The present study focuses on the adsorption of Pb(II) by the H-form of titanosilicates (ETS-4, GTS-1) and clinoptilolite. The H-forms were prepared by first exchanging the extra-framework cations—Na+, K+, Ca2+, etc.—with NH4+, and by subsequent thermal treatment for obtaining H-forms. The purity and thermal behaviour of the initial, NH4+, and H-forms of ETS-4, GTS-1, and clinoptilolite were analysed by powder XRD, while the morphology and size of the particles were determined by SEM. The chemical composition of the solids and the solutions was obtained by WDXRF and ICP-OES, respectively. The kinetics research of the Pb(II) adsorption processes was based on WDXRF and ICP-OES. The H-forms of the materials displayed favourable properties for the adsorption of Pb(II). The best behaviour in this respect was demonstrated by GTS-1 when compared to ETS-4 and clinoptilolite.
Geopolymers based on Bulgarian natural zeolite (clinoptilolite) were synthesized using alkaline activators in order to prepare plaster/render mortar. The influence of the alkali concentrations of the activator solution was examined in regard to tensile strength and adhesion to concrete. Microstructure of the obtained geopolymer pastes was analysed by XRD, FTIR, SEM. The results showed adhesive strength to concrete up to 3.6 MPa and tensile strength up to 5.44 MPa. The present study shows a promising potential of the geopolymers as coating material for concrete.
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