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β-sitosterol (BS) is a phytosterol with wide potential in cosmeceutical, biomedical and food applications. In acid sulphite pulp cooking, BS and its derivatives are considered an underutilized natural source of bioactive compounds, which are adsorbed on the resulting pulp or dispersed in the spent liquor. In this work, a new method for the isolation of BS from alkaline extract (AE) of unbleached sulphite pulp purification stage is proposed. BS was recovered by two-step acidification of AE up to pH 3 under pre-selected conditions, followed by fractionation of the formed precipitate with water-miscible organic solvents, having obtained best results (>90% of BS purity; yield of 70-210 mg/dm3 of AE) with methanol fractionation followed by BS crystallization induced via addition of water (ca. 10% vol.). When ethanol was used instead, BS was detected in low amounts in the isolate, being fatty acid sterol esters and fatty acid glycerides the major components, as revealed from analyses by wet chemistry coupled with gas chromatography-mass spectrometry and thin layer chromatography (TLC). The method is adaptable for large-scale industrial production of BS and may represent an important source of sterol-based products. published

Competition issues with food industry have recently boosted the exploration of alternative solutions capable of replacing starch in papermaking to a certain extent. Covalent grafting of quaternary ammonium groups onto LignoBoost® Eucalyptus kraft lignin has recently shown promise in this regard as the cationic products feature excellent water solubility across the entire pH scale. Considering these suitable properties, cationic kraft lignin was applied and evaluated, for the first time, in the perspective of partial substitution of cationic starch in papermaking, using bleached Eucalyptus kraft pulp. Based on an assessment of key paper properties, such as mechanical (tensile, bursting, and tearing indexes), structural (roughness, capillarity rise, air resistance, internal strength, and water contact angle), and optical ones (brightness, opacity, and relative color change), it is safe to conclude that the partial replacement of conventional cationic starch by cationic lignin does not compromise these features. The results also show that properties can be fine-tuned by varying the degree of lignin derivatization, providing paper-specific solutions for replacing starch by lignin potentially available at large-scale at the pulp and paper industry, closing the loop within the circular economy concept.

Reactive washing (RW) is a key process for disinfecting, purifying, and bleaching of cork stoppers to seal bottles with alcoholic beverages. Excessively severe treatment conditions deteriorate the surface properties of cork stoppers and must be strictly controlled. In this study, the conventional RW of natural cork stoppers was optimized employing a fractional factorial design. The RW variables (H

Publisher Copyright: © 2021 The Authors. Published by American Chemical Society. Although extractives have been symbolized as major bioactive pharmacological compounds from Salix (Salicaceae) bark, we speculated that these pharmaceutical effects cannot be solely attributed to phenolic components and their derivatives, but the long-chain suberin acids also contribute to their therapeutic effects. Hence, isolation and deconstruction of suberin were conducted, for the first time, to enrich our knowledge about the macromolecular components at the cell wall of willow bark. Saponification was adopted to obtain suberin extracts at a yield of approximately 5 wt % based on the bark of the studied hybrids. Gas chromatography-mass spectrometry allowed qualification and quantification of 23 compounds from the released suberin monomers, from which fatty acids represented majority of the isolated suberin, namely, fatty acid methyl esters (C17-C19); mono-carboxylic acid (C7-C16); alpha, omega-dicarboxylic acid (C7-C16); and omega-hydroxy long-chain fatty acids (C16-C22). Additionally, the lipophilic extractive was dominated by piceol, heptacosane, β-sitosterol, and fatty acids (C16-C28) from the studied hybrids. These findings could boost our integrative approach toward full valorization of willow bark.

