121. Depassivation and repassivation of stainless steels by stepwise pH changeEmir Mujanović, Bojan Zajec, Andraž Legat, Tadeja Kosec, Janez Kovač, Gregor Mori, Stefan Hönig, Gerald Zehethofer, 2020, original scientific article Abstract: Immersion tests with different stainless steels have been performed, while the pH was stepwise decreased and then increased again. During 8.5-day exposure, the depassivation and repassivation pH values as a function of pitting resistance equivalent number were determined. There is always a gap between both pH values (depassivation and repassivation), indicating that for every steel, there are conditions where an existing passive layer can be maintained but cannot be rebuilt after depassivation. In such environments, the passive layer is thicker, consisting mainly of molybdenum and iron rich oxides, while chromium is dissolved. Usually, depending on conditions, the passive layer is more chromium-rich, especially the inner layer. This is relevant, for example, for acidizing jobs in oil and gas industry, proving that repassivation after acidizing will happen promptly, when the pH is increased again.
Keywords: stress corrosion cracking, surface finish impact, tapered tensile specimen, autoclave, accelerated testing, light water nuclear reactor, critical threshold stress
Published in DiRROS: 30.08.2023; Views: 300; Downloads: 155
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122. Environmental impacts of mixed aggregates for use in unbound layers in road constructionMetka Gostečnik, Predrag Šinik, Ana Mladenovič, Janez Ščančar, Radmila Milačič, 2020, original scientific article Abstract: During carbon steel manufacturing, large amounts of electric arc furnace (EAF) slag are generated. EAF slag, if properly treated and processed into aggregate, is an alternative source of high-quality material, which can substitute the use of natural aggregates in most demanding applications in the construction sector, mostly for wearing asphalt courses. In this screening process of high-quality aggregates, a side material with grainsize 0/32 mm is also produced, which can be used as an aggregate for unbound layers in road construction. In this study, the environmental impacts of slag aggregate (fraction 0/32 mm) were evaluated in mixed natural/slag aggregates. Different mixtures of natural/slag aggregates were prepared from aged (28 days) and fresh slag, and their environmental impacts were evaluated using leaching tests. It was shown that among the elements, chromium (Cr) was leached from some mixed aggregates in quantities that exceeded the criterion for inert waste. The data from the present investigation revealed that mixed aggregates, prepared from aged slag (fraction 0/32 mm) and natural stone in the ratio 10/90, are environmentally acceptable and can be safely used in unbound materials for road construction.
Published in DiRROS: 30.08.2023; Views: 255; Downloads: 124
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123. Mikološka flora in entomofavna v obmejnih gozdovih okoli Lokve in KozineStana Hočevar, Janez Titovšek, 1969, professional article Keywords: gozdarstvo, gozdovi, mikologija, entomologija, vegetacija, glive, žuželke
Published in DiRROS: 29.08.2023; Views: 366; Downloads: 101
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127. Vegetacijske in talne razmere v izbranih gozdovih GGE Marija Reka : (delavnica Javne gozdarske službe in projekta Life-IP Natura.SI na OE ZGS Celje)Valerija Babij, Lado Kutnar, Aleksander Marinšek, Matej Tajnikar, Egon Vočko, Janez Černec, 2023, other monographs and other completed works Keywords: vegetacija, tla, rastišče, ekologija gozda, delavnice, Javna gozdarska služba, Slovenija, fitocenologija, gozdne združbe, gozdni rastiščni tipi
Published in DiRROS: 17.08.2023; Views: 315; Downloads: 127
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129. Effect of belowground deployment of entomopathogenic fungus Metarhizium brunneum on strawberry plants and aboveground pestsJaka Razinger, Darinka Koron, Špela Modic, Eva Praprotnik, Primož Žigon, Uroš Žibrat, Matej Knapič, Janez Lapajne, Andrej Vončina, Lovro Sinkovič, Nika Cvelbar Weber, 2023, short scientific article Keywords: biological control, integrated pest management, agricultural entomology, entomopathogenic fungi, hyperspectral imaging, remote sensing, plant-microbe-pest interaction, plant physiology, rhizosphere competence
Published in DiRROS: 27.07.2023; Views: 316; Downloads: 0 |
130. Environmental impacts and immobilization mechanisms of cadmium, lead and zinc in geotechnical composites made from contaminated soil and paper-ashMarija Đurić, Primož Oprčkal, Vesna Zalar Serjun, Alenka Mauko Pranjić, Janez Ščančar, Radmila Milačič, Ana Mladenovič, 2021, original scientific article Abstract: Paper-ash is used for remediation of heavily contaminated soils with metals, but remediation efficiency after longer periods has not been reported. To gain insights into the mechanisms of immobilization of cadmium (Cd), lead (Pb), and znic (Zn), a study was performed in the laboratory experiment in uncontaminated, artificially contaminated, and remediated soils, and these soils treated with sulfate, to mimic conditions in contaminated soil from zinc smelter site. Remediation was performed by mixing contaminated soil with paper-ash to immobilize Cd, Pb, and Zn in the geotechnical composite. Partitioning of Cd, Pb, and Zn was studied over one year in seven-time intervals applying the sequential extraction procedure and complementary X-ray diffraction analyses. This methodological approach enabled us to follow the redistribution of Cd, Pb, and Zn over time, thus, to studying immobilization mechanisms and assessing the remediation efficiency and stability of newly formed mineral phases. Cd, Pb, and Zn were effectively immobilized by precipitation of insoluble hydroxides after the addition of paper-ash and by the carbonization process in insoluble carbonate minerals. After remediation, Cd, Pb, and Zn concentrations in the water-soluble fraction were well below the limiting values for inertness: Cd by 100 times, Pb by 125 times, and Zn by 10 times. Sulfate treatment did not influence the remediation efficiency. Experimental data confirmed the high remediation efficiency and stability of insoluble Cd, Pb, and Zn mineral phases in geotechnical composites.
Keywords: cadmium, lead, zinc, contaminated soil, paper ash, immobilization mechanisms
Published in DiRROS: 04.07.2023; Views: 331; Downloads: 220
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