{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,20]],"date-time":"2026-10-20T15:28:40Z","timestamp":1792510120249,"version":"4.5.0"},"reference-count":48,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2022,11,24]],"date-time":"2022-11-24T00:00:00Z","timestamp":1669248000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["32271797"],"award-info":[{"award-number":["32271797"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Lignin is a natural polymer second only to cellulose in natural reserves, whose structure is an aromatic macromolecule composed of benzene propane monomers connected by chemical bonds such as carbon\u2013carbon bonds and ether bonds. Degradation is one of the ways to achieve the high-value conversion of lignin, among which the heating degradation of lignin by deep eutectic solvent (DES) can be an excellent green degradation method. In this study, choline chloride (CC) was used as the hydrogen bond acceptor, and urea (UR), ethylene glycol (GC), glycerol (GE), acetic acid (AA), formic and acetic mixed acid (MA), oxalic acid (OX), and p-toluenesulfonic acid (TA) were used as hydrogen bond donors to degrade lignin. NMR hydrogen spectroscopy was used for the simple and rapid determination of phenolic hydroxyl groups in lignin. FT-IR spectroscopy was used to characterize the changes of functional groups of lignin during DES treatment. GPC observed the molecular weight of lignin after degradation and found a significant increase in the homogeneity (1.6\u20132.0) and a significant decrease in the molecular weight Mw (2478\u20134330) of the regenerated lignin. It was found that acidic DES was more effective in depolymerizing alkaline lignin, especially for the toluene\u2013choline chloride. Seven DES solutions were recovered, and it was found that the recovery of DES still reached more than 80% at the first recovery.<\/jats:p>","DOI":"10.3390\/polym14235100","type":"journal-article","created":{"date-parts":[[2022,11,24]],"date-time":"2022-11-24T02:54:05Z","timestamp":1669258445000},"page":"5100","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":47,"title":["Comparison of the Degradation Performance of Seven Different Choline Chloride-Based DES Systems on Alkaline Lignin"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7071-6547","authenticated-orcid":false,"given":"Penghui","family":"Li","sequence":"first","affiliation":[{"name":"Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuan","family":"Lu","sequence":"additional","affiliation":[{"name":"College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoyu","family":"Li","sequence":"additional","affiliation":[{"name":"College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianpeng","family":"Ren","sequence":"additional","affiliation":[{"name":"Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China"},{"name":"College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhengwei","family":"Jiang","sequence":"additional","affiliation":[{"name":"College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bo","family":"Jiang","sequence":"additional","affiliation":[{"name":"Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China"},{"name":"College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4802-2191","authenticated-orcid":false,"given":"Wenjuan","family":"Wu","sequence":"additional","affiliation":[{"name":"Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China"},{"name":"College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"107180","DOI":"10.1016\/j.fuproc.2022.107180","article-title":"Catalyst-free liquefaction of lignin for monophenols in hydrogen donor solvents","volume":"229","author":"Liu","year":"2022","journal-title":"Fuel Process. Technol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"131895","DOI":"10.1016\/j.foodchem.2021.131895","article-title":"Ethanol organosolv lignin from different agricultural residues: Toward basic structural units and antioxidant activity","volume":"376","author":"Sheng","year":"2022","journal-title":"Food Chem."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"123156","DOI":"10.1016\/j.fuel.2022.123156","article-title":"Spherical NiCo-MOFs catalytic hydrogenolysis of lignin dimers and enzymatic lignin to value-added liquid fuels under nitrogen atmosphere","volume":"315","author":"Zhou","year":"2022","journal-title":"Fuel"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"8951658","DOI":"10.1155\/2017\/8951658","article-title":"Structural characterization of lignin and its degradation products with spectroscopic methods","volume":"2017","author":"Lu","year":"2017","journal-title":"J. Spectrosc."