Corncob as a sorbent for crude oil and its lower fractions
This study reports oil sorption capacity, sorbed oil recoverability and sorbed oil retention of corncob and a standard: conventional synthetic sorbent used in the oil industry to clean oil spill. The result of the study shows that corncob has lesser oil sorption capacity and sorbed oil recoverability than the standard, but higher sorbed oil retention than the standard. Corncob sorbed per unit mass 3.30 ±0.49 g of crude oil, 2.90 ±0.99 g of diesel and 2.50 ±0.72 of kerosene, while, the standard sorbed per unit mass 11.50 ±0.54 g of crude oil, 10.35 ±0.77 g of diesel and 8.20 ±0.93 g of kerosene. Sorbed oil recovered from corncob and standard are 2.00 ± 0.55 g of crude oil, 1.90 ± 0. 83 g of diesel, 1.40 ±0.71 g of kerosene and 9.67 ±0.36 g of crude oil, 8.40 ±0.95 g of diesel, 6.50 ± 0.49 g of kerosene respectively. 1.25 ± 0.68 g (37 % of sorbed crude oil), 0.95 ± 0.33 g (32 % of sorbed diesel) and 1.05 ± 0.83 g (42 % of sorbed kerosene) were retained by a unit mass of corncob while 1.83 ± 0.33 g (15 % of sorbed crude oil), 1.94 ± 0.97g(19 % of sorbed diesel) and 1.70 ± 0.89 g (20 % of sorbed kerosene) were retained by a unit mass of the standard. Amount of water sorbed together with each sorbate onto corncob and synthetic sorbent is minimal; 14 ml (2.9 g) for corncob and 6 ml (1.2 g) for the standard. Adsorption isotherm and kinetic studies shows that the sorption process of crude oil, diesel and kerosene onto corncob is by Langmuir model, pseudo second order kinetics, intraparticle diffusion and liquid film diffusion mechanism.Corncob can be applied on land and aqueous environment in oil spill clean-up. Comparatively, corncob is not a very effective oil spill sorbent.
Key words: Corncob, crude oil, diesel, kerosene, oil sorption capacity, sorbed oil recoverability.