Aiming the sustainability of 3D-printed objects, in this study, pine bark particles were used as filler reinforcement for polyamide 6 (PA). In order to enhance the performance of the produced composites, the biomass was chemically modified via a two-step procedure. In the first step, the OH groups present on the particles surface were reacted with ethylenediamine, which were subsequently reacted with a polyol. Fourier-transform infrared spectroscopy (FTIR), 13C solid-state cross polarization–magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) and scanning electron microscopy coupled with energy-dispersive X-ray analysis confirmed the chemical modification of biomass. The masterbatch was prepared from modified pine bark particles and polymeric matrix (PA) being processed into test specimens. The ensuing composites revealed a significant increase in Young's modulus and maximum stress. Thus, the introduction of 10% modified biomass increases the Young's modulus by 87% and the maximum stress by 15%. Furthermore, analyzing the glass transition temperature (Tg), melting flow index and thermogravimetric analysis results, the modified biomass ensuing composites proved to be suitable for 3D printing. This was attributed to better compatibility between chemically modified biomass and matrix and, further, easier processing.

The dioxane lignin was isolated from extractives- and suberin-free cork (Quercus suber L.) by a modified acidolytic procedure and submitted to structural analysis by permanganate oxidation, analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC-MS), liquid- and solid-state nuclear magnetic resonance (NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The molecular weight (Mw = 2500 Da) was assessed by size exclusion chromatography (SEC). The results obtained show that the cork lignin is of syringyl (S)/guaiacyl (G) type with a small proportion of p-hydroxyphenyl (H) units (S:G:H molar ratio of 23:72:5). Among a dozen detected lignin structures, those linked by ether bonds, such as β-O-4' (38 mol %) and 4-O-5' (5 mol %), were the most abundant. The frequency of occurrence of β-5', β-β', 5-5', tetrahydrofuran type, and structures arising from the condensation with concomitant procyanidins was assessed. Ferulates were the only cinnamic structure detected in the cork dioxane lignin.

Laser-induced graphene (LIG) is a foam-like porous material consisting of few-layer graphene obtained by laser irradiation of a wide range of carbon-containing substrates. Among these, the ability to synthesize LIG from paper and other cellulose-related materials is particularly exciting, as it opens the door to a wide assortment of potential applications in the form of low-cost, flexible, and biodegradable devices. Here, the synthesis of this material, dubbed paper-LIG, on different types of filter papers and xylan biopolymer is discussed. In particular, we report the formation of paper-LIG by single-step irradiation, providing an improvement over the conventional multiple lasing approach and giving an explanation of the conditions that allow this simplified synthesis. All the relevant process parameters are covered, assessing their effect on the resulting electrical properties, structure, and morphology. Additionally, we demonstrate the application of LIG obtained from xylan, an abundant and often underutilized biopolymer, for temperature sensing. These results provide a better understanding of the conditions required for the synthesis of highly conductive LIG from paper and related materials, paving the way for its application, with reduced cost and low environmental impact, in fields ranging from biomonitoring to consumer electronics. published

Lignin obtained by Lignoboost® procedure from black liquor after kraft pulping of Eucalyptus globulus wood was characterized and converted into liquid polyols via an innovative and safe procedure using base catalyzed oxyalkylation with propylene carbonate (PC). The effect of four catalysts, Potassium carbonate (K2CO3), 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU), dicyanodiamide (DICY), and 1,4-diazabicyclo [2.2.2] octane (DABCO) was evaluated in terms of lignin polyol yield and weight gain. The ensuing polyols were also characterized by fourier transform infrared (FTIR), 1H NMR, 13C NMR, and size exclusion chromatography (SEC) to determine the degree of the substitution (DS), degree of polymerization (DP), and the molecular weight, respectively. Only a minor proportion of PC (ca. 3–15%) was converted to propylene glycol/homooligomers as revealed by high performance liquid chromatography (HPLC). All catalysts promoted preferential derivatization of lignin phenolic OH groups by oxypropyl moieties. The maximum average DP of propylene oxide chains in oxyalkylated Lignoboost® kraft lignin (oKL) was 1.85 per one phenylpropane unit (PPU) using DBU. Conversely, the DP of oKL using DICY was very low (0.27/PPU). DICY’s catalytic activity seems to be jeopardized due to the formation of unreactive adducts with lignin. The oKL obtained using DBU, DABCO, and K2CO3 have potential to be used as polyols in the production of polyurethanes as the corresponding hydroxyl number (IOH) is in the range of 198–410 mg KOH g−1.

