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1.
Mathematical model-based optimization of trace metal dosage in anaerobic batch bioreactors
Tina Kegl, Balasubramanian Paramasivan, Bikash Chandra Maharaj, 2025, original scientific article

Abstract: Anaerobic digestion (AD) is a promising and yet a complex waste-to-energy technology. To optimize such a process, precise modeling is essential. Developing complex, mechanistically inspired AD models can result in an overwhelming number of parameters that require calibration. This study presents a novel approach that considers the role of trace metals (Ca, K, Mg, Na, Co, Cr, Cu, Fe, Ni, Pb, and Zn) in the modeling, numerical simulation, and optimization of the AD process in a batch bioreactor. In this context, BioModel is enhanced by incorporating the influence of metal activities on chemical, biochemical, and physicochemical processes. Trace metal-related parameters are also included in the calibration of all model parameters. The model’s reliability is rigorously validated by comparing simulation results with experimental data. The study reveals that perturbations of 5% in model parameter values significantly increase the discrepancy between simulated and experimental results up to threefold. Additionally, the study highlights how precise optimization of metal additives can enhance both the quantity and quality of biogas production. The optimal concentrations of trace metals increased biogas and CH4 production by 5.4% and 13.5%, respectively, while H2, H2S, and NH3 decreased by 28.2%, 43.6%, and 42.5%, respectively.
Keywords: anaerobic digestion, batch bioreactor, methane production, model parameters calibration, active set optimization method, perturbation of model parameter, gradient based optimization, trace metals
Published in DKUM: 30.01.2025; Views: 0; Downloads: 2
.pdf Full text (4,66 MB)

2.
Contaminants in the soil and typical crops of the Pannonian region of Slovenia
Žiga Jelen, Milan Svetec, Peter Majerič, Stanko Kapun, Lara Resman, Tatjana Čeh, Granit Hajra, Rebeka Rudolf, 2024, original scientific article

Abstract: Soil contamination and the uptake of pollutants by food crops are widespread issues that vary greatly by region and are influenced by the mineral composition of the soil and local human activities. The Pannonian region, where agriculture has played a key role since Roman times, has been particularly impacted by the long-standing agricultural and industrial practices. While soil contamination with heavy metals is monitored by the Slovenian government, microplastic contamination and the uptake of pollutants into food crops have yet to become a regular component of monitoring efforts. In this study, we conducted a preliminary investigation into soil and crop contamination across the Pannonian region, focusing on identifying harmful contaminants and their potential uptake into food crops. Both soil and crop samples were analyzed for the presence of heavy metals with proven methods such as atomic absorption spectrometry (FASS), graphite furnace atomic absorption spectrometry (GF-AAS), atomic fluorescence spectrometry (AFS), and inductively coupled plasma–mass spectrometry (ICP-MS). Energy-dispersive X-ray spectroscopy (EDS) was found to be a potentially faster method of obtaining data on soil composition. Special attention was also given to the potential presence of microplastics in the region’s soils.
Keywords: soil contamination, Pannonia, soil, food crops, heavy metals, microplastics
Published in DKUM: 28.11.2024; Views: 0; Downloads: 0
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3.
4.
Efficient Removal of Cr(VI) Ions from Aqueous Solutions using Arabinogalactan Coated Magnetic Nanoparticles
Katja Vasić, Mateja Primožič, Željko Knez, Maja Leitgeb, 2023, original scientific article

Keywords: magnetic nanoparticles, heavy metals, chromium
Published in DKUM: 18.04.2024; Views: 114; Downloads: 4
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5.
Transitioning towards Net-Zero Emissions in Chemical and Process Industries : A Holistic Perspective
Peter Glavič, Zorka Novak-Pintarič, Helena Levičnik, Vesna Dragojlović, Miloš Bogataj, 2023, review article