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"119050","DOI":"10.1016\/j.carbpol.2021.119050","article-title":"Effects of hydrothermal pretreatment on the dissolution and structural evolution of hemicelluloses and lignin: A review","volume":"281","author":"Sun","year":"2022","journal-title":"Carbohyd. Polym."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"531","DOI":"10.1016\/j.jaap.2013.05.016","article-title":"Thermal degradation of various lignins by TG-MS\/FTIR and Py-GC-MS","volume":"104","author":"Brebu","year":"2013","journal-title":"J. Anal. Appl. Pyrol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"133473","DOI":"10.1016\/j.chemosphere.2021.133473","article-title":"Extraction methodology of lignin from biomass waste influences the quality of bio-oil obtained by solvothermal depolymerization process","volume":"293","author":"Prakash","year":"2022","journal-title":"Chemosphere"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"504","DOI":"10.1016\/j.apcata.2013.07.044","article-title":"Depolymerization of lignin by catalytic oxidation with aqueous polyoxometalates","volume":"467","author":"Zhao","year":"2013","journal-title":"Appl. Catal. A Gen."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"787","DOI":"10.1007\/s00226-020-01183-4","article-title":"Lignin valorization and cleavage of arylether bonds in chemical processing of wood: A mini-review","volume":"54","author":"Evstigneyev","year":"2020","journal-title":"Wood Sci. Technol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"100700","DOI":"10.1039\/C6RA22967K","article-title":"A thermal behavior and kinetics study of the catalytic pyrolysis of lignin","volume":"6","author":"Bu","year":"2016","journal-title":"RSC Adv."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"e202200099","DOI":"10.1002\/cssc.202200099","article-title":"Selective catalytic transfer hydrogenation of lignin to alkyl guaiacols over NiMo\/Al-MCM-41","volume":"15","author":"Lu","year":"2022","journal-title":"ChemSusChem"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3379","DOI":"10.1021\/acssuschemeng.0c06715","article-title":"Hydrogenolysis of lignin-derived aromatic ethers over heterogeneous catalysts","volume":"9","author":"Shivhare","year":"2021","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"3111","DOI":"10.1021\/cs400636k","article-title":"Aerobic oxidation of beta\u20131 lignin model compounds with copper and oxovanadium catalysts","volume":"3","author":"Sedai","year":"2013","journal-title":"ACS Catal."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3828","DOI":"10.1039\/C8GC00502H","article-title":"Revisiting alkaline aerobic lignin oxidation","volume":"20","author":"Schutyser","year":"2018","journal-title":"Green Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"128719","DOI":"10.1016\/j.jclepro.2021.128719","article-title":"Deep eutectic solvent assists Bacillus australimaris to transform alkali lignin waste into small aromatic compounds","volume":"320","author":"Yu","year":"2021","journal-title":"J. Clean. Prod."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"18577","DOI":"10.1021\/acssuschemeng.0c06655","article-title":"Kraft lignin solubility and its chemical modification in deep eutectic solvents","volume":"8","author":"Sosa","year":"2020","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"10248","DOI":"10.1021\/acssuschemeng.8b05816","article-title":"Facile extraction of wheat straw by deep eutectic solvent (DES) to produce lignin nanoparticles","volume":"7","author":"Lou","year":"2019","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_18","first-page":"20","article-title":"Application of deep eutectic solvents in lignocellulosic biomass processing","volume":"5","author":"Li","year":"2020","journal-title":"J. For. Eng."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"114430","DOI":"10.1016\/j.indcrop.2021.114430","article-title":"Experimental and theoretical study on the catalytic degradation of lignin by temperature-responsive deep eutectic solvents","volume":"177","author":"Wang","year":"2022","journal-title":"Ind. Crops Prod."