Solubility of Calcined Kaolinite, Montmorillonite, and Illite in High Molar NaOH and Suitability as Precursors for Geopolymers

Abstract Clays and clay minerals dissolve over a broad pH range, such as during sediment diagenesis in variety of applications, including nuclear waste storage, landfills, geopolymer binders the construction industry. The solubility depends on process parameters (pH, temperature, pressure, etc.) material properties (phase content, mineral composition, particle size, etc.). Pretreatments calcination or severe grinding change could enhance solubility, which is called activation. aim current study was to determine three different after (metakaolinite, metamontmorillonite, metaillite) high molar alkaline solutions (NaOH) up 10.79 mol/L = 14.73. Furthermore, an Al(OH) 3 powder solution analyzed, it can be used adjust Si:Al ratio precursors. residues treatment were investigated disclose potential alterations their phase contents. Based results thermal activation, conclusions about suitability precursors made. All showed increase proportional concentration solution. decreased order metakaolinite > metamontmorillonite metaillite. Thereby, dissolution incomplete for all (<90%) 7 days congruent metaillite but incongruent metamontmorillonite.