Effect of Choline-Based Deep Eutectic Solvent Pretreatment on the Structure of Cellulose and Lignin in Bagasse

Abstract

Deep eutectic solvents (DESs) is a newly developed green solvent with low cost, easy preparation and regeneration. Because of its excellent solubility and swelling effect in lignocellulose, it has received widespread attention and recognition. In this study, choline-based deep eutectic solvents (DESs)—choline chloride-urea (CC-U), choline chloride-ethylene glycol (CC-EG), choline chloride-glycerol (CC-G), choline chloride-lactic acid (CC-LA), and choline chloride-oxalic acid (CC-OA)—were used to extract and separate bagasse. The effects of hydrogen bond donors on lignin separation and the fiber and lignin structure were investigated. All five DESs could dissolve lignin from bagasse; acidic DESs exhibited higher solubility than basic DESs. CC-OA effectively separated lignin and hemicellulose. CC-LA showed weaker lignin separation ability than CC-OA. CC-G, CC-EG, and CC-U were more inclined to selectively separate lignin than hemicellulose. The crystalline cellulose II structure was retained after DES pretreatment. Acidic DESs effectively improved the crystallinity of bagasse fiber; the crystallinities for CC-OA and CC-LA pretreatment were 62.26% and 61.65%, respectively. The lignin dissolved in DES was mainly syringyl lignin. The lignin dissolved in CC-U, CC-LA, and CC-OA contained a small amount of guaiacyl lignin.

Combining acid-based deep eutectic solvents and microwave irradiation for improved chestnut shell waste valorization

“…As mentioned above, the ability of acidic DESs to depolymerize and fractionate the lignin component of lignocellulosic biomass, as well of hemicellulose, is well known. [67][68][69][70][71] Although a literature comparison of the quantity of extracted biomolecules is of limited value on account of the different biomass sources, extraction protocols, and pretreatment carried out on the waste (for instance brulage or boiling), the here reported MWDA process using DES ChCloxalic acid dihydrate represents an appealing extraction system. This holds true both in terms of yield and TPC as well as for its innovative use of an alternative energy source.…”

Polymerizable Choline- and Imidazolium-Based Ionic Liquids Reinforced with Bacterial Cellulose for 3D-Printing

“…This makes them interesting for increasing sustainability in chemical technology. Due their capability to form hydrogen bond networks, DES have demonstrated outstanding ability to interact with polysaccharides [ 22 ] and they are being intensely studied as prospective plasticizers for chitosan [ 50 , 51 , 52 , 53 ], starch [ 54 ] and as media for treatment of chitin [ 55 , 56 , 57 ] or cellulose [ 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 ]. Additionally, using unsaturated acids such as acrylic or methacrylic acids as hydrogen bond donors [ 66 ] provides DES the ability to polymerize in a new green way for preparation of functional materials [ 67 ].…”

Degumming of Hemp Fibers Using Combined Microwave Energy and Deep Eutectic Solvent Treatment

“…Smink et al (Smink et al 2019) found that the addition of choline chloride in the DES made of lactic acid and choline chloride, accelerates the pulping process, meaning that a higher ber-DES ratio increases the lignin removal. Li et al (Li et al 2021) found that choline chloride as a hydrogen bond acceptor with the urea (hydrogen bond donor) is prone to cleave the lignin-carbohydrate linkages than the breakage of hemicellulose linkages.…”