New aspects in cationization of lignocellulose materials. I. Preparation of lignocellulose materials containing quarternary ammonium groups

TMAHP derivatives were prepared by the reaction of beech sawdust with CHMAC in alkaline medium. The examination of the reaction conditions showed that the most suitable molar ratio was NaOH/CHMAC = 1.8 (1 ml 17.5% NaOH/1 mL 50% CHMAC). At this ratio the maximum degree of substitution expressed by the exchange capacity of 0.35 mmol/g of modified sawdust was obtained by using 1.5–2mL of 50% aqueous solution of CHMAC/g sawdust. The optimal reaction time at 60°C was 2 h. This condition gave yields of modified sawdust above 90% and soluble derivatives mainly consisting of hemicelluloses up to 12%.     

New aspects in cationization of lignocellulose materials. VII. Modification of spruce wood meal with quarternary ammonium groups

Trimethylammonium-2-hydroxypropyl (TMAHP) derivatives of spruce wood meal (SWM) and holocellulose of this specia were prepared by the reaction of wood meal with 3-chlor-2-hydroxy-propyltrimethylammoniumchloride (CHMAC) in alkaline medium. The TMAHP samples were fractionated and yields and exchange capacity (Q) of individual fractions were compared with beech and aspen fractions obtained under the same conditions. As it is evident from ¹³C-NMR spectroscopy and GPC analysis the water soluble fraction from TMAHP–SWM consists only of lignin–saccharide degradation products. The NaOH extracts of TMAHP–SWM and TMAHP–holocellulose as well as the water-soluble fraction from TMAHP–holocellulose are polymeric materials. From TMAHP–SWM only 3.1% of alkali-soluble material could be extracted, while from TMAHP–holocellulose 15.7% of water-soluble and 7.9% of alkali-soluble materials were obtained.     

New aspects in cationization of lignocellulose materials. VIII. Modification of immitted spruce wood with quarternary ammonium groups

Immitted spruce wood meal (ISWM) was modified with 3-chlor-2-hydroxypropyltrimethyl-ammoniuchloride (CHMAC) or 1,3-bis(3-chlor-2-hydroxypropyl)imidazoliumhydrogensulphate (BCHIHS) in alkaline medium. The obtained material was gradually extracted with water and 5% NaOH. The yields of water-soluble hemicelluloses modified with quarternary ammonium groups were lower in comparison to healthy spruce material obtained under the same conditions but even more material could be obtained from ISWM-holocellulose. The quantity of alkali-soluble polysaccharides from ISWM was the same as obtained from undamaged spruce. The residues after alkali extractions are suitable ion exchangers with low solubility in dilute alkali solutions. The yields of extracts from material modified with BCHIHS were lower than yields of extracts from material modified with CHMAC because ISWM was crosslinked when alkylated with bifunctional chemicals.     

New aspects in cationization of lignocellulose materials. IV. Modification of aspen wood meal with quarternary ammonium groups

Trimethylammonium-2-hydroxypropyl (TMAHP) derivatives of aspen wood were prepared by the reaction of wood meal with 3-chloro-2-hydroxypropyltrimethylammoniumchloride (CHMAC) in alkaline medium. The TMAHP sample was fractionated and yields and exchange capacities (Q) of individual fractions were compared with beech sawdust fractions obtained under the same conditions. The most evident difference between the two studied wood types was the higher yield (14.5% of starting material) of water-soluble TMAHP–hemicelluloses obtained from aspen wood.     

New aspects in cationization of lignocellulose materials. VI. Modification of steam-exploded aspen wood chips with quarternary ammonium groups

Holocellulose prepared from steam-exploded aspen wood was gradually fractionated with 2.5% NH₄OH, 4.5% NaOH, and 17.5% NaOH, respectively. Some residual polysaccharides were extracted from the material in this way, but their yield was only about 5%. Trimethylammonium-2-hydroxypropyl (TMAHP)-derivatives, exploded aspen wood (EXAW), were prepared by the reaction with 3-chlor-2-hydroxypropyl trimethylammoniumchloride (CHMAC) in alkaline medium. The quantity of water and alkali extracted TMAHP–polysaccharides (yield 2.6%) was lower than the yields from modified healthy beech and aspen, as well as rotten aspen. On the other hand, we can obtain more modified cellulose-rich and lignin-rich material than from previously mentioned species. The steam-explosion process is suitable for increasing the accessibility of cellulose component in lignocellulose material for chemical modification.     

