POLYELECTROLYTE COMPLEX NANOPARTICLES OF SOLUBLE LIGNIN AND CHITOSAN AS INTERFACIAL MODIFIER

A water-soluble non-stoichiometric polyelectrolyte complex (LCP) was obtained as a result of the interaction of oppositely charged kraft lignin and high molecular chitosan by mixing their dilute water solutions. The sizes of the LCP nanoparticles were characterized by a bimodal distribution at pH 6, and their values were essentially smaller than the sizes of the chitosan particles. It was found that the LCP nanoparticles were characterized by remarkably lower values of surface tension at the air-water and the water-organic liquid interface in comparison with the initial biopolymers. With decreasing pH and increasing concentration of the LCP nanoparticles in the water solution, their adsorption ability at the interfaces was enhanced. The interface tension at the water-heptane interface changed non-linearly with increasing the polyelectrolyte complex concentration that was associated with the “saturation” effect. The dependence of the ability of the LPC nanoparticles to stabilize oil-in-water emulsion on pH values of the water phase was found.

DIFFERENCE IN THE TREATMENT EFFECTIVENESS OF WOODWORKING WASTEWATER BETWEEN POLYALUMINIUM CHLORIDE-BASED COAGULANTS

in the work, a comparative study of the efficiency of coagulation of a model solution, simulating woodworking wastewater, with the known composition of polyaluminium chloride (РАС) with aluminium sulphate and a new РАС-based composite coagulant was carried out. It has been found that, in comparison with the known composition, the developed composite coagulant makes it possible to enhance the efficiency of the wastewater treatment and to decrease the content of residual aluminium therein, which enables the return of the treated water in the technological cycle. The enhancement of the coagulation ability of the developed composite coagulant relative to the known composition of РАС with aluminium sulphate is governed by the formation, in the AlCl3/РАС system, of polynuclear Аl-complexes with a high-molecular structure. This is testified by the results of the comparative study of those coagulants by the Ferron and ion mass spectroscopy methods

Functionalized Bark for Recycled Polypropylene-Based Composites

A new method for the modification of the bark surface using N,N-diethyl-2,3-epoxypropylamine (DEEPA) was developed. As a result, the part of the bark phenolic hydroxyl groups were replaced with amine groups. The conditions of the modification were found, and the modified products were analysed. The different amount of the introduced amino groups in hardwood and softwood bark was gained by the various contents of lignin in the wood species. The recycled propylene-based composites filled with the modified bark were characterised by higher mechanical parameters in comparison with the composites filled with unmodified bark. The differences in the mechanical properties of the polymer composites filled with softwood - pine (Pinus sylvestris) bark and hardwood - grey alder (Alnus incana) bark has been established

COMPARATIVE STUDY OF INDUSTRIAL LIGNOSULFONATES AND SOME THEIR PROPERTIES

The aim was to compare the chemical composition and some properties of three industrial lignosulfonates produced as a by-product at three pulp and paper mills (Russia). Using the classical methods of lignin chemistry, it was found that there were differences in the elemental composition and the content of functional groups of the industrial lignosulfonates, but in general, they were not very significant. The Kondopoga lignosulfonates contained the highest content of methoxy, aliphatic hydroxyl groups and carbonyl groups. The Vyborg lignosulfonates had the highest degree of sulfonation and the lowest content of carbonyl groups. The content of the functional groups in the chemical composition of the Syassky lignosulfonates was intermediate between the functional composition of the Vyborg and Kondopoga lignosulfonates. The Vyborg lignosulfonates had the lowest values of the viscosity average molecular mass, dynamic viscosity and surface tension at the air-water interface in comparison with these parameters of the Kondopoga and Syassky lignosulfonates

MECHANICAL PROPERTIES OF WOOD PLASTIC COMPOSITES WITH THE ACTIVATED WOOD FILLER

The aim of the research was a study of the effect of activation of birch sawdust microparticles with a dilute solution of sodium hydroxide at a low temperature on mechanical properties and water sorption of the obtained wood plastic composite (WPC) samples obtained from a by-product of a domestic wood mechanical processing and a recycled polymer municipal waste. It was found that the mechanical (tensile, bending) properties of the WPC samples filled with the activated birch sawdust microparticles were higher than those of the samples filled with the initial sawdust. The sorption and swelling degree of the WPC samples with the activated filler were lower than those for the samples with the initial sawdust. However, the difference in the values of the water sorption and the swelling degree for the samples filled with the activated and initial wood microparticles were relatively low in comparison with the observed essential difference in their mechanical properties. This fact was explained by the enhanced content of carbonyl groups in the activated sawdust microparticles that are able to absorb water