Three industrial Eucalyptus globulus acid sulphite dissolving pulps of different intrinsic viscosity (ca. 490–570 cm3/g) with similar xylan content (2.4–3.0%) were partially (ca. 60%) converted to cellulose II by treatment with 12% NaOH and hornified by drying for 8 h at 105 °C to induce changes in physical structure. All three initial and modified pulps were analysed on their Fock reactivity method and Chinese filterability. These dissolving pulps were also examined for the crystallinity degree and the crystallite dimensions assessed by wide-angle X-ray scattering and the fibril aggregation assessed by solid-state 13C nuclear magnetic resonance. The results showed that the reactivity of the dissolving pulp was negatively correlated with the degree of cellulose crystallinity and depended almost linearly on the lateral dimension of the fibril and the dimensions of the fibril aggregates. In hornified pulps, the effect of cellulose physical structure on reactivity was even more pronounced than the intrinsic viscosity of the dissolving pulp. In addition, no unambiguous dependence between the reactivity and the filterability of dissolving pulps was found. Filterability did not correlate clearly with lateral dimension of fibril or fibril aggregates, but depended only on pulp viscosity.

The structural features of macromolecular components of cork (suberin, lignin, cellulose and hemicelluloses) from Quercus suber L. used for the production of stoppers were assessed after their isolation and purification. Suberin is the major component of cork (ca. 44%) and is constituted mainly by hydroxy fatty acids (C14–C26). Cork lignin was found to be highly condensed (16.2%) and revealed a syringyl:guaiacyl:p-hydroxyphenyl (S:G:H) ratio of 26:71:3 with predominant β-O-4′ (0.38%), β-5′, β-β and tetrahydrofuran (THF) type (totally ca. 27%) structures. Cork lignin also has a remarkable amount of ferulic acid structures, which are considered the binding point between lignin and suberin. The cellulose of cork cells (17.2%) is a typical cellulose I polymorph with a degree of crystallinity (DC) of 70.3% and an average crystallite width of 3.5 nm. The major hemicellulose of cork is glucuronoxylan (near 6.0%) possessing a molar Xylp:MeGlcpA ratio of 14:1.

The accessibility of glucuronoxylan from a refined, bleached Eucalyptus globulus industrial kraft pulp in 0–18% aqueous NaOH solution at room temperature (25°C) was studied. The extraction profile revealed a maximum extraction of xylan in the pulp at about 10–12% NaOH concentration and was explained by the maximum swelling of the pulp according to the Gibbs-Donnan equilibrium. The kinetics of xylan removal and the monitoring of its structural features were performed at 5 and 10% NaOH concentrations. The maximum yields of xylans with 10% and 5% NaOH were as high as 90% and 60% for 2 h extraction, respectively. The structural features of xylan were assessed by acid methanolysis and one-dimensional (1D)/two-dimensional (2D) nuclear magnetic resonance (NMR), and the molecular weight by size exclusion chromatography (SEC). The xylan extracted with 10% NaOH had a slightly higher molecular weight and a lower branching with uronic moieties than the xylan extracted with 5% NaOH. The former was less pure (contained more β-cellulose) than the latter. Structural studies by NMR resulted in the conclusion that there are at least two types of xylans removed from the pulp: one xylan with relatively high 4-O-methyl-α-D-glucuronosyl [MeGlcA-(1→] and [→2)-MeGlcA-(1→] substituents and another xylan with a much lower substitution with uronic residues.

Lignosulfonates (LS) from acidic magnesium-based sulfite cooking of Eucalyptus globulus wood were modified via laccase-catalyzed oxidative treatment with the aim to improve their performance as plasticizing additives in concrete formulations. The target parameters were the increment of molecular weight (Mw) and the amount of oxidized groups. The laccase-assisted oxidation under optimized conditions (40°C, pH 4.5, enzyme loads of 83–500 U g−1 for 90 min) allowed Mw increment up to 11-fold and almost doubled the amount of carbonyl and carboxyl groups without using any mediators. Modified LS maintained their solubility in water and possessed a zeta- potential close to that of initial LS. The characterization of modified LS has been carried out by ultraviolet-visible (UV-Vis), Fourier transform infrared-attenuated total reflectance (FTIR-ATR) and quantitative 13C nuclear magnetic resonance (NMR) spectroscopy, and the sulfonic and phenolic groups were assessed by conductometric titration. It was concluded that LS polymerization occurred mostly via the formation of new aryl ether bonds (two thirds of the modification) and biphenyl bonds (the remaining third). However, part of the newly formed bonds of unknown origin are temperature labile and cleaved during the concentration of LS at pH 4 and 80°C under vacuum, which led to the reduction of the Mw of the modified lignin to almost one third.

