Liquid-Phase Exfoliation of Graphite Using the Serum from Skim Natural Rubber Latex

The green exfoliation of graphite by using the serum from skim natural rubber latex together with ultrasonication was investigated. The rubber particles were coagulated with 0.7% w/v cationic polyacrylamides solution and the remaining serum containing ammonia was used as an exfoliating medium. The suspension with 25 mg graphite/ml serum was sonicated for 2 h at 29-53 degrees C in an ultrasonic bath at 40 kHz and was left standing for 2 h at room temperature. The top part was centrifuged at 2000 rpm for 30 min and then the top section of this was centrifuged at 10500 rpm for 30 min to collect the solid. This process was repeated 2-3 times using the bottom part of the sedimentation. The yield of exfoliated graphite sample from each exfoliation process ranged from 0.20-0.35% and showed quality of multilayer graphene based on Raman spectroscopy results, which was comparable to the commercial graphene. The samples were also checked with scanning electron microscope and underwent some experiments, including sedimentation and methylene blue adsorption. It was found that the high-quality exfoliated sample showed better dispersion in water, resulting in 99% turbidity after 20-min sedimentation and yielded higher adsorption capacity than that of the commercial graphene.