Papers by Oskars Bikovens
Key Engineering Materials, Apr 1, 2019
In the present study, the Fucus vesiculosus is considered as perspective feedstock for obtaining ... more In the present study, the Fucus vesiculosus is considered as perspective feedstock for obtaining fertilizers and valuable biologically active compounds. Polyphenols (phlorotannin) and sulfated polysaccharide (fucoidan) were isolated using sequential extraction from the above-mentioned seaweed. The total content of polyphenolics in hydrophilic extracts is 680 GAE/g. The yield of fucoidan from brown algae was 7 % on the oven dry seaweed. The assessment of biological activity of Fucus vesiculosus was performed using germination test and vegetation test. The results of the tests revealed that the Fucus vesiculosus promotes the growth of the agricultural plants, is not phytotoxic, and has a good potential in sustainable agriculture
Holzforschung, 2015
The new organosolv process of wheat straw fractionation elaborated by Compagnie Industrielle de l... more The new organosolv process of wheat straw fractionation elaborated by Compagnie Industrielle de la matiere Vegetale (France) corresponds to the biorefinery approach, which allows separating cellulose, hemicelluloses, and lignin. The straw lignin (Biolignin™) is an attractive product, for which new applications are sought. In the present work, straw lignin (L) was converted into liquid lignopolyols via a batch reaction with propylene oxide (PO). The effects of the lignin content (L%) in the initial reaction mixture (L/(L+PO) on the oxypropylation process and the properties of whole lignopolyols and L/PO copolymers were studied. Almost complete disappearance of L-OHphen and L-COOH groups in copolymers was accompanied by an increase in the L-OHaliph groups’ content therein. The polydispersity (M w /M n ) of all copolymers obtained decreased essentially compared to the reference. The extent of PO grafting onto OH groups increased with decreasing lignin content in the initial reaction mi...
Production of bioethanol by lignocellulosics hydrolysis has a long history, and nowadays bioethan... more Production of bioethanol by lignocellulosics hydrolysis has a long history, and nowadays bioethanol application as transport fuel makes it a topical task worldwide. In all configurations of hydrolysis including moderns ones, a significant amount of a raw material (up to 40-45%) remains as a rich-in-lignin non-hydrolyzed residue (LHR), and the feasible use of this residue is the necessary condition for the cost-effective operation of bioethanol production. The large potential of LHR as the raw material for obtaining products useful for environment protection, agriculture and industry is good recognized. The aim of the present work was to study LHRs composition with emphasis on their lignin component chemical structure modification upon various stages of the bioethanol production process carried out in three different configurations: softwood acid hydrolysis (AH), separate enzymatic hydrolysis and fermentation (SHF), and simultaneous saccharification and fermentation (SSF) in pilot plant conditions in Sweden. The characterization of LHRs structure on molecular level was done applying Py-GC/MS. High portion of the carbohydrates-derived pyrolytic products for LHR samples after SHF and AH processes indicates on non-completeness of processing or development of side reactions and visa versa high portion of lignin-derived compounds – up to 80% (SSF) shows the efficiency of hydrolysis process. Using Py-GC/MS the changes in molecular structure of lignin component of non-hydrolyzed residues on various stages of the technological process of bioethanol production were revealed: development of condensation reactions, ether bonds cleavage, destruction of side propane chain, oxidation. The results of the present investigation allow to conclude that the application of Py-GC/MS opens the opportunity for prompt, detailed and reliable characterization of changes of the composition of ligno-carbohydrate complexes
Vide. Tehnoloģija. Resursi, Aug 5, 2015
The composition of diarylhepatnoids fraction isolated from bark of two alder species (grey alder ... more The composition of diarylhepatnoids fraction isolated from bark of two alder species (grey alder and black alder) was studied. The efficiency of three extraction methods used for isolation of diarylhepatnoids from alder bark was compared. Two diarylhepatnoids: 1,7-bis-(3,4-dihydroxyphenyl)-heptan-3-one-5-O-β-D-xylopyronoside (oregonin) and 1,7-bis-(3,4-dihydroxyphenyl)-3-hydroxyheptane-5-O-β-Dxylopyranoside were isolated from the bark of grey alder. The phenolic components of the extracts were analyzed by high-performance liquid chromatography (HPLC). Quantitative determination of oregonin was performed using an internal standard method. The results obtained show that alder barks are rich source of diarylhepatnoids.
