Deep eutectic solvent delignification: Impact of initial lignin

BioResources ◽  
2017 ◽  
Vol 12 (4) ◽  
pp. 7301-7310
Author(s):  
Veronika Majová ◽  
Silvia Horanová ◽  
Andrea Škulcová ◽  
Jozef Šima ◽  
Michal Jablonský

This study aimed to resolve the issue of the lack of detailed understanding of the effect of initial lignin content in hardwood kraft pulps on pulp delignification by deep eutectic solvents. The authors used Kappa number of the concerned pulp, intrinsic viscosity, and selectivity and efficiency of delignification as the parameters of the effect. The pulp (50 g oven dry pulp) was treated with four different DESs systems based on choline chloride with lactic acid (1:9), oxalic acid (1:1), malic acid (1:1), and system alanine:lactic acid (1:9); the results were compared to those reached by oxygen delignification. The results showed that the pulp with a higher initial lignin content had a greater fraction of easily removed lignin fragments.

2021 ◽  
Vol 10 (1) ◽  
pp. 666-676
Author(s):  
Veronika Majová ◽  
Michal Jablonský ◽  
Marek Lelovský

Abstract The processing of lignocellulosic materials is very limited because of their low solubility in water and some organic solvents. Fifteen ternary deep eutectic solvents (DESs) were prepared and tested as solvents suitable for delignification of unbleached pulp. The selected ternary DESs are composed of quaternary ammonium salts and amino acids as hydrogen-bond acceptors, and organic acids and polyvalent alcohols as hydrogen bond donors, with molar ratios varying for the individual components. The delignification efficiency is significantly influenced by the degree of penetration of the solvent into the pulp fibre structure. Therefore, the density and viscosity analysis of individual solvents was performed. Unbleached beech pulp with initial kappa number 13.9 was treated with the prepared DESs. The kappa number indicates the residual lignin content or the bleachability of pulp. The efficiency of the solvents ranged from 1.4% to 28.1%. The most suitable for the pretreatment of fibres, based on lignin removal efficiency, were found to be three DESs, in the following order: malonic acid/choline chloride/1,3-propanediol (1:1:3) > choline chloride/acetamide/lactic acid (1:2:3) > choline chloride/urea/lactic acid (1:2:3).


BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3344-3355
Author(s):  
Hongyan Yang ◽  
Jinyan Lang ◽  
Junliang Lu ◽  
Ping Lan ◽  
Heng Zhang

The direct conversion of microcrystalline cellulose (MCC) degrading into 5-hydroxymethyl furfural (5-HMF) was studied using four synthetic deep eutectic solvents (DESs) as solvents and choosing four metal chlorides as catalysts. The factors that affected the yields of the products, such as the type of DESs, the type and dosage of catalysts, the ratio of DESs to MCC, and reaction temperature were researched. It was found that the DES synthesized from oxalic acid and choline chloride (O-DES) and SnCl4 showed the better performance. The highest 5-HMF and glucose yields of 11.0% and 22.0% were obtained, respectively, for a reaction carried out at 160 °C for 90 min in O-DES (the ratio of it to MCC was 25:1) using 1.42 wt% SnCl4 as the catalyst. As a new type of dissolution and catalysis system, the DESs were not only cheaper but also easy to obtain. Most importantly, the realization of the concept of green chemistry was achieved in this study.


