PMID- 37210053 OWN - NLM STAT- MEDLINE DCOM- 20230619 LR - 20230619 IS - 1879-0003 (Electronic) IS - 0141-8130 (Linking) VI - 242 IP - Pt 2 DP - 2023 Jul 1 TI - Mechanistic insights into the lignin dissolution behavior in amino acid based deep eutectic solvents. PG - 124829 LID - S0141-8130(23)01723-3 [pii] LID - 10.1016/j.ijbiomac.2023.124829 [doi] AB - Deep eutectic solvents (DESs) composed by amino acids (L-arginine, L-proline, L-alanine) as the hydrogen bond acceptors (HBAs) and carboxylic acids (formic acid, acetic acid, lactic acid, levulinic acid) as hydrogen bond donors (HBDs) were prepared and used for the dissolution of dealkaline lignin (DAL). The mechanism of lignin dissolution in DESs was explored at molecular level by combining the analysis of Kamlet-Taft (K-T) solvatochromic parameters, FTIR spectrum and density functional theory (DFT) calculations of DESs. Firstly, it was found that the formation of new hydrogen bonds between lignin and DESs mainly drove the dissolution of lignin, which were accompanied by the erosion of hydrogen bond networks in both lignin and DESs. The nature of hydrogen bond network within DESs was fundamentally determined by the type and number of functional groups in both HBA and HBD, which affected its ability to form hydrogen bond with lignin. One hydroxyl group and carboxyl group in HBDs provided active protons, which facilitated proton-catalyzed cleavage of beta-O-4, thus enhancing the dissolution of DESs. The superfluous functional group resulted in more extensive and stronger hydrogen bond network in the DESs, thus decreasing the lignin dissolving ability. Moreover, it was found that lignin solubility had a closed positive correlation with the subtraction value of alpha and beta (net hydrogen donating ability) of DESs. Among all the investigated DESs, L-alanine/formic acid (1:3) with the strong hydrogen-bond donating ability (acidity), weak hydrogen-bond accepting ability (basicity) and small steric-hindrance effect showed the best lignin dissolving ability (23.99 wt%, 60 degrees C). On top of that, the value of alpha and beta of L-proline/carboxylic acids DESs showed some positive correlation with the global electrostatic potential (ESP) maxima and minima of the corresponding DESs respectively, indicating the analysis of ESP quantitative distributions of DESs could be an effective tool for DESs screening and design for lignin dissolution as well as other applications. CI - Copyright (c) 2023 Elsevier B.V. All rights reserved. FAU - Zhang, Yuling AU - Zhang Y AD - Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia; Pollution Prevention Biotechnology Laboratory of Hebei Province, School of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, China. FAU - Ren, Hongwei AU - Ren H AD - Pollution Prevention Biotechnology Laboratory of Hebei Province, School of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, China. Electronic address: renhongweirhw@126.com. FAU - Li, Baochai AU - Li B AD - Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia; Department of Applied Chemistry, Hengshui University, Hengshui, Hebei 0530002, China. FAU - Udin, Syarah Mat AU - Udin SM AD - Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Johor, Malaysia. FAU - Maarof, Hasmerya AU - Maarof H AD - Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Johor, Malaysia. FAU - Zhou, Wen AU - Zhou W AD - The State Grid Hebei Electric Power Company Electric Power Research Institute, Shijiazhuang, Hebei 050021, China. FAU - Cheng, Fengfei AU - Cheng F AD - Hebei Pollutant Emission Rights Trading Service Center, Shijiazhuang, Hebei 050026, China. FAU - Yang, Jiaoruo AU - Yang J AD - Pollution Prevention Biotechnology Laboratory of Hebei Province, School of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, China. FAU - Liu, Yize AU - Liu Y AD - Pollution Prevention Biotechnology Laboratory of Hebei Province, School of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, China. FAU - Alias, Hajar AU - Alias H AD - Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia. Electronic address: r-hajar@utm.my. FAU - Duan, Erhong AU - Duan E AD - Pollution Prevention Biotechnology Laboratory of Hebei Province, School of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018, China. Electronic address: duan_eh@163.com. LA - eng PT - Journal Article DEP - 20230519 PL - Netherlands TA - Int J Biol Macromol JT - International journal of biological macromolecules JID - 7909578 RN - 9005-53-2 (Lignin) RN - 0 (Deep Eutectic Solvents) RN - 0 (Amino Acids) RN - 0 (Solvents) RN - OF5P57N2ZX (Alanine) RN - 9DLQ4CIU6V (Proline) RN - 0 (Carboxylic Acids) SB - IM MH - *Lignin/chemistry MH - *Deep Eutectic Solvents MH - Solubility MH - Amino Acids MH - Solvents/chemistry MH - Biomass MH - Alanine MH - Proline MH - Carboxylic Acids OTO - NOTNLM OT - Deep eutectic solvent OT - Density functional theory OT - Electrostatic potential OT - Hydrogen bond interaction OT - Kamlet-Taft parameters OT - Lignin dissolution COIS- Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. EDAT- 2023/05/21 01:05 MHDA- 2023/06/19 13:08 CRDT- 2023/05/20 19:31 PHST- 2023/02/14 00:00 [received] PHST- 2023/05/04 00:00 [revised] PHST- 2023/05/08 00:00 [accepted] PHST- 2023/06/19 13:08 [medline] PHST- 2023/05/21 01:05 [pubmed] PHST- 2023/05/20 19:31 [entrez] AID - S0141-8130(23)01723-3 [pii] AID - 10.1016/j.ijbiomac.2023.124829 [doi] PST - ppublish SO - Int J Biol Macromol. 2023 Jul 1;242(Pt 2):124829. doi: 10.1016/j.ijbiomac.2023.124829. Epub 2023 May 19.