Polyacrylonitrile/natural loofah sponge with spider web structure as a novel platform for enhanced oil adsorption

Three-dimensional, inexpensive and environmentally friendly adsorbent materials were urgently in demand for the absorption of organic compounds. In this study, the 3D ultralight sponge was assembled from fragmented electrospun nanofibers of polyacrylonitrile (PAN) and natural loofah. The PAN nanofibers and loofah short fibers were dispersed in an aqueous solution using polyvinyl alcohol (PVA) as the adhesive, and then formed the 3D ultralight sponge by freeze-drying technology. By adjusting the content of loofah, a kind of spider web structure which was beneficial to enhance oil adsorption was developed arising from polymers dissolution and reconstruction. At the same time, the loofah was integrated with the PAN by -OH···N≡C- hydrogen bonds to stabilize the structure. Finally, due to the high porosity (99.3%), low density (7.63 kg/m³) and unique spider web structure, our prepared PAN/loofah sponges could absorb organic compounds up to 177 times of their own weight. Hence, the developed PAN/loofah sponge as an environmentally friendly adsorbent would be promising in wastewater treatment.