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

粘土和粘土矿物在广泛的 pH 值范围内溶解，例如在沉积物成岩过程中以及在各种应用中，包括核废料储存、垃圾填埋场和建筑行业中的地质聚合物粘合剂。溶解度取决于工艺参数（pH、温度、压力等）和材料特性（相含量、粘土矿物组成、粒度等）。诸如煅烧或剧烈研磨等预处理会改变材料的性质并可以提高溶解度，这称为活化。本研究的目的是确定煅烧后三种不同粘土矿物（偏高岭石、偏蒙脱石和金属石）在高达 10.79 mol/L 和 pH = 14.73 的高摩尔碱性溶液 (NaOH) 中的溶解度。此外，Al(OH) _{3的溶解度}分析了碱性溶液 (NaOH) 中的粉末，因为它可用于调整地质聚合物前体的 Si:Al 比。研究了碱处理后粘土矿物的残留物，以揭示其相含量的潜在变化。根据热活化和碱活化的结果，得出了作为地质聚合物前体的适用性结论。所有粘土矿物都显示出与碱性溶液浓度成正比的溶解度增加。溶解度按偏高岭石>偏蒙脱石>金属石的顺序降低。因此，7 天后所有三种粘土矿物（<90%）的溶解不完全，偏高岭石和金属石一致，但偏蒙脱石不一致。