Predicting structural change of lignin macromolecules before and after heat treatment using the pyrolysis-GC/MS technique

Kim, Jae‐Young; Hwang, Hyewon; Park, Jeesu; Oh, Shinyoung; Choi, Joon Weon

doi:10.1016/j.jaap.2014.09.020

Cited by 25 publications

(22 citation statements)

References 42 publications

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“…Indeed, these temperature-dependent structural modifications have been studied in detail previously. For example, Kim et al (2014b, a) heated milled wood lignin to between 150 and 300 • C and analysed modifications in the functional group composition using chromatography methods, nitrobenzene oxidation and NMR (nuclear magnetic resonance). Briefly, the results from this study showed that from a heating temperature of 150 • C, first ether bonds connecting methoxyl groups to aromatic rings within the polymer are broken and then bonds to increasingly bigger side-chains and terminal func-tional groups are cleaved.…”

Section: Effect Of Heatingmentioning

confidence: 99%

Lignin's ability to nucleate ice via immersion freezing and its stability towards physicochemical treatments and atmospheric processing

Bogler

Borduas-Dedekind

2020

Atmos. Chem. Phys.

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Abstract. Aerosol–cloud interactions dominate the uncertainties in current predictions of the atmosphere's radiative balance. Specifically, the ice phase remains difficult to predict in mixed-phase clouds, where liquid water and ice co-exist. The formation of ice in these clouds originates from heterogeneous ice nucleation processes, of which immersion freezing is a dominant pathway. Among atmospheric surfaces capable of forming a template for ice, mineral dust, biological material and more recently organic matter are known to initiate freezing. To further our understanding of the role of organic matter in ice nucleation, we chose to investigate the ice nucleation (IN) ability of a specific subcomponent of atmospheric organic matter, the biopolymer lignin. Ice nucleation experiments were conducted in our custom-built freezing ice nuclei counter (FINC) to measure freezing temperatures in the immersion freezing mode. We find that lignin acts as an ice-active macromolecule at temperatures relevant for mixed-phase cloud processes (e.g. 50 % activated fraction up to −18.8 ∘C at 200 mg C L−1). Within a dilution series of lignin solutions, we observed a non-linear effect in freezing temperatures; the number of IN sites per milligram of carbon increased with decreasing lignin concentration. We attribute this change to a concentration-dependant aggregation of lignin in solution. We further investigated the effect of physicochemical treatments on lignin's IN activity, including experiments with sonication, heating and reaction with hydrogen peroxide. Only harsh conditions such as heating to 260 ∘C and addition of a mixture with a ratio of 1 : 750 of grams of lignin to millilitres of hydrogen peroxide were able to decrease lignin's IN activity to the instrument's background level. Next, photochemical and ozone bubbling experiments were conducted to test the effect of atmospheric processing on lignin's IN activity. We showed that this activity was not susceptible to changes under atmospherically relevant conditions, despite chemical changes observed by UV–Vis absorbance. Our results present lignin as a recalcitrant IN-active subcomponent of organic matter within, for example, biomass burning aerosols and brown carbon. They further contribute to the understanding of how soluble organic material in the atmosphere can nucleate ice.

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Section: Effect Of Heatingmentioning

confidence: 99%

Lignin's ability to nucleate ice via immersion freezing and its stability towards physicochemical treatments and atmospheric processing

Bogler

Borduas-Dedekind

2020

Atmos. Chem. Phys.

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“…After that, the fraction of crystalline cellulose increases due to the thermal degradation of amorphous cellulose, and the extractives are thermally degraded, forming new compounds due to the decomposition of the polysaccharides [8]. Simultaneously, autocondensation of lignin via cross-linked bounds [3,11] and a cleavage of ˇ-O-4 linkage (depolymerization) [13][14][15] occur during the heat treatment at high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Thermochemical and physical properties of two fast-growing eucalypt woods subjected to two-step freeze–heat treatments

et al. 2015

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“…Table 3 and Figure A2 (in Appendix A) show the relative mass contents of sawdust torrefied in the vacuum and the nitrogen systems at 300 • C for 60 min. The liquid products were largely composed of condensable components such as phenols, acids, alcohols, aldehydes, and ketones (see Table 3) [43][44][45]. All of the results reported in Table 3 are mutually comparable because they were obtained under the same operating conditions as programed in the MS instrument.…”

Section: Gc/ms Analysis Of Liquid Compoundsmentioning

confidence: 83%

Product Characteristics of Torrefied Wood Sawdust in Normal and Vacuum Environments

et al. 2019

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To investigate the efficacy of torrefaction in a vacuum environment, wood sawdust was torrefied at various temperatures (200–300 °C) in different atmospheres (nitrogen and vacuum) with different residence times (30 and 60 min). It was found that the amount of biochar reduced at the same rate—regardless of atmosphere type—throughout the torrefaction process. In terms of energy density, the vacuum system produced biochar with better higher heating value (HHV, MJ/kg) than the nitrogen system below 250 °C. This was the case because the moisture and the high volatility compounds such as aldehydes diffused more easily in a vacuum. Over 250 °C, however, a greater amount of low volatility compounds evaded from the vacuum system, resulting in lower higher heating value in the biochar. Despite the mixed results with the solid products, the vacuum system increased the higher heating value of its liquid products more significantly than did the nitrogen system regardless of torrefaction temperature. It was found that 23% of the total energy output came from the liquid products in the vacuum system; the corresponding ratio was 19% in the nitrogen system. With liquid products contributing to a larger share of the total energy output, the vacuum system outperformed the nitrogen system in terms of energy density.

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Predicting structural change of lignin macromolecules before and after heat treatment using the pyrolysis-GC/MS technique

Cited by 25 publications

References 42 publications

Lignin's ability to nucleate ice via immersion freezing and its stability towards physicochemical treatments and atmospheric processing

Lignin's ability to nucleate ice via immersion freezing and its stability towards physicochemical treatments and atmospheric processing

Thermochemical and physical properties of two fast-growing eucalypt woods subjected to two-step freeze–heat treatments

Product Characteristics of Torrefied Wood Sawdust in Normal and Vacuum Environments

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