Galia Shulga

Latvian State Institute of Wood Chemistry, Lignin Chemistry, Leading research scientist

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Leading researcher of a Department of Lignin Chemistry of the Latvian State Institute of Wood Chemistry (LSIWC). Publications: author/co-author over 300 scientific papers, 23 patents. Research interests: wood chemistry and technology, lignin modification, biocomposites, soil structuring agents, surface-active agents, environmental technologies.

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Anna Croft

Loughborough University

Leigh Aldous

King's College London

Joseph Banoub

Memorial University of Newfoundland

Diène NDIAYE

Université Gaston Berger de Saint-Louis, Sénégal

Claude Farrugia

University of Malta

Michal Jablonsky

Slovak University of Technology

Anuj Kumar

Yeungnam University

Maderas. Ciencia y Tecnologia

Universidad del Bio-bio

Md. Iftekhar Shams

Khulna University

Oskars Bikovens

Latvian State Institute of Wood Chemistry

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Papers by Galia Shulga

Characteristics and Properties of Soda Lignin Obtained from Aspen Wood By-Products

Latvijas Ķīmijas Žurnāls, Dec 1, 2012

In the work, soda lignin was obtained under laboratory alkaline delignification conditions from a... more In the work, soda lignin was obtained under laboratory alkaline delignification conditions from aspen sawdust. The chemical composition and the surface-active properties of this lignin in aqueous solutions were studied. The high indices of Klason lignin and the content of methoxyl groups indicated the insignificant presence of non-lignin admixtures, including lignocarbohydrate complexes, in the purified lignin. It was shown that aspen lignin was a surface active substance, the surface activity of which at the water-air interface grew with falling the solution рН values. Simultaneously, with decreasing рН, the particle sizes of aspen lignin in the aqueous solutions increased, but zeta potential of the lignin particles had the tendency to decrease.

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Self-Organization of Birch Lignin and Its Water Solution Properties

publication.editionName, 2010

The chemical structure of the low-molecular birch lignin, isolated from the hydrolyzate of model ... more The chemical structure of the low-molecular birch lignin, isolated from the hydrolyzate of model wood thermohydrolysis has been established. A pronounced amiphilic character of the isolated lignin, which governs its high tendency to self-organizing in water and water-salt solutions, and its pronounced surface-active properties at the water-air and the liquid-liquid interface have been show

Specific features of the interpolymer interaction between sodium lignosulfonate and poly(acrylic acid) in aqueous media

Polymer science. Series A, Chemistry, physics, 1997

The interaction between equally charged sodium sulfonate and poly(acrylic acid) was studied in aq... more The interaction between equally charged sodium sulfonate and poly(acrylic acid) was studied in aqueous media under different conditions of solution mixing. It was established by surface tension measurements using the Wilhelmy plate method, viscometry, and UV spectroscopy that interpolymer associates are formed in this system. Due to this association, sodium lignosulfonate and poly(acrylic acid) become compatible in the acidic media. At pH > 5, the equilibrium of the interpolymer reaction is shifted to the dissociation of macromolecular associates, the surface-active properties of the reaction mixtures deteriorate dramatically, and the compatibility of polyelectrolytes in aqueous solutions is decreased or may be lost completely.

Properties of Isolated Lignin From Model Wastewater

Vide. Tehnoloģija. Resursi, Aug 5, 2015

Model wastewater, imitating the hydrothermal treatment of birch wood in the basins of veneer prod... more Model wastewater, imitating the hydrothermal treatment of birch wood in the basins of veneer production, was obtained under laboratory conditions. Birch lignin (BLIG) was isolated from the model wastewater by precipitation with concentarted sulphuric acid. The increase in reduced viscosity with decreasing concentration of BLIG in the water solutions indicated its polyelectrolyte behaviour. The presence of both ionized functional groups and hydrophobic aromatic fragments in the BLIG molecules favoured its surface active properties. With decreasing pH and increasing concentration, the surface activity of BLIG at the air-water and oil-water interfaces increased, indicating the enhanced hydrophobicity of lignin fragments due to the protonization of its acidic groups. The pronounced surface activity of BLIG was in accordance with the very low value of its critical micelle concentration. The dependence of the emulsion stability on the ionic strength may testify the predominant structural mechanical mechanism of the stabilization of the rapeseed oil-in-water emulsion, containing BLIG as a stabilizer. The revealed surface properties of the isolated lignin allow predicting its application for lowering surface tension in different disperse systems to prevent the coalescence and agglomeration phenomena.

