Facile, cost-effective and mechanically stable graphene-melamine sponge for efficient oil/water separation with enhanced recyclability

Abstract

Water contamination due to the accidental release of oil spills and the discharge of industrial wastes into water bodies is considered an ecological disaster worldwide. At present, it is imperative to establish a low-cost method for the efficient separation of oils from water to address this problem. Here, a facile and cost effective approach to fabricate graphene modified melamine sponge (MS) is reported (rGO-MS) for efficient oil/water separation. The pristine MS is dip coated with graphene oxide (GO) followed by post treatment with thiourea to obtain the final rGO-MS with enhanced hydrophobic behavior. The water contact angle of the prepared rGO-MS is about ∼145°, which signifies its excellent hydrophobic character. The prepared rGO-MS shows excellent mechanical integrity with no significant deformation in its shape after applying load on it for 500 cycles. Only 10% of deformation occurred after 100 cycles of the pressing-releasing cycle by hand. The rGO-MS shows excellent absorption capacity for various oils such as soybean oil, kerosene, petrol, diesel, mustard oil and organic solvents such as acetone, ethanol, chloroform, toluene and DMF (Dimethylformamide). The rGO-MS has an absorption capacity in the range of ∼ 79–149 g/g, with enhanced recyclability up to 20 numbers of cycles for various oils and organic solvents. Moreover, the sponge shows high separation efficiency of 99.9% for kerosene, diesel and petrol oil. For soybean oil and mustard oil, the separation efficiency is about ∼97.0% and ∼95.4% respectively. The use of very less expensive material with ease of fabrication technique will lead to the large scale production of the rGO-MS, which will help in the efficient oil/water separation process very economically.