Dolomite Surface Modification with Titania and Silica Precursors and its Morphostructural and Thermal Characterisation

The aim of the paper is to modify the surface of dolomite with titania (TiO2) and silica (SiO2) precursors, in order to use it as a potential reinforcement material in a polymeric matrix or for environmental applications (photocatalyst for the degradation of organic pollutants based on TiO2). The dolomite surface modification was performed by 2 methods. The first method consisted in modifying the direct dolomite surface with SiO2 and TiO2. The second method consisted in the initial treatment of dolomite with TEOS, in order to form silanol bonds, followed by the addition of SiO2 and TiO2 precursors. The obtained powders were characterized by FTIR, SEM-EDS and DSC-TG. The FTIR spectra prove the formation of the silica network while the samples modified with PDMS exhibit the characteristic peaks of methyl groups from PDMS. In EDS, the presence of the characteristic elements of dolomite (calcium, magnesium, oxygen and carbon) can be observed. When analyzing the modified dolomite powders the presence of titanium and silicon can be observed. The characteristic morphology of the dolomite is preserved in all the samples but, the surface of the larger particles is decorated with smaller particles proving the functionalization of the dolomite, according to the two routes. The thermal analysis is characteristic for dolomite-based materials, the main difference between the samples appearing as a consequence of the burning of the organic part of PDMS, which occur between 400 and 600°C.