Thermal and spectral characterization of bottom sediment from the water reservoir RuA3/4in No. I in Eastern Slovakia and the kinetics of heavy metal cation leaching

The main aim of this study was to describe the physicochemical and thermal properties of the bottom sediment collected in summer 2011 from the Hnilec River branch of the water reservoir RuA3/4in No. I, which is well known for its past mining and metallurgical activities over the last four decades. The influences of various sorbent additions on the release of cadmium, copper, and lead cations from the sediment were also evaluated. Sediment was collected from a monitoring station on the water reservoir RuA3/4in No. I located on the river Hornad during the year 2011. The mineralogical composition of the sediment was investigated by X-ray powder diffraction (XRPD) integrated with differential (DTA) and thermogravimetric analysis (DTG). The mineralogy was also determined by infrared spectroscopy (FTIR). The concentrations of metals were analyzed using X-ray fluorescence (XRF) spectrometry. X-ray powder diffractometry (XRPD) revealed that the study sediment contained quartz as the major mineral and that other minerals, such as sericite and the plagioclase mineral series, were present in smaller amounts. It was found that the highest concentration of trace metals occurred in the fraction < 40 mu m, and, after the addition of sorbents, the leach ability of selected metal cations decreased approximately 50 % for each sorbent. Sorbent addition caused metal immobilization, most likely due to the adsorption of cations on the illite surfaces and the precipitation of metal hydroxides. A combination of thermal (TG/DTG, DTA) and spectral (XRPD, XRF, FTIR) techniques was used to characterize the contaminated sediment. The obtained results provide insights for the planning of further sediment utilization.