Physicochemical and sorption characteristics of poplar seed fiber as a natural oil sorbent

Oil spills have become a global concern due to their environmental and economic impact. Various methods, including the use of fibers as sorbents, have been developed for oil spill concern. Poplar seed fiber is a plant biomass that has the potential of being used as low-cost sorbent. In this study, the physicochemical and sorption characteristics of poplar seed fiber as an oil sorbent was evaluated. Fourier transform infrared and scanning electron microscopy analyses showed that poplar seed fiber was a lignocellulosic material with smooth surface and hollow lumen. Oil sorption tests showed that loose poplar seed fibers could absorb 53.74 g/g of diesel oil, 65.85 g/g of motor oil and 67.97 g/g of vegetable oil, which were higher than that of kapok and cotton fiber. The availability of void fraction inside the fiber assembly coupled with hollow fiber structure and hydrophobicity/oleophilicity of poplar seed fiber were the main contributing factors. Moreover, the oil sorption kinetics of poplar seed fiber, including the effect of packing density of fiber assembly, oil types on sorption capacity and rate, was analyzed by a wicking method. Results illustrated that the oil sorption capacity was closely related to the packing density of fiber assembly, with an apparent decrease when the packing density changed from 0.05 g/cm3 to 0.09 g/cm3. For sorption rate, the highest oil sorption coefficients were observed for diesel oil, of 0.36 g2/s, 0.32 g2/s and 0.30 g2/s at the packing densities of 0.05 g/cm3, 0.07 g/cm3 and 0.09 g/cm3, respectively, which were about 10 times higher than that of vegetable oil and 70 times higher than that of motor oil.