Impact of pre-extraction on xylose recovery from two lignocellulosic agro-wastes

Abstract

A dilute acid hydrolysis of rice husk (RH), wheat straw (WS), and their extractive-free residues was investigated with the objective of recovering the highest yield of xylose while keeping at minimum its conversion into furfural. The hydrolysis conditions were determined for different concentrations of sulfuric acid and different reaction times at 121 °C. The pre-extraction with ethanol-water (1:1, v/v) was also examined as a parameter. Using response surface methodology, the optimum conditions for xylose production were identified as 1.8% of acid and 41.4 min of hydrolysis time for RH, while those for its counterpart EF-RH (extractives-free rice husks) were 1.0% acid concentration, for 60 min. The same conditions were also predicted for WS and its EF-WS. Under these conditions, the xylose yield was 79.6%, 82.8%, 94.3%, and 88.6% for RH, EF-RH, WS, and EF-RW, respectively. Under these conditions the minimal furfural yields obtained were 1.2% and 1.3% for RH and EF-RH, and 0.8% and 1.5%, for WS and EF-WS, respectively. These results suggested that the pre-extraction step before the acid hydrolysis affected, at least in part, the xylose recovery from RH, but it was not necessary for a better xylose yield of WS for its bioconversion into valuable bioproducts like xylitol.

Optimization of the Electrospray Process to Produce Lignin Nanoparticles for PLA-Based Food Packaging

“…The lignin (RHL) was then isolated from rice husk biomass using the organosolv process described by Koumba-Yoya and Stevanovic [20]. Prior to organosolv step, the rice husk underwent acid hydrolysis (a complementary study within the same project) leading to maximum xylose production while limiting its conversion to furfural using conditions optimized by Kasangana et al [21]. The isolated organosolv lignin (RHL) had a high purity of 96% (2% ash and 2% carbohydrate content), β-O-4 aryl ether as its major substructure (58.1%), followed by guaiacyl, syringyl, and p-hydroxyphenyl content of 77.4%, 12.9%, and 9.7%, respectively.…”