Plants, Feb 26, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Holzforschung, May 11, 2013
The oxidative modification of Biolignin (BL) has been investigated to make it more suitable as an... more The oxidative modification of Biolignin (BL) has been investigated to make it more suitable as an adsorbent for transition/heavy metals. BL is a by-product of a wheat straw organosolv process for the production of pulp, ethanol, and pentoses (CIMV S.A. pilot plant, Levallois Perret, France). It was subjected to oxidation by a polyoxometalate (POM) H 3 [PMo 12 O 40 ], aiming at the increment of oxygen-containing adsorption-active sites. The POM oxidation of BL was performed under moderate conditions (1 bar, 60-90 ° C, and 200 ° C) with the co-oxidants O 2 or H 2 O 2. The resulting lignin functionality and structure was evaluated by pyrolysis-gas chromatography/mass spectrometry, solid-state 13 C nuclear magnetic resonance, Fourier transform infrared, and chemical analysis. The condensation degree of BL and its COOH and aliphatic OH group contents increased significantly, whereas the polymer structure was maintained. Under optimal conditions with POM/H 2 O 2 , the sorption capacity of lignins toward Cd(II) and Pb(II) was increased threefold and twofold, respectively.
Frontiers in Marine Science, Oct 20, 2021
Biomass is defined as organic matter from living organisms represented in all kingdoms. It is rec... more Biomass is defined as organic matter from living organisms represented in all kingdoms. It is recognized to be an excellent source of proteins, polysaccharides and lipids and, as such, embodies a tailored feedstock for new products and processes to apply in green industries. The industrial processes focused on the valorization of terrestrial biomass are well established, but marine sources still represent an untapped resource. Oceans and seas occupy over 70% of the Earth's surface and are used intensively in worldwide economies through the fishery industry, as logistical routes, for mining ores and exploitation of fossil fuels, among others. All these activities produce waste. The other source of unused biomass derives from the beach wrack or washedashore organic material, especially in highly eutrophicated marine ecosystems. The development of high-added-value products from these side streams has been given priority in recent years due to the detection of a broad range of biopolymers, multiple nutrients and functional compounds that could find applications for human consumption or use in livestock/pet food, pharmaceutical and other industries. This review comprises a broad thematic approach in marine waste valorization, addressing the main achievements in marine biotechnology for advancing the circular economy, ranging from bioremediation applications for pollution treatment to energy and valorization for biomedical applications. It also includes a broad overview of the valorization of side streams in three selected case study areas: Norway, Scotland, and the Baltic Sea.
Materials
Lignocellulosic biomass (LCB)-based thermal insulation materials available in the market are more... more Lignocellulosic biomass (LCB)-based thermal insulation materials available in the market are more expensive than conventional ones and consist mainly of wood or agricultural bast fibers which are primarily used in construction and textile industries. Therefore, it is crucial to develop LCB-based thermal insulation materials from cheap and available raw materials. The study investigates new thermal insulation materials from locally available residues of annual plants like wheat straw, reeds and corn stalks. The treatment of raw materials was performed by mechanical crushing and defibration by steam explosion process. Optimization of thermal conductivity of the obtained loose-fill thermal insulation materials was investigated at different bulk density levels (30–45–60–75–90 kg m−3). The obtained thermal conductivity varies in range of 0.0401–0.0538 W m−1 K−1 depending on raw material, treatment mode and a target density. The changes of thermal conductivity depending on density were de...
