Nanocarbons from acid pretreated waste coffee grounds using microwave radiation

This study investigates the use of microwave radiation to produce nanocarbons from Waste Coffee Grounds (WCG). It is first step to demonstrate the potential of integrating the microwave power to conventional methods of carbonaceous materials and nanocarbons production, aiming to overcome their high production cost. The process parameters and interactions investigated were: microwave radiation power (W), temperature (°C) and residence time (min). Results obtained from the lab-scale experiments indicated the optimum conditions for maximizing the nanocarbons yield (wt%) from the H₂SO₄ acid pretreated WCG at 200 °C, 850 for 60 min resulting in a 87.6 wt% char yield which ranged between the average size of 100–140 nm and lower. Moreover, the optimum conditions to achieve the maximum yield of nanocarbons (wt%) where: same temperature (200 °C), lower microwave power (650 W) and residence time (45 min). Then a yield of 60 wt% nanocarbons of average sizes 60 nm were produced, indicating the potential of this method to produce value-added biomaterials (spherical shaped nanocarbons) applicable for future scientific breakthroughs