Kinetics and Thermodynamics Properties of Glucose Production from Pineapple and Pawpaw Peels by Acid Hydrolysis

Abstract

The production of value-added fuels and chemicals from renewable non-fossil carbon, such as organic wastes and biomasses offers advantages over the fossil-based products, with potential economic and environmental solution. In this study, the kinetics and thermodynamic properties of acid (1M H2SO4) hydrolysis of isolated cellulose from two agricultural wastes: pineapple and pawpaw peels to glucose were studied. The effect of acid concentration (1.0 – 3.5 M), temperature (60 – 90 oC) and hydrolysis time (0- 140 min) on cellulose hydrolysis were investigated. The cellulose isolates and the hydrolyzed glucose were characterized with Fourier Transform Infrared (FT-IR) spectrophotometer. The glucose yields increased with increasing acid concentration over the first 60 minutes, but decreases with increasing temperature. The data obtained fitted to the pseudo-first order kinetic model and the estimated activation energies (from Arrhenius model) were10.05 KJ/mole and 56.05 KJ/mole for the conversion process of pawpaw and pineapple peels based cellulose respectively. The positive enthalpy indicates the endothermic nature of the hydrolysis processes, while the entropy (ΔS) values suggested a more chaotic breakage of β (1→ 4) linkage of cellulose isolated from pawpaw peels for its conversion to glucose unit. This was further confirmed by FTIR results. The optimum condition for the 1M H2SO4 hydrolysis of cellulose to glucose for the studied peels wastes samples was 60 oC within 1 hour of hydrolysis time.Keywords: Acid hydrolysis; Agricultural wastes; cellulose; glucose; kinetics; thermodynamics