Wood Science and Technology, Nov 19, 2022
Design of adhesive joints with different elastic propertie
Proccedings of International Scientific Conference "RURAL DEVELOPMENT 2017"
The seaweed collected after stranding on beaches of Latvia is underexploited natural resource, wh... more The seaweed collected after stranding on beaches of Latvia is underexploited natural resource, which has a potential as raw material for biologically active compound extraction for cosmetic and pharmacy and fertilizer in sustainable agriculture. The aim of the present study was development of the approach for the processing of brown alga Fucus vesiculosus biomass, collected from the Gulf of Riga. The thorough characterization of the chemical composition of Fucus vesiculosus has shown that it is a potential source for obtaining of nitrogen-containing fertilizers, and biologically active compounds. One of the proposed approaches for the processing of the Fucus vesiculosus biomass under study includes algae extraction with organic solvents and CaCl2 solution and obtaining soil organic amendment on the basis of the extract-free residue. The ethyl acetate extract was rich in phenolic compounds (430 ± 30 GAE mg/g) with high antioxidant activity in DPPH• and ABTS•+ tests. The ethanol extra...
Materials
In the current decade, based on the European Green Deal, new challenges of the wood-based panel i... more In the current decade, based on the European Green Deal, new challenges of the wood-based panel industry have arisen, seeking for formaldehyde-free bio-based adhesives and broadening raw lignocellulosics. In order to contribute to the potential solution to the challenges, binder-less boards of steam-exploded (SE 220 °C/2 min) hemp shives and wheat straw were investigated. The objective of this study was to find out the optimal hot-pressing conditions in terms of temperature (150–200 °C) and time (5–16 min) for the boards with three density levels (800–1000–1200 kg·m−3). An experimental design was created and the influence of the variables on binder-less panels were evaluated using a randomized central composite design of the response surface methodology. Water absorption (WA) and thickness swelling (TS) during 24 h, modulus of elasticity (MOE), and modulus of rupture (MOR) in bending test, internal bonding (IB), and Fourier-transform infrared spectroscopy were determined for the obt...
Materials
Toxic formaldehyde emissions, and the necessity to reduce the consumption of petrochemicals, stim... more Toxic formaldehyde emissions, and the necessity to reduce the consumption of petrochemicals, stimulates the development of environmentally friendly adhesives. The aim of this research was to study, for the first time, the possibility of using condensed tannins (CTs)-rich extracts from grey alder (Alnus incana) and black alder (Alnus glutinosa) bark in the production of particleboards and plywood adhesives. The chemical structure, composition, and molecular weight of the CTs were identified by a 13C-NMR and TOF-MS analysis. Three innovative adhesive systems were studied: CTs-phenol-formaldehyde (CTs-PF) resin; a CTs-polyethyleneimine (PEI) adhesive system; and CTs–PEI combined with an ultra-low emitting formaldehyde resin (ULEFR)—CTs–PEI–ULEFR. The results showed that CTs-PF resin has properties close to commercial PF resin, and the formaldehyde emission was twice lower. CTs–PEI bonded particleboards corresponded to the requirements of the EN 312:2010 standard for particleboards in d...
Industrial Crops and Products, 2022
Plants, 2022
For sustainable sea buckthorn (Hippophae rhamnoides) berry production, the task at hand is to fin... more For sustainable sea buckthorn (Hippophae rhamnoides) berry production, the task at hand is to find an application for the large amount of biomass waste arising at harvesting. Sea buckthorn (SBT) vegetation is currently poorly studied. The purpose of this research was to assess the composition and potential of SBT twigs as a source of valuable biologically active substances. Water and 50% EtOH extracts of twigs of three Latvian SBT cultivars with a high berry yield and quality, popular for cultivation in many countries (H. rhamnoides ‘Maria Bruvele’, ‘Tatiana’, ‘Botanicheskaya Lubitelskaya’), were investigated for the first time. The phytochemical composition (UHPLC-ESI-MS/MS analysis) and biological activity of the obtained hydrophilic extracts were determined. The highest yield of polyphenolic compounds and serotonin was observed for ‘Maria Bruvele’. Hydrophilic extracts were investigated for radical scavenging activity (DPPH˙ test), antibacterial/antifungal activity against five p...