Author(s):  
Viktoria Vorobyova ◽  
Margarita Skiba

Deep eutectic solvents (DESs) are a new class of solvents that can offset some of the primary drawbacks of typical solvents and ionic liquids. They are synthesized by simply mixing the components that interact with each other through hydrogen bonds, and form a eutectic mixture with a melting point much lower than each component individually. Deep eutectic solvents is usually liquid at temperatures below 100 °C. Thanks to these great advantages, deep eutectic solvents is attracting more and more attention in many areas of research. Very recently, great attention has been paid to new pioneering attempts aiming at deep eutectic solvents into the field of chemical engineering, including membrane science and technology. Even if just a same works have been currently reported in applying deep eutectic solvents in membranes, the consideration on this new type of solvents is continuously growing. New deep eutectic solvents based on choline chloride (ChCl)–lactic acid (1:2 M ratio) was obtained and its electrochemical characteristics was studied. The synthesis of deep eutectic solvents was confirmed by FA nuclear magnetic resonance (NMR) spectrometry method. FTIR study provided further details into hydrogen bonding upon mixing. FTIR results confirmed that H-bonds, occurring between two components in deep eutectic solvents, were the main force leading to the eutectic formation. The frequency at 3221 cm−1 can be attributed to the oscillations of the O-H bond in the formation of OH-Cl-ChCl. The main physicochemical characteristics of deep eutectic solutions (density, pH) are determined. The electrochemical behavior was investigated of choline chloride (ChCl)–lactic acid deep eutectic solvent (DES) by cyclic voltammetry. The method of cyclic voltammetry found that the oxidation of deep eutectic solvents is fixed at a potential of Ea1 = 0.54 V.


Author(s):  
Renita Manurung ◽  
Oktavianna Winda ◽  
Herianto Silalahi ◽  
Alwi Gery Agustan Siregar

The conversion of lignocellulosic biomass to biofuel as potential sources of transportation fuels, and for being both non-toxic and biodegradable. 5- Hydroxymethylfurfural (5-HMF) has been discovered to be a precursor for biofuel production and can be produced from biomass, which is readily available, renewable, and sustainable. Cellulose content in cassava peels is an opportunity to produce bio-based chemical products called 5-hydroxymethylfurfural. This study aims to determine the proper condition of glucose dehydration reaction of cassava peels hydrolysis. The optimum condition of dehydration reaction in this study was a glucose mass ratio: deep eutectic solvent of 1:6 and a reaction temperature of 80 ᵒC and the highest yield of 5-hydroxymethylfurfural using deep eutectic solvents (DES) based on choline chloride/oxalic acid was 70.22% and using DES based on choline chloride/oxalic acid was 64.50% at 5.70% glucose initial concentration using 1.5% H2SO4 catalyst on hydrolysis reaction cellulose of cassava peels. Physicochemical properties of deep eutectic solvents (DES) were pH of 5.8, density of 1.1574 gr/cm3 and viscosity of 119.33 cP. The results in this study indicate that the addition of DES choline chloride/oxalic acid can increase the yield of 5-hydroxymethylfurfural obtained.


2021 ◽  
Vol 9 ◽  
Author(s):  
Alan D. Pérez ◽  
Juha Fiskari ◽  
Boelo Schuur

Deep eutectic solvents (DESs) are considered as a green and environmentally benign solvent class for various applications, including delignification of biomass. One of the major challenges in the delignification of biomass by DES is attributed to the limitations in mass transfer. By subjecting wood chips to a low-energy mechanical refining, i.e., the Asplund process, the accessible surface area increases greatly, which in turn improves the mass transfer and increases the reaction rate. In this research, the DES delignification of Asplund fibers made of Norway spruce was studied as a strategy to produce papermaking fibers under mild conditions. A DES consisting of lactic acid and choline chloride was used due to its proven performance in delignification. Various operational conditions, such as temperature, time, DES-to-wood ratio, and the type of stirring were studied. A novel parameter, Q, allowed to evaluate the impact of the operational conditions on the quality of the pulp in terms of delignification degree and fiber length. The results showed that cooking temperature had the most significant effect on the pulp quality. Additionally, it was observed that cooking times between 30 and 45 min result in a pulp yield of about 50%, while fibers have a lignin content of about 14% and a fiber length of 0.6 mm. These results demonstrate that it is possible to obtain fibers of relatively good quality from DES delignification using Asplund fibers as the starting material.


