Lignin Recovery Research Articles

Pretreatment of sugarcane bagasse using ionic liquid for enhanced enzymatic saccharification and lignin recovery: process optimization by response surface methodology

Pretreatment of sugarcane bagasse using ionic liquid for enhanced enzymatic saccharification and lignin recovery: process optimization by response surface methodology

Long-term stability of cellulose membranes in spent deep eutectic solvent used in the recovery of lignin from lignocellulosic biomass

Deep eutectic solvents (DESs) are a novel class of solvents that can be used to fractionate biomass compounds. However, their sustainability depends strongly on their recyclability. In previous research, it was seen that membrane filtration with commercial cellulose membranes (RC70PP and Ultracel 5 kDa) might be a solution for purification of spent deep eutectic solvent (DES) that has been used in lignin extraction (Choline Chloride: Lactic Acid 1:10 molar ratio) from woody biomass. This DES is, however, very acidic (pH 1.3), which can have detrimental effects on the longevity of the membrane. In a previous study, the time that the membranes were exposed to the spent DES was relatively short. This study aims to increase knowledge of how cellulose membranes withstand spent DES over longer time periods of up to 8 weeks. The results show that cellulose membranes are quite stable under exposure to spent DES in terms of pure water flux and PEG retention for up to 4 weeks. After 8 weeks, the RC70PP membrane demonstrated an increase in pure water permeability of 45% and a noticeable decrease in PEG retention. Surface characterization revealed, however, that the chemical structure of the cellulose membranes changed already after 2 weeks of exposure prior to any changes in pure water permeability were observed. Experimentally revealed esterification of cellulose membrane by Lactic Acid of DES led to more negative charge of the exposed samples compared to their references. This esterification was accompanied by hydrolysis that removed amorphous parts and increased the crystallinity of the membrane.

Flux decline in crossflow ultrafiltration-based diafiltration process for lignin recovery from a deep eutectic solvent comprised of lactic acid and choline chloride

This study investigates a continuous ultrafiltration (UF)-based diafiltration (DF) method to separate and purify lignin from a deep eutectic solvent (DES) containing lactic acid and choline chloride after biomass delignification. A crossflow setup with a polyether sulfone UF membrane with a molecular weight cut off of 5000 Da was used to evaluate flux decline and fouling in this process. Under different pressure, feed flowrate, lignin, and DES concentrations, lignin rejection is around 0.90. Higher lignin and DES concentrations increase filtration resistance, and thus decrease flux at constant pressure. On the basis of a previously setup model based on dead-end filtration, a modeling approach was further developed to predict the system size required to implement UF-DF on a large scale. The results shows that at a constant pressure, the membrane system's area increases as the cake layer thickness over the membrane's surface increases.

Evaluation on the recovery of lignin from basic [Ch][Lys] systems using low-cost alcohols as anti-solvents under acid-free conditions

An acid-free, high efficiency, and mild method of precipitating and separating lignin from basic ionic liquids (BIL) such as choline lysinate ([Ch][Lys]) by using alchohols (such as tert-butanol) as anti--solvents.

UTILIZAREA LIGNINEI PENTRU ÎNDEPĂRTAREA PARTICULELOR DE MICROPLASTIC DIN APĂ

The focus of the research was to evaluate the use of lignin from different sources as an agent for the removal of diverse types of microplastics when present in wastewater. Organosolv lignin was obtained from three different sources (Miscanthus sp., pine bark and solid anaerobic digestates from Organic Fraction of Municipal Solid Wastes) by an ethanol-based organosolv treatment carried out in a pressurized stirred-tank reactor. The lignins obtained were evaluated as an adsorbent for diverse types of microplastics: High-density polyethylene (HDPE), Polystyrene (PS), Expanded Polystyrene (EPS), and Polypropylene (PP). All lignins used had the capacity to capture plastic particles from all plastic types, but a differential absorbance potential was found both for plastic types and lignin samples. EPS was the least adsorb type for all lignin sources, with the remaining plastics presenting equivalent results. Pine bark lignin was the best adsorbent among the tested feedstocks, always presenting the best performance for all plastic types. The direct utilization of organosolv hydrolysates, avoiding lignin recovery presented a similar behaviour. These results open the possibility to develop new natural, plant-based, adsorbents for microplastic removal from contaminated wastewater.

