Metallic nanoparticles roughened Calotropis gigantea fiber enables efficient It absorption of oils and organic solvents

Calotropis gigantea fiber (CGF) is the fruit fiber of C. procera, and belongs to a typical cellulosic fiber. This fiber has large lumens with thin walls and wax coating on its surface, and then shows the potential as one kind of promising oil sorbents for collecting oils and organic solvents for separation or recovery. To improve further its oil-absorbing performance, a facile method is proposed in this study to obtain the metallic nanoparticles roughened fiber by deposition of Ni or Cu nanoparticles onto the surfaces of CGF. The raw fiber and roughened fiber were well characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersion spectrum (EDS), and X-ray photoelectron spectroscopy (XPS), etc. The resulting fibers, marked as Ni-CGF and Cu-CGF, show a wonderful hydrophobicity and an outstanding oil absorption for a wide range of oils and organic solvents, with the oil-absorbing capacity of up to 120 g/g within a few seconds. In addition, the Ni-CGF and Cu-CGF exhibit excellent oil-water selectivity, rendering that they can quickly absorb the model oils without any water absorption when the fibers are contacted with the oil-water mixtures. After a 10-cycle test, the oil-absorbing capacity has no significant decrease, suggesting its excellent reusability. Owing to the characteristics of abundance, high efficiency and environmental compatibility, the roughened fibers will find more opportunities for removal of oils and organic solvents from wastewater in the future as a kind of efficient and environmentally friendly oil sorbents.