Thermo-Kinetic Analysis of Corncob-Water Hyacinth Co-Pyrolysis for Synergistic Insights and Biochar Characteristics for Soil Amendment

The co-pyrolysis of corncob (CC) and water hyacinth (WH) was investigated to characterize their thermal decomposition behavior, kinetic properties, and resulting biochars. Thermogravimetric (TGA) and derivative thermogravimetric (DTG) analyses were conducted at heating rates of 5 and 20 °C min−1 for the individual feedstocks and their blends. Biochars from CC, WH, and CC50:WH50 were produced at 350 °C and characterized for physicochemical properties. At 5 °C min−1, apparent activation energies estimated using the Coats–Redfern method were 135.4, 73.2, 83.1, 96.4, and 103.6 kJ mol−1 for CC, WH, CC30:WH70, CC50:WH50, respectively. Experimental and theoretical thermogravimetric profiles were compared to assess deviations from additive behavior. Biochar yields ranged from 39.22% to 46.17%, while mean pH values ranged from 9.34 to 9.56. One-way analysis of variance indicated significant treatment differences in yield, electrical conductivity, total nitrogen, available phosphorus, cation exchange capacity, and bulk density, whereas pH differences were not significant. WH biochar exhibited the highest electrical conductivity, total nitrogen, and available phosphorus, while CC50:WH50 had the highest cation exchange capacity and bulk density. These findings show that feedstock composition influences thermal behavior and biochar properties.