EFFECT OF THE ACIDIC TREATMENT OF DOMESTIC WOOD RESIDUE ON BIOCOMPOSITE WETTABILITY AND MOISTURE SORPTION PROPERTIES

The aim of the work was to evaluate the effect of the acidic treatment temperature of aspen sawdust as a filler on the moisture sorption, wetting and mechanical properties of wood-polymer composites. Aspen wood sawdust was treated with the dilute hydrochloric acid solution at 60oC and 90oC during 5 h. Both the treated particles and the filled composites were studied in terms of moisture sorption and wettability; their surface free energy was calculated using the Owens-Wendt-Rabel-Kaelble (OWRK) approach. The obtained results have shown that the acidic treatment of aspen wood sawdust at 90oC leads to an increase in its hydrophobicity that decreases the wettability and moisture sorption of the obtained composite and increases its mechanical properties

Wood Biomass from the Model Wastewater and Its Fractionation

The production of veneer in Latvia and many countries of East Europe is accomplished by the hydrothermal treatment of hardwood in special water basins. As a result, formed effluents contain wood-originated pollutants, which are responsible for the enhanced chemical oxygen demand and the intensive colour of the wastewater. Keeping in mind the volume of the polluted effluents formed annually at the Latvian plywood plants, it is very important to extract qualitatively and quantitatively the formed biomass from the effluent. The choose of an effective method of the waste biomass extraction depends on chemical characterisation of the effluent. In this work, for imitating woodworking wastewater, birch sawdust was hydrothermally treated in mild alkaline conditions at 90°C. The yield of the solid biomass did not exceed 7% and contained, mainly, hemicelluloses in the polysaccharide form and lignin. The applied instrumental analysis (FTIR-, UV-, Raman spectroscopy) testify the dominant content of hemicelluloses in the obtained biomass. The fractionation of the biomass was performed using concentrated sulphuric acid and ethanol. As the obtained results have shown, the content of lignin, hemicelluloses and water-soluble degraded wood products in the solid biomass corresponded to the following mass ratio: 1.2 /6.7 /1.0, respectively

VALORIZED SODA LIGNIN AND ITS POSSIBLE APPLICATION

The aim was to obtain a valorized soda lignin and to study its properties for the followed treatment of hardwood sawdust as a filler for obtaining a wood-polymer composite. It was shown that the treatment of aspen sawdust microparticles by their immersion into a water solution of the valorized soda lignin, that is a water-soluble soda lignin/polyethylenimine polyelectrolyte complex, leads to hydrophobisation of the sawdust particles, which in turn positively affects the mechanical performance of the obtained wood-polymer composite

Penetration of Wood Preservatives into Thermally Modified Birch and Pine Wood

The objective of the present study was to investigate the interaction between Cu-containing preservatives and birch (Betula spp.) and pine (Pinus sylvestris L.) wood, modified at a relatively mild temperatures (150 – 180ºC). The disposition of wood to absorb water was evaluated by capillary absorption (CA) tests through the specimens’ tangential and radial surface. Changes in wood drying characteristics due to thermal modification (TM) were evaluated by monitoring wood moisture dynamics after impregnation. In order to assess the capacity of wood to absorb preservatives, a vacuum/pressure process was used to impregnate small specimens for which uniform saturation into the entire volume can easily be reached. Quantitative determination of copper Cu content in the specimens was performed by using atomic absorption spectroscopy (AAS). The fixation of the absorbed Cu was evaluated by subjecting the specimens to leaching procedures according to EN 84 and assessing the ratio of retained Cu in the specimens. The CA test showed deceleration of capillary absorption in TM birch wood through both surfaces, with similar absorption rates regardless of treatment temperatures. A significant increase in the absorption rate through the tangential surface was recorded for TM pine wood and the increase was greater for specimens treated at higher temperatures. The results of moisture content monitoring showed a similar reduction in the drying rate due to thermal modification regardless of species. Comparing wood of one species with similar densities, less preservative was absorbed by TM wood. However, the results of AAS showed that, in comparison with unmodified wood, 10% (birch) and 25% (pine) more Cu per one gram of wood was introduced during impregnation. Nevertheless, TM also resulted in higher Cu leaching rates for both species

Wood processing by-products treated with the lignin-based conditioner as mulch for soil protection

Wood processing by-products such as bark of different wood species and hydrolysis lignin were applied as soil mulch. The lignin-based soil conditioner (LSC) representing a lignin-based polyelectrolyte complex with the different composition (a lignin/polymer mass ratio) was obtained under laboratory conditions and was intended to protect sandy soil from erosion by simultaneous application of a soil conditioner as an adhesive, mulch and plant seeds by hydroseeding. The study revealed the pronounced dependence of the properties of the treated wood-originated mulch on the wood species as well as on the composition, the applied concentration and the application rate of LSC. A comparison of the obtained results showed that the treated hydrolysis lignin was characterised by higher compressive strength, higher water resistance and lower moisture losses from sandy soil for a given LSC composition and application rate than the bark-based mulch. The conditioner concentrations don't have negative impact on the germination of seeds plants of the coastal dune zone. First published online: 21 Oct 201