Statistical optimization for alkali pretreatment conditions of narrow-leaf cattail by response surface methodology

Response surface methodology with central composite design was applied to optimize alkali pretreatment of narrow-leafcattail (Typha angustifolia). Joint effects of three independent variables; NaOH concentration (1-5%), temperature (60-100 ºC),and reaction time (30-150 min), were investigated to evaluate the increase in and the improvement of cellulosic componentscontained in the raw material after pretreatment. The combined optimum condition based on the cellulosic content obtainedfrom this study is: a concentration of 5% NaOH, a reaction time of 120 min, and a temperature of 100 ºC. This result has beenanalyzed employing ANOVA with a second order polynomial equation. The model was found to be significant and was able topredict accurately the response of strength at less than 5% error. Under this combined optimal condition, the desirable cellulosic content in the sample increased from 38.5 to 68.3%, while the unfavorable hemicellulosic content decreased from 37.6 to7.3%

Pretreatment and enzymatic hydrolysis of lignocellulosic biomass for reducing sugar production

Conversion of lignocellulosic biomass into reducing sugar has contributed to an alternative use of lignocellulose source, especially in the production of value-added products such as amino acids, biofuels, and vitamins. In the bioconversion process, pretreatment of lignocellulosic biomass is important to enhance the accessibility of enzyme hydrolysis, thus increasing the yield of reducing sugar. Lignocellulosic biomass has a very complex arrangement of structure that needs a proper study in pretreatment and enzymatic hydrolysis process to obtain an optimum yield of reducing sugar. This chapter discusses chemical and enzymatic pretreatment methods that are commonly applied to effectively modify the chemical structures of lignocellulosic biomass. Acid pretreatment using dilute sulfuric acid (H2SO4) is the most commonly employed for chemical pretreatment while sodium hydroxide (NaOH) is the most commonly applied for alkaline pretreatment because of its ability to delignify biomass. Then, enzymatic hydrolysis of lignocellulosic biomass for the production of reducing sugar is discussed in detail. The kinetics and optimization of hydrolysis which are the key parameters that determine the yields of reducing sugar are also presented. The right pretreatment method combined with an efficient hydrolysis process will ensure successful conversion of lignocellulosic biomass into reducing sugar, thus providing a sustainable production of reducing sugar from biomass for various applications