Optimization of oxidation time of Kahatagaha vein graphite and reduction time of microwave assisted hydrothermal reduction of Kahatagaha graphene oxide

Abstract

The present study was aimed to obtain the optimum yield of graphene oxide (GO) from Kahatagaha graphite by optimizing oxidation time, and to effectively utilize hydrothermal microwave irradiation technique to produce high quality reduced graphene oxide (rGO) with the optimum level of reduction from Kahatagaha graphene oxide. Kahatagaha vein graphite was specifically selected for the study due to its remarkable morphological, structural, compositional and carbon isotropic variations from the other types of graphite. Oxidation time of Kahatagaha graphite was optimized and subsequently, microwave irradiation time was optimized to obtain maximumly reduced graphene oxide from the synthesized GO. XRD, SEM, FTIR and gravimetric analyses were employed to characterize the synthesized GO and rGO. The optimized oxidation time for the complete conversion of Kahatagaha graphite to GO was 5 hours that resulted in a yield of 170 % (w/w) with respect to the amount of graphite used. This level of yield would be highly beneficial for commercial productions of GO. The maximum level reduction of GO (production of rGO) was achieved in 20 minutes of microwave irradiation at 160 ºC with the microwave power of 500 W. Microwave-assisted hydrothermal reduction of graphene oxide is highly beneficial in term of energy consumption (low temperature and short processing time) and eco-friendliness (no solvents involved).