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In this paper, the dominance of the physical effects of ultrasound (US) pretreatment in improving the delignification of wheat straw at a 1:20 solid/liquid (biomass/water) ratio is reported showing low-frequency/high power (25 kHz, 2 or 3 kW) as preferred conditions. The sonochemical pretreatment with alkali was identified as an optimal method to make the cellulose more susceptible to further enzymatic hydrolysis, thereby increasing the yield of soluble sugars. Previous bench-scale studies have shown that US pretreatment has a positive effect on delignification, nevertheless this has not yet been demonstrated on a larger scale. The objective of this study was to demonstrate the effectiveness of US pretreatment for wheat straw delignification from lab to semi-industrial scale (40 kg biomass) in terms of sugar yield and energy efficiency. A 59.2% of lignin removal was recorded after the cavitational treatment of wheat straw with a subsequent 68 ± 5.7% yield in terms of enzymatic hydrolysis (52.6% glucose, 42.9% xylose and 4.5% arabinose). It was demonstrated that the positive effect of US alkali pretreatment of wheat straw on sugar yield was due to a combination of factors, including (i) an easier accessibility of the biomass carbohydrate network to enzymes due to the increased wheat straw porosity, (ii) the partial removal of lignin, which increases the relative proportion of carbohydrates in the treated biomass, and (iii) the disordering (amorphization) of the cellulose structure, which promotes carbohydrate hydrolysis as well as saponification of the acetyl groups in the hemicellulose. With respect to the Life Cycle Assessment (LCA) and the Cost Benefit Analysis the US pretreatment process herein reported was compared to an alternative Steam Explosion pretreatment. The results of the LCA analysis showed, that for all five environmental categories (energy consumption, global warming potential, water and fossil depletion, and the land occupation) the US pretreatment has advantages in comparison with the standard industrial Steam Explosion pretreatment.

The barks of aspen (

An experimentally proven novel analytical approach for chromatographic analysis of diarylheptanoids in grey alder (Alnus incana) and black alder (Alnus glutinosa) bark matrices was established. A method for qualitative and quantitative determination of oregonin (dominant diarylheptanoid) and semiquantitative analysis of related diarylheptanoids from alder bark using a photodiode array (PDA) detector coupled to a high-resolution mass spectrometer (QTOF-MS) was developed. A comparison of different liquid chromatography detectors (UV, MS and ELS) showed that only a combination of them is applicable for comprehensive analysis of multicomponent extracts. A total of sixteen different diarylheptanoids were simultaneously identified and semi-quantified in alder bark extracts. This is the first report of the method for individual and total diarylheptanoid determination in alder bark extracts, discussed in detail. The liquid chromatography complex is suggested as a tool for the reliable identification and quality control of the diarylheptanoids containing extracts isolated from the Alnus species and their dominant component - oregonin. The semiquantitative methodology established, and the dominant compound quantification provided means for assessing comparative sample complexities.

The barks of aspen (Populus tremula) and pine (Pinus sylvestris) are byproducts of wood processing, characterized by their low economic value. In the present study, microwave-assisted one-cycle water extraction was explored as a tool for the valorization of this biomass as a source of biologically active compounds. The microwave extractor of the original construction equipped with a pressurized extraction chamber and a condenser section was used. The microwave-assisted extraction (MAE), specially including dynamic dielectric heating up to 70 °C followed by 30 min of isothermal heating, promoted the isolation of salicin from aspen bark, allowing for the obtention of a two-times-higher free salicin concentration in water extracts (−14% vs. 7%) reached by multi-cycle accelerated solvent extraction (ASE), which is an advanced technique used as a reference. The MAE of pine bark with dynamic heating up to 90–130 °C, avoiding the isothermal heating step, allowed for the obtention of a 1.7-times-higher concentration of proantocyanidin dimers-tetramers, a 1.3-times-higher concentration of catechin and a 1.2-times-higher concentration of quinic acid in water extracts in comparison to a more time- and solvent-consuming ASE performed at the same temperature. The biological activity of the obtained extracts was characterized in terms of their ability to inhibit xahntine oxidase enzyme, which is a validated target for the therapeutic treatment of hyperuricemia.

