Characterization of Sunflower Waste Carbonization: Energy Balance and Water Holding Properties

This paper characterizes the carbonization process of biomass wastes, including sunflower husk pellets and sunflower sponge stalk pellets, at carbonization temperatures of 450 and 550 °C. These studies are important because of the reductions in wood resources for the preparation of barbecue charcoal, as well as agricultural benefits in terms of soil additives. In terms of energy balance, the obtained pyrolysis ensures the autothermal process. The heating characteristics of fixed bed showed that, due to the difference in bulk density, the bed temperature of the sunflower husk pellets reached 450 °C in 110 min, whereas the bed temperature of the sunflower stalk sponge reached the same temperature in 200 min. Additionally, the energy used for the sunflower husk carbonization increased from 2.9 kWh at 450 °C to 3.3 kWh at 550 °C, while the sunflower stalk sponge increased from 3.5 to 3.9 kWh. The combustion characteristics assessed using TGA showed that the carbonization of sunflower husk leads to obtained biochar with a higher combustion activity than biochar derived from sunflower stalk sponge. According to the experimental results, biochar from sunflower husk pellets has a higher water content capacity and water absorption rate than biochar from sunflower stalk sponge pellets.