Iskanje po katalogu digitalne knjižnice

Opis: Hydrothermal degradation processes are a particularly promising eco-friendly approach to keratin isolation from biomass. They, however, result in products with a broad molecular weight distribution, which can be particularly unfavorable for fiber production. In this study, we aimed to determine whether hydrothermally degraded feather and wool waste is suitable to produce nanofibers that retain the key functional properties of keratin, such as antioxidant activity and biocompatibility. Keratin/PEO blends were used for needleless electrospinning of nanofibers cross-linked with two different cross-linkers, ethylene glycol diglycidyl ether (EGDE) and pentaerythritol triacrylate (PETA), to improve their stability to water. The surface tension, pH, turbidity, zeta potential, and protein concentration of the keratin extract solutions were analyzed. The morphology of the produced nanofibers was analyzed using a scanning electron microscope, the surface chemical structure by attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR analysis), and the cross-linking success by water contact angle measurements. The antioxidant capacity and the biocompatibility of the nanofiber mats with skin cells were investigated using a 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) vitality test, respectively. The results showed that despite the unfavorable starting materials with a wide molecular mass range from 3 to 15 kDa and low average molecular weights keratin products obtained by a green hydrothermal extraction process can be used to produce nanofibers with excellent antioxidant properties and skin cell biocompatibility. The cross-linking of the nanofibers resulted in hydrophobic nanofiber surfaces; however, it impaired their biocompatibility with skin cells compared to noncross-linked nanofibers.
Ključne besede: waste chicken feathers, wool, keratin nanofibers, greene xtraction process, subcritical water, hydrothermal isolation process, electrospinning, cross-linking
Objavljeno v DKUM: 28.11.2025; Ogledov: 0; Prenosov: 2
Celotno besedilo (6,51 MB)
Gradivo ima več datotek! Več...

Opis: With the world facing the twin pressures of a warming climate and an ever-increasing amount of waste, it is becoming increasingly clear that we need to rethink the way we generate energy and use materials. Despite growing awareness, our energy systems are still largely dependent on fossil fuels and characterized by a linear ‘take-make-dispose’ model. This leaves us vulnerable to supply disruptions, rising greenhouse gas emissions, and the depletion of critical raw materials. Hydrogen is emerging as a potential carbon-free energy vector that can overcome both challenges if it is produced sustainably from renewable sources. This study reviews hydrogen production from a circular economy perspective, considering industrial, agricultural, and municipal solid waste as a resource rather than a burden. The focus is on the reuse of waste as a catalyst or catalyst support for hydrogen production. Firstly, the role of hydrogen as a new energy carrier is explored along with possible routes of waste valorization in the process of hydrogen production. This is followed by an analysis of where and how catalysts from waste can be utilized within various hydrogen production processes, namely those based on using fossil fuels as a source, biomass as a source, and electrocatalytic applications.
Ključne besede: hydrogen production, waste-derived catalysts, renewable energy, biomass conversion
Objavljeno v DKUM: 25.09.2025; Ogledov: 0; Prenosov: 7
Celotno besedilo (1,66 MB)

Opis: Awareness is growing that human health cannot be considered in isolation but is inextricably woven with the health of the environment in which we live. It is however under-recognised that the sustainability of human activities strongly relies on preserving the equilibrium of the microbial communities living in/on/around us. Microbial metabolic activities are instrumental for production, functionalization, processing and preservation of food. For circular economy, microbial metabolism would be exploited to produce building blocks for the chemical industry, to achieve effective crop protection, agri-food waste revalorization or biofuel production, as well as in bioremediation and bioaugmentation of contaminated areas. Low pH is undoubtedly a key physical-chemical parameter that needs to be considered for exploiting the powerful microbial metabolic arsenal. Deviation from optimal pH conditions has profound effects on shaping the microbial communities responsible for carrying out essential processes. Furthermore, novel strategies to combat contaminations and infections by pathogens rely on microbial-derived acidic molecules that suppress/inhibit their growth. Herein, we present the state-of-the-art of the knowledge on the impact of acidic pH in many applied areas and how this knowledge can guide us to use the immense arsenal of microbial metabolic activities for their more impactful exploitation in a Planetary Health perspective.
Ključne besede: antimicrobial, bio-hydrogen, phytopathogen, organic acids, food preservation, waste valorisation
Objavljeno v DKUM: 28.08.2025; Ogledov: 0; Prenosov: 2
Celotno besedilo (2,40 MB)
Gradivo ima več datotek! Več...

