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1.
Composite materials based on waste chicken feather fibers for oil-spill management
Simona Strnad, Andraž Jug, Zdenka Peršin Fratnik, 2024, original scientific article

Abstract: Oil spills remain one of the greatest man-made ecological threats, despite numerous advanced cleanup approaches. They still pose a major challenge in the search for materials and technologies that work as efficiently and sustainably as possible. Promising natural materials include poultry feathers, which are produced in large quantities every day as a byproduct of the meat industry. In this study, the influence of different forms of absorbents (loose feathers, pillows, and sheets) based on chicken feathers and the addition of an inorganic absorbent, sepiolite, on their absorption capacity was investigated. The chemical and physical surface properties, like morphology, chemical composition, zeta potential, surface free energies and oil absorption capacities were analyzed. The Gibbs free energy of immersion wetting with oil and the work of adhesion of the adsorbents, calculated based on contact angle measurements, were confirmed by the tests of adsorption capacities according to the ASTM 726–12 standard. The results showed that pure loose feathers have the highest oil adsorption capacity, while feather pillows have only half, and composite sheets have only a quarter of this capacity. The addition of inorganic adsorbent sepiolite did not increase the absorption capacity of the composites.
Keywords: chicken feather fibers, composites, sepiolite, surface properties, oil adsorption, oil-spill management
Published in DKUM: 10.05.2024; Views: 99; Downloads: 8
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2.
Utilisation of renewable electricity to produce synthetic methane
Klemen Rola, Sven Gruber, Danijela Urbancl, Darko Goričanec, 2023, original scientific article

Keywords: power-to-methane, P2M, synthetic methane, CO2 methanation, Aspen Plus, Aspen Adsorption
Published in DKUM: 18.04.2024; Views: 143; Downloads: 7
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3.
Bioactive functional nanolayers of chitosan-lysine surfactant with single- and mixed-protein-repellent and antibiofilm properties for medical implants
Urban Ajdnik, Lidija Fras Zemljič, Olivija Plohl, Lourdes Pérez, Janja Trček, Matej Bračič, Tamilselvan Mohan, 2021, original scientific article

Abstract: Medical implant-associated infections resulting from biofilm formation triggered by unspecific protein adsorption arethe prevailing cause of implant failure. However, implant surfaces rendered with multifunctional bioactive nanocoatings offer apromising alternative to prevent the initial attachment of bacteria and effectively interrupt biofilm formation. The need to researchand develop novel and stable bioactive nanocoatings for medical implants and a comprehensive understanding of their properties incontact with the complex biological environment are crucial. In this study, we developed an aqueous stable and crosslinker-freepolyelectrolyte−surfactant complex (PESC) composed of a renewable cationic polysaccharide, chitosan, a lysine-based anionicsurfactant (77KS), and an amphoteric antibiotic, amoxicillin, which is widely used to treat a number of infections caused by bacteria.We successfully introduced the PESC as bioactive functional nanolayers on the“model”and“real”polydimethylsiloxane (PDMS)surfaces under dynamic and ambient conditions. Besides their high stability and improved wettability, these uniformly depositednanolayers (thickness: 44−61 nm) with mixed charges exhibited strong repulsion toward three model blood proteins (serumalbumin,fibrinogen, andγ-globulin) and their competitive interactions in the mixture in real-time, as demonstrated using a quartzcrystal microbalance with dissipation (QCM-D). The functional nanolayers with a maximum negative zeta potential (ζ:−19 to−30mV at pH 7.4), water content (1628−1810 ng cm−2), and hydration (low viscosity and elastic shear modulus) correlated with themass, conformation, and interaction nature of proteins. In vitro antimicrobial activity testing under dynamic conditions showed thatthe charged nanolayers actively inhibited the growth of both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcusaureus) bacteria compared to unmodified PDMS. Given the ease of fabrication of multifunctional and charged biobased coatingswith simultaneous protein-repellent and antimicrobial activities, the limitations of individual approaches could be overcome leadingto a better and advanced design of various medical devices (e.g., catheters, prosthetics, and stents).
Keywords: silicone implants, protein-repellent, antimicrobial, chitosan, lysine, bioactive coatings, adsorption, QCM-D
Published in DKUM: 15.04.2024; Views: 178; Downloads: 7
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4.
5.
Cellulose nanofibrils-reinforced pectin membranes for the adsorption of cationic dyes from a model solution
Alenka Ojstršek, Selestina Gorgieva, 2024, original scientific article