New aspects in cationization of lignocellulose materials. V. Modification of rotten aspen wood meal with quarternary ammonium groups

Holocelluloses prepared from clear and rotten aspen wood were gradually fractionated with 2.5% NH₄OH, 4.5% NaOH, and 17.5% NaOH, respectively. A higher yield of polysaccharides (24.4%) was obtained from the rotten sample in comparison with clear wood (20.9%). Trimethyl ammonium-2-hydroxypropyl (TMAHP) derivatives of rotten aspen were prepared by the reaction of wood with 3-chlor-2-hydroxypropyltrimethylammoniumchloride (CHMAC) in alkaline medium. The quantity of TMAHP—hemicelluloses (yield 14.1%) is only slightly lower in comparison with TMAHP—hemicelluloses (yield 15.8%) obtained by modification and subsequent extraction from clear aspen wood meal. The hemicelluloses isolated from the rotten aspen wood meal are contaminated with low molecular cellulose fraction, the degradation products of cellulose attacked by fungi. The lignin component of rotten wood is less intensively attacked by fungi than the polysaccharidic one.     

New aspects in cationization of lignocellulose materials. IX. Flame retardancy effect of modification with nitrogen and sulfur containing groups

Lignocellulose materials were modified with 3-chlor-2-hydroxypropyltrimethylammoniumchloride, 1,3-bis(3-chlor-2-hydroxypropyl)imidazoliumhydrogensulphate, and 2-chlorethyl-sodiumsulphonate and the flame-retardant properties of materials obtained were studied. The flame-retardant effect was proved using the limited oxygen index (LOI) method and values up to 32.8 vol % of oxygen were determined. The LOI values were higher when the modification was done without using NaOH for activation, but in that case the alkylating groups were not chemically bonded to the material. The NaOH activation was necessary to obtain material with flame-retardant properties stable against washing. No synergistic effects were observed when the material was modified with both nitrogen- and sulfur-containing groups.     

New aspects in cationization of lignocellulose materials. X. Thermooxidation of TMAHP–sawdust

With the help of dynamic and isothermic thermogravimetry in inert and oxidative atmosphere the thermooxidation of TMAHP–sawdust in individual anionic forms was studied. The values obtained indicate that the most resistant samples against thermooxidation are H₂PO^?₄ and Br^? anionic forms. The most easily thermooxidized sample is the OH^? form. The thermooxidation seems to be a less energy-consuming reaction than thermolysis.     

Characteristics of hemicellulose,cellulose and lignin pyrolysis

The pyrolysis characteristics of three main components (hemicellulose, cellulose and lignin) of biomass were investigated using, respectively, a thermogravimetric analyzer (TGA) with differential scanning calorimetry (DSC) detector and a pack bed. The releasing of main gas products from biomass pyrolysis in TGA was on-line measured using Fourier transform infrared (FTIR) spectroscopy. In thermal analysis, the pyrolysis of hemicellulose and cellulose occurred quickly, with the weight loss of hemicellulose mainly happened at 220–315 °C and that of cellulose at 315–400 °C. However, lignin was more difficult to decompose, as its weight loss happened in a wide temperature range (from 160 to 900 °C) and the generated solid residue was very high (∼40 wt.%). From the viewpoint of energy consumption in the course of pyrolysis, cellulose behaved differently from hemicellulose and lignin; the pyrolysis of the former was endothermic while that of the latter was exothermic. The main gas products from pyrolyzing the three components were similar, including CO₂, CO, CH₄ and some organics. The releasing behaviors of H₂ and the total gas yield were measured using Micro-GC when pyrolyzing the three components in a packed bed. It was observed that hemicellulose had higher CO₂ yield, cellulose generated higher CO yield, and lignin owned higher H₂ and CH₄ yield. A better understanding to the gas products releasing from biomass pyrolysis could be achieved based on this in-depth investigation on three main biomass components.     

New aspects in cationization of lignocellulose materials. III. Influence of delignification on reactivity and extractability of TMAHP–hemicelluloses

Beech sawdust samples with different lignin content were alkylated with 3-chloro-2-hydroxypropyltrimethylammoniumchloride (CHMAC). The yields and the degree of subtitution of trimethylammonium-2-hydroxypropyl (TMAHP) samples were similar. Differences were found in extractability of hemicelluloses from this materials both with water and dilute alkali. To obtain the maximum yield of TMAHP–hemicelluloses (ca. 90% of the amount originally present), it is sufficient to remove about 50% of lignin. The lignin component does not influence the reactivity of hemicelluloses. The isolated hemicelluloses differ only in the distribution of functional groups and extractability.     

Prediction of pyrolysis of pistachio shells based on its components hemicellulose, cellulose and lignin

The objective of this contribution is to describe thermal degradation of pistachio shells by a detailed reaction mechanism. Pistachio shells are assumed to be composed of hemicellulose, cellulose and lignin of which degradation is described by relevant kinetics based on experimental data. The mechanism yields a detailed composition of product gases, and therefore, is well-suited to predict evolution of both thermal decomposition and products. Thermal degradation is described by a system of coupled differential conservation equations for mass, momentum, species, and energy for a pistachio shell particle. The relevant conservation equations are discretised by the Finite Volume Method (FVM) and solved within the conversion module of the Discrete Particle Method (DPM). A comparison between experimental data and predicted results yielded good agreement.     