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Eco-Friendly Composite Fabricated from Recycled Waste Paper and Recycled Polypropylene

Cellulose Chemistry and Technology, May 10, 2023

The goal of the work was to recycle waste paper, utilize it as a filler and investigate the prope... more The goal of the work was to recycle waste paper, utilize it as a filler and investigate the properties of the obtained recycled polypropylene-based composite. Crystalline cellulose from the waste paper was regenerated in accordance with the developed method in acid medium under mild conditions. The morphology, crystallinity degree, shape, and sizes of the obtained cellulose particles were characterized. It was found that the extracted crystalline cellulose contained more amorphous regions than the kraft pulp, and was characterized by a more hydrophilic structure. The extracted crystalline cellulose microparticles were used as a biofiller in the recycled polypropylene-based composite in its binary and ternary formulations, incorporating maleic anhydride-grafted polypropylene as an adhesion enhancer. The binary composite was characterized by unsatisfactory mechanical and wetting properties. The presence of the adhesion enhancer in the composite's formulation improved the mechanical properties, increased the hydrophobicity and thermal stability of the composite.

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Physicochemical Characteristic of Sulfate Lignin Obtained from Black Liquor of Kehra Pulp and Paper Mills “Horizon”

No Kehras celulozes un papīra rūpnīcas “Horizon” melnā atsārma iegūta sulfātlignīna fizikāli ķīmiskais raksturojums

Pašlaik Baltijas valstīs darbojas tikai viena celulozes rūpnīca Horizon Pulp & Paper Ltd Kehr... more Pašlaik Baltijas valstīs darbojas tikai viena celulozes rūpnīca Horizon Pulp & Paper Ltd Kehrā, Igaunijā, kas ražo plaša klāsta papīra izstrādājumus iesaiņojumu industrijai. Tas ir arī vienīgais šā brīža lignīna avots Baltijas valstīs. Tomēr līdz šim Kehras celulozes rūpnīcā iegūtā melnā atsārma sastāvā ietilpstošais lignīns nav izpētīts. Mūsu darba mērķis bija no Kehras rūpnieciskā melnā atsārma izdalīt sulfātlignīnu, raksturot tā ķīmisko sastāvu un pārbaudīt virsmas aktīvās īpašības. Pamatojoties uz darbā iegūtajiem rezultātiem tika konstatēts, ka izdalītais sulfātlignīns pēc saviem rādītājiem būtiski neatšķiras no pārējiem rūpnieciskajiem un komerciālajiem sulfātlignīniem. Noskaidrots, ka ar sulfātlignīna koncentrācijas palielināšanu un šķīduma pH pazemināšanu, sulfātlignīna virsmas aktivitāte šķīdums-gaiss fāzu robežā un eļļa-ūdens emulsijās palielinās. Pie tā lielām koncentrācijām labāka emulsiju stabilitāte novērojama skābā vidē, bet pie mazām – sārmainā vidē, kas izskaidrojams ar dažādiem emulsiju stabilizācijas mehānismiem. Noteikts, ka 0,1 M NaCl klātbūtne šķīdumā labvēlīgi iedarbojas uz sulfātlignīna virsmas aktivitāti, kas saistīts ar sulfātlignīna molekulu hidrofobitātes paaugstināšanos jonu spēka palielināšanās rezultātā