Abstract: Given the urgency to combat climate change and ensure environmental sustainability, this review examines the transition to net-zero emissions in chemical and process industries. It addresses the core areas of carbon emissions reduction, efficient energy use, and sustainable practices. What is new, however, is that it focuses on cutting-edge technologies such as biomass utilization, biotechnology applications, and waste management strategies that are key drivers of this transition. In particular, the study addresses the unique challenges faced by industries such as cement manufacturing and highlights the need for innovative solutions to effectively reduce their carbon footprint. In particular, the role of hydrogen as a clean fuel is at the heart of revolutionizing the chemical and process sectors, pointing the way to cleaner and greener operations. In addition, the manuscript explores the immense importance of the European Green Deal and the Sustainable Development Goals (SDGs) for the chemical industry. These initiatives provide a clear roadmap and framework for advancing sustainability, driving innovation, and reducing the industry's environmental impact, and are a notable contribution to the existing body of knowledge. Ultimately, alignment with the European Green Deal and the SDGs can bring numerous benefits to the chemical industry, increasing its competitiveness, promoting societal well-being, and supporting cross-sector collaboration to achieve shared sustainability goals. By highlighting the novelty of integrating cutting-edge technologies, addressing unique industrial challenges, and positioning global initiatives, this report offers valuable insights to guide the chemical and process industries on their transformative path to a sustainable future.
Keywords: net zero, energy, process industries, emissions, climate, chemicals, biomass, waste, cement, metals
Published in DKUM: 19.02.2024; Views: 333; Downloads: 33
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6.
Celovita učinkovitost opreme v Omco Metals Slovenia d.o.o. : magistrsko delo
Denis Arnšek, 2023, master's thesis

Abstract: Vpeljava kazalnika OEE (celovita učinkovitost opreme) omogoča podjetju zaznavanje ključnih pomanjkljivosti v proizvodnjem procesu in posledično optimizacijo le-tega. V nalogi je najprej predstavljen kazalnik OEE in njegovo teoretično ozadje. Osrednji del naloge predstavlja analiza učinkovitosti opreme (proizvodne linije) v obravnavanem podjetju. Vse 3 postavljene hipoteze so izračuni potrdili, kar kaže na precejšenj potencial za izboljšave. Za konec so podani predlogi za nadaljno vpeljavo kazalnika in možne izboljšave procesa s ciljem optimizacije proizvodnje.
Keywords: OEE, celovita učinkovitost opreme, OMCO Metals Slovenia d.o.o., razpoložljivost, zmogljivost, kakovost
Published in DKUM: 02.06.2023; Views: 456; Downloads: 0
.pdf Full text (2,50 MB)

7.
Analysis of trace heavy metals in a sample droplet with lab-on-a-chip system : diplomsko delo univerzitetnega študijskega programa I. stopnje
Nika Žurga, 2020, undergraduate thesis

Abstract: The aim of this work was to develop and validate an electroanalytical method for simultaneous determination of Zn(II), Cd(II), and Pb(II) in a sample droplet with lab-on-a-chip system. Unmodified screen-printed electrodes (bare SPE using Ag/AgCl reference electrode) and Bi-film SPEs (BiFSPE) were used as electrochemical sensors. Cyclic voltammetry of [Fe(CN)6]3–/[Fe(CN)6]4– redox couple was employed for testing the reversibility of the diffusion-controlled system and square-wave anodic stripping voltammetry (SWASV) for determination of Zn(II), Cd(II), and Pb(II). SWASV was performed at deposition potential of –1.5 V vs. Ag/AgCl and deposition time of 60 s. The following validation parameters were examined: limit of detection (LOD), limit of quantification (LOQ), linearity, accuracy, and precision. LOD and LOQ for Zn(II) were both lower with BiFSPE than with bare SPE. For Cd(II), LOD and LOQ were similar for both bare SPE and BiFSPE. For Pb(II), LOD and LOQ with bare SPE could not be determined (due to intense background contribution) but were obtained with BiFSPE. Linear concentration ranges were obtained for all analytes with bare SPE and BiFSPE. Accuracy and precision were evaluated for different spiked concentrations; however, the method with bare SPE was neither accurate nor precise. With BiFSPE, the method was found to be both accurate and precise for Pb(II) at a spiked concentration of 140.0 μg/L, but not for Zn(II) or Cd(II). For the latter, problems with accuracy and precision were encountered with both bare SPE and BiFSPE. Both methods were selective for Zn(II), Cd(II), and Pb(II) determination. It can be concluded that the optimization of both methods is required for future studies.
Keywords: SPE, BiFSPE, heavy metals determination, SWASV, validation
Published in DKUM: 31.08.2020; Views: 1211; Downloads: 187
.pdf Full text (1,91 MB)

