Kinetics and genetic algorithm study of acid catalysed hydrolysis of water hyacinth biomass

Abstract

Industrialization has elevated our energy demand during the last century by many a folds, to deal with the rapid social growth. Non-renewable energy sources, like petroleum being the main source of energy, have become scarce due to their overuse and limited available reserve. Water hyacinth can be considered as a good source of lignocellulosic biomass. Cellulose and hemi-cellulose derived from water hyacinth via effective bioprocess can be converted to bioethanol. Production of liquid fuel from biomass can only be made economically viable and sustainable only if the de-polymerization of the recalcitrant hemi-cellulosic fraction of the biomass can be optimally utilized. The study aims to obtain an in-depth mechanistic understanding of the catalytic reaction involved in dilute sulphuric acid pre-treatment of water hyacinth biomass. Acid catalysed hemi-cellulose hydrolysis reaction kinetics in water hyacinth was studied based on a bi-phasic model. Arrhenius equation was used to study the kinetic modelling in a greater depth. A distinct relationship of soaking time of the biomass in the acid before hydrolysis on the activation energy and frequency factor was observed. A maximum xylose yield of 76.96% was predicted by the genetic algorithm based model for the optimum operating conditions; operating temperature (135.8 °C), concentration of sulphuric acid (5.6%), treatment time (17.45 min), and soaking time (3.99 h).