Investigation of the interaction of Greek dolomitic marble with metal aqueous solutions using Rutherford backscattering and X-ray photoelectron spectroscopy

The interaction of dolomitic marble from Thassos Island (northern Aegean sea, Greece) with Co2+-, Cd2+-, Pb2+- and Cr3+- aqueous solutions (metal concentration: 1000 mgL-1) was investigated using Rutherford backscattering (RBS) and X-ray photoelectron spectroscopy (XPS). The initial material as well as the interaction products were also characterized by scanning electron microscopy (SEM/EDS), radioisotope induced X-ray fluorescence analysis (RI-XRFA), powder X-ray diffraction (Powder-XRD) and Fourier transform infra-red spectroscopy (FT-IR). The contact time of the samples with the aqueous solutions was one week and took place under ambient temperature. To our knowledge, the sorption of the above mentioned metals with dolomite (CaMg(CO3)2) has not yet been presented in the literature and the only data available concern the adsorption of Ca, Mg and Nd from NaCl solutions. The Thassos island dolomitic marble is a snow-white homogeneous carbonate metamorphic rock, with fine physicochemical and mechanical properties, currently used as natural building stone in many parts of the world (see http://www.thassosmarble.com), This dolomite-bearing material was also extensively used in the past as construction material of many .classical Greek and Roman sculptures and architectural elements; in 301 AD the Roman emperor Diocletian included 'Thassian marble' in the list of the 19 most expensive and important 'marbles' produced in the imperial quarries. Previous literature presented the isotopic analysis(δ13C, δ18O) and EPR studies (Mn2+ and Fe3+) of this stone. The obtained results indicated a limited Cd2+ - and Co2+ -sorption on the dissolved surface of the carbonate substrate, whereas, under the same experimental conditions, the Pb2+- and Cr3+-interaction is more intense leading to extended overgrowth of crystalline Pb-carbonates and surface precipitation of amorphous Cr-hydroxides/oxyhydroxides.