Depolymerization of Kraft Lignin Using a Metal Chloride-Based Deep Eutectic Solvent: Pathways to Sustainable Lignin Valorization

Driven by the urgent need for sustainable alternatives to fossil fuels, the focus on the exploration of lignocellulosic biomass, particularly lignin, as a promising renewable feedstock for biofuels and high-value chemicals has intensified. This study investigated the depolymerization of KL using a D...

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Main Authors: Shubho Ghosh, Masud Rana, Jeong-Hun Park
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/14/24/11571
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author Shubho Ghosh
Masud Rana
Jeong-Hun Park
author_facet Shubho Ghosh
Masud Rana
Jeong-Hun Park
author_sort Shubho Ghosh
collection DOAJ
description Driven by the urgent need for sustainable alternatives to fossil fuels, the focus on the exploration of lignocellulosic biomass, particularly lignin, as a promising renewable feedstock for biofuels and high-value chemicals has intensified. This study investigated the depolymerization of KL using a DES comprising ChCl and ZnCl<sub>2</sub>. Our analysis systematically focused on the effects of reaction temperature, time, and the DES-to-lignin ratio on the yields and characteristics of the products. Optimal KL depolymerization was observed at a temperature of 190 °C and a duration of 8 h, yielding a maximum liquid product yield of 54.44% and RL yield of 45.56%. The results revealed that increasing the reaction temperature enhanced the depolymerization process owing to a reduction in the viscosity of the DES, which improved mass transfer and interactions with lignin. Under these optimal conditions, the molecular weight of the bio-oil was considerably lower (M<sub>w</sub> = 1498 g/mol and M<sub>n</sub> = 1061 g/mol) than that of the bio-oil obtained without DES treatment (M<sub>w</sub> = 1872 g/mol and M<sub>n</sub> = 1259 g/mol), indicating a more favorable molecular weight distribution with DES treatment. Furthermore, elemental analysis revealed a reduction in the O, N, and S contents of the RL following DES treatment, increasing the high heating value from 24.82 MJ kg<sup>−1</sup> for the non-DES-treated RL to 26.44 MJ kg<sup>−1</sup> for the DES-treated RL. These findings underscore the potential of the (ChCl:ZnCl<sub>2</sub>) DES as a sustainable and effective medium for lignin valorization, paving the way for the synthesis of high-quality biofuels and chemicals from lignocellulosic biomass.
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spelling doaj-art-cb4adb23d5f74f91ba88e6f770ece0fd2025-08-20T02:00:54ZengMDPI AGApplied Sciences2076-34172024-12-0114241157110.3390/app142411571Depolymerization of Kraft Lignin Using a Metal Chloride-Based Deep Eutectic Solvent: Pathways to Sustainable Lignin ValorizationShubho Ghosh0Masud Rana1Jeong-Hun Park2Department of Environment and Energy Engineering, Chonnam National University, Gwangju 61186, Republic of KoreaDepartment of Environment and Energy Engineering, Chonnam National University, Gwangju 61186, Republic of KoreaDepartment of Environment and Energy Engineering, Chonnam National University, Gwangju 61186, Republic of KoreaDriven by the urgent need for sustainable alternatives to fossil fuels, the focus on the exploration of lignocellulosic biomass, particularly lignin, as a promising renewable feedstock for biofuels and high-value chemicals has intensified. This study investigated the depolymerization of KL using a DES comprising ChCl and ZnCl<sub>2</sub>. Our analysis systematically focused on the effects of reaction temperature, time, and the DES-to-lignin ratio on the yields and characteristics of the products. Optimal KL depolymerization was observed at a temperature of 190 °C and a duration of 8 h, yielding a maximum liquid product yield of 54.44% and RL yield of 45.56%. The results revealed that increasing the reaction temperature enhanced the depolymerization process owing to a reduction in the viscosity of the DES, which improved mass transfer and interactions with lignin. Under these optimal conditions, the molecular weight of the bio-oil was considerably lower (M<sub>w</sub> = 1498 g/mol and M<sub>n</sub> = 1061 g/mol) than that of the bio-oil obtained without DES treatment (M<sub>w</sub> = 1872 g/mol and M<sub>n</sub> = 1259 g/mol), indicating a more favorable molecular weight distribution with DES treatment. Furthermore, elemental analysis revealed a reduction in the O, N, and S contents of the RL following DES treatment, increasing the high heating value from 24.82 MJ kg<sup>−1</sup> for the non-DES-treated RL to 26.44 MJ kg<sup>−1</sup> for the DES-treated RL. These findings underscore the potential of the (ChCl:ZnCl<sub>2</sub>) DES as a sustainable and effective medium for lignin valorization, paving the way for the synthesis of high-quality biofuels and chemicals from lignocellulosic biomass.https://www.mdpi.com/2076-3417/14/24/11571kraft lignindeep eutectic solventphenolic compoundsrecovered ligninbio-oil
spellingShingle Shubho Ghosh
Masud Rana
Jeong-Hun Park
Depolymerization of Kraft Lignin Using a Metal Chloride-Based Deep Eutectic Solvent: Pathways to Sustainable Lignin Valorization
Applied Sciences
kraft lignin
deep eutectic solvent
phenolic compounds
recovered lignin
bio-oil
title Depolymerization of Kraft Lignin Using a Metal Chloride-Based Deep Eutectic Solvent: Pathways to Sustainable Lignin Valorization
title_full Depolymerization of Kraft Lignin Using a Metal Chloride-Based Deep Eutectic Solvent: Pathways to Sustainable Lignin Valorization
title_fullStr Depolymerization of Kraft Lignin Using a Metal Chloride-Based Deep Eutectic Solvent: Pathways to Sustainable Lignin Valorization
title_full_unstemmed Depolymerization of Kraft Lignin Using a Metal Chloride-Based Deep Eutectic Solvent: Pathways to Sustainable Lignin Valorization
title_short Depolymerization of Kraft Lignin Using a Metal Chloride-Based Deep Eutectic Solvent: Pathways to Sustainable Lignin Valorization
title_sort depolymerization of kraft lignin using a metal chloride based deep eutectic solvent pathways to sustainable lignin valorization
topic kraft lignin
deep eutectic solvent
phenolic compounds
recovered lignin
bio-oil
url https://www.mdpi.com/2076-3417/14/24/11571
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AT masudrana depolymerizationofkraftligninusingametalchloridebaseddeepeutecticsolventpathwaystosustainableligninvalorization
AT jeonghunpark depolymerizationofkraftligninusingametalchloridebaseddeepeutecticsolventpathwaystosustainableligninvalorization