Hydrotropic Fractionation of Birch Wood into Cellulose and Lignin: A New Step Towards Green Biorefinery

Abstract

Hydrotropic treatment is an attractive process that uses water-soluble and environmentally friendly chemicals. Currently, this method is practically unexploited on a large scale due to the long treatment times required. In this study, the hydrotropic process was modified by the addition of hydrogen peroxide, formic acid, or both. The modified treatments were more selective than the reference, and the pulps obtained using the modified treatments had lower lignin contents. After bleaching, the resultant pulps were comparable to dissolving pulps with respect to the content of hemicelluloses and viscosity. Cellulose solutions were successfully obtained in a 7% NaOH/12% urea aqueous solvent after pretreating the bleached pulp with a HCl/EtOH mixture. Hydrotropic lignin was recovered from the spent solution by precipitation in water. The lignin had very low contents of carbohydrates and sulphur. The preliminary results show that a hydrotropic process can be used for such biorefinery applications as fractionation of fibres, cellulose polymer, and lignin from birch wood. The green cellulose and lignin biopolymers can potentially be used for shaping biomaterials or production of biobased chemicals.

Sequential fractionation of the lignocellulosic components in hardwood based on steam explosion and hydrotropic extraction

“…These include organosolv, alkali treatments, deep eutectic solvents, ionic liquids, and hydrotropic extraction (HEX) [23–25]. HEX has gained increasing attention as a green biorefinery technology, due to its efficient delignification of woody [26, 27] and non-woody biomass [28–30], its neutral pH conditions, the relative ease with which sulfur-free lignin is recovered, and the possibility of reusing the hydrotrope [31, 32].…”

Topochemistry of Environmentally Friendly Pretreatments To Enhance Enzymatic Hydrolysis of Sugar Cane Bagasse to Fermentable Sugar

“…Hydrotropic treatment has shown certain potential to be a cost-effective method. 14,15 The distribution of lignin on the surface of biomass materials has shown to directly influence the enzyme hydrolysis efficiency. 16 XPS and ToF-SIMS are surface sensitive techniques and able to supply the surface chemical composition and image the distribution of surface components in biomass and biomaterials.…”

Carbon Fiber from Biomass

“…Hydrotropic pulping is a process that uses concentrated aqueous solutions of hydrotropic agents (salts that, at high concentration, considerably improve the aqueous solubility of poorly soluble substances) at elevated temperatures (Gabov et al 2014). This process was extensively studied from the 1950s through 1980s as an alternative to traditional sulfite and kraft methods (Gabov et al 2013). Some of the advantages listed for this process include higher cellulose yield, lower capital costs, heat savings, and simplicity of the process in comparison to kraft pulping (Willför and Gustafsson 2010).…”