Прегледај по Аутор "Smiljanić, Slavko"

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    Efficient separation of strontium radionuclides from high‑salinity wastewater by zeolite 4A synthesized from Bayer process liquids
    (Nature, 2021) Smičiklas, Ivana; Coha, Ivana; Jović, Mihajlo; Nodilo, Marijana; Šljivić‑Ivanović, Marija; Smiljanić, Slavko; Grahek, Željko
    The efficient, selective, and economical sorbents for the removal of Sr radionuclides are largely needed for the decontamination of effluents with high salinity. In this study, the removal of Sr was investigated using the zeolite produced from the Bayer process liquids. Based on the XRD, SEM/EDS analysis, the product was pure and highly crystalline zeolite 4A (Z4A). Removal of Sr was fast (5 min for 100% removal at 8.80 mg/L), with high maximum sorption capacity (252.5 mg/L), and independent on the initial pH in the range 3.5–9.0. Specific sorption of Sr by protonated groups on the Z4A surface was operating in addition to ion-exchange with Na ions. The selectivity of Z4A decreased in the order Sr > Ca > K > Mg > Na. 84% of Sr was separated from seawater within 5 min, at the Z4A dose of 5 g/L, while efficiency increased to 99% using the dose of 20 g/L. Desorption of radioisotope 89Sr from seawater/Z4A solid residue was very low in deionized water (0.1–0.2%) and groundwater (0.7%) during 60 days of leaching. Z4A is a cost-effective, selective, and high-capacity medium for Sr removal, which provides high stability of retained radionuclides.
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    Examining the Effects of the Destroying Ammunition, Mines and Explosive Devices on the Presence of HeavyMetals in Soil of Open Detonation Pit; Part 2: Determination of Heavy Metal Fractions
    (Springer, 2018) Tešan Tomić, Neda; Smiljanić, Slavko; Jović, M.; Gligorić, M.; Povrenović, D.; Došić, A.
    As a result of the destruction of ammunition, mines, and explosive devices by the method of open detonation, the increased concentration of heavy metals is often recorded in the soil of military polygons, which is a serious ecological problem. However, in order to determine the potential risk of such locations to the environment, it is necessary to determine, in addition to the total content, the forms in which the metals are present. In this paper, a sequential extraction method was used to analyze the six fractions of five heavy metals (cadmium, lead, nickel, copper, and zinc) in the soil of the polygon for destruction of ammunition, mines, and explosive devices. Samples were collected from the place of direct detonation (so-called pits) and from the edge of the pit. The aim of this research is determination of metal speciation in order to obtain a better insight in their mobility and risk arising from this. The results showed that heavy metals are predominantly present in the residual, oxide, and organic fractions. Cd and Cu were also significantly present in the mobile fractions due to conducted activities on the polygon. To assess the potential environmental risk of soil, the risk assessment code (RAC) and individual (ICF) and global (GCF) contamination factors were used. According to the RAC, the mobility and bioavailability of the analyzed heavy metals decreases in the following order: Cd > Cu > Zn > Pb > Ni. ICF results show low to moderate risk, while GCF results show low risk in terms of heavy metal contamination in the examined area.
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    Recovery of Rare Earth Elements through Spent NdFeB Magnet Oxidation (First Part)
    (MDPI, 2022) Stopic, Srecko; Polat, Buse; Chung, Hanwen; Emil-Kaya, Elif; Smiljanić, Slavko; Gürmen, Sebahattin; Friedrich, Bernd
    Due to their remarkable magnetic properties, such as a high maximum energy product, high remanence, and high coercivity, NdFeB magnets are used in a variety of technological applications. Because of their very limited recycling, high numbers of spent NdFeB magnets are widely available in the market. In addition to China’s monopoly on the supply of most rare earth elements, there is a need for the recovery of these critical metals, as their high import price poses an economic and environmental challenge for manufacturers. This paper proposes a pyrometallurgical recycling method for end-of-life NdFeB magnets by oxidizing them in air as first required step. The main goal of this method is to oxidize rare earth elements from NdFeB magnets in order to prepare them for the carbothermic reduction. The experimental conditions, such as the oxidation temperature and time, were studied in order to establish the phase transformation during oxidation using the Factsage Database and experimental conditions. Our thermogravimetric analysis TGA analysis revealed an increased sample mass by 35% between room temperature and 1100 C, which is very close to the total calculated theoretical value of oxygen (36.8% for all elements, and only 3.6% for rare earth elements REE), confirming the complete oxidation of the material. The obtained quantitative analysis of the oxidation product, in (%), demonstrated values of 53.41 Fe2O3, 10.37 Fe3O4; 16.45 NdFeO3; 0.45 Nd2O3, 1.28 Dy2O3, 1.07 Pr2O3, and 5.22 -Fe