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52. The development and assessment of alkali activated paving blocksAna Frankovič, Vilma Ducman, Lubica Kriskova, Efthymios Tatsis, Petrica Petrica, Yiannis Pontikes, 2022, published scientific conference contribution Abstract: In recent years great attention has been placed by the building sector on alkali-activated technology based on metakaolin, fly ash and ground granulated blast furnace slag (GGBFS), but also on emerging precursors such as by-products from non-ferrous metallurgy. The present work focuses on the development of alkali-activated binders from two slags, one from primary and one from secondary copper production, which were finely milled, blended with GGBFS, and activated with K-based alkali silicate solution with a 1.7 SiO2/K2O molar ratio. The aggregate to paste mass ratio was 2. The mixtures were cast, and cured for a designated time at room temperature and 60% RH. The so-obtained paving blocks were then tested in accordance with European standard for concrete paving blocks. The following properties were measured: splitting tensile strength, abrasion resistance, slip and skid resistance, resistance to freeze-thaw and resistance to freeze-thaw in the presence of de-icing salts. Their properties were compared to those of commercially available concrete paving blocks, and it was found that the performance of the alkali-activated pavers was generally comparable with the concrete pavers, while certain properties (e.g., abrasion resistance, freeze-thaw resistance and freeze-thaw resistance in presence of de-icing salts) were considerably better.
Keywords: slags, alkali activated pavers, properties
Published in DiRROS: 21.12.2023; Views: 178; Downloads: 67
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55. Heavy metal signature and environmental assessment of nearshore sediments: Port of Koper (Northern Adriatic Sea)Nastja Rogan Šmuc, Matej Dolenec, Sabina Dolenec, Ana Mladenovič, 2018, original scientific article Abstract: Heavy metal abundance and potential environmental risks are reported for surface sediments (n = 21) from the Port of Koper area, Republic of Slovenia. The enrichment factor (EF) indicates minor enrichment in arsenic (As), cadmium (Cd), copper (Cu), molybdenum (Mo), lead (Pb), antimony (Sb), and zinc (Zn), moderately to severely enriched with nickel (Ni). The trace metal chemistries, in the context of sediment quality guidelines (SQG), imply adverse threshold effect concentrations (TEC) and probable effect concentrations (PEC), for Ni only. Sediment sequential leaching experiments demonstrated that the majority of heavy metals were of natural lithogenic origin and low bioavailability. The heavy metals’ potential for “Risk Assessment Code” values exhibited no or low anthropogenic environmental burden, with the exception of Mo.
Keywords: port sediments, heavy metals, chemical speciation, risk assessment, Northem Adriatic Sea
Published in DiRROS: 12.12.2023; Views: 203; Downloads: 112
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56. PS-AAS : portfolio selection for automated algorithm selection in black-box optimizationAna Kostovska, Gjorgjina Cenikj, Diederick Vermetten, Anja Janković, Ana Nikolikj, Urban Škvorc, Peter Korošec, Carola Doerr, Tome Eftimov, 2023, published scientific conference contribution Keywords: automated algorithm selection, portfolio selection, black box optimization
Published in DiRROS: 11.12.2023; Views: 351; Downloads: 136
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57. Selective glucose oxidation to glucaric acid using bimetallic catalysts : lattice expansion or electronic structure effect?Žan Lavrič, Janvit Teržan, Ana Kroflič, Janez Zavašnik, Joanna E. Olszówka, Štefan Vajda, Matej Huš, Miha Grilc, Blaž Likozar, 2024, original scientific article Abstract: Our study presents a comprehensive approach for the selective oxidation of glucose to glucaric acid (GA) by heterogeneous catalysis. We have synthesized and characterized Au/ZrO2, AuCu/ZrO2 and AuPt/ZrO2 catalysts using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and oxygen pulse chemisorption (OPS) techniques. Combining experimental observations with in-depth density functional theory (DFT) studies, we found that bimetallic catalysts form alloys, which exhibit different characteristics than monometallic counterparts for the given reaction. We performed batch reactions, varying temperature and oxygen pressure, and used the data to construct a predictive microkinetic model. As it turned out, AuPt/ZrO2 showed the highest selectivity, yielding 32 % of GA at 100 °C and 30 barg O2. Our results provide valuable insights for the developing of efficient catalysts and point out the bottlenecks for the oxidation of glucose to GA.
Keywords: glucaric acid, glucose oxidation, catalyst characterization, density functional theory, microkinetic modelling
Published in DiRROS: 06.12.2023; Views: 224; Downloads: 134
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60. Mining waste in circular economy - legislative aspectSenko Pličanič, Ana Mladenovič, Alenka Mauko Pranjić, Petra Vrhovnik, 2020, original scientific article Abstract: One of the common European commitments is a transition towards a green circular economy in which waste is not discarded and considered to be just an environmental problem, but should be recognized as an important potential source of raw materials for industry. In a priority order in waste management activities, introduced by the Waste Directive in 2012, recycling is set just behind the waste prevention and reuse. Many types of waste can be recycled, the most perspective being construction, industrial and mining wastes. The latter are produced and disposed of at mine sites during the excavation and processing of ore and are extremely perspective due to large quantities and remaining of different metals, however still underutilized, with low recycling rate. Many mining wastes are inert and do not releases contaminants into environment, however, some of them are problematic and even require monitoring. Reprocessing of these wastes, which include beneficiation and sequential extraction of valuable metals in the first phase and recycling of residues in both structural and civil engineering in the second phase establishes a zero waste model with several benefits for economy, environment and society. Out of the South-East European countries, North Macedonia has great potential to establish this model. As a consequence of long mining tradition and abundant ore resources, there are many mining and metallurgical tailings, on the other hand vivid economy and numerous sinks for use of recycled materials in construction sector can accommodate these quantities. However, there are open questions in terms of administrative procedures and legislation. What are those obstacles that accompany the smooth establishment of the proposed model from a legislative point of view? This paper deals with the situation in North Macedonia, in terms of opportunities, legislative options and the need to adopt new legislation, taking also into account the current problems in this field in Europe.
Keywords: circular economy, zero-waste approach, mining waste, construction sector, legislation, krožno gospodarstvo, pristop ničelnega odpadka, rudarski odpadki, gradbeništvo, zakonodaja
Published in DiRROS: 04.12.2023; Views: 224; Downloads: 131
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