Higher heating value, exergy, pyrolysis kinetics and thermodynamic analysis of ultrasound-assisted deep eutectic solvent pretreated watermelon rind biomass.

The higher heating value (HHV) and exergy of ultrasound-assisted deep eutectic solvent pretreated watermelon rind (WMR) biomass were investigated. Thereafter, the co-pyrolysis of the WMR biomass and coal blends was studied. The pyrolysis kinetics and thermodynamic parameters of the WMR-coal blends were determined using four isoconversional models (Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Friedman and Starink). The HHVs of the pretreated WMR ranged between 12.73 and 19.28 MJ/kg, while the exergy value for the raw and pretreated WMR were 16.08 and 21.55 MJ/kg, respectively. The lower heating value related exergy had the greatest influence on the overall exergy of the WMR. The values of the pre-exponential factor showed variations in wide range, and the change in entropy of the system displayed both negative and positive entropies. The activation energy and enthalpy varied directly with the amount of coal in the blends. Amongst the isoconversional model methods, Friedman model was the best predictor of the kinetic parameters.