Investigations on the kinetics and thermodynamics of dilute acid hydrolysis of Parthenium hysterophorus L. substrate

Parthenium hysterophorus L. commonly known as parthenium weed, is one of the seven obnoxious weed in the world. Being a lignocellulosic biomass, with a composition (w/w) of cellulose: 27.8%, hemicellulose: 21.01% and lignin: 13.9%; as analyzed in the present work, it may be considered as the potential source of fuel ethanol production through pretreatment, saccharification and fermentation route. Batch hydrolysis of P. Hysterophorus L. with 1-5% sulfuric acid at a temperature range of 150-210 °C for 4-30 min treatment time and 2-6 h soaking period has been conducted to study the xylose yield. It is realized through the kinetic plots and analysis of various parameters that the process undergoes through first order kinetics and consequently follows Arrhenius law. It has also been understood that the reaction rate, the activation energy and the frequency factor of Arrhenius equation as well as all other related thermodynamic parameters depend largely on the treatment temperature during hydrolysis, the concentration of acid medium used and the soaking period of parthenium substrate before the actual hydrolysis reaction. The present investigation demonstrated that maximum xylose yield was 46.1% of original hemicelluloses present in the biomass under the process parameters considered, where higher treatment temperature, higher concentration of acid medium and higher soaking time favors the formation of stable depolymerised products.