Processing of biomass for obtaining of liquid ethanol, platform chemicals and solid biofuel, is topical biorefinery schema intensively developing. Acid hydrolysis, separated hydrolysis and fermentation, and simultaneous saccharification and fermentation are integrated with other treatments for the advanced technology development. The aim of this work was estimation of effect of softwood and wheat straw hydrolysis type on fuel characteristics of rich-in-lignin residues with emphasis on content and component composition of ash and feedstock. Elemental Analysis; Atomic absorption spectroscopy; calorimetric method; Klason lignin determination were used. Laboratory scale pellet mill KAHL 14-175 and original small pilot-scale gasifier were used for study of residues granulation ability and combustion behavior of pellets obtained. The ash content in softwood residues slightly increase but does not exceed 1%, for wheat straw residues it is >14% (0,2% and 10% for feedstock, correspondingly). The ashing temperature of 650 o C is experimentally established as optimal. Detection of ash component allows to foreseen possible contamination connected with materials of the devices and chemicals used in the technological stream. Combustion mechanism of solid residues differs from that of feedstock by increasing of ratio duration of glue combustion to flame combustion steps, that is more characteristic for coal. The efficiency of biomass combustion was regulated by changing the ratio of primary and secondary air supply. Direct correlation established between higher heating value and Klason lignin content for samples, allows to recommend these analyses for evaluation of biomass potential as a fuel. Residues under study meet the requirements of EU Standard CN/TS 335. Keywords: biofuel, calorific value, combustion characteristics, inorganic admixtures, lignocellulosic hydrolysis, rich-in-lignin residues, softwood, wheat straw Article DOI: http://doi.org/10.15544/RD.2017.087

Rigid polyurethane (PUR) foams with the apparent density in the range of 45—60 kg/m 3 were produced from tall oil polyol (TOP) and organosolv wheat straw lignin as filler. PUR foams were filled with lignin in the amount of 0—6.3 wt %. Mechanical properties, dimensional stability, water absorption and thermal conductivity of prepared foams were investigated. The use of lignin increased the content of renewable materials in the end product, reaching together with TOP the value of 23.6 wt %. The viscosity of polyol system and foaming process parameters (cream time, gel time, tack-free time and full rise time) were determined. The viscosity of polyol system rose exponentially when concentration of lignin in the PUR foam was increased. The maximum value of compressive strength (0.35 MPa parallel to the foaming direction) was reached in the PUR sample where the concentration of lignin in foam was 1.2 wt %. It was concluded that wheat straw lignin can be used as a filler to obtain rigid PUR foams having the characteris- tics of thermal insulation material.

The modern biorefinery concept is aimed at the elaboration of sustainable processes with the most profitable utilization of all biomass products obtained at the technological cycle. Lignin separated as by-product in the lignocellulosic chemical processing is recognized as an important component of polymer systems. The presence of sterically hindered phenolic hydroxyl groups in the lignin macromolecule opens the possibility of its application as antioxidant for composites, e.g. polyurethanes (PU), which are considered as one of the most versatile polymeric materials. In the present work, the object of investigations was lignin obtained as a product, so-called BIOLIGNIN™, of wheat straw organosolv processing for pulp and fuel ethanol production (CIMV pilot plant, France). However, heterogeneity of the lignin obtained negatively influences its applicability that can be overcome by fractionation. Three soluble fractions were isolated from CIMV lignin by a sequential extraction with dichloromethane (A fraction), methanol (B fraction) and mixture of both the solvents (C fraction) and characterized in terms of their composition, functionality and structure using analytical pyrolysis (Py-GC/MS), 31P NMR and Size Exclusion Chromatography (SEC) methods. Antioxidant properties of BIOLIGNIN™ fractions were assessed in the tests with free radicals ABTS+ and DPPH. Application of Py-GC/MS for characterization of the fractions opened an opportunity to found some novel “structure–activity” correlations needed for understanding and tuning of antioxidant properties of lignins. The antioxidant activity of the fractions under investigation was tested by their influence on thermo-oxidative destruction of prepared model PU films. The data of TGA method (oxidative conditions) clearly testified the antioxidant effect of all three fractions with the most prominent activity for C fraction. The shifting of the exothermal maxima connected with oxidizing of volatile products of PU destruction to the higher temperature region by 20–30 K and 30–40 K was registered.