Galina Telysheva

Lignin - a useful bioresource for the production of sorption-active materials.

Sorption characteristics of acid hydrolysis lignins, commercial by-products of wood conversion to fuel ethanol, and their nitrogen-containing derivatives have been examined to determine the most suitable areas of application of lignin-based sorbents. The results obtained have shown that the sorption capacity for organic contaminants of an aromatic nature increases significantly as a result of the modification of hydrolysis lignins with quaternary ammonium compounds. The amination of lignin with epoxy amines enhanced its sorption activity towards heavy metals. Aminolignins have a high sorption capacity for bile acids and cholesterol. Sorption properties of nitrogen-containing lignin derivatives are such that they can be proposed for use in the environment-protection field and as enterosorbents.

On-line study of lignin behaviour in dilute alkaline solution by the SEC-UV method

Abstract The dynamic method for monitoring ionisation of the lignin functional groups in a 0.1 N NaOH solution at ambient temperature by means of the SEC technique with multiwave UV detection was performed. An increase in absorbance at 210, 278, 304, 320 and 350 nm was examined to reveal the ionisation dynamics in respect to functional groups’ acidity; that is, carboxyl groups, carbonyl- and double-bond conjugated phenol hydroxyls. A distinctive response of absorbance at 210 and 278 nm on the ionisation of carbonyl- and double-bond-conjugated phenols was found. Simultaneous characterisation of lignin by molecular weight (MW) and chemical heterogeneity was performed. A non-uniform distribution of reactive sites over the MW distribution for commercial kraft lignin (Curan) was found employing the family of chemical composition distribution curves. The redistribution of extended chromophore structures over time along the lignin’s MW distribution causes a misrepresentation of the UV chromatogram pattern and influences the accuracy of MW values.

Elucidation of antioxidant properties of wood bark derived saturated diarylheptanoids: A comprehensive (DFT-supported) understanding

A series of diarylheptanoids, namely 1,7-bis-(3,4-dihydroxyphenyl)-heptan-3-one-5-O-D-xylopyranoside (oregonin), 1,7-bis-(3,4-dihydroxyphenyl)-3-hydroxyheptane-5-O-β-D-xylopyranoside and 1,7-bis-(4-hydroxyphenyl)-heptane-3-one-5-O-β-D-glucopyranoside (platyphylloside), were isolated from the bark of alder family trees, a species widely spread over in Europe. As antioxidants, these natural polyphenols have a promising potential in various fields of application, but their redox reactivity is insufficiently characterized. In this work, their antioxidant activity is described using assays based on DPPH and ABTS(+) radical scavenging, oxygen anion radicals (O2(-)) quenching. The standardized ORAC assay was also achieved, which measures the capacity to protect fluorescent molecules against oxidative degradation. The measured antioxidant activity was higher than that of the well-known antioxidant and biologically active diarylheptanoid curcumin. Molecular modeling was used to rationalize the differences in activity and the mechanisms of action. Thermodynamic descriptors mainly O-H bond dissociation enthalpies (BDEs) establish a clear structure-activity relationship.

Antioxidant activity of various lignins and lignin-related phenylpropanoid units with high and low molecular weight

Abstract The antioxidant activities (AoAs) of 50 different technical lignins have been determined. The lignins of various botanical origins (annual plants, coniferous trees, and deciduous trees) were isolated and fractionated by different techniques (delignification by alkali, kraft process, fast pyrolysis, and hydrolysis). The structure and the functionality of lignins were characterized by functional group analyses (phenolic OH, carboxyl, and methoxyl groups), analytical pyrolysis pyrolysis/gas chromatography/mass spectrometry/flame ionization detector (Py-GC/MS/FID), electron paramagnetic resonance, size exclusion chromatography, and titrimetric methods, and the AoAs were evaluated as the capacity to scavenge the DPPH· and ABTS·+ free radicals. The relationship between the lignin structure and the AoA was characterized by pair correlation, partial correlation, and multivariate regression analyses, including correlated components regression. The results were compared with those of lignin model compounds and low molecular weight phenylpropanoids. It has been shown that molecular weight does not influence essentially the AoA of lignins. There is a relationship between the activities of low and high molecular weight polyphenols; their mechanisms of action are also similar. The structure-related AoA of lignins has been quantified for the first time.

Comparative studies of grass compost lignin and the lignin component of compost humic substances

The aim of this research was to compare the structural features of lignin and alkali-soluble humic substances isolated from grass compost at different stages of composting, and to estimate the applicability of basic analytical techniques used in lignin chemistry for characterising the lignin structures transformed during composting. Elemental, functional analyses, alkaline nitrobenzene oxidation, analytical ozonation and FT-IR techniques were applied. Compost Björkman lignins were used as reference samples. FT-IR of the compost Björkman lignins was typical for guaiacyl–syringyl lignins. The humic substances contained methoxyl groups and gave the same products as Björkman lignins by nitrobenzene oxidation and ozonation. The lignin component of humic substances, calculated on the basis of chemical markers, was lower than that for the Klason procedure and decreased in following order: methoxyl group>nitrobenzene oxidation products>ozonation products. Methoxyl groups are recommended for lignin content evaluation in compost because of their higher stability in the compost environment among the chemical markers under study. Our results showed that lignin macromolecules were already sufficiently modified at the early stage of composting to be dissolved in alkali. Modified lignin constituted a significant part of grass compost humic substances.

