Correlating lignin structural features to phase partitioning behavior in a novel aqueous fractionation of softwood Kraft black liquor

Stoklosa, Ryan J.; Velez, Julian; Kelkar, Shantanu; Saffron, Christopher M.; Thies, Mark C.; Hodge, David B.

doi:10.1039/c3gc41182f

Cited by 48 publications

(45 citation statements)

References 46 publications

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“…6). In these spectra, the weak peaks in the chemical shift ranged from 130 ppm to 170 ppm, corresponding to the aromatic carbons attached to oxygen atoms (=C-O-), strong peaks from 100 ppm to 130 ppm to the secondary aromatic carbons (=CH-C), weak peaks from 100 ppm to 130 ppm to the tertiary aromatic carbons (=C-C), strong peaks in the range 50 ppm to 80 ppm to the (OCH3) carbons, and other aliphatic carbons attached to oxygen atoms, and the peaks in the range 0 ppm to 40 ppm to the aliphatic carbons (Stoklosa et al 2013).…”

Section: Resultsmentioning

confidence: 99%

Characterization of Hardwood Soda-AQ Lignins Precipitated from Black Liquor through Selective Acidification

2016

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In the development of integrated biorefinery process alternatives to produce value-added by-products, various black liquors from sulfur-free pulping processes offer potential feedstocks for recovering their main chemical constituents, lignin and aliphatic carboxylic acids. In this study, lignin fractions were obtained from silver birch (Betula pendula) sodaanthraquinone black liquor by carbonation (pH to about 8.5) or by acidification (pH to about 2) with H2SO4 after carbonation or directly. These fractions were characterized by Fourier transform infrared (FTIR), ultraviolet (UV), energy dispersive X-ray fluorescence (ED XRF), and 13 C nuclear magnetic resonance ( 13 C NMR) spectroscopy. In addition, the molecular weight distributions of these lignin fractions were determined. All the experimental data clearly suggested that only small differences between the precipitated lignins existed, and thus, their equal chemical utilization seems possible.

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Section: Resultsmentioning

confidence: 99%

Characterization of Hardwood Soda-AQ Lignins Precipitated from Black Liquor through Selective Acidification

2016

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“…The substantial quantity of sugars in the filter cake represents an opportunity for both recovery and utilization. Previous work demonstrated that alkalisolubilized sugar oligomers preferentially precipitate at higher pH than lignin (Stoklosa et al, 2013) suggesting that sequential CO 2 precipitation could be employed to selectively enrich and recover xylan from lignin-containing liquors. The high recovery of xylan and remaining acetic acid (2.6%) is the result of withdrawing the liquor from the upper section of the digester corresponding to the early stages of the cook.…”

Section: Characterization and Hydrolysis Of Xylan-rich Precipitatementioning

confidence: 99%

Biobutanol production by Clostridium acetobutylicum using xylose recovered from birch Kraft black liquor

Kudahettige-Nilsson

Helmerius

Nilsson

et al. 2015

Bioresource Technology

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Acetone-butanol-ethanol (ABE) fermentation was studied using acid-hydrolyzed xylan recovered from hardwood Kraft black liquor by CO2 acidification as the only carbon source. Detoxification of hydrolyzate using activated carbon was conducted to evaluate the impact of inhibitor removal and fermentation. Xylose hydrolysis yields as high as 18.4% were demonstrated at the highest severity hydrolysis condition. Detoxification using active carbon was effective for removal of both phenolics (76-81%) and HMF (38-52%). Batch fermentation of the hydrolyzate and semi-defined P2 media resulted in a total solvent yield of 0.12-0.13g/g and 0.34g/g, corresponding to a butanol concentration of 1.8-2.1g/L and 7.3g/L respectively. This work is the first study of a process for the production of a biologically-derived biofuel from hemicelluloses solubilized during Kraft pulping and demonstrates the feasibility of utilizing xylan recovered directly from industrial Kraft pulping liquors as a feedstock for biological production of biofuels such as butanol.

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“…Monodisperse poly(ethylene glycol)/poly(ethylene oxide) (PEG/ PEO) standards (part no. PL2080-0101, Agilent Technologies) were 19 Acetylated liquidlignin samples were prepared at a concentration of 44 mg/mL in deuterated chloroform, which contained a trace amount of trimethylsilane (TMS) as a reference peak. Pentafluorobenzaldehyde (PFB) was added as an internal standard for functional-group quantification.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…No previous investigations have been performed, at least partly because only recently have researchers discovered 1,18,19 that lignin recovery from blackliquor solutions can be carried out at such temperatures.…”

Section: ■ Introductionmentioning

confidence: 97%

Temperature Effects on the Molecular Properties of Liquid Lignin Recovered from Kraft Black Liquor

Velez

Thies

2015

ACS Sustainable Chem. Eng.

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The effect of temperature on the molecular properties of a "liquid-lignin" phase recovered from Kraft black liquor via CO 2 acidification at elevated temperatures was investigated. For softwood black liquors, up to a 4-fold increase in the molecular weight (mol wt) of the recovered liquid-lignin phase was observed as the acidification temperature was increased from 100 to 150°C. Thus, experiments were carried out in which the CO 2 -acidification steps of preheating, acidification, and phase separation were decoupled from each other in order to elucidate the mechanisms for the observed changes in molecular weight. Results indicate that some lignin cleavage and a corresponding decrease in molecular weight occur during the black-liquor preheating step. However, a significant net increase in molecular weight occurs after the lignin has phase-separated from the black liquor in the form of a new, denser liquid phase, pointing to condensation reactions as the most likely cause. Minimal changes in lignin aromatic content were observed in the new liquid-lignin phase. Because elevated-temperature, CO 2 acidification can be carried out continuously via the SLRP process, adjusting residence times in the black liquor−liquid lignin phase separator would be an effective method for controlling the molecular weight of the recovered lignin for a given product application.

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Correlating lignin structural features to phase partitioning behavior in a novel aqueous fractionation of softwood Kraft black liquor

Cited by 48 publications

References 46 publications

Characterization of Hardwood Soda-AQ Lignins Precipitated from Black Liquor through Selective Acidification

Characterization of Hardwood Soda-AQ Lignins Precipitated from Black Liquor through Selective Acidification

Biobutanol production by Clostridium acetobutylicum using xylose recovered from birch Kraft black liquor

Temperature Effects on the Molecular Properties of Liquid Lignin Recovered from Kraft Black Liquor

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