Thermogravimetric and differential thermal analysis of cellulose,hemicellulose, and lignin

The thermal degradation of samples of cellulose, hemicellulose, and lignin have been investigated using the techniques of thermogravimetric analysis (TGA) and differential thermal analysis (DTA) between room temperature and 600°C. The results calculated from static and dynamic TGA indicated that the activation energy E for thermal degradation for different cellulosic, hemicellulose, and lignin samples is in the range 36–60, 15–26, and 13–19 kcal/mole, respectively. DTA of all the wood components studied showed an endothermic tendency around 100°C in an atmosphere of flowing nitrogen and stationary air. However, in the presence of flowing oxygen this endothermic effect was absent. In the active pyrolysis temperature range in flowing nitrogen and stationary air atmospheres, thermal degradation of Avicel cellulose occurred via a sharp endothermic and a sharp exothermic process, the endothermic nadir and exothermic peak being at 320° and 360°C, respectively. In the presence of oxygen, combustion of Avicel cellulose occurred via two sharp exothermic processes. DTA studies of different cellulose samples in the presence of air showed that the shape of the curve depends on the sources from which the samples were prepared as well as on the presence of noncellulosic impurities. Potassium xylan recorded a sharp exothermic peak at 290°C in a nitrogen atmosphere, and in a stationary air atmosphere it yielded an additional peak at 410°C, while in the presence of oxygen the curve showed two sharp exothermic peaks. DTA traces of periodate lignin in flowing nitrogen and air were the same and showed two exothermic peaks at 320° and 410°C, while in the presence of oxygen there were two exothermic peaks in the temperature range 200°–500°C.     

Investigation of liquefied wood residues based on cellulose,hemicellulose, and lignin

Chinese eucalyptus was subjected to a liquefaction process using glycerol/ethylene glycol (EG) as liquefaction solvent. The effects of various liquefaction conditions, including reaction time, liquefaction temperature, acid concentration, and liquor ratio on the chemical composition of liquefied wood residues were studied. The results showed that the whole liquefaction process took place in two stages, the liquefaction yield of wood depended on the reaction temperature, acid concentration and liquor ratio. With increased acid concentration the liquefaction yield, acid‐insoluble lignin, and hemicellulose content of the residues were increased, and the relative content of cellulose was decreased. Fourier transform infrared (FT‐IR) analyses of the residues showed that hemicellulose and lignin were almost decomposed at the initial stages of reaction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Multiphase materials with lignin. IV. Blends of hydroxypropyl cellulose with lignin

Polymer blends of hydroxypropyl cellulose (HPC) and organosolv lignin (OSL) were prepared by mixing in solutions of both pyridine and dioxane, and casting as films, and by mixing in the melt followed by extrusion. All preparations exhibited partial miscibility as evidenced by a single T_g up to a composition of 40 wt % lignin above which phase separation was detected. Dioxane-cast and injection-molded blends were distinguished from the pyridine-cast materials by a positive T_g deviation from additivity, an approximation which adequately described the latter. This positive deviation in T_g is attributed to the formation of a liquid-crystal mesophase with a resultant reduction of amorphous HPC available for interaction with the lignin component. This explanation is supported by a rapid rise in modulus (～150%) and tensile strength with very low lignin content, and by an associated sharp decline in ultimate elongation. The development of morphological features, as observed by scanning electron microscopy provide further substantiation of this hypothesis.     

Multiphase materials with lignin. XV. Blends of cellulose acetate butyrate with lignin esters

Commercially available cellulose acetate butyrate (CAB, unplasticized) was blended in melt and solution with lignin esters having different ester substituents—acetate (LA), butyrate (LB), hexanoate (LH), and laurate (LL). All lignin esters formed phase‐separated blends with CAB with domain size depending on processing conditions and the interaction between phases depending on blend components. CAB/LA and CAB/LB revealed the strongest interactions with domain sizes on the 15–30 nm scale as probed by dynamic mechanical thermal analysis and differential scanning calorimetry. The glass transitions (T_g) followed the Fox equation. Broader transitions corresponding to the T_gs of the two parent components were observed for CAB blends with LH and LL. Transmission electron micrographs revealed differences in the phase dimensions of the blends in accordance with chemical and processing (i.e., melt vs solvent) differences. Modest gains in modulus were observed for low contents (<20 wt %) of LA and LB. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 448–457, 1999     

Molar mass-dependent profiles of functional groups and carbohydrates in kraft lignin