Behaviour of the Lignin-Based Polyelectrolyte Complex at the Water-Heptane Interface

A Study on Waste Paper Reinforced Recycled Polypropylene Biocomposite

Materials Science Forum, Oct 18, 2022

The growing global request to make green materials nowadays expresses in reducing environmental p... more The growing global request to make green materials nowadays expresses in reducing environmental problems and obtaining biomaterials with high-performed properties. Aside from being carbon neutral, the use of biomass for obtaining green materials contributes to energy security and climate change mitigation. The aim of the work was to fabricate and study a recycled polypropylene-based composite filled with recycled waste paper obtained by the acid hydrolysis of de-inked newsprint. It has been found that, with increasing the content of the recycled paper microparticles in the bio-composite, its mechanical and wetting properties deteriorated. The presence of maleic anhydride grafted polypropylene as a compatibilizer increased the homogeneity of the structure of the bio-composite, which improved its mechanical properties and decreased its ability to be wetted with water.

Environmentally friendly lignin-based adhesives for reinforcement of drainage channel slopes

The Study of Birch Lignin Isolated from Hydrolyzate Imitating Wastewater of Veneer Production

Hydrothermal treatment of wood in a special water basin is employed before its mechanical process... more Hydrothermal treatment of wood in a special water basin is employed before its mechanical processing for veneer production. Due to the wood autohydrolysis, the wastewater of the hydrothermal treatment is dramatically polluted, mainly with low-molecular lignin fragments, hemicelluloses and extractives. The waste biomass from the plywood basins may serve as a raw material for the development of new products with a value-added benefit. In this work, a chemical structure of lignin isolated from laboratory birch wood hydrolysate, imitating wastewater of plywood production, as well as its compositional features in comparison with commercial alkaline lignin has been studied

Cooperative intermacromolecular reactions with lignosulphonates

Polymer science USSR, 1982

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Wood Processing Wastewater Treatment, Using Various Coagulants and Ozonation

One of the most significant birch wood processing with a high added value is plywood production. ... more One of the most significant birch wood processing with a high added value is plywood production. If not taking into account the last year’s economic situation in the world, production and demand of plywood is increasing in Latvia and EU every year. The reaģent method of wastewater purification after wood hydrothermal hydrolysis in veneer manufacture from the released biomass (lignin, hemicelluloses and extractive substances) is one of the most perspective methods, which allows to recycle purified wastewater in technological cycle. The aim of the study was to compare the effectiveness of the biomass (BM) removal from the modei wastewater of the wood hydrothermal treatment, using separately polymer cation and inorganic salts as coagulants

Utilization of a polymer complex based on technical lignosulphonates for soil improvement

Recovery of lignin and extractive substances from the hydrolysate of model birch wood hydrolysis with aluminium

the Chemical Technology, 2016

One of the most significant sectors of forest industry in Latvia is the production of wood boards... more One of the most significant sectors of forest industry in Latvia is the production of wood boards, especially plywood. Latvia is the biggest producer of plywood in Eastern Europe. One of the plywood production steps is a hydrothermal treatment of birch wood. Wastewater from plywood hydrothermal pools is characterized by a high contamination level. One of the main contaminants is birch lignin which accounts for the color of water and high chemical oxygen demand (COD). Insufficient efficiency of purification from high molecular weight components requires application and development of physical-chemical methods (coagulation method). The aim of this work was to find the optimal conditions for coagulation of lignin compounds in hydrolysate of a model birch wood hydrolysis in the presence of aluminium salts. The obtained model hydrolysate imitated wastewater from the plywood hydrothermal basin. Optimal conditions of lignin compounds recovery by aluminium salts were studied by varying the ...

