Chemical and structural changes of calcium ion exchange silica pigment in 0.5M NaCl and 0.5M Na 2SO 4 solutions
2011
Granizo, N. | Martín, M. I. | López Gómez, Félix Antonio | Vega, J. M. | Fuente, Daniel de la | Morcillo, Manuel
This paper studies the suitability of an environmentally-friendly anticorrosive pigment (Si/Ca) to replace Cr(VI) pigments, characterising the initial pigment and the products obtained after interaction with aqueous solutions containing aggressive ions from a corrosion viewpoint (Cl - and S0 4 -2). X-ray diffraction (XRD), calorimetry (DTA-TG), Fourier transform IR spectroscopy (FTIR) and scanning electron microscopy (SEM-EDAX) techniques are used. The ion exchange capacity of the pigment is studied and the solutions obtained after the pigment-solution interaction are analysed. The results obtained show that a series of physical/chemical transformations take place in the pigment on interaction with the Cl - and S0 4 -2) solutions, in some cases accompanied by the appearance of new crystalline phases, mainly calcium and sodium silicates and calcium sulphate. Analysis of the solutions obtained after interaction shows a rise in the calcium content as the ionic force of the medium increases. These results suggest that the mechanism by which the pigment acts is not only based on ion exchange reactions but also on a structural modification of the pigment itself and consequently on (co) precipitation reactions that form insoluble compounds in the studied aggressive media.
Show more [+] Less [-]Peer Reviewed
Show more [+] Less [-]Bibliographic information
This bibliographic record has been provided by Centro Nacional de Investigaciones Metalúrgicas
