Reduced graphene oxide-based superhydrophobic magnetic nanomaterial as high selective and recyclable sorbent for oil/organic solvent wastewater treatment

The oily wastewater treatment has become a serious global challenge to tackle environmental pollution from oil leak and spill disasters. In this study, a facile fabrication of a new recyclable reduced graphene oxide-based superhydrophobic magnetic nanomaterial is described for selective oil/organic solvent absorption from wastewater. First, synthesis and physicochemical characterizations of graphene oxide and RGO are performed. GO and RGO are obtained using the modified Hummers method from graphite and chemical reduction of GO, respectively. Second, magnetic MgFe2O4 nanoparticles (NPs) are obtained by sol–gel process and their structural/morphological characteristics are also determined. Finally, new superhydrophobic magnetic sponges, named PU/MgFe2O4/PDMS and PU/MgFe2O4/RGO/PDMS, are elaborated using polyurethane sponge, magnetic MgFe2O4 NPs, polydimethylsiloxane and with or without RGO through the immersion coating method. Studies of PU/MgFe2O4/PDMS and PU/MgFe2O4/RGO/PDMS sponges as sorbents have investigated and highlighted the positive impact of using RGO into the superhydrophobic magnetic sponge to enhance absorption capacity for oil and various organic solvents. PU/MgFe2O4/RGO/PDMS sponge shows i) excellent mechanical/superhydrophobic properties, ii) an ability to repel water whilst highly absorbing oil and organic liquids of various densities (i.e., absorption capacity of 12–36 g/g and separation efficiency up to 99.7%), iii) a reusability for oil and organic solvent removals for more than 20 cycles, and iv) an easy separation from water with a magnet. In conclusion, the new PU/MgFe2O4/RGO/PDMS sponge is a promising candidate for reusable sorbent for collecting oil and can be used also as hydrophobic filter due to its excellent mechanical properties.