Extraction and characterization of cattail fibre and lignin recovery from retting bath

Cattail is an aquatic perennial with upright, flat, rhizomatous leaves that can grow to heights of 2.5 to 5 m and looks capable of filling this need. The main objective of this research was to separate and individualize the fibres by partial delignification of cattail fibre and recovery of lignin from the used retting bath of cattail fibre. The alkaline formulations were opted to the separation and removing gummy lignin materials for effective retting of cattail fibre. The retting parameters were studied to obtain the least strength loss and optimum lignin removal in the cattail fibres. The lignin recovery yielded 6.75 gram per litre (gpl) by keeping acidic medium for 1 h at room temperature. Recovered lignin was characterized through Fourier infrared spectroscopy and particle size analysis. The retted Cattail single fibre average diameter and fineness was 109 μm and tex, respectively. Tensile strength retained up to 60 % after retting.

Influence of pulping conditions on the pulp yield and fiber properties for pulping of spruce chips by deep eutectic solvent

AbstractThe chemical pulping of wood chips using deep eutectic solvents (DES-pulping) has emerged as an alternative technology to conventional pulping in the paper industry, allowing the production of pulp in combination with the recovery of lignin and sugars for valorization. A challenge in the development of this technology is the understanding of how the operating conditions influence the crucial pulp manufacturing parameters such as delignification percentage, pulp yield, and fiber quality. This work is focused on investigating the effect of operating conditions such as cooking temperature, cooking time, liquor-to-wood ratio, initial water content on DES, type of mixing, the addition of a pre-treatment step (pre-impregnation of DES into the wood chips) to cooking process, and DES composition (lactic acid:choline chloride, lactic acid:sodium chloride, and lactic acid:sodium bromide) on the cooking of wood chips by DES. A shortcut quality evaluation parameter (Q), defined as the product of the fiber length and the degree of delignification quantified the quality of the pulping process in a single value, shows values similar to a reference unbleached kraft pulp for cooking at 130 °C in a range of cooking times from 3 to 4.5 h at a L/W of 10:1 by using lactic acid:choline chloride DES. More elaborate property analysis on the fibers showed that several of the the quality-indicating properties of the fibers (coarseness, shape factor, fibril area, and crill index) are comparable with typical sulfite pulping fibers.

OPEFB pretreatment using the low-cost N,N,N-dimethylbutylammonium hydrogen sulfate ionic liquid under varying conditions

This study investigates the effects of temperature and period on the pretreatment of OPEFB using the low-cost N,N,N-dimethylbutylammonium hydrogen sulfate ionic liquid ([DMBA][HSO4] IL) with 20 wt% of water. The results demonstrate that higher pretreatment temperatures (120, 150, and 170 °C) and longer periods (0.5, 1, and 2 h) enhanced lignin recovery, resulting in increased purity of the recovered pulp and subsequently enhanced glucose released during enzymatic hydrolysis. However, at 170 °C, prolonging the period led to cellulose degradation and the formation of pseudo-lignin deposited on the pulps, resulting in a decreasing-trend in glucose released. Finally, the analysis of extracted lignin reveals that increasing pretreatment severity intensified lignin depolymerisation and condensation, leading to a decrease in number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (Đ) values.

Lignin recovery from hazelnut shells

Lignin recovery from hazelnut shells

White-rot fungus Phlebia floridensis ITM 12: Laccase production, oxidoreductase profile, and hydrogen-peroxide independent activity.

Phlebia genus is a relevant group of fungi with a crucial role in numerous ecosystems. In tropical and subtropical areas this genus allows the efficient degradation of lignin and carbon recovery; however, the majority of these fungal species remain undiscovered. The main purpose of this work was to determine the enzymatic activity of extracellular proteins of a novel Phlebia floridensis strain isolated in Yucatan Peninsula, Mexico. The results that are reported here demonstrate that the soluble protein extract of P. floridensis can degrade a broad spectrum of recalcitrant compounds. This induced protein extract is able to modify not only phenolic and nonphenolic compounds, but also anthroquinone dyes, even without the addition of exogenous hydrogen peroxide. Using liquid chromatography-mass spectrometry (LC-MS), we were able to identify a novel chloroperoxidase in enzymatic extract. As far as we know, this is the first report about the presence of this type of enzyme in the Phlebia genus.

