Understanding the impact of different pretreatment methods on the conversion of Casuarina equisetifolia biomass to 5-hydroxymethylfurfural and their energy cost assessment

Abstract

The objective of this study was to compare the relative efficiencies of physical, chemical, and biological strategies in saccharification of the Casuarina equisetifolia biomass and to employ the so-derived sugars to synthesize furanic compound, namely 5-hydroxymethylfurfural catalytically. Alkali and acid treatments yielded 47.48% and 25.12% of sugars, whereas microwave and ultrasound treatment yielded 5.67% and 1.83% of sugars, respectively. Enzymatic treatment yielded 48.46% of sugars, whereas fungal treatment yielded 1.76% of sugars. The feasibility of these processes towards the industrial application was pondered by energy-cost analysis. Amongst the treatment technology, alkaline treatment and acid treatment accounted for 0.83 and 0.93 USD/kg for the cost-effective conversion of biomass into sugar syrup, respectively. Henceforth, for the dehydration of sugars, alkaline treatment was selected as the best method for the conversion to furanic compounds with silica microspheres as catalysts, producing a 21.9% yield of 5-hydroxymethylfurfural from the initial biomass with optimum process parameters of 110 °C, 25 min, with catalyst loading of 1.5:200 (w/v)). • Saccharification of Casuarina biomass through various strategies were explored. • Energy-cost analysis for the conversion of biomass into sugar syrup was performed. • Amongst, the alkaline treatment was chosen to produce HMF from sugar syrup. • Chemical transformation of Casuarina biomass to HMF with 21.9% yield was reported.