Abstract
This study presents investigations of zeolitic tuff samples from the ?Igros- -Vidojevici? deposit. The aim of the research was to determine the quality of samples taken from all deposit parts. Thus, samples were taken from the footwall (?Zeolit 1?), and four samples from the central deposit part (?Zeolit 2?, ?Zeolit 3?, ?Zeolit 4? and ?Zeolit 5?). Characterization of the samples included chemical analysis, determination of the adsorption coefficient for methylene blue dye and cation-exchange capacity (CEC), X-ray powder diffraction analysis (XRPD), differential thermal and thermogravimetric analysis (DTA and TGA), and Fourier transform Infrared spectroscopic analysis (FTIR). Results have shown that the footwall consists mostly of clays, whereas zeolite minerals dominate in the rest of the deposit. XRD analysis of the ?Zeolit 1? sample confirmed presence of smectite and kaolinite clays, while zeolite of analcime type and quartz are present as smaller fractions. Chemical composition analysis and determination of heavy metal contents showed a significant amount (7.58%) of Fe2O3 in this sample. Therefore, further research can be pursued to find a method for removal of magnetic impurities in this deposit portion in order to utilize the clay fraction. On the other hand, according to XRD, FTIR, DTA/TGA and SEM/EDS analyses, samples which belong to the central deposit part (?Zeolit 2?5?) consist of clinoptilolite zeolite type, while clays are present in less than 10%. Thus, clays (smectites and kaolinite) accompanied with analcime and quartz are the most abundant footwall minerals while central deposit parts contain predominantly clinoptilolite accompanied with small amounts of clays. Mineragenetically, zeolites are most abundant in the ?Zeolit 2? and ?Zeolit 3? samples. The smallest value of CEC was determined for the ?Zeolit 1? sample (46.98 mmol/100g). According to CEC values determined for ?Zeolit 2? and ?Zeolit 3? (141.99 and 121.01 mmol/100 g, respectively) these samples are of the best quality, and could be utilized as adsorbents of inorganic pollutants from contaminated waters. Moreover, they could be potentially used for removal of mycotoxins from cattle feed. ?Zeolit 4? and ?Zeolit 5? samples have shown slightly lower CEC values (89.48 and 83.75 mmol/100 g, respectively), which implies lower quality, and, therefore, could be used for soil quality improvement. Finally, determination of the external CEC has revealed a significant difference between ?Zeolit 1? and ?Zeolit 5? samples (17.9 and 5.31 mmol/100 g, respectively).
Highlights
S obzirom na to da izmenljivi katjoni u zeolitskoj strukturi (Na+, K+, Ca2 i Mg2+) nisu toksični zeoliti se izučavaju kao jono-izmenjivači i adsorbensi za primenu u prečišćavanju otpadnih voda, rekultivaciji flotacijskih jalovišta, adsorpciji mikotoksina [1– –6]
Kapacitet katjonske izmene (KKI) određen je standardnom metodom sa 1 mol/dm3 NH4Cl [8]
Na DTA dijagramima uzoraka „Zeolit 2 i 3“, u temperaturskom intervalu od 25 do 300 °C zapaža se jedan endotermni pik sa minimumom na ≈130 °C koji potiče od dehidratacije [20] i prevoj na ≈220 °C koji su karakteristični za kalcijumski zeolit [21]
Summary
Zeoliti su kristalni hidratisani alumosilikati alkalnih i zemnoalkalnih elemenata. Strukturu zeolita čini prostorna mreža TO4 tetraedara (T je atom silicijuma ili atom aluminijuma) međusobno povezanih atomima kiseonika. Usled izostrukturne zamene silicijuma aluminijumom alumosilikatna rešetka je negativno naelektrisana. Negativno naelektrisanje je kompenzovano prisustvom vezanih pozitivnih jednovalentnih ili dvovalentnih alkalnih ili zemnoalkalnih katjona. S obzirom na to da izmenljivi katjoni u zeolitskoj strukturi (Na+, K+, Ca2 i Mg2+) nisu toksični zeoliti se izučavaju kao jono-izmenjivači i adsorbensi za primenu u prečišćavanju otpadnih voda, rekultivaciji flotacijskih jalovišta, adsorpciji mikotoksina [1– –6]. Postoje radovi u kojima se proučava i upotreba zeolita kao adsorbensa u veterini [7,8], farmaciji [9] i uklanjanju teških metala iz industrijskih otpadnih voda [10,11,12]
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