Optimizing the conditions of deep eutectic solvents pretreatment for the production of bioethanol from Water hyacinth using Response Surface Methodology (RSM)

¹ Biorefinery and Process Automation Engineering Center, Department of Chemical Engineering and Management, The Sirindhorn International Thai-German Graduate School of Engineering, King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand
² Faculty of Chemistry, Aalen University, Aalen, Germany

^* Corresponding author: suksun.a@tggs.kmutnb.ac.th

Abstract

Water hyacinth reproduces rapidly, causing numerous issues across various sectors, including irrigation, agriculture, and invasion to native plant species and ecosystems. As a lignocellulosic biomass, water hyacinth holds potential as a raw material in chemical and biotechnological applications. However, its resistance to enzymatic breakdown during hydrolysis necessitates pretreatment to enable the efficient production of bioproducts from its components. This study aimed to determine the optimal Deep Eutectic Solvent (DES) pretreatment conditions for water hyacinth using the Box-Behnken design under the Response Surface Methodology (RSM) in order to maximize the sugar recovery rate. The DES pretreatment conditions, using a mixture of choline chloride and monoethanolamine (ChCl:MEA) in a 1:4 molar ratio, were optimized by varying the solid-to-liquid ratio (1:5 to 1:15, w/w), temperature (90–130 °C), and reaction time (60–240 min). The RSM model estimated the optimal pretreatment conditions to be a solid-to-liquid ratio of 1:9.58 (w/w) at 90 °C for 60 min, resulting in a maximum sugar recovery rate of 44.22%. The impact of pretreatment on chemical structure, as revealed by Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analyses, confirmed the efficiency of the DES pretreatment (ChCl:MEA). Therefore, this study highlights the potential of water hyacinth as a source for producing value-added compounds..