The fitting kinetic evaluation during co-pyrolysis of coal and water hyacinth (Eichhornia crassipes) to explore its potential for energy

The pyrolysis characteristics and kinetic parameters of coal and water hyacinth blend have been investigated by using thermogravimetric analysis. Those of pure coal and pure water hyacinth were also each studied as a comparison. The coal sample was taken from a Sub-district of Gunung Panjang, Berau, East Kalimantan, Indonesia. The as-received sample was ground to be a mesh size of 60. The sample of water hyacinth originated from Dams of Selorejo and Sengguruh, district of Malang, Indonesia. The raw material was cleaned with water and subsequently cut and dried at the temperature of around 85 °C for 6 hours. The dried biomass was then crushed and sieved at a size of 60 mesh as well. The blended fuel was composed of coal and water hyacinth in a mass ratio of 40:60 (wt%). The thermogravimetric experiment was performed for the coal, the water hyacinth, and their blend under the instrumentality of thermal analyzer at a single heating rate of 40 °C/min. The sample was heated up from 27 to 1000 °C with a nitrogen flow rate of 100 ml/min. Thermogravimetric (TG) and derivative thermogravimetric (DTG) curves were obtained. The kinetic evaluation was performed under the fitting method of Coats-Redfern. The results indicated that three stages of decomposition process were encountered during thermal degradation of the individual samples of coal and water hyacinth, as well as their blend. The addition of 60% water hyacinth to the coal provoked the thermal degradation toward the lesser temperature and forced the increase of maximum mass loss rate. The activation energy went to decrease together with the increasing of water hyacinth fraction, i.e., 84.02, 66.72, and 44.45 kJ/mol for respectively the coal, blended fuel, and water hyacinth. These results could be valuable in designing and developing of the reactor of the thermal conversion system on an industrial scale.