Fluorine-Free Sustainable Three-Dimensional Superhydrophobic and Superoleophilic Robust Foam for Efficient Oil/Water Separation
Monami Mukherjee, Surya Kanta Ghadei, Benadict Rakesh, Umapathi Balaji, R. Sakthivel, Kamatchi Jothiramalingam Sankaran
Abstract
The development of sustainable, environmentally friendly, and efficient materials for oil/water separation is the need of the hour. The utilization of renewable or waste resources to develop value-added materials poses as the key toward sustainability. This work reports the fabrication of an economical, salt-tolerant, superhydrophobic, and superoleophilic waste rice husk-derived silica (SiO 2 )/reduced graphene oxide (rGO)-coated polyurethane (PU) foam for effective oil/water separation. Herein, SiO 2 and graphene oxide (GO) are synthesized from rice husk by using precipitation and thermal exfoliation methods. A simple dip-coating method was carried out to coat the materials on PU foam, followed by a reduction process to form SiO 2 /rGO@PU foam. The adhesion of SiO 2 on rGO enhances the surface roughness and thus promotes superhydrophobic (water contact angle = 164°) and superoleophilic (oil contact angle = 0°) behaviors. The SiO 2 /rGO@PU foam exhibits excellent adsorption capacity of different oils as well as stability at extreme pH, ultraviolet irradiation, salt concentration, pressure, and humidity with a separation efficiency above 98%. The foam is used to separate a wide range of oil and water mixtures. Utilizing this foam, a device is fabricated, which demonstrated successfully the separation and recovery of crude oil from water. Therefore, the SiO 2 /rGO@PU foam has the potential to be a promising adsorbent for oil spill cleanup.