Frontiers in Marine Science, 2021
Biomass is defined as organic matter from living organisms represented in all kingdoms. It is rec... more Biomass is defined as organic matter from living organisms represented in all kingdoms. It is recognized to be an excellent source of proteins, polysaccharides and lipids and, as such, embodies a tailored feedstock for new products and processes to apply in green industries. The industrial processes focused on the valorization of terrestrial biomass are well established, but marine sources still represent an untapped resource. Oceans and seas occupy over 70% of the Earth’s surface and are used intensively in worldwide economies through the fishery industry, as logistical routes, for mining ores and exploitation of fossil fuels, among others. All these activities produce waste. The other source of unused biomass derives from the beach wrack or washed-ashore organic material, especially in highly eutrophicated marine ecosystems. The development of high-added-value products from these side streams has been given priority in recent years due to the detection of a broad range of biopolym...
International Journal of Agricultural Resources, Governance and Ecology, 2020
Seaweed is one of Latvia's underexploited natural resources. Green and brown algae collected ... more Seaweed is one of Latvia's underexploited natural resources. Green and brown algae collected after stranding on beaches were co-composted with lignocellulosic substratum - grass and/or hardwood sawdust. Six different compost compositions were prepared. Composting was carried out indoors in the autumn-winter season. The correspondence of the obtained composts to the national and EU legislation was evaluated. The best results were obtained for compost prepared from green algae, grass and sawdust mixture. Compost raw material, compost and compost humic acids were characterised by elemental analysis, UV and Fourier transform infrared spectroscopy and monosaccharides analyses. The compost humic substance composition was found to be dependent on the compost raw materials. Compost humic acids constituted of recognisable algae and plants biomolecules structures, including lignin-derived structures and carbohydrates. Humic acids of the obtained compost contained around 8% monosaccharides. Fucose is a deoxy sugar typical for algae and not for higher plants, and can be used as a chemical indicator of algae biomass in compost.
Journal of Renewable Materials, 2020
Novel mycelium-based biocomposites (MBB) were obtained from local agricultural (hemp shives) and ... more Novel mycelium-based biocomposites (MBB) were obtained from local agricultural (hemp shives) and forestry (wood chips) by-products which were bounded together with natural growth of fungal mycelium. As a result, hemp mycocomposites (HMC) and wood mycocomposites (WMC) were manufactured. Mechanical, water absorption and biodegradation properties of MBB were investigated. MBB were characterized also by ash content and elemental composition. The results of MBB were compared with the reference materials such as the commercial MBB material manufactured by Ecovative ® Design (EV), hemp magnesium oxychloride concrete (HC) and cemented wood wool panel (CW), manufactured by CEWOOD ®. The mechanical properties of HMC and WMC showed that the bending strength difference was about 30%, with a better result for HMC. Compression strength was better for WMC by about 60% compared to that of HMC. The mechanical strength of HMC and HC materials was equal; both materials contained hemp shives but differed by the binding material. Water absorption and volumetric swelling tests showed that HMC and WMC could be considered as potential biosorbents. Ash content and elemental analysis showed that reference materials (CW, HC) contained significant amounts of inorganic compounds that decreased the biodegradation rate, compared to the case of HMC and WMC materials. The biodegradation results of HMC and WMC, after 12 weeks, revealed a mass loss (ML) above 70%, while in the case of EV, HC and CW, it was about 60%, 17% and only 6%, respectively. MBB were completely biodegradable.
Journal of Archaeological Science: Reports, 2019
In this paper, a diagnostic evaluation of the state of the art of archaeological waterlogged foun... more In this paper, a diagnostic evaluation of the state of the art of archaeological waterlogged foundation piles in Riga Cathedral (1211 CE) was carried out. Microscopic, chemical and instrumental methods were applied to study the impact of deterioration of piles leading to the deformations of the Cathedral building. Severe biodeterioration by microorganisms in the majority of pile samples was determined. Chemical analyses showed an extensive depletion of hemicellulose and cellulose sugars while lignin seemed to be unaffected. Restricted degradation of hemicellulose sugars-arabinose and galactose-was characteristic of bacterial degradation of wood. FTIR spectroscopy proved itself as a quick and efficient method for determination of changes in wood components in foundation piles in comparison with chemical method. The increased ash content (up to 70%) in waterlogged wood consisted of deposited salts, oxides and other inorganic compounds. The X-ray diffraction method determined the main inorganic impurities, including calcite, quartz, sodium magnesium silicate and muscovite.
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Papers by Oskars Bikovens