No abstract

An efficient lignocellulosic biomass pre-treatment is a crucial step for the valorization of these kind of raw materials. Lignocellulosic biomass is a potentially valuable resource for transformation into biofuels and bio-based products. The use of ionic liquids as media for the biomass pre-treatment is an alternative method that follows the green chemistry concept. This work proposes a new methodology for wheat straw pre-treatment with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([emim][OAc]), which allowed the production of cellulose, hemicellulose and lignin-rich fractions in a rapid and simple three-step fractionation process. Various temperatures (80-140 uC) and processing times (2-18 h) of the pretreatment were studied. The quantitative and qualitative analysis of each lignocellulosic biomass fraction was determined by FTIR measurements. The glucan content in recovered cellulose-rich fractions was investigated by enzymatic hydrolysis. The cellulose recovery dependence on the pre-treatment conditions was ascertained through regression analysis. The optimal result for the recovery of the cellulose-rich fraction was obtained at 140 uC during 6 h achieving 37.1% (w/w) of the initial biomass loading. For the same conditions, optimal results were also produced regarding the amount of glucan present (81.1% w/ w biomass ) in cellulose-rich fractions, the carbohydrate enrichment in the hemicellulose fraction (96% wt) and the purity of lignin (97% wt). The recovery of IL was performed after each pre-treatment and the obtained yields were up to 86% (w/w). The recovered ILs were analyzed by 13 C and 1 H NMR. The presence of value-added phenolic compounds in the recovered ILs was analyzed by capillary electrophoresis. Vanillin and its derivatives, as well as other lignin-based products, were identified.

h i g h l i g h t sA physical air-entraining method has been reported. The properties of high porosity cement-based foam materials have been investigated. Influence of water-cement ratio and HPMC on material properties has been analyzed. Pore structure formation mechanism has been clarified. a b s t r a c tHigh porosity cement-based foam materials were prepared through physical air-entraining method and the pore structure and the properties of materials were characterized. The results show that water-cement ratio and Hydroxypropyl Methyl Cellulose (HPMC) content have crucial influence on material properties. When the water-cement ratio was 0.9 and the content of HPMC was 0.4%, the cement-based foam material with the porosity of 94.33% and thermal conductivity value of 0.049 W/(m K) could be obtained. The formation mechanism of pore structure was analyzed that water-cement ratio and HPMC content affect the bubble film toughness which influence on material properties.