Green solvents-based fractionation process for kraft lignin with controlled dispersity and molecular weight

Ajao, Olumoye; Jeaidi, Jawad; Benali, Marzouk; Abdelaziz, Omar Y.; Hulteberg, Christian

doi:10.1016/j.biortech.2019.121799

Cited by 39 publications

(27 citation statements)

References 23 publications

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“…Moreover, solvent fractionation of the solid OKL using different water/acetone ratios to achieve oligomeric lignin fragments with narrow molecular weight distribution (polydispersity index (PDI) ≤ 3) was investigated. Kraft lignin fractionation by multistage fractionation of distinct fractions from native lignin with reduced molecular weight and a low degree of polydispersity using organic solvents has already been reported [34][35][36][37]. Boeriu et al [38] investigated the solvent fractionation of five technical lignins via selective fractionation in green solvents such as acetone/water mixtures or ethyl acetate.…”

Section: Introductionmentioning

confidence: 99%

Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments

et al. 2020

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The extraction and characterization of defined and carboxyl-rich oligomeric lignin fragments with narrow molecular weight distribution is presented herein. With regard to the well-known pulp bleaching process, oxidative lignin depolymerization was investigated using hydrogen peroxide in an aqueous alkaline solution (i.e., at T = 318 K, t = 1 h) and subsequent selective fractionation with a 10/90 (v/v) acetone/water mixture. While the weight average molecular weight (MW) of lignin in comparison to the starting material was reduced by 82% after oxidation (T = 318 K, t = 1 h, clignin = 40 g L−1, cH2O2 = 80 g L−1, cNaOH = 2 mol L−1) and subsequent solvent fractionation (T = 298 K, t = 18 h, ccleavage product = 20 g L−1), the carboxyl group (–COOH) content increased from 1.29 mmol g−1 up to 2.66 mmol g−1. Finally, the successful scale-up of this whole process to 3 L scale led to gram amounts (14% yield) of oligomeric lignin fragments with a MW of 1607 g mol−1, a number average molecular weight (MN) of 646 g mol−1, a narrow polydispersity index of 3.0, and a high –COOH content of 2.96 mmol g−1. Application of these oligomeric lignin fragments in epoxy resins or as adsorbents is conceivable without further functionalization.

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Section: Introductionmentioning

confidence: 99%

Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments

et al. 2020

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“…Methanol (MeOH), ethanol (EtOH), propan-2-one (DMK), ethyl acetate (EtOAc), propan-1-ol (nPrOH), propan-2-ol (iPrOH), butan-2-one (MEK), and butan-1-ol (tBuOH) were selected as suitable green solvents for the process (Ajao et al, 2019). These eight solvents were tried separately, and solubilisation yield of lignins and molecular weights of the solubilised lignin fractions were determined.…”

Section: Selection Of the Organic Solvents And Order For The Fractionationmentioning

confidence: 99%

“…Moreover, solvents mixed with water show better solubility than pure solvents, leading to increased hydrogen bonding capacity and facilitating the diffusion of organic solvents into lignin (Domínguez-Robles et al, 2018). Nevertheless, the addition of water represents another variable, affecting the properties of the fractions obtained and the unappealing formation of azeotropes, which may also affect the enticement of the process in the economic aspect (Ajao et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Fine-tune of lignin properties by its fractionation with a sequential organic solvent extraction

Izaguirre

Robles

Llano‐Ponte

et al. 2022

Industrial Crops and Products

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In this work, different lignins were obtained from two different extraction methods (kraft and organosolv) but from the same raw material (Eucalyptus globulus sp.). They were subsequently fractionated to determine the differences of each extraction method and their corresponding physicochemical properties found in fractionation sequence and obtained fractions. The goal of the fractionation was to obtain lignin fractions with narrower molecular weight distribution and lower polydispersity index (PI). The solvent sequence was designed based on the environmental friendly properties, health and safety assessments of the selected organic solvents: (methanol (MeOH), ethanol (EtOH), propan-2-one (DMK), ethyl acetate (EtOAc), propan-1-ol (nPrOH), propan-2-ol (iPrOH), butan-2-one (MEK), and butan-1-ol (tBuOH)). The different fractions obtained were characterised to determine their chemical structure by several analytical techniques, such as Fourier Transformed Infrared Spectroscopy (FTIR), Ultraviolet (UV), Phosphorus-31 Nuclear Magnetic Resonance ( 31 P NMR), Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS), Thermogravimetric analysis (TGA), and Differential scanning calorimetry (DSC). In addition, Gel Permeation Chromatography (GPC) was used to obtain the molecular weight distribution. This study showed an effective method for obtaining homogeneous lignins with specific structures and properties depending on the solvent and molecular weight attained. Moreover, the method designed was found to be effective regardless of the lignin extraction process employed; besides, various lignin fractions were obtained which were different from each other, having specific target applications depending on their structure and chemical properties, ranging from small molecules with abundant reactive sites to act as active materials or copolymer reagents for many applications, to larger and more inactive molecules with higher thermal resistivity.

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“…KL depolymerization studies employing mixtures of solvents and water are numerous. There are two main reasons for this: solubility of KL is higher in alcohol-water mixtures [60], and most short-chain alcohols display some degree of hydrogen donating capacity through the steam reforming and water gas shift reaction that occurs simultaneously [35,36]. The most common combination seen is ethanol and water [61][62][63][64][65].…”

Section: Solvent-water Mixturesmentioning

confidence: 99%

Solvolysis of Kraft Lignin to Bio-Oil: A Critical Review

2020

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Lignin, a component of lignocellulosic biomass, is abundant and is produced extensively as a waste product of the Kraft pulping process, lignin obtained from this process is called Kraft lignin (KL). Lignin’s three-dimensional structure composed of aromatic alcohols (monolignols) makes it a potential source of renewable aromatic chemicals or bio-oil, if depolymerized. Among all the depolymerization methods for KL, solvolysis is the most popular, showing consistently high bio-oil yields. Despite the large number of studies that have been carried out, an economically feasible industrial process has not been found and comparison among the various studies is difficult, as very different studies in terms of reaction media and catalysts report seemingly satisfactory results. In this review, we compare and analyze KL solvolysis studies published, identify trends in bio-oil composition and give a comprehensive explanation about the mechanisms involved in the processes. Additional commentary is offered about the availability and future potential of KL as a renewable feedstock for aromatic chemicals, as well as logistical and technical aspects.

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Green solvents-based fractionation process for kraft lignin with controlled dispersity and molecular weight

Cited by 39 publications

References 23 publications

Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments

Valorization of Lignin via Oxidative Depolymerization with Hydrogen Peroxide: Towards Carboxyl-Rich Oligomeric Lignin Fragments

Fine-tune of lignin properties by its fractionation with a sequential organic solvent extraction

Solvolysis of Kraft Lignin to Bio-Oil: A Critical Review

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