New dry technology of environmentally friendly biomass refinery: glucose yield and energy efficiency

Abstract

BackgroundToday, most of pretreatments used to convert biomass into biofuels are based on expensive chemical processes that not only do not keep the major components intact after separation, but also consume water and generate many effluents. However, dry fractionation technologies are an important step for future biomass biorefineries since they do not require chemicals and do not generate wastewater. Therefore, the aim of the present study was to evaluate the feasibility of using milling combined with an electrostatic fractionation (ES) of wheat straw (WS) as a way to separate fractions that are enriched in cellulose and more enzymatically accessible, from recalcitrant tissues enriched in lignin-hemicelluloses, in order to produce biofuels.ResultsAfter milling, WS particles are introduced into a tribo-electrostatic separator, where they are positively or negatively charged by tribo-electricity. Then they are introduced into a separation cell comprising two electrodes (+ and –). The negative electrode attracts the positively charged particles and the positive electrode attracts the negatively charged particles. Results show that amorphous cellulose rich particles were clearly more abundant in positively charged fractions (F+), and loose crystalline cellulose, lignin-xylan and ash-containing material were more abundant in negatively charged fractions (F–). Indeed, positively charged fractions (F+) are more accessible upon enzymatic hydrolysis, which resulted, for example, in sugars yield of 43.5% glucose (254 gKg−1) for F2B + compared to 25.2% (103 gKg-1) for F2A–, and 26.3% (130 gKg−1) for unfractionated WS F0, respectively.ConclusionsThe combination strategy of milling and ES fractionation could improve the economic feasibility by low energy consumption (10.5 WhKg−1) and it produces reactive lignocelluloses particles with different physicochemical structures, which can be converted easily into biofuels and biomaterials without generating toxic effluents.

The PHENOLEO project or how to separate and add-value to phenolic compounds present in rapeseed and sunflower meals

“…Indeed, classical procedures for the recovery of such molecules are based solid-liquid extraction with organic (and sometimes toxic) solvents (Naczk and Shahidi, 2004;Stalikas, 2007;Pérez-Serradilla and Luque de Castro, 2011). However, these methods generally do not leave intact the other components of the raw materials, they are expensive in energy, reagents and solvents, and require the treatment of effluents (Barakat and Rouau, 2014). Consequently, various extraction techniques were studied for the separation of simple phenolic compounds from the different meals, including novel dry fractionation processes or solvents assisted extractions with hydro-alcoholic mixtures.…”

Chemical- and Solvent-Free Mechanophysical Fractionation of Biomass Induced by Tribo-Electrostatic Charging: Separation of Proteins and Lignin

“…Recently, ultrafine milling (UFM) coupled to tribo-electrostatic separation (tES) have emerged as eco-friendly technologies for plant and agro-resource material fractionation under dry conditions [18][19][20][21] . Electrostatic separation is significantly more energy efficient and is able to produce enriched fractions with retained (native) functionality.…”

Conversion of Lignocellulosic Biomass to Reducing Sugars in High Pressure and Supercritical Fluids: Greener Alternative for Biorefining of Renewables

“…[ 69 ] It is reported that particles smaller than 1 mm have high surface area and a significant influence on penetration of reaction media into the polysaccharides during the pretreatment of LC biomass, but particles smaller than 0.4 mm did not result in further improvement in sugar yield. [ 77,78 ]…”