Zeolite A Synthesis Employing a Brazilian Coal Ash as the Silicon and Aluminum Source and its Applications in Adsorption and Pigment Formulation

Zeolite A was synthesized using the coal ash from Sideropolis/RS - Brazil. The synthesis was based on a standard IZA synthesis using coal ash as the Si and Al source. XRF analysis showed that the coal ash has a Si/Al ratio of 1.52, which is close to the Si/Al ratio required to produce zeolite A (1.0). The synthesized materials were analyzed by XRD, SEM and N-2 adsorption. More crystalline materials were obtained during synthesis when an additional treatment was applied at a temperature of 353 K at the dissolution of NaOH step. The product formed after 4 hours was the most crystalline, but even the product formed after 1 hour proved to be better than that formed using the standard 4 hours IZA synthesis. The zeolites synthesized by this method had an adsorption capacity of 120 mg.g(-1) for Ca2+, half the capacity of commercial zeolite A (300 mg.g(-1)). It was not possible to obtain blue or green pigments using the synthesized zeolite A.