Opis: Waste heat recovery technologies play an important role in enhancing energy efficiency and supporting sustainable energy production. This study investigates the utilization of waste heat from aluminium production through an Organic Rankine Cycle (ORC) system to generate electricity and heat simultaneously. Based on operational data from an aluminium plant, the system is firstly optimized from both the thermodynamic and economic perspectives. To maximize performance and to identify optimal configurations, a mathematical model is developed and solved using GAMS, capturing the complex interdependencies between the operational, economic and thermodynamic parameters. The environmental impact of the optimized scenarios is subsequently evaluated using a Life Cycle Assessment (LCA), considering a broad range of impact categories. The results indicate a maximum power output of 830.9 kW and a maximum net present value (NPV) of 51.71 M€, confirming the system’s technical and economic viability. The environmental assessment demonstrates the potential of ORC systems as sustainable energy solutions, with significant environmental unburdening under optimized operating conditions (up to -606.0 kg CO2 eq./h). A sensitivity analysis indicates that the greatest environmental benefits occur under the optimal thermodynamic scenario, achieved through the utilization of higher-energy flue gas streams (up to -515.0 kg CO2 eq./h), and under the optimal economic scenario by balancing the electricity and heat prices optimally for simultaneous heat and power production (up to -696.7 kg CO2 eq./h). These findings highlight the importance of the thermal input quality and availability in maximizing ORC performance. With the ability to prioritize electricity, heat, or both, the optimized ORC systems support flexible energy solutions tailored to specific applications and environmental conditions, offering a promising pathway for unburdening the environment through the efficient utilization of industrial waste heat.
Ključne besede: waste heat recovery, aluminium production, organic rankine cycle, environmental impact, life cycle assessment, sustainable energy solutions
Objavljeno v DKUM: 13.06.2025; Ogledov: 0; Prenosov: 19
Celotno besedilo (1,30 MB)

Opis: More energy-efficient industries could reduce the problems of pollution, global warming, energy security, and fossil fuel depletion, including processing waste into raw materials and more efficient energy cogeneration. This research project considers the novelties of the upgraded electricity cogeneration technique, including one open gas turbine during the high-pressure product reaction loop and a second turbine during the exhaust gas for co-product production with only one compressor. The upgraded electricity cogeneration was carried out in two steps and based on the productive use of otherwise useless polyethylene waste, flue gas, and wood. The first step can simulate the simulation model from the existing product production with well-known technology and process units using the Aspen Plus® simulator. The maximum available electricity cogeneration can previously be determined from the thermodynamics of the products and co-products, and an existing energy unit’s characteristic capacity. In the second step, conventional natural gas can be replaced with waste as the raw materials by using the same simulated model from the first step, including electricity cogeneration using the gas turbines during the high-pressure reaction loop, and the exhaust gas as the co-product with only one compressor. This research on electricity generation is based on processes that include the pressure drop during the product reaction loop. This approach is illustrated using an existing methanol production process, using wastes as sustainable raw materials, including electricity cogeneration during the reaction loop and exhaust gas, generating a possible increase in annual profit of 7.28 MEUR/a.
Ključne besede: waste recovery, cogeneration, exothermic reactor, gas turbine, exhaust gas, combined compressor
Objavljeno v DKUM: 15.05.2025; Ogledov: 0; Prenosov: 6
Celotno besedilo (1,06 MB)
Gradivo ima več datotek! Več...