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1851","DOI":"10.1039\/D0GC00006J","article-title":"In-depth interpretation of the structural changes of lignin and formation of diketones during acidic deep eutectic solvent pretreatment","volume":"22","author":"Hong","year":"2020","journal-title":"Green Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"573198","DOI":"10.3389\/fenrg.2020.573198","article-title":"Insights into structural transformations of lignin toward high reactivity during choline chloride\/formic acid deep eutectic solvents pretreatment","volume":"8","author":"Hong","year":"2020","journal-title":"Front. Energy Res."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"112729","DOI":"10.1016\/j.indcrop.2020.112729","article-title":"Evaluation on the properties of deep eutectic solvent-extracted lignin for potential aromatic bio-products conversion","volume":"154","author":"Tan","year":"2020","journal-title":"Ind. Crops Prod."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"219","DOI":"10.32604\/jrm.2021.012099","article-title":"A bifunctional bronsted acidic deep eutectic solvent to dissolve and catalyze the depolymerization of alkali lignin","volume":"9","author":"Li","year":"2021","journal-title":"J. Renew. Mater."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"7219","DOI":"10.1039\/D0GC02439B","article-title":"Structure-function relationships of deep eutectic solvents for lignin extraction and chemical transformation","volume":"22","author":"Hong","year":"2020","journal-title":"Green Chem."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"6415","DOI":"10.1039\/D0GC02189J","article-title":"A methanol-choline chloride based deep eutectic solvent enhances the catalytic oxidation of lignin into acetovanillone and acetic acid","volume":"22","author":"Yu","year":"2020","journal-title":"Green Chem."},{"key":"ref_26","first-page":"2666","article-title":"Research progress in quantitative determination of phenolic hydroxylgroups in lignin","volume":"42","author":"Li","year":"2022","journal-title":"Spectrosc. Spect. Anal."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1312","DOI":"10.1016\/j.ijbiomac.2020.11.012","article-title":"Formaldehyde-free self-polymerization of lignin-derived monomers for synthesis of renewable phenolic resin","volume":"166","author":"Yang","year":"2021","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Li, P., Jiang, Z., Yang, C., Ren, J., Jiang, B., and Wu, W. (2023). Degradation of alkaline lignin in the lactic acid-choline chloride system under mild conditions. J. Renew. Mater.","DOI":"10.32604\/jrm.2023.025279"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"5969","DOI":"10.1021\/acs.energyfuels.8b00383","article-title":"Fast, easy, and economical quantification of lignin phenolic hydroxyl groups: Comparison with classical techniques","volume":"32","author":"Serrano","year":"2018","journal-title":"Energy Fuels"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"5181","DOI":"10.1021\/acssuschemeng.6b01205","article-title":"Isolation and characterization of organosolv and alkaline lignins from hardwood and softwood biomass","volume":"4","author":"Nitsos","year":"2016","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"3103","DOI":"10.15376\/biores.16.2.3103-3120","article-title":"Pretreatment of kraft lignin by deep eutectic solvent and its utilization in preparation of lignin-based phenolic formaldehyde adhesive","volume":"16","author":"Xian","year":"2021","journal-title":"BioResources"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"113692","DOI":"10.1016\/j.indcrop.2021.113692","article-title":"Insights into bamboo delignification with acidic deep eutectic solvents pretreatment for enhanced lignin fractionation and valorization","volume":"170","author":"Li","year":"2021","journal-title":"Ind. Crops Prod."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1016\/j.indcrop.2015.07.039","article-title":"Degradation on hydrogenolysis of soda lignin using CuO\/SO42\u2212\/ZrO2 as catalyst","volume":"77","author":"Zhang","year":"2015","journal-title":"Ind. Crops Prod."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"809","DOI":"10.1002\/ep.12276","article-title":"Degradation of lignin in ionic liquid with HCl as catalyst","volume":"35","author":"Xue","year":"2016","journal-title":"Environ. Prog. Sustain."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"5133","DOI":"10.1039\/C6GC01007E","article-title":"Unique low-molecular-weight lignin with high purity extracted from wood by deep eutectic solvents (DES): A source of lignin for valorization","volume":"18","author":"Ma","year":"2016","journal-title":"Green Chem."