Model-free isoconversional methods to determine the intrinsic kinetics and thermodynamic parameters during pyrolysis of boiled banana peel: influence of inorganic species

Abstract

Raw banana peel was hydrolyzed to produce boiled banana peel (BBP) that exhibited enhanced volatile matter, calorific value; and lower ash content. BBP was analyzed for proximate, ultimate, TGA, DTG, SEM-EDX and FTIR. TGA and DTG curves exhibited variation in thermal lag at higher heating rates. XPS studies confirmed the dominance of inorganic species in BBP. The activation energy computed using isoconversional models increased with increasing conversion up to 60 %. Beyond that, activation energy suddenly decreased due to the influence of potassium, chlorine, and calcium containing compounds which lowered thermal stability of lignin which decomposed at a faster rate. The average activation energy (Eav) using isoconversional models such as KAS, Starink, FWO, Tang and Friedman are 457.75, 458.16, 468.01, 470.67, and 488.20 kJ/mol, respectively. Enthalpy, entropy, and Gibbs free energy were computed. Reaction mechanism during pyrolysis of BBP at various heating rates was predicted using Criado method (Z-master plots).