Capability of Thai Mission grass (Pennisetum polystachyon) as a new weedy lignocellulosic feedstock for production of monomeric sugar

•Two-stage pretreatment via microwave irradiation is much more effective.•Thai Mission grass has a great potential as a feedstock for monomeric sugar production.•40.9g of the total monomeric sugar yield per 100g of dried biomass was obtained. Mission grass (Pennisetum polystachyon) grown in Pakchong District, Nakornratchasima Province, Thailand, with high cellulose and hemicellulose contents were harvested to determine the fermentable monomeric sugars for bioethanol production by two-stage microwave/chemical pretreatment process. Microwave-assisted NaOH pretreatment effectively removed approximately 85% lignin content in Mission grass, using 3% (w/v) NaOH, 15:1 liquid-to-solid ratio (LSR) at 120°C temperatures for 10min. As a result, in the second stage, microwave-assisted H2SO4 pretreatment of an alkaline-pretreated Mission grass solid releasedan impressively high fermentable sugar content (34.3±1.3g per 100g of dried biomass), consisting mainly of 31.1±0.8g of glucose per 100g of dried biomass, using 1% (w/v) H2SO4, 15:1 LSR at 200°C temperature for a very short pretreatment time (5min). The total monomeric sugar yield obtained via two-stage microwave/chemical process was 40.9g per 100g of dried biomass.