Abstract: In the presented research, a facile, one-step method for the fabrication of cellulose nanofibrils/pectin (CNFs/PC) membranes is described, which were tested further for their ability to remove cationic dyes from the prepared model solutions. For this purpose, ten membranes were prepared with different quantities of CNFs and PC with/without citric acid (CA) or CaCl2 as mediated crosslinking agents, and they were characterised comprehensively in terms of their physical, chemical, and hydrophilic properties. All the prepared CNFs/PC membranes were hydrophilic with a Water Contact Angle (WCA) from 51.23◦ (without crosslinker) up to 78.30◦ (CaCl2 ) and swelling of up to 485% (without crosslinker), up to 437% (CaCl2 ) and up to 270% (CA). The stability of membranes was decreased with the increase in PC; thus, only four membranes (M1, M2, M3 and M5) were stable enough in water after 24 h, and these were additionally applied in the adsorption trials, using two structurally different cationic dyes, i.e., C.I. Basic Yellow 28 (BY28) and C.I. Basic Blue 22 (BB22), in four concentrations. The highest total surface charge of M3 (2.83 mmol/g) as compared to the other membranes influenced the maximal removal efficiency of both dyes, up to 37% (BY28) and up to 71% (BB22), depending on the initial dye concentration. The final characteristics of the membranes and, consequently, the dye’s absorption ability could be tuned easily by changing the ratio between the CNFs and PC, as well as the type and amount of crosslinker.
Keywords: cellulose nanofibrils, pectin, cationic dyes, adsorption, dye removal
Published in DKUM: 12.03.2024; Views: 219; Downloads: 11
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6.
Polyvinylpyrrolidone-stabilised gold nanoparticle coatings inhibit blood protein adsorption
Hanuma Reddy Tiyyagura, Matej Bračič, Rebeka Rudolf, 2024, original scientific article

Abstract: In this work, the ability of polyvinylpyrrolidone (PVP)-stabilised gold nanoparticle (AuNP) coatings to inhibit blood protein adsorption was evaluated by studying timeresolved solid–liquid interactions of the coatings with the model blood protein bovine serum albumin (BSA). Inhibiting unspecific blood protein adsorption is of crucial importance for blood-contacting implant devices, e.g. vascular grafts, stents, artificial joints, and others, as a preventive strategy for bacterial biofilm formation. A quartz crystal microbalance was used in this work to coat the AuNPs on piezoelectric sensors and to follow time-resolved solid–liquid interactions with the proteins. The AuNP coatings were evaluated for their wettability by contact angle measurements, their surface morphology by lightand atomic force microscopy, and their chemical composition by energy-dispersive X-ray spectroscopy. Results revealed a homogeneous distribution of AuNPs on the sensor surface with a dry mass coverage of 3.37 ± 1.46 µg/cm2 and a contact angle of 25.2 ± 1.1°. Solid–liquid interaction studies by quartz crystal microbalance showed a high repellence of BSA from the PVP-stabilised AuNP coatings and the importance of the PVP in the mechanism of repellence. Furthermore, the conformation of the polymer on the coatings as well as its viscoelastic properties were revealed. Finally, the activated partial thrombin time test and fibrinogen adsorption studies revealed that the AuNPs do not accelerate blood coagulation and can partially inhibit the adhesion of fibrinogen, which is a crucial factor in the common blood coagulation cascade. Such AuNPs have the potential to be used in blood-contact medical applications.
Keywords: gold nanoparticles, ultrasonic spray pyrolysis, haemocompatibility, protein adsorption, quartz crystal microbalance
Published in DKUM: 30.01.2024; Views: 291; Downloads: 15
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7.
RFCS project methenergy+ methane recovery and harnessing for energy and chemical uses at coal mine sites
Matjaž Kamenik, Janez Rošer, Salvador Ordonez, 2022, original scientific article

Abstract: Ventilation Air Methane emissions (VAM) from coal mines lead to environmental concern because of their high global warming potential and the loss of methane (CH4) resources. How to tackle methane harnessing and its use was studied and analysed in the scope of the RCFS project, which was performed from 2017 till 2020, and coordinated by the University of Oviedo in Spain within the scope of an international consortium of eleven entities from Poland, Spain, the United Kingdom, Czechia, Greece, Slovenia and Sweden, combining universities, research institutions and industry (mostly Polish mines and the Slovenian Velenje mine). The main challenge tackled in the project was the use of methane released from both operating and abandoned mines, which is an environmental and safety hazard and also a useful source of energy. Therefore, the effective extraction of methane, its enrichment, purification, separation, thermal or chemical upgrading, and its use, considering coal mine site specifics, was assessed. Despite good operational results, after in-depth economic analysis of the integration, CAPEX and OPEX calculation, there turned out to be a high economic dependence on the cost of adsorbent, since adsorption was the most promising technology for concentrating the methane in these emissions. Therefore, the economic viability depends on the development of materials that meet a minimum cost and performance. Within the scope of the project, a lot of activities were carried out in order to widen and exploit the results.
Keywords: ventilation air methane, abandoned mine methane, coalmining, methane recovery, harnessing, thermal upgrading, chemical upgrading, adsorption-based technologies, materials development, thermal regenerative oxidizers, catalytic regenerative oxidizers, methanol, greenhouse gases
Published in DKUM: 30.10.2023; Views: 429; Downloads: 5
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8.
Izraba obnovljivih virov energije za proizvodnjo sintetičnega metana : magistrsko delo
Klemen Rola, 2023, master's thesis

