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Browsing TFBor by Subject "Adsorption"

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    Microplastics
    (University of Belgrade, Technical Faculty in Bor, 2023) Cvetković, Aleksandar; Tasić, Žaklina; Petrović Mihajlović, Marija; Nujkić, Maja; Radovanović, Milan; Simonović, Ana
    This paper is an illustrated review of the microplastics phenomenon which is caused by human activity and has global reach. Microplastics are insoluble solid particles in the range of sizes between 1µm and 5mm. There can be a further divide into larger macro- and meso- plastics and smaller nanoplastics. Regardless of the size all microplastics can carry adsorbed toxic materials like insoluble organic materials and heavy metals. With these materials microplastics can integrate themselves into the food chain and though it come in contact with the human body where desorption of toxic materials can takes place. It is difficult to recognize the type of microplastics, only with the employment of different recognition methods a sample of microplastics can be correctly identified. The removal of microplastics can be carried out with classic methods or with bioreactors.
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    pH and conductivity change during the rinsing and adsorption of copper ions onto walnut shells
    (University of Belgrade, Technical Faculty in Bor, 2021) Marković, Miljan; Gorgievski, Milan; Štrbac, Nada; Grekulović, Vesna; Mitovski, Aleksandra; Božinović, Kristina; Zdravković, Milica
    The change in pH and conductivity values during the rinsing of the walnut shells as well as during the adsorption of copper ions wasinvestigated in this study. The pH value increases during the rinsing of the adsorbent, reaching a constant value after the passing of 100 ml of distilled water. The increase in the pH value during the rinsing of the adsorbent occurs as a result of the transfer of H+ ions from the aqueous phase into the molecular structure of the adsorbent, where they are exchanged with alkali and alkaline- earth metal ions. As for conductivity change, a sudden increase in conductivity occurs after passing the first 50 ml of distilled water, followed by a decrease in conductivity with further rinsing. The increase in conductivity is most likely caused by the increase in the concentration of alkali and alkaline earth metal ions in the solution, which are being transferred from the adsorbent structure into the aqueous phase. During the adsorption process, the pH value rapidly increases for the first few minutes, after which starts to decline. The release of H+ ions from the adsorbent structure into the aqueous phase causes a rapid decrease in pH value as a result of the deprotonation of functional groups in the adsorbent molecular structure. The conductivity increases during the adsorption process. This increase is due to an increase in the concentration of alkali and alkaline earth metal ions in the solution, which are exchanged with copper ions during the adsorption process.