8.
Determination of microstructural changes by severely plastically deformed copper-aluminum alloy : optical study
Nebojša Romčević, M. Gilić, Ivan Anžel, Rebeka Rudolf, Miodrag Mitrić, M. Romčević, B. Hadžić, D. Joksimović, Milica Petrović Damjanović, Matija Kos, 2014, original scientific article

Abstract: Our work deals with the problem of producing a complex metal-ceramic composite using the processes of internal oxidation (IO) and severe plastic deformation. For this purpose, Cu-Al alloy with 0.4wt.% of Al was used. IO of sample serves in the first step of the processing as a means for attaining a fine dispersion of nanosized oxide particles in the metal matrix. Production technology continues with repeated application of severe plastic deformation (SPD) of the resulting metal matrix composite to produce the bulk nanoscaled structural material. SPD was carried out with equal channel angular pressing (ECAP), which allowed that the material could be subjected to an intense plastic strain through simple shear. Microstructural characteristics of one phase and multiphase material was studied on internally oxidized Cu with 0.4wt.% of Al sample composed of one phase copper-aluminum solid solution in the core and fine dispersed oxide particles in the same matrix in the mantle region. In this manner AFM, X-ray diffraction and Raman spectroscopy were used. Local structures in plastically deformed samples reflect presence of $Cu$, $CuO$, $Cu_2O$, $Cu_4O_3$ or $Al_2O_3$ structural characteristics, depending on type of sample.
Keywords: metals, oxides, atomic force microscopy, Raman spectroscopy, microstructure
Published in DKUM: 08.08.2017; Views: 1803; Downloads: 174
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9.
Synthesis and structure of transition metal bisalkinylselenolato complexes
Rudolf Pietschnig, Carmen Moser, Stefan Spirk, Sven Schäfer, 2005, published scientific conference contribution

Abstract: We synthesized closely related cis and trans platinum complexes of SeCC-n-C5H11 and elucidated their structures in solution and the crystalline state. In line with previous work we find exclusive coordination of the selenium atom of the ambident alkynylselenolate ligand and a preference for the obviously more stable trans isomer. In contrast to previous work we find auniform increase of all metal ligand bond lengths in the cis vs. the trans isomers. Moreover we studied the coordination of alkynykselenolate ligands to group 4 metals.
Keywords: analytical chemistry, isomers, stability, metals
Published in DKUM: 22.06.2017; Views: 1246; Downloads: 364
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10.
Sensing heavy metals using mesoporous-based optical chemical sensors
Špela Korent Urek, Nina Frančič, Matejka Turel, Aleksandra Lobnik, 2013, review article

Abstract: Heavymetal pollution is one of the more serious environmental problems; therefore, there is a constant demand for the development of new analytical tools for its monitoring. An optical chemical sensor represents a good alternative to classical instrumental methods.The mesoporous materials used in optical chemical sensorsʼ fabrications have properties such as high porosity, exceptional adsorption capacity, tuneable 3D shape, geometry, and morphology, which enable improved limit of detection, response time, and selectivity properties of optical sensors. In this review, we firstly present the properties of mesoporous materials, provide a brief description of sensing mechanisms, and briefly discuss the importance of continuous monitoring. Recent advances in those mesoporous silica-based optical sensors used for heavy metal detection have been reported and their advantages and limitations also discussed. This review covers publications that have appeared since 2008.
Keywords: heavy metals, magnetic properties, structural properties, heavy metal pollution
Published in DKUM: 14.06.2017; Views: 3227; Downloads: 352
.pdf Full text (3,19 MB)
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