Abstract: Magistrsko delo predstavlja proizvodnjo sintetičnega metana, ki bi lahko nadomestil zemeljski plin. Za reakcijo metanacije je potreben vodik. Ta se v delu proizvede z elektrolizo, ki jo poganja elektrika obnovljivih virov. Proces je namenjen sezonskemu shranjevanju energije, kjer se viški elektrike poletnega časa shranijo v obliki metana za obdobja primanjkljajev energije. V ta namen, smo s programom Aspen Plus najprej izvedli poenostavljeno enostopenjsko simulacijo metanacije CO2. Pretok CO2 je baziral na ocenjeni sestavi in pretoku bioplina iz realne bioplinarne. Upoštevali smo, da se tudi celoten bioplin lahko uporabi kot reaktant. Enostopenjska metanacija je služila predvsem za razumevanje obnašanja reakcije. Ker z eno reakcijsko stopnjo v produktu nismo dosegali dovolj visokega deleža metana, smo izvedli še poenostavljeno dvostopenjsko metanacijo. Določili smo pogoje, pri katerih bi dosegali dovolj visoko vsebnost metana, da bi produkt bil primeren za injiciranje v plinovode. Za primer, ko se bioplin ne uporabi v metanaciji, smo v programu Aspen Adsorption izvedli dinamični simulaciji nadgradnje bioplina z adsorpcijskimi tehnikami. Mešanico bioplina smo z nizkimi izgubami metana uspešno nadgradili do biometana, s sestavo, ki je primerna za injiciranje v plinovode. S pomočjo rezultatov začetne dvostopenjske simulacije smo razvili delno integrirano shemo s sočasno proizvodnjo elektrike, ki je sposobna proizvesti od 1 t/h do 1,3 t/h sintetičnega metana. Pri tem je v procesu možna uporaba čistega CO2, ali pa celo mešanice bioplina in CO2. Proizveden sintetični metan je vseboval več kot 97 mol.% CH4, po dehidraciji s silikagelom, pa smo zagotovili sestavo, ki je primerna za injiciranje v plinovode mnogih Evropskih držav.
Keywords: Sintetični metan, bioplin, metanacija CO2, adsorpcija, Aspen Plus, Aspen Adsorption
Published in DKUM: 14.09.2023; Views: 523; Downloads: 0
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9.
Assessment of the Capability of Magnetic Nanoparticles to Recover Neodymium Ions from Aqueous Solution
Ana Ambrož, Irena Ban, Thomas Luxbacher, 2022, original scientific article

Abstract: Magnetic nanoparticles (MNPs) have received increasing attention for various applications due to their fast synthesis, versatile functionalization, and recyclability by the application of a magnetic field. The high surface-to-volume ratio of MNP dispersions has suggested their use as an adsorbent for the removal of heavy metal ions. We investigated the applicability of MNPs composed of a maghemite core surrounded by a silica shell functionalized with aminopropylsilane, γ-Fe2O3-NH4OH@SiO2(APTMS), for the removal of neodymium ions (Nd3+) from aqueous solution. The MNPs were characterized for their size, composition, surface functionality and charge. Despite of the promising properties of MNPs, their removal from the aqueous dispersion with an external magnet was not sufficient to reliably quantify the adsorption of Nd3+ by UV-Vis spectroscopy.
Keywords: rare earth elements, maghemite, nanoparticles, UV-Vis spectroscopy, adsorption
Published in DKUM: 08.08.2023; Views: 381; Downloads: 23
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10.
Protein-repellent surface coatings made of polycaprolactone-polysaccharide blends : master's thesis
Jan Marko, 2022, master's thesis

Abstract: This work is focused on surface characterization and fibrinogen adsorption studies of polycaprolactone/chondroitin sulfate (tetrabutylammonium hydroxide) blends. Mixed polymer solutions were spin-coated to form two-phase thin films, which exhibit various patterns depending on the mass ratio of the spin-coating solution. Stability in the aqueous media, however, presents an uncertainty, due to the solubility of chondroitin sulfate (tetrabutylammonium hydroxide) in water. In spite of this, it is observed that the introduction of chondroitin sulfate (tetrabutylammonium hydroxide) in the film increases the repulsion of fibrinogen. Two methods frequently used for polymer characterization, mass determination using Quartz Crystal Microbalance with Dissipation monitoring and the zeta potential measurement, were found to be comparable techniques when studying protein adsorption and complementary techniques when analysing the stability of thin films.
Keywords: polycaprolactone, chondroitin sulfate, zeta potential, QCM-D, fibrinogen, adsorption
Published in DKUM: 15.07.2022; Views: 564; Downloads: 41
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