An eco-friendly scheme to eliminate silica problems during bamboo biomass fractionation

In this study, an eco-friendly scheme to resolve the silica associated challenges encountered in processing bamboo for biorefineries was evaluated. Bamboo chips were pretreated with sodium hydroxide (NaOH) at low temperature to completely extract silica and partially extract hemicelluloses for follow up conventional kraft pulping or bioethanol production. Silica and hemicellulose in the alkaline pre-extraction liquor (APEL) were sequentially isolated through carbon dioxide (CO2) and ethanol precipitation. High purity (> 99.8%) amorphous silica particles were recovered by carbonating the effluent at 60 degrees C to a pH of 8.2 with CO2. The CO2 adsorption capacity of the APEL was determined to be 7.15 g CO2 per liter. After recovering more than 96% of available silica in the APEL, hemicellulose in the CO2-treated liquor was subsequently separated. This study demonstrated the feasibility of preextraction and recovery of silica and hemicellulose to alleviate the silica challenges, thereby allowing to expand bamboo as a feedstock for industrial processes.