engleski

Investigation of clays and clay minerals in Croatia: Current state and future perspectives

Clays and clay minerals in Croatia are important geologically and used in construction, industry, agriculture, engineering and environmental related applications. Construction clay deposits (smectite-kaolinite-illite in composition) and bentonite deposits are mainly situated in the Pannonian part of Croatia. The first published paper in which “tonsubstanz” (clay substance) is mentioned in Croatia dates from the year 1912 and is related to mineralogical investigation of the insoluble residue of limestone and dolomite. Investigation of clays and clay minerals was mainly related to terra rossa and bauxite studies until seventies of the 20th century. Since that time the research intensified. The following phyllosilicates, their characteristics and processes were investigated by powder and single-crystal methods XRD, “wet” chemical analysis, AAS, ICP-AES, EPMA, FTIR, SEM and thermal techniques: the polytypism of biotites and muscovites by means of Weissenberg goniometer; the possibility of determination of the polytypes of trioctahedral micas using XRD powder methods; the mechanisms of hydrothermal alteration of biotites to chlorites; the weathering processes of biotites and chlorites and alteration products; interstratified minerals, e.g. biotite-vermiculite, chlorite-vermiculite; chlorite-smectite and illite-montmorillonite; glauconite and glauconitic materials in sandstones; heating products of pure, chemically different, glauconitic materials in the temperature range 980-1300ºC; celadonites in altered tuffs; illitization of smectites in Cretaceous paleosols; neoformation of kaolinite in terra rossa soils; the sorption of surfactants by bentonites, arrangement of DMDSA+ and C18EO11 within montmorillonite interlayer space and thermal properties of resulting organo-montmorillonite complexes; montmorillonites from bentonites and their heating products. Investigation of surface characteristics and colloidal behaviour of clay mineral particles, in view of their electrokinetic phenomenology, physico-chemical processes at clay solid/liquid interfaces, and finally, their role in the adsorption, transfer, and deposition of organic and inorganic compounds in natural environments are in progress. The use of clays and clay minerals in environmental related applications is increasing in Croatia. Clays are used as liners and barriers in many applications. The investigation of organophilic clays as absorbers of organic contaminants from oil and gasfield waste (drilling muds) has started. Future efforts should also be directed to investigation of clays and clay minerals as mineral raw materials for construction and industry, and in the protection of soil and groundwater.

clays; clays minerals; Croatia

nije evidentirano