TAPPI Journal ◽  
2013 ◽  
Vol 12 (11) ◽  
pp. 49-53 ◽  
Author(s):  
CHRISTINE CHIRAT ◽  
LUCIE BOIRON ◽  
DOMINIQUE LACHENAL

Autohydrolysis and acid hydrolysis treatments were applied on mixed softwood chips. The cooking ability was studied by varying the alkali and duration of the cook. Pulps with kappa numbers varying from 30 to 70 were obtained. The bleaching ability of these pulps was studied and compared to control kraft pulps. The prehydrolyzed pulps were shown to be more efficiently delignified by oxygen than the control kraft pulps starting from the same kappa number. Furthermore, the final bleaching was also easier for these pulps. It was also shown that extensive oxygen delignification applied on high-kappa pre-hydrolyzed pulps could be a way to improve the overall yield, which is a prerequisite for the development of such biorefinery concepts. Lignin was isolated from the control kraft and the two pre-hydrolyzed kraft pulps and analyzed by 13C NMR. Lignins from pre-hydrolyzed kraft pulps had similar free phenolic groups content to the control kraft lignin, but their aliphatic hydroxyl groups and β-O-4 content were lower than for the control lignin. The quaternary carbon content was the same for all the samples.


Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2149
Author(s):  
Chan-Woo Park ◽  
Song-Yi Han ◽  
Rajkumar Bandi ◽  
Ramakrishna Dadigala ◽  
Eun-Ah Lee ◽  
...  

In this study, the effect of lignin esterification with fatty acid chloride on the properties of lignin and lignin/poly(lactic acid) (PLA) composites was investigated. Lignocellulose (Pinus densiflora S. et Z.) was treated using a deep eutectic solvent (DES) with choline chloride (ChCl)/lactic acid (LA). From the DES-soluble fraction, DES-lignin (DL) was isolated by a regeneration process. Lignin esterification was conducted with palmitoyl chloride (PC). As the PC loading increased for DL esterification, the Mw of esterified DL (EDL) was increased, and the glass transition temperature (Tg) was decreased. In DL or EDL/PLA composite films, it was observed that EDL/PLA had cleaner and smoother morphological characteristics than DL/PLA. The addition of DL or EDL in a PLA matrix resulted in a deterioration of tensile properties as compared with neat PLA. The EDL/PLA composite film had a higher tensile strength and elastic modulus than the DL/PLA composite film. DL esterification decreased water absorption with lower water diffusion coefficients. The effect of lignin esterification on improving the compatibility of lignin and PLA was demonstrated. These results are expected to contribute to the development of high-strength lignin composites.


2021 ◽  
Vol 23 (3) ◽  
pp. 1300-1311 ◽  
Author(s):  
Dasom Jung ◽  
Jae Back Jung ◽  
Seulgi Kang ◽  
Ke Li ◽  
Inseon Hwang ◽  
...  

The in vitro and in vivo studies suggest that choline chloride-based deep eutectic solvents may not be considered as pure, safe mixtures even if they consist of safe compounds.


2020 ◽  
Vol 32 (4) ◽  
pp. 733-738 ◽  
Author(s):  
R. Manurung ◽  
Taslim ◽  
A.G.A. Siregar

Deep eutectic solvents (DESs) have numerous potential applications as cosolvents. In this study, use of DES as organic solvents for enzymatic biodiesel production from degumming palm oil (DPO) was investigated. Deep eutectic solvent was synthesized using choline chloride salt (ChCl) compounds with glycerol and 1,2-propanediol. Deep eutectic solvent was characterized by viscosity, density, pH and freezing values, which were tested for effectiveness by enzymatic reactions for the production of palm biodiesel with raw materials DPO. Deep eutectic solvent of ChCl and glycerol produced the highest biodiesel yield (98.98%); weight of DES was only 0.5 % of that of the oil. In addition, the use of DES maintained the activity and stability of novozym enzymes, which was assessed as the yield until the 6th usage, which was 95.07 % biodiesel yield compared with the yield without using DES. Hence, using DES, glycerol in enzymatic biodiesel production had high potentiality as an organic solvent for palm oil biodiesel production


2021 ◽  
Vol 131 ◽  
pp. 368-375
Author(s):  
Filipa Lima ◽  
Luis C. Branco ◽  
Nuno Lapa ◽  
Isabel M. Marrucho

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