Sorption and regeneration of magnetic exfoliated graphite as a new sorbent for oil pollution

Magnetic exfoliated graphite (MEG) with high sorption capacity and magnetism was prepared by citric acid sol-gel method. Compared with exfoliated graphite (EG), the characteristics of MEG were manifested by scanning electron microscopy, energy diffraction spectroscopy, X-ray diffraction and mercury intrusion pore size distribution. The sorption capacity and rate of MEG were discussed, including the recovery ratios of oils (engine oil, crude oil, diesel oil and gasoline) and the regeneration of MEG. The results show that cobalt ferrite was deposited effectively and uniformly on/in MEG. The myrmekitic and multilevel pore structures of MEG were expanded and developed in comparison with that of EG. The maximum sorption capacity was obtained in about 2 min. The sorption capacity of MEG increased from 41.46 and 40.46 g g(-1) to 48.93 and 42.75 g g(-1), increased by 18.01% and 5.65% for engine oil and crude oil. While that was decreased from 37.26 and 31.96 g g(-1) to 33.18 and 30.48 g g(-1) for diesel oil and gasoline, decreased by 10.95% and 4.63% respectively. The average recovery ratios were 77.07%, 78.83%, 85.34% and 88.71%, and the average regeneration ratios were 76.01%, 87.12%, 86.39% and 85.31%. Finally, the experiment to remove heavy oil on surface water easily and conveniently with MEG was simulated. (C) 2010 Elsevier B.V. All rights reserved.