The re-profiling from paper-grade to dissolving pulp production is a common trend for acid sulfite cooking of wood. This provides substantial changes in the composition of the spent sulfite liquor (SSL) affecting its potentialities in subsequent processing within the biorefinery concept. In this work, a comparative analysis of the chemical composition of SSL was performed from the magnesium-based acid sulfite cooking of Eucalyptus globulus wood to produce the paper-grade and dissolving pulps. More severe pulping conditions required for dissolving pulp production led to a substantial increase in volatile compounds in SSL, such as acetic acid, methanol, and furfural. At the same time, the amounts of dissolved sugars and lignosulfonates (LS) were increased to a less extent. The main changes detected in LS were related to the increase of its molecular weight, degree of condensation, and sulfonation degree. The increased concentration of the sulfuric acid in SSL was one of the reasons for these change published

In this study, the sulphur oxide anions profile at all stages of the Mg acid sulphite pulping process was evaluated by Ion Chromatography (IC). The concentration of bisulphite anions decreased almost two-third along the cooking, while the sulphate concentration increased progressively. Of the bisulphite consumed, only a third was converted to sulfates. Unexpectedly, the maximum thiosulphate concentration was found in the pulping acid filling step, being further decreased along the cooking. The chloride ions rise progressively during the cooking being extracted essentially from the wood, although a noticeable part of the phosphate anions belongs to pulping reagents and inlet water. The low molecular weight fraction of lignosulphonates (LS) appeared in the cooking liquor in the residual delignification step and, together with xylonic acid, contributed to an overestimation of the fluoride concentration determined by the IC due to the same retention time in the chromatographic column during the analysis.

The increasing demand for cellulosic fibres is continuously driven by the growing earth population and requirements of the textile industry. The annual cotton production of ca. 25 million tons is no longer enough to meet the market demands. This market gap of cellulosic fibres is progressively filled by regenerated cellulosic fibres derived from the dissolving pulp. The conventional industrial process of viscose production is far from being environmentally friendly due to the use of hazardous reagents. Alternatively, new trends in the production of regenerated fibres are related to the direct dissolution of cellulose in appropriate environmentally sound recyclable solvents, allowing high quality rayon fibres. This article reviews the sources of dissolving pulps used for the production of viscose and its quality parameters related to the performance of viscose production. The prospective cellulose regeneration processes, both commercialized and under development, are reviewed regarding current and future developments in the area.

The feasibility of using lignosulfonate (LS) from acid sulphite pulping of eucalyptus wood as an unmodified polyol in the formulation of polyurethane (PU) adhesives was evaluated. Purified LS was dissolved in water to simulate its concentration in sulphite spent liquor and then reacted with 4,4′-diphenylmethane diisocyanate (pMDI) in the presence or absence of poly(ethylene glycol) with Mw 200 (PEG200) as soft crosslinking segment. The ensuing LS-based PU adhesives were characterized by infrared spectroscopy and thermal analysis techniques. The adhesion strength of new adhesives was assessed using Automated Bonding Evaluation System (ABES) employing wood strips as a testing material. The results showed that the addition of PEG200 contributed positively both to the homogenization of the reaction mixture and better crosslinking of the polymeric network, as well as to the interface interactions and adhesive strength. The latter was comparable to the adhesive strength recorded for a commercial white glue with shear stress values of almost 3 MPa. The optimized LS-based PU adhesive formulation was examined for the curing kinetics following the Kissinger and the Ozawa methods by non-isothermal differential scanning calorimetry, which revealed the curing activation energy of about 70 kJ·mol−1.