Applying biorefinery concepts for sugarcane straw upcycling using alkaline and enzymatic treatments to produce value-added compounds and bioenergy

The objective of this study was to develop a sugarcane straw biorefinery that targets the valorization of glucan, hemicellulose, and lignin streams generated through sequential and integrated treatments. Complementary biocatalytic strategies include ferulic acid isolation and biotransformation into high-value compounds, such as coniferol (a molecule with broad application in chemical synthesis) using a genetically engineered Escherichia coli strain (BL21-pROB) and xylooligosaccharides (XOS) using a feruloyl esterase and xylanase chimeric enzyme (XynZ). This biorefinery scheme also considers lignin recovery for solid biofuel and lignin nanoparticle synthesis. The evaluation of integration scenarios showed that a mild-alkaline pretreatment followed by enzymatic hydrolysis with XynZ and subsequent biotransformation with BL21-pROB strain, saccharification, and fermentation steps allowed up to 85% (w/w) of sugarcane straw plant cell wall component conversion into coniferol, XOS, fermentable sugars, bioethanol, lignin nanoparticles, and solid biofuel.

Acid-Catalyzed Atmospheric Organosolv Treatment By Using gamma-Valerolactone and Ethylene Glycol For The Delignification of Hazelnut Shell and Precipitation of Lignin

Lignin-based biorefineries are gaining importance day by day to obtain many value-added products from lignin. One of the most important processes that allow the recovery of both cellulose and lignin in those biorefineries is organosolv pretreatment. In this study, organosolv pretreatment was applied to the hazelnut shell at 130 °C for 60 min with ethylene glycol and γ-valerolactone solvents in the presence of a catalyst (either phosphoric acid or acetic acid). The success of solvent-catalyst systems was assessed by delignification efficiency and lignin recovery. Lignins obtained by precipitation were also analyzed by FTIR, TGA, DSC and Py-GC/MS. Highest delignification efficiency (33.9%) was detected for ethylene glycol- phosphoric acid solvent-catalyst pair. It was observed that acetic acid was not an effective catalyst compared to phosphoric acid. The delignification efficiency of γ-valerolactone was low (< 26 %) under atmospheric conditions, and in the presence of acetic acid, lignin was not precipitated from GVL system.

Liquor recycling of oxidative-organosolv pretreatment of maize cob and lignin recovery

Liquor recycling of oxidative-organosolv pretreatment of maize cob and lignin recovery

Effect of solvent and acid catalyst selection on lignin recovery and purity in autoclave-assisted organosolv extraction

This study leverages the autoclave-assisted method to explore a range of acid catalysts (H2SO4, HCl, HNO3, H3PO4) and solvents (methanol, ethanol, acetone, 2-butanol, 2-propanol) for lignin extraction, with a focus on identifying optimal efficiency-enhancing combinations. By contrasting the performance of various acid catalysts and solvents, this work transcends previous efforts in this field. Notably, H2SO4 yields the highest lignin recovery (44.7 %) but with lower purity (78.4 %) compared to HCl (85.7 %) in the same solvent. Methanol yields the highest recovery (45.1 %), yet lower purity (79.2 %) than ethanol (85.7 %) with a similar catalyst. A pivotal improvement lies in the elucidation of structural purity, substantiated by IR and NMR resulting signals, supported by microscale morphology and chemical composition (SEM-EDX). This study extends current understanding, providing profound insights into optimizing extraction procedures for producing lignin with desired attributes.

Recent advances in biorefineries based on lignin extraction using deep eutectic solvents: A review

Considering the urgent need for alternative biorefinery schemes based on sustainable development, this review aims to summarize the state-of-the-art in the use of deep eutectic solvent pretreatment to fractionate lignocellulose, with a focus on lignin recovery. For that, the key parameters influencing the process are discussed, as well as various strategies to enhance this pretreatment efficiency are explored. Moreover, this review describes the challenges and opportunities associated with the valorization of extraction-derived streams and highlights recent advancements in solvent recovery techniques. Furthermore, the utilization of computational models for process design and optimization is introduced, as the initial attempts at the economic and environmental assessment of this lignocellulosic bioprocess based on deep eutectic solvents. Overall, this review offers a comprehensive perspective on the recent advances in this emerging field and serves as a foundation for further research on the potential integration of deep eutectic pretreatment in sustainable multi-product biorefinery schemes.

Techno-Economic Assessment of Peruvian Stipa Ichu Microfibres by Steam Explosion

ABSTRACT Steam explosion as a pre-treatment for lignocellulosic fibers is an eco-friendly technology for obtaining cellulose microfibres. This study used a sustainable process design to produce Stipa Ichu (endemic fiber) cellulose microfibres on a pilot scale. Pseudolignin models and experimental data from recent studies were used to validate and simulate the steam explosion in a range of 150 to 220°C using acetic acid concentrations of 0.1 to 0.3 g/g of fiber. A peak yield of 92% was obtained for lignin recovery. The proposed process, which would produce 5 tons of dried cellulose microfibres per year, is economically feasible with an ROI of 48% and a PBP of 2.45 years. Additionally, the process is environmentally viable, with an E-factor of 9.42.

