bulk density of exfoliated graphite is discussed.