Yi Liu, Baifa Zhang, Mohammad Fahimizadeh, Ting Yu, Zhou Ou, Zhineng Peng, Peng Yuan
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引用次数: 0
Abstract
This study investigated the effects of mechanical activation on the transformation of kaolinite to sodalite under mild conditions. The sodalite prepared via alkaline leaching of kaolinite under different milling times, alkaline concentrations, and leaching times was studied. The prepared zeolites were physically, chemically, and morphologically characterized. The results show that ball milling can significantly reduce the particle size and increase the specific surface area of kaolinite. Highly crystalline sodalite (Na8Al6Si6O24(OH)2) can be prepared from kaolinite with ball milling for 2 h after alkaline leaching at 6 M NaOH for 24 h. Ball milling destroyed the crystal lattice of kaolinite, generating structural defects and dislocations, destabilizing the framework of kaolinite and increasing its reactivity. Furthermore, mechanically activated kaolinite demonstrated a hybrid transformation under alkaline leaching, involving both direct transformation (kaolinite → sodalite) and a two-step transformation (kaolinite → zeolite A → sodalite), depending on the dehydroxylation degree. The complete dehydroxylation of kaolinite induced a two-step transformation under alkaline leaching, as the thermally activated kaolinite did. Kaolinite was directly transformed into sodalite under alkaline conditions (≥ 4 M NaOH), exhibiting heterogeneous nucleation on the surface of kaolinite. Interestingly, the conversion of zeolite A into sodalite required a higher alkaline concentration for the thermal activation of kaolinite under atmospheric pressure, reflecting the advantages of mechanical activation. Mechanical activation can reduce the alkaline concentration required for the preparation of sodalite from kaolinite despite the conversion route, indicating that the preparation of sodalite can be completed under mild conditions.
期刊介绍:
Applied Clay Science aims to be an international journal attracting high quality scientific papers on clays and clay minerals, including research papers, reviews, and technical notes. The journal covers typical subjects of Fundamental and Applied Clay Science such as:
• Synthesis and purification
• Structural, crystallographic and mineralogical properties of clays and clay minerals
• Thermal properties of clays and clay minerals
• Physico-chemical properties including i) surface and interface properties; ii) thermodynamic properties; iii) mechanical properties
• Interaction with water, with polar and apolar molecules
• Colloidal properties and rheology
• Adsorption, Intercalation, Ionic exchange
• Genesis and deposits of clay minerals
• Geology and geochemistry of clays
• Modification of clays and clay minerals properties by thermal and physical treatments
• Modification by chemical treatments with organic and inorganic molecules(organoclays, pillared clays)
• Modification by biological microorganisms. etc...