ESR as a method for monitoring lignins activity during the interaction with monomer and oligomer silicon containing compounds

The Chemistry and Processing of Wood and Plant Fibrous Material, 1996

ABSTRACT ESR was employed to study the interaction of lignins with silicon-organic compounds. The... more ABSTRACT ESR was employed to study the interaction of lignins with silicon-organic compounds. The comparison of the ESR spectra of the co-reagents and products of interaction of lignosulphonates (LS) with the water-soluble oligomer sodium alumomethyl siloxanolate (SAHS) has demonstrated different characters of their interaction in acid and alkaline media. The observation of the behaviour of the lignin radicals as spin probes in a wide temperature range (77-448 K) made it possible to reveal a considerable decrease in the rigidity of the lignin matrix as a result of lignin silylation with monomeric silicon-organic compounds (hexamethylsilazane, phenylaminomethyl-(methyl)-diethoxysilane).

Characteristics of the Coagulate Obtained During the Process of Model Wastewater Treatment

Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference, 2015

In the process of wastewater treatment by coagulation a large amount of sediment is being produce... more In the process of wastewater treatment by coagulation a large amount of sediment is being produced, which is the main drawback of this method. Therefore, the development of utilization or recirculation technology of the waste obtained, the research of the obtained by-products should be conducted. Within the scope of this work, the sediment, that is being formed during the coagulation of the model wastewater containing the wood originated pollutants, was studied. Using the aluminium-containing composition coagulant on a base of polyaluminium chloride, coagulates characterized by the low sludge volume index within 30 minutes (89 ml g-1), and the optimal time of sedimentation is 20-30 minutes. The coagulate particles have an average size of 45.8 μm. The derived coagulate is composed primarily of carbon (27.9%), oxygen (49.4%) and aluminum (10.9%). Carbon, oxygen and hydrogen belong to an organic part of coagulate-the wood pollutants, which, in turn, has a high content of hemicellulose....

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Difference in the Treatment Effectiveness of Woodworking Wastewater Between Polyaluminium Chloride-Based Coagulants

Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference, 2015

In the work, a comparative study of the efficiency of coagulation of a model solution, simulating... more 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 AlCl 3 /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.

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Obtaining the “Green” Surface-Active Agents, Their Characterisation and Advanced Application

In association with increasing requirements to environmental protection, as also in connection wi... more In association with increasing requirements to environmental protection, as also in connection with the aggressive rise in prices on oil and the synthetic products produced on its basis, obtaining “green” surface-active agents from natural feedstock represents both scientific and practical interes

Biorefinery of the Lignocellulosic Waste of Wood Processing for Environmental Sustainability

The lignocellulosic biomass remaining after the chemical and mechanical processing of wood in Eas... more The lignocellulosic biomass remaining after the chemical and mechanical processing of wood in Eastern European countries is commonly used to produce energy that is not beneficial from the economic, social and environmental points of view. Owing to the notable deposits of a lignocellulosic by-product such as hydrolysis lignin in Belarus and Lithuania (as a waste of the post-hydrolysis industry), its tailored biorefinery is an urgent problem. In this paper, results of the application of the hydrolysis lignin modified with various chemical methods as a filler in the wood polymer composite and a mulch for prevention of soil erosion are presented. The obtained results testify that the purposeful modification of hydrolysis lignin by the treatment of the non-stoichiometric polyelectrolyte complex, incorporating quaternary polymeric amine and sulphate lignin, as well as by diethylepoxypropylamine with the aim of the partial replacement of the more expensive wood flour in the wood polymer composite, favours the remarkable improvement of the mechanical properties of the composite and the decrease of its ability to adsorb water. The modification of the hydrolysis lignin particles as a mulch with a non-stoichiometric polyelectrolyte complex sulphite lignin/acrylic polymer by the impregnation method creates more favourable conditions in the soil for decreasing water evaporation, increasing mulch cohesiveness and fertility of soil, in comparison with the case of the initial hydrolysis lignin.

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Characteristics and Properties of Soda Lignin Obtained from Aspen Wood By-Products

Latvijas Ķīmijas Žurnāls, Dec 1, 2012

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Self-Organization of Birch Lignin and Its Water Solution Properties

publication.editionName, 2010