Technical lignins are complex, irregular, polyphenolic compounds obtained in large quantities as by-products of the pulp and paper industries or according to current biorefinery setups. The availability of kraft lignin is increasing due to larger scale retrieval from process liquors, which opens new possibilities for further refining or new applications of such lignins. In the present study, sequential ultrafiltration of kraft lignin was performed to fractionate the lignin and to elucidate molar mass-dependent changes in lignin structure. Two industrial black liquors and three precipitated lignins were fractionated, and their functional groups were determined, providing molar mass-dependent profiles. Interrelations between structural parameters and functional groups, the molecular weight ranges, and the different lignin sources are discussed. This will help to establish structure-property-application relationships (SPARs) for technical lignins which are required for any future large-scale application.     

Is it possible to predict gas yields of any biomass after rapid pyrolysis at high temperature from its composition in cellulose, hemicellulose and lignin?

Ligno-cellulosic biomass from different sources presents very variable compositions. Consequently, there is a wide variation in the nature and quantities of gaseous products obtained after thermal treatment of biomasses.The objective of this work is to establish a link between the composition of a biomass and its pyrolysis gas yields and composition. Experimental flash pyrolysis of several biomasses at a temperature of 950 °C and a gas residence time of about 2 s was carried out. An attempt was then made to predict gas yields of any biomass according to its composition. We show that an additivity law does not allow the gas yields of a biomass to be correlated with its fractions of cellulose, hemicellulose and lignin. Several potential explanations are then offered and quantitatively demonstrated: it is shown that interactions occur between compounds and that mineral matter influences the pyrolysis process.     

New methods for the one-pot processing of polysaccharide components (cellulose and hemicelluloses) of lignocellulose biomass into valuable products. Part 1: Methods for biomass activation

Literature published mainly between 1995 and 2015 in the field of investigations aimed at finding promising new catalysts for the industrial processing of polysaccharide components of lignocellulose biomass, for new methods to achieve these processes, and for new ways of transforming polysaccharides into valuable chemicals and fuel is reviewed. In the first section, modern methods for activating lignocellulose biomass in order to separate main components and/or treat polysaccharide feedstock (cellulose, hemicelluloses) for further processing are considered. The second will deal with catalytic acidic transformations of these components into monosaccharides and furans. The third will focus on with the main focus on the production of 5-hydroxymethylfurfurol the application of biotechnological enzymatic methods for producing valuable chemicals such as ethanol, isobutanol, lactic acid.     

The graft copolymerization of styrene and lignin. II. Kraft softwood lignin

The radiation-induced graft copolymerization of styrene and various kraft softwood lignins was studied. Expression of the results as the usual “per cent graft” was impossible, because grafting caused the lignin to become extractable in solvents for the styrene homopolymer. However, evaluation of the effects of various solvents on the degree of reaction was made through an indirect, and possibly more characteristic, measure. Grafting was least pronounced under conditions of low lignin accessibility (e.g., when less than 10% methanol was present), but increased with the addition of better lignin solvents or with higher methanol concentrations. The precipitating nature of the latter conditions was also found to contribute to an accelerated rate of grafting. Surprisingly, the graft copolymer was found to degrade at higher doses. Proof of grafting is offered in a fractionation scheme. Measurement of the molecular weight of the polystyrene separated from the lignin backbone allows the estimation of approximately one polystyrene graft per lignin molecule in benzene-extractable copolymers. Two glass transition temperatures could be detected in several fractionated copolymers.     

Preparation of cellulose filters with covalently bound dithiocarbamate, 8-hydroxyquinoline,and aminocarboxylic acid functional groups

Filter papers with covalently bound chelating groups are produced with the aim to enrich metal ions simultaneously for measurement by X-ray fluorescence spectrometry. The selectivity of the chelating groups to transition elements is of utmost importance. Some analytically important chelating groups dithiocarbamate-, 8-hydroxyquinoline-derivatives, and aminocarboxylic acid (EDTA analogue) are immobilized on cellulose filter papers. These filters are produced in a flow reactor, filled with commercially prefabricated analytical grade filter papers. They are synthesized in a three-step-reaction. First, an epoxyactivated cellulose is produced which in the second step is converted into an aminocellulose. This aminocellulose is the starting material for the dithiocarbamate-, the 8-hydroxyquinoline, and EDTA-analogue cellulose. The immobilization of 8-hydroxyquinoline or 8-hydroxyquinoline-5-sulfonic acid is accomplished through an aminomethylation. The analytically useful capacity of the various chelating filter papers is for dithiocarbamate, 8-hydroxyquinoline, 8-hydroxyquinoline-5-sulfonic acid, and EDTA-analogue derivatives 600, 700, 400, and 600 μmol/g, respectively.