Naslov
Mineralogical and chemical characteristics of Croatian bentonites

Autori
Gverić, Zvonka ; Kampić, Štefica ; Marković, Tamara ; Jozić, Dražan ; Biševac, Vanja ; Tibljaš, Darko

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Informator, 49, Book of Abstracts / Šťastný Martin Žigová Anna - Průhonice : Czech National Clay Group, 2012, 150-150

Skup
6th Mid-European Clay Conference (MECC'12)

Mjesto i datum
Průhonice, Češka Republika, 04.09.2012. - 09.09.2012

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
bentonite ; beidellite ; montmorillonite ; CEC ; heavy metals adsorption

Sažetak
In Croatia several bentonite deposits have already been described. The aim of the present study was to obtain additional information on mineralogical and chemical characteristics of bentonites from several deposits: Maovice-Štikovo (Middle Dalmatia, S Croatia), Gornja Jelenska (Moslavina, N Croatia), Bednja and Poljanska Luka (Hrvatsko Zagorje, NW Croatia), and Divoselo (Lika, SW Croatia). In addition bentonite from nearby deposit Šipovo in W Bosnia and Herzegovina was analyzed for comparison. All of the investigated deposits have been formed by alteration of volcanic material. The deposits' ages range from Upper Jurassic (Maovice-Štikovo), through Lower Miocene (Gornja Jelenska and Bednja), to Upper Miocene (Poljanska Luka). The age of the Divoselo deposit is still unknown due to extensive erosion of the uppermost layers. The samples (whole rock and <2µm fraction) were analyzed by X-ray diffraction, FTIR spectroscopy, thermal and chemical (ICP-AES and ICP-MS) methods. The cation exchange capacity (CEC) of the samples was determined with two different methods (ammonia electrode and [Cu(en)2]2+), while the exchangeable cations were measured by atomic emission and absorption spectroscopy. Additionally, the ability of the studied bentonites to adsorb heavy metals (Pb, Cu and Zn) from aqueous solution was measured by atomic absorption spectroscopy. According to the trace elements content, original volcaniclastic material was andesitic to rhyolitic in composition. The main constituent in all the samples is dioctahedral smectite ; montmorillonite in all the samples except in those from Divoselo and Šipovo deposits in which chemical analyses (primarily higher content of Al), lower dehydroxylation temperature as well as the results of the Greene-Kelly test revealed the presence of beidellite. Other constituents, type and quantity of which vary within and between deposits, are clinoptilolite, calcite, quartz, opal-CT and plagioclase. In all the samples the main exchangeable cation measured is calcium. Adsorption of Pb, Cu and Zn on studied bentonites is positively correlated with their CEC. The results showed that analysed bentonites preferentially remove Pb from aqueous solutions containing these heavy metals.

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Rudarstvo, nafta i geološko inženjerstvo

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