The production of regenerated cellulosic fibres, such as viscose, modal and lyocell, is based mainly on the use of dissolving wood pulp as raw material. Enzymatic processes are an excellent alternative to conventional chemical routes in the production of dissolving pulp, in terms of energy efficiency, reagent consumption and pulp yield. The two main characteristics of a dissolving pulp are the cellulose purity and the molecular weight, both of which can be controlled with the aid of enzymes. A purification process for paper-grade kraft pulp has been proposed, based on the use of xylanases in combination with hot and cold caustic extraction, without the conventional pre-hydrolysis step before kraft pulping. This enzyme aided purification allowed the production of a dissolving pulp that met the specifications for the manufacture of viscose, < 3% xylan, > 92% ISO brightness and 70% Fock’s reactivity. Endoglucanases (EGs) can efficiently reduce the average molecular weight of the cellulose while simultaneously increasing the pulp reactivity for viscose production. It is shown in this study that lytic polysaccharide monooxygenases act synergistically with EGs in the modification of bleached dissolving pulp.

The dioxane lignin was isolated from extractives- and suberin-free cork (

This work studies the extraction and purification of a novel arabinogalactan from pistachio external hull. It was extracted with a simple method from pistachio hull which is considered as unexploited waste. Based on the results of sugar analysis by GC-FID, glycosidic linkage by GC–MS, NMR spectroscopy, and molecular weight by Size Exclusion Chromatography, pistachio hull water soluble polysaccharides (PHWSP) were identified as a type II arabinogalactan (AG), with characteristic terminally linked α-Araf, (α1 → 5)-Araf, (α1 → 3,5)-Araf, terminally linked β-Galp, (β1 → 6)-Galp, and (β1 → 3,6)-Galp. DEPT-135, HSQC, HMBC and COSY NMR data suggested the presence of (β1 → 3)-Galp mainly branched at O-6 with (β1 → 6)-Galp chains, α-Araf chains, and terminally linked α-Araf. These AG from pistachio external hulls showed in vitro stimulatory activity for B cells, suggesting their possible use as an immunological stimulant in nutraceutical and biomedical applications.

Non-enzymatic transglycosylation reactions are known to occur under high sugar concentrations, high temperatures, low moisture environments and acidic conditions. Although honey is not a thermally processed food, its high sugars concentration under an acidic and low moisture environment for prolonged periods of time may also promote these reactions. To test this hypothesis six model solutions containing combinations of sucrose and glucose or fructose, prepared with water and diluted citric acid at pH 4.0 and 2.0, were incubated at 35 °C during up to 5 months, similar to the honey under hive conditions. Electrospray ionization mass spectrometry (ESI-MS) allowed to observe polymerization products soon after their incubation. After 5 months, a degree of polymerization of 6 was detected, similarly to the honey samples used for comparison. Maltose, isomaltose, inulobiose, sophorose, gentiobiose, 1-kestose and panose were detected in both model solutions and honey samples, showing that non-enzymatic transglycosylation reactions also contribute to oligosaccharides origin and diversity in honey.

In order to close the water cycle in pulp mills with condensates instead of fresh water, the malodorous/hazardous volatile compounds and colored substances have to be removed by appropriate efficient methods. In the present work, the condensate from the evaporation of black liquor (BL) from a kraft mill was purified by a batch adsorptive process by means of commercial activated carbon (AC). The effluent was found to contain a wide range of aromatic and organosulfur volatile compounds, including toluene, ethylguaicol, syringaldehyde, dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), 2,3-dimethylthiophene, benzothiol and benzothiophene derivatives. Methanol was the major volatile organic component in the condensate (201 mg l−1), which was, however, poorly adsorbed on the AC surface. Aromatics and organosulfur contaminants were adsorbed almost completely in 2–5 min at 23°C under the optimized AC load (900 mg l−1). The treatment allowed the elimination of up to 99% of the obnoxious odor, color and turbidity of the condensate. The adsorption equilibrium followed the Langmuir model and the pseudo-second-order kinetics. The new process could be incorporated in the pulp mill with relatively low additional reagent costs.

