Production of Bioethanol from Macroalgae Cellulosic Residue Using Solid Acid Catalyst Pretreatment and Enzymatic Hydrolysis

I.S. Tan, K.T. Lee
Universiti Sains Malaysia, MY

Keywords: bioethanol, cation-exchange resin, macroalgae cellulosic residue

Summary:

The aim of this study is to investigate the technical feasibility of utilizing macroalgae cellulosic residue (MCR) that contains large amount of cellulosic materials and converting it into bioethanol, a promising alternative energy source. Production of bioethanol from MCR involves three main steps: pretreatment, enzymatic hydrolysis and fermentation. Attempt was made to present a novel environmentally friendly and economical method of pretreatment process that enhances enzymatic conversion of MCR to glucose by using strong acid cation-exchange resin as catalyst, Dowex (TM) Dr-G8. The pretreatment parameters studied are catalyst loading (0-6 % w/v), pretreatment time (15-60 min) and pretreatment temperature (110-140oC). The maximum yield of glucose reached 94.6% under the optimal condition of solid acid pretreatment (4% w/v, 45 min, 120oC) followed by enzymatic hydrolysis (45 FPU/g of cellulase, 50oC, pH 4.8, 48 h). The yield of glucose obtained after the pretreatment process was found far more superior than conventional pretreatment process using NaOH and H2SO4. The catalyst was separated and reused for six times, resulting to only a slight decrease in glucose yield. Subsequent simultaneous saccharification and fermentation (SSF) process gave an optimized bioethanol concentration of 14.1 g/L and yield of 81.5%.