THERMOANALYTICAL EVENTS AND ENTHALPIES OF PHASES AND SYSTEMS OF THE CHEMISTRY AND TECHNOLOGY OF CONCRETE PART II. HYDRATED CEMENTS

Essential focus of the study has been to acquire thermoanalytical events, incl. enthalpies of decompositions - ΔH, of technological materials based on two types of Portland cements. The values of thermoanalytical events and also ΔH of probes of technological compositions, if related with the data of a choice of minerals of calcium-silicate-sulfate-aluminate hydrates, served as a valued input for the assessment of phases present and phase changes due to the topical hydraulic processes. The results indicate mainly the effects of "standard humidity" or "wet storage" of the entire hydration/hydraulic treatment, but also the presence of cement residues alongside calcium-silicate-sulfate-aluminate hydrates (during the tested period of treatment). "A diluting" effect of unhydrated cement residues upon the values of decomposition enthalpies in the studied multiphase system is postulated and discusse

Synthesis and characterization of a Hg(II) selective II-butyl acetate cerium(IV) phosphate as a new intercalated fibrous ion exchanger: Effect of surfactants on the adsorption behaviour

1856-1860n-butyl acetate Ce(IV) phosphate, a new Hg(II) selective, intercalated fibrous ion exchanger, has been synthesized and characterized by its ion exchange properties, thermal stability and adsorption behaviour for metal ions, X-ray, IR, TGA/DTA and SEM studies. Effect of surfactants on the adsorption behaviour of the material has also been studied. The exchanger has been found to be selective for Hg(II), hence, it can be utilized for the separation of this metal ion from other heavy metals from aqueous media. Studies on the effect of surfactants on the adsorption behaviour of this material show that for heavy metals ion, the adsorption increases with the concentration of anionic surfactants up to the CMC value and then decreases. But, for cationic, surfactants, the reverse is true. For non-ionic surfactant, adsorption remains constant up to the CMC value and then increases. For alkaline earths, the exchanger shows the same trend as above for cationic and non-ionic surfactants. However, for anionic surfactants, it is constant throughout the whole concentration range