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"889","DOI":"10.1016\/j.indcrop.2017.10.059","article-title":"Thermal stability, degradation kinetics, and molecular weight of organosolv lignins from Pinus radiata","volume":"111","author":"Santos","year":"2018","journal-title":"Ind. Crops Prod."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"103755","DOI":"10.1016\/j.isci.2022.103755","article-title":"Promising and efficient lignin degradation versatile strategy based on DFT calculations","volume":"25","author":"Wang","year":"2022","journal-title":"iScience"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"2130","DOI":"10.1021\/acssuschemeng.9b05106","article-title":"Structural and morphological transformations of lignin macromolecules during bio-based deep eutectic solvent (DES) pretreatment","volume":"8","author":"Shen","year":"2020","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_39","first-page":"63","article-title":"Assessment of the thermal behavior of lignins from softwood and hardwood species","volume":"19","author":"Poletto","year":"2017","journal-title":"Maderas Cienc. Tecnol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"8713","DOI":"10.1039\/D0GC03240A","article-title":"New ternary deep eutectic solvents for effective wheat straw deconstruction into its high-value utilization under near-neutral conditions","volume":"22","author":"Ci","year":"2020","journal-title":"Green Chem."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"e202200553","DOI":"10.1002\/cssc.202200553","article-title":"Unveiling the migration and transformation mechanism of lignin in eucalyptus during deep eutectic solvent pretreatment","volume":"15","author":"Hong","year":"2022","journal-title":"ChemSusChem"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"841","DOI":"10.1016\/j.jmrt.2021.07.017","article-title":"Comparison of structure, thermal stability, and pyrolysis products of lignin extracted with ChCl-formic acid\/lactic acid systems","volume":"14","author":"Li","year":"2021","journal-title":"J. Mater. Res. Technol."},{"key":"ref_43","first-page":"101","article-title":"Effect of lignin condensation on cellulose enzymatic hydrolysis during deep eutectic solvent fractionation of lignocellulose","volume":"6","author":"Yu","year":"2021","journal-title":"J. For. Eng."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Liu, R., Ding, T., Deng, P., Yan, X., Xiong, F., Chen, J., and Wu, Z. (2021). Structure and properties of deep eutectic solvent lignin degraded by H2O2. Biomass Conv. Bioref.","DOI":"10.1007\/s13399-021-02016-5"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"114696","DOI":"10.1016\/j.indcrop.2022.114696","article-title":"Revealing structural and functional specificity of lignin from tobacco stalk during deep eutectic solvents deconstruction aiming to targeted valorization","volume":"180","author":"Wang","year":"2022","journal-title":"Ind. Crops Prod."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"294","DOI":"10.1016\/j.ijbiomac.2021.02.088","article-title":"New deep eutectic solvent assisted extraction of highly pure lignin from maritime pine sawdust (Pinus pinaster Ait.)","volume":"177","author":"Fernandes","year":"2021","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"9689","DOI":"10.1007\/s10570-021-04157-2","article-title":"Integrated and sustainable preparation of functional nanocellulose via formic acid\/choline chloride solvents pretreatment","volume":"28","author":"Wu","year":"2021","journal-title":"Cellulose"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1016\/j.ijbiomac.2020.09.145","article-title":"Effect of hydrogen bond donor on the choline chloride-based deep eutectic solvent-mediated extraction of lignin from pine wood","volume":"165","author":"Oh","year":"2020","journal-title":"Int. J. Biol. Macromol."}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/14\/23\/5100\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T01:25:37Z","timestamp":1760145937000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/14\/23\/5100"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,11,24]]},"references-count":48,"journal-issue":{"issue":"23","published-online":{"date-parts":[[2022,12]]}},"alternative-id":["polym14235100"],"URL":"https:\/\/doi.org\/10.3390\/polym14235100","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,11,24]]}}}