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35 results on '"Verovkins, Anrijs"'

5. POLYELECTROLYTE COMPLEX NANOPARTICLES OF SOLUBLE LIGNIN AND CHITOSAN AS INTERFACIAL MODIFIER

Author

Shulga, Galia, Shakels, Vadims, Vitolina, Sanita, Neiberte, Brigita, Verovkins, Anrijs, and This work was carried out due to the financial support of the performed research from the Base Financing provided by the Latvian Ministry of Education and Science.

Subjects
kraft lignin, chitosan, polyelectrolyte complex, interfacial modifier, oil-in-water emulsion
Abstract

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.

Published
2023

10. Environmental performance of combined treated wood.

Author

Kuka, Edgars, Cirule, Dace, Andersone, Ingeborga, Andersons, Bruno, Kurnosova, Nina, Verovkins, Anrijs, and Puke, Maris

Subjects
WOOD, SERVICE life, COPPER, WOOD products, WOOD preservatives
Abstract

Modification can significantly improve the service life of wood products, however, from the environmental perspective, the process has its drawbacks causing excessive influence in some specific impact categories. To reduce the impact that is characteristic of each individual modification process and to gain benefits due to synergy, the potential of using a combined treatment (copper azole impregnation + thermal modification) is evaluated. The results show that a combined treatment can provide enhanced environmental performance over each individual modification. [ABSTRACT FROM AUTHOR]

Published
2023
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16. VALORIZED SODA LIGNIN AND ITS POSSIBLE APPLICATION

Author

Shulga, Galia, primary, Vitolina, Sanita, additional, Neiberte, Brigita, additional, Jaunslavietis, Jevgenijs, additional, Verovkins, Anrijs, additional, Ozolins, Jurijs, additional, Livcha, Sandra, additional, and Betkers, Talrits, additional

Published
2019
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35. PENETRATION OF WOOD PRESERVATIVES INTO THERMALLY MODIFIED BIRCH AND PINE WOOD.

Author

CIRULE, Dace, KURNOSOVA, Nina, VEROVKINS, Anrijs, KUKA, Edgars, ANTONS, Andis, ANDERSONE, Ingeborga, and ANDERSONS, Bruno

Subjects
*WOOD preservatives, *PINE, *SCOTS pine, *TEMPERATURE effect, *THERMAL analysis
Abstract

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 - 180°C). 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. [ABSTRACT FROM AUTHOR]

Published
2018

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