Oil spill sorption capacity of raw and thermally modified orange peel waste

Oil spill cases in the river Nile have been reported in the recent decade. Orange peel is a major waste of the food processing industry in Egypt, one of the six largest orange peel producers of the world. The purpose of the current work was to evaluate the oil sorption capacity of dried raw orange peel waste (OP) and thermally modified (300 °C and 500 °C) orange peel waste (TMOP). The effect of oil type, sorption time, particle size and reusability on the oil uptake of raw dried orange peel was assessed. Results have indicated that the oil sorption capacity of OP ranged between 3 and 5 g/g at 25 °C, while its water uptake was found to be below 1 g/g, making the selectivity of OP to oil relatively higher than other bio-sorbents. Orange peel could not be used for more than 5 oil sorption cycles, since the oleophilic nature of the peel surface was lost during the regeneration process. Compared to OP, limited percent increase in oil sorption capacity (18–40%) was observed after the thermal modification of orange peel. However, the water uptake of the TMOP is significantly higher than OP. Based on the liquid retention model data fit; the TMOP had better oil retention characteristics than the dried orange peel. According to the results presented, dried orange peel waste is a potentially cheap efficient oleophilic oil spill sorbent that losses its inherent oil selectivity after carbonization.