Lignin recovery from a mixture of SIX lignocellulosic biomasses within a biorefinery scheme based on a sequential process of autohydrolysis and organosolv

A mixture of six lignocellulosic biomasses could be a solution for sustainable biorefinery supply throughout the year compared with seasonal feedstock. In this study, a sequential process of autohydrolysis and organosolv was used for this mixture. To optimize lignin extraction, an experimental design was used to study the impacts of temperature, ethanol concentration, and time on lignin yield and related characteristics of the organosolv process. A highly pure organosolv lignin (OL) (ca. 90% Klason lignin) was recovered. FTIR analysis showed the main lignin structure was almost unchanged. NMR confirmed this and revealed the presence of guaiacyl-syringyl type with small amounts of p-hydroxyphenyl units (25% G, 70% S, and 5% H), predominantly presenting β-O-4 units (ca. 80%). Tg from 73 to 85 °C was detected. OL showed radical scavenging activity as high as the commercial antioxidant BHT. Moreover, enzymatic susceptibility of delignified biomass was accessed, in which 50% glucose yield was achieved.

Kraft lignin recovery from de-oiled Jatropha curcas seed by potassium hydroxide pretreatment and optimization using response surface methodology

The present study explores resource recovery from the de-oiled Jatropha curcas seed (DJS) using alkaline pretreatment. Potassium hydroxide (KOH) was utilized for the alkaline hydrolysis at a solid loading rate of 10 % w/v for the kraft lignin (KL) recovery. The process variables optimized were reaction time (6.36–73.63 min), temperature (85.68–156.3 °C), and KOH concentration (0.61–12.38 % w/w). Response surface methodology was used to optimize the process parameters. The maximum amount of KL recovered under optimal conditions was observed to be 89.6 %. The functional group changes in treated and untreated DJS were explored through Fourier transform infrared spectroscopy (FTIR) analysis. 1H NMR and FTIR techniques were employed to characterize recovered lignin. Nitrobenzene oxidation of the lignin was performed to understand the lignin monomer profile. The recovered lignin has an S/G ratio of 0.36. The pretreated DJS biomass can be subjected to enzymatic hydrolysis for enhanced sugar yield.

New approach to recycle and valorize the first filtrate of the LignoForce system™: Lignin extraction and its use in rigid lignin-based polyurethane foams

In this work, we report on the fractionation, recovery and characterization of softwood kraft lignin from the first filtrate of the LignoForce™ process. It is estimated that the lignin content in this stream could be >20–30 % of the lignin present initially in the black liquor. The use of a membrane filtration system was experimentally validated as an effective method for fractionating the first filtrate. Two membranes with different nominal molecular weight cut-offs (4000 and 250 Da) were tested. Higher lignin retention and recovery was obtained using the 250-Da membrane. This lignin (lignin_250) was found also to have a lower molecular weight and a tighter molecular weight distribution compared to the lignin obtained using the 4000-Da membrane (lignin_4000). The lignin_250 was characterized for it's hydroxyl group content and used to produce polyurethane (PU) foams. Up to 30 wt% petroleum-based polyol replacement by lignin_250, the resulting lignin-based PU (LBPU) foams presented the same thermal conductivity as the control (0.0303 W/m.K (control) vs 0.029 W/m.K (30 wt%)), as well as comparable mechanical (max stress: 145.8 kPa (control) vs 222.7 KPa (30 wt%), modulus 64.3 kPa (control) vs 75.1 (30 wt%)) and morphological properties to the petroleum polyol-based PU foams.

Lignin Recovery Using Alkaline Pretreatment of Walnut Shells

The effects of alkaline pretreatment of walnut shells (WS) utilizing NaOH, Ca(OH)2, or KOH were studied. The highest lignin recovery was obtained from WS pretreated with NaOH-glycerol. The optimum lignin recovery after pretreatment could be achieved when the NaOH/solid value was 20:1 (mL g−1). CaCl2 loading could enhance lignin flocculation, which improved the lignin recovery. Also, the efficiency of enzymatic hydrolysis was determined when xylanase and cellulase were added to the pretreated residue. WS pretreated in NaOH-water and NaOH-glycerol solutions were found to result in the highest xylose and glucose concentrations. This study indicates the broad application prospects of alkaline pretreatment of lignocellulosic biomass in agriculture and industry.