Recovery of Xylan for the production of xylose from Meranti Wood Sawdust (MWS) by two stage pretreatment process / Suharti Md Ishak

Faculty of Chemical & Natural Resources Engineering

Thesis (Master of Engineering (Bioprocess)) -- Universiti Malaysia Pahang – 2015

Bibliography : p. 107-118

Meranti wood sawdust (MWS) is a lignocellulosic material that contains three main components of polymer, which are cellulose, hemicellulose and lignin. It consists of more than 29% xylan, which is made up from the pentose sugar xylose. This study was carried out to produce xylose from Meranti wood sawdust (MWS) using two stage pretreatment processes; physical (autohydrolysis process) and biological (enzymatic process). Following that, comparison was done in order to determine between the two stage pretreatment process and acid hydrolysis which is the best method for xylose production. Optimization of MWS autohydrolysis was conducted with statistical design including one factor at a time (OFAT) method for maximum xylan recovery. The results of the OFAT study indicate that residence time, temperature and liquid solid ratio (LSR) are the major factors for improving xylan recovery. The factors were further optimized by response surface methodology (RSM), and the optimum values obtained for temperature, residence time and LSR were 140 ºC, 15 minutes and 8 g/g, respectively. Under these conditions, 19.34 % of xylan was recovered. Xylanase from Trichoderma viride was used in the enzymatic hydrolysis process to enhance the production of xylose from xylan. Under selected operational conditions (pH 5, temperature at 37 oC, 150 rpm for 12 hr), maximum xylose and arabinose were recovered at 13.60 g/L and 9.78 g/L respectively. During acid hydrolysis, sulfuric acid was used to hydrolyse xylose from MWS at operational condition 3.24% w/w H2SO4, 40 min reaction time and 121 ºC temperature, giving maximum xylose, glucose and arabinose production of 14.13 g/L, 4.776 g/L and 2.48 g/L, respectively. The byproducts that obtained from acid hydrolysis were furfural and acetic acid with 2.64 g/L and 3.91 g/L, respectively. The two stage pretreatment process was successful in obtaining purified xylose without producing any byproduct. The results obtained from the present study clearly demonstrate the potential of both methods for the production of xylose, which can serve as a functional food ingredient such as xylitol, from MWS