During the hydrolytic degradation of cellulose caused by acidic transition metal sulphates, new low molecular products such as monosaccharides and their degradation products are usually formed which can increase the cellulose sensitivity to oxidation. This work was aimed at elucidation of the chemical and structural changes of cellulose in silver fir (Abies alba Mill.) wood treated with iron, copper and zinc salts to achieve a detailed understanding of cellulose deterioration during accelerated ageing. Cellulose samples were isolated from the wood by the Kurschner-Hoffer method and the Seifert method. Changes in cellulose structure were evaluated by wide-angle X-ray scattering (WAXS) measurements, Fourier transform infrared spectroscopy (FTIR), and high performance liquid chromatography. The presence of metal cations (Cu2+, Zn2+, Fe3+) caused a significant loss in the content of cellulose for treated and aged wood samples. Wet-thermal accelerated ageing led to a decrease (~ 20%) in the content of monosaccharides. The Seifert cellulose samples had a higher crystallinity than the Kurschner-Hoffer samples. A strong correlation was found between crystallinity indices obtained from the FTIR and WAXS measurements. Two cluster groups of cellulose samples, segregated from each other, were identified within each cellulose type in a multivariate cellulose trait analysis.

A levan-type fructooligosaccharide was produced by a Paenibacillus strain isolated from Brazilian crude oil, the purity of which was 98.5% after precipitation with ethanol and dialysis. Characterization by FTIR, NMR spectroscopy, GC-FID and ESI-MS revealed that it is a mixture of linear (26) fructosyl polymers with average degree of polymerization (DP) of 18 and branching ratio of 20. Morphological structure and physicochemical properties were investigated to assess levan microstructure, degradation temperature and thermomechanical features. Thermal Gravimetric Analysis highlighted degradation temperature of 218°C, Differential Scanning Calorimetry (DSC) glass transition at 81.47°C, and Dynamic Mechanical Analysis three frequency-dependent transition peaks. These peaks, corresponding to a first thermomechanical transition event at 86.60°C related to the DSC endothermic event, a second at 170.9°C and a third at 185.2°C, were attributed to different glass transition temperatures of oligo and polyfructans with different DP. Levan showed high morphological versatility and technological potential for the food, nutraceutical, and pharmaceutical industries., São Paulo Research Foundation (FAPESP) within Grants 2020/13271-6 and 2018/25511-1. Additionally, the authors acknowledge the financial support by National Council for Scientific and Technological Development – CNPq and by Coordination for the Improvement of Higher Education Personnel (CAPES), Finance Code 001. In addition, this study was supported by the Portuguese Science Foundation (FCT) under the scope of the strategic funding of UID/BIO/04469/2020 unit and the Project FOSYNBIO (POCI-01-0145-FEDER-029549)., info:eu-repo/semantics/publishedVersion

Ellagitannins, condensed tannins, and pectic-derived polysaccharides were removed from natural cork stoppers using hydroalcoholic solution. Two main populations of migrated compounds were determined; the major one with molecular weight (

The changes in the cellulose structure of eight Eucalyptus species (E. botryoides, E. globulus, E. grandis, E. maculata, E. propinqua, E. rudis, E. saligna and E. viminalis) in a mild torrefaction (from 160 &deg, C to 230 &deg, C, 3 h) were studied in situ and after cellulose isolation from the wood by solid-state carbon nuclear magnetic resonance (13C NMR), wide angle X-ray scattering (WAXS), Fourier transform infrared spectroscopy (FTIR) and by analytic pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). Changes in molecular weight were assessed by viscosimetry. A small decrease in cellulose crystallinity (ca. 2%&ndash, 3%) was attributed to its amorphization on crystallite surfaces as a result of acid hydrolysis and free radical reactions resulting in the homolytic splitting of glycosidic bonds. The degree of the cellulose polymerization (DPv) decreased more than twice during the heat treatment of wood. It has been proposed that changes in the supramolecular structure of cellulose and in molecular weight during a heat treatment can be affected by the amount of lignin present in the wood. The limitations of FTIR and Py-GC/MS techniques to distinguish the minor changes in cellulose crystallinity were discussed.

