Process optimization for the pretreatment of rice husk with deep eutectic solvent for efficient sugar production

ABSTRACT

Deep eutectic solvent (DES) has been identified as a potential green solvent in biomass processing. In the present investigation, a deep eutectic solvent i.e. choline chloride: urea (ChCl/U) was synthesized and employed to pretreat rice husks. Plackett- Burman response surface methodology was used to optimize the factors which are DES molar ratio, residence time, temperature, and biomass concentration. A total of 11 experimental conditions were evaluated and the highest amount of reducing sugar was obtained when 2 g rice husk was pretreated with 1:2 ChCl/U at 80°C for 6 h i.e. 0.67 ± 0.05 mg/mL. Furthermore, scanning electron microscopy (SEM), Fourier transforms infrared (FTIR), and X-ray diffraction (XRD) studies were used to characterize the structural and compositional changes in which DES demonstrates a great performance in the pretreatment of rice husk by eliminating amorphous lignin and hemicellulose content. Therefore, the facile process used in this study has the potential to be used on a massive scale to produce fermentable sugars and other compounds.

GRAPHICAL ABSTRACT

KEYWORDS:

• Pretreatment
• deep eutectic solvent
• response surface methodology
• Plackett-Burman design
• reducing sugar

Acknowledgement

The authors are grateful for the support provided by Central Instrumentation Facility (CIF) at Birla Institute of Technology Mesra in Ranchi, Jharkhand.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.