Two approaches for introduction of wheat straw lignin into rigid polyurethane foams

In present work the BIOLIGNIN TM obtained in the result of wheat straw organosolv processing in CIMV pilot plant (France) was investigated as a component of rigid polyurethanes (PUR) foam systems. Different separate approaches of lignin introduction into PUR foam system were studied: as filler without chemical preprocessing and as liquid lignopolyol obtained by lignin oxypropylation in alkali conditions. The incorporation of increasing amount of lignin as filler into reference PUR foam systems on the basis of mixture of commercial polyethers Lupranol 3300 and Luprano 3422 steadily decreased the compression characteristics of foams, their dimensional stability and hydrophobicity. The complete substitution of Lupranol 3300 by lignopolyol increases its cell structure uniformity and dimensional stability and does not reduce the physical-mechanical properties of foam. In both cases the incorporation of lignin into PUR foam leads to the decreasing of maximum values of thermodegradation rates. The lignin filler can be introduced into lignopolyol based PUR foam in higher quantity than in the reference Lupranol based PUR without reduction of compression characteristics of material. In this work the optimal lignin content in the end product - PUR foam as both polyol and filler is 16%.

Characterisation of humic substances formed during co-composting of grass and wood wastes with animal grease

Meat processing grease wastes were composted with lignocellulosic material. Judging by the reduction in the yield of compost lipophilic extract, grease was degraded during the first 20 days of composting. Compost humic acids (HA) and fulvic acids (FA) were characterized by elemental analysis, Fourier transform infrared (FT-IR) spectroscopy and analytical pyrolysis. The compost HA and FA fractions contained a ligno-protein complex. The presence of grease (6.7% dry weight) during composting had a slight influence on the chemical composition of HA and FA. Analytical pyrolysis indicated that, during composting, major changes were observed in the FA fraction, namely, the proportion of nitrogen-bearing compounds increased and carbohydrate-derived products decreased drastically in the final compost. In addition, the shortening of the aliphatic chains of lignin-derived compounds was observed with an increase in the C6C(0−2)/C6C3 ratio in pyrolysates.

Functionality and physico-chemical characteristics of wheat straw lignin, BioligninTM, derivatives formed in the oxypropylation process.

Abstract The new organosolv process of wheat straw fractionation elaborated by Compagnie Industrielle de la matiere Vegetale (France) corresponds to the biorefinery approach, which allows separating cellulose, hemicelluloses, and lignin. The straw lignin (Biolignin™) is an attractive product, for which new applications are sought. In the present work, straw lignin (L) was converted into liquid lignopolyols via a batch reaction with propylene oxide (PO). The effects of the lignin content (L%) in the initial reaction mixture (L/(L+PO) on the oxypropylation process and the properties of whole lignopolyols and L/PO copolymers were studied. Almost complete disappearance of L-OHphen and L-COOH groups in copolymers was accompanied by an increase in the L-OHaliph groups’ content therein. The polydispersity (Mw/Mn) of all copolymers obtained decreased essentially compared to the reference. The extent of PO grafting onto OH groups increased with decreasing lignin content in the initial reaction mixture. At a lignin content of 15–30% in the initial reaction mixture, the lignopolyols fulfil the requirements of polyol polyethers for rigid polyurethane foam production. The further increase in the lignin content leads to the appearance of the non-liquefied fraction and the undesirable increase in the viscosity of the liquefied part.

Wood-based activated carbons for supercapacitors with organic electrolyte

Abstract The thermocatalytical synthesis conditions required for the activation of wood charcoal with NaOH in terms of the formation of pores in its structure were investigated. The present study was conducted to explore the potential application of activated carbons as electrodes in supercapacitors with organic electrolyte. The total pore volume and micro- and mesopore ratio were controlled by the activation temperature and alkali addition rate. The working characteristics of carbon electrodes (e.g., specific capacity and ohmic losses) in supercapacitors are strongly influenced by the properties of the pores in their structures. Herein, the optimal ratio of raw material to activator and activation temperature are established: an increase in the ratio of NaOH to carbonizate rate by a factor of 2 and setting the synthesis temperature at 700°C positively influence the electrochemical characteristics of supercapacitors and provide them with specific capacities of up to 160 F g-1.

Evaluation of the changes induced by gasification biochar in a peat-sand substrate**

Abstract Gasification biochar represents one of the biochar types tested for agricultural needs. The aim of this study was to clarify the physico-chemical and biological changes occurring in a peat-sand substrate amended with hardwood-derived gasification biochar in the rates of 2, 4 and 20 g l-1. The pH(H2O) of the substrate with 4 g l-1 and 20 g l-1 biochar was increased from 5.6 to 6.2 and 6.7, respectively. The testing of the substrate in the respirometry device showed that the increase in the biochar rate led to a decrease in the amount of CO2 evolved at the maximum pressure drop. The continuous decrease in pressure observed in the respirometry bottles filled with pure biochar allows explaining this effect by biochar sorption activity. Addition of 2 and 4 g l-1 biochar to the peat-sand substrate stimulated the growth of cucumbers in an 18-day pot vegetation experiment. An increase in the number of root tips and root volume with a decreasing average root diameter was shown in the presence of biochar. Stimulation of plant growth on the background of low rates of biochar requires a further study with emphasis on the specific combination of biochar, soil type, plant species, and climatic conditions.