Zeolitization of kaolin from M'Batra village (Cote d’Ivoire) by NaOH and Na2O.SiO2 treatment

Abstract

Kaolin has been used as an alternative cheap raw material for the synthesis of zeolite NaY. The objective of this study is to synthesize a zeolite NaY from a natural clay (kaolin) from M'Batra. Two steps are involved in the reaction: (1) dehydroxylation of kaolin at 550°C to form an amorphous material called metakaolin; (2) hydrothermal treatment of metakaolin with aqueous alkali to form the zeolite. SEM, BJH and BET techniques were used respectively to study the morphology, pore size distribution and adsorption-desorption isotherms of N2 at 77 K. Structural and compositional studies were conducted using X-ray fluorescence (XRF), solid-state nuclear magnetic resonance of 27 Al and 29 Si. XRF analysis showed an increase in the Si/Al ratio of 1.91 to 2.95 compared to natural clay. The SEM of the zeolite NaY gave a homogeneous and porous material. The specific surface area of the zeolite NaY increased by 5.03 times compared to the natural clay. The XRD of the zeolite NaY showed a well crystallized material. The MAS NMR spectrum of 27 Al revealed a single Al environment. In conclusion, the results of the different characterizations show us that the material obtained by modification of the natural clay (kaolin) of M'Batra has a zeolithic structure.