Thermo-chemical pretreatment of wood biomass from giant sensitive plant (Mimosa pigra L.) for levulinic acid production

Levulinic acid is a C5-chemical with a ketone and a carboxylic group which can used to produce value-added product including fuel additives and chemical intermediates. It can be produced from cellulose, a major component of lignocellulosic biomass. In order to obtain cellulose from lignocellulosic biomass, pretreatment process is employed to remove lignin and hemicellulose. Thermo-chemical pretreatment have been widely used because it could effectively remove lignin and hemicellulose. Wood biomass from giant sensitive plant (Mimosa pigra L.) contained high cellulose content which can be utilized as a substrate for levulinic acid production. So, the aims of this study are to investigate the feasibility of thermo-chemical pretreatment (microwave-assisted chemical and autoclave-assisted chemical pretreatment) from giant sensitive plant and to produce levulinic acid from pretreated wood biomass. The wood biomass was pretreated via 2 stages. The first stage, wood biomass was pretreated by using microwave (at 300 W for 10 min) or autoclave (at 121 ºC for 1 h), combined with 5%, 10%, 15% NaOH (w/v) or 0.5%, 1%, 1.5% H₂SO₄ (w/v). The second stage, the pretreated wood biomass was bleached with 2% H₂O₂ at 70 ºC for 2 h.  Afterwards, the pretreated wood biomass with the optimum condition was used to produce levulinic acid via hydrothermolysis process. The results revealed that the optimum conditions for the pretreatment was microwave combine with 10% NaOH by increasing cellulose content approximately 33%, and decreasing hemicellulose and lignin content approximately 58% and 11% respectively, which gave the highest levulinic acid yield at 6% (w/w).