Ionic liquids (ILs), being related to the design of new environmentally friendly solvents, are widely considered for applications within the “green chemistry” concept. Due to their unique properties and wide diversity, ILs allow tailoring new separation procedures and producing new materials for advanced applications. However, despite the promising technical performance, environmental concerns highlighted in recent studies focused on the toxicity and biodegradability of ILs and their metabolites have revealed that ILs safety labels are not as benign as previously claimed. This review refers to the fundamentals about the properties and applications of ILs also in the context of their potential environmental effect. Toxicological issues and harmful effects related to the use of ILs are discussed, including the evaluation of their biodegradability and ecological impact on diverse organisms and ecosystems, also with respect to bacteria, fungi, and cell cultures. In addition, this review covers the tools used to assess the toxicity of ILs, including the predictive computational models and the results of studies involving cell membrane models and molecular simulations. Summing up the knowledge available so far, there are still no reliable criteria for unequivocal attribution of toxicity and environmental impact credentials for ILs, which is a challenging research task.

A sensor consisting of an optical fibre with the exposed tip coated with the polyoxometalate salt [(C4H9)4N]4H[PMo10V2O40], specially designed to be insoluble in water, which UV–Vis spectrum changed in contact with formaldehyde, is presented. The sensor limit of detection for formaldehyde was 0.2 mg L−1, and the limit of quantification was 0.6 mg L−1, which were close to the conventional spectrophotometric method values of 0.2 mg L−1 and 0.5 mg L−1, respectively, and lower than the tolerable limit for ingested food. The sensor was tested for formaldehyde quantification in milk, as its deliberate addition is a matter of concern. The results obtained analysing formaldehyde in milk samples by the optical sensor and by the conventional method were not statistically different (α = 0.05).

This study reports the synthesis of polyurethane&ndash, lignin copolymer blended with carbon multilayer nanotubes to be used in all-solid-state potentiometric chemical sensors. Known applicability of lignin-based polyurethanes doped with carbon nanotubes for chemical sensing was extended to eucalyptus LignoBoost&reg, kraft lignin containing increased amounts of polyphenolic groups from concomitant tannins that were expected to impart specificity and sensitivity to the sensing material. Synthesized polymers were characterized using FT-MIR spectroscopy, electrical impedance spectroscopy, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry and are used for manufacturing of all solid-state potentiometric sensors. Potentiometric sensor with LignoBoost&reg, kraft lignin-based polyurethane membrane displayed theoretical response and high selectivity to Cu (II) ions, as well as long-term stability.

Changes in the lignin structure of eight eucalypt species (E. botryoides, E. globulus, E. grandis, E. maculata, E. propinqua, E. rudis, E. saligna, and E. viminalis) upon mild thermal treatment, where the temperature was gradually raised from 160 to 230 °C over 3 h, were studied by solid-state carbon nuclear magnetic resonance (13C NMR) and after lignin isolation from the wood by acidolysis employing liquid-state 1D and 2D NMR techniques. The molecular weight of the isolated lignins was assessed by size exclusion chromatography (SEC) and their composition by analytic pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). The thermal treatment induced in lignin partial demethylation (up to ca. 30% from total) and a remarkable reduction in β-O-4 structures (up to ca. 60%), in an extent depending on the ratio of syringyl and guaiacyl units of the specific lignins. The lignin molecular weight reduced only ca. 25% under the thermal treatment due to the likely occurrence of condensation reactions by homolytic and heterolytic mechanisms. The noticeable increase in phenylcoumaran (β-5) and pinoresinol/syringaresinol (β-β) structures in lignin after thermal treatment was tentatively explained by their relative thermal resistance and by newly formed structures as the result of radical coupling reactions occurred during homolytic dissociation of the β-O-4 linkages. Lignins in thermally treated wood contained more than twice phenolic hydroxyls and more aliphatic carboxyl groups than lignins in untreated wood.