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The dissolution kinetics of raw and mechanochemically treated kaolinites in industrial spent liquor – The effect of the physico-chemical properties of the solids
Abstract Using industrial spent Bayer-liquor solution and 95 °C temperature, the dissolution and desilication products formation kinetics of five raw kaolinite samples obtained from different sources were found to display profound differences. It was hypothesized that these differences were connected to the physico-chemical properties of the solids. The solids were characterized by powder X-ray diffractometry, N2 adsorption-desorption isotherms, temperature-programmed NH3 desorption, infrared and ultraviolet–visible diffuse reflectance spectroscopies, scanning electron microscopy connected with energy dispersive X-ray analysis, dynamic light scattering and thermal analysis. The detailed structural study of the as-received samples was supplemented by exploring the effect of mechanochemical treatment. It was found that beside specific surface area and pore volume, the amount of the Lewis acid sites proved to be the most important factors, and the picture was found to be modulated by the degree of aggregation of the primary particles. On mechanochemical treatment (60 min milling in a mixer mill), the number of the acid sites increased significantly (from 0.004–0.013 to 0.055–0.066 mmol/g), and largely as a result of this, the dissolution of all raw kaolinites became practically instantaneous and source-independent.
Graphical abstract Display Omitted
Highlights Dissolution of kaolinite was studied in hot and highly alkaline aluminate solution. Dissolution behavior of kaolinites from five different sources was compared. Physico-chemical data of the initial, milled and calcined solids were determined. Increased dissolved silica concentration is due to the formation of metakaolinite. The number of Lewis-acid centres plays important role in the kaolinite dissolution.
The dissolution kinetics of raw and mechanochemically treated kaolinites in industrial spent liquor – The effect of the physico-chemical properties of the solids
Abstract Using industrial spent Bayer-liquor solution and 95 °C temperature, the dissolution and desilication products formation kinetics of five raw kaolinite samples obtained from different sources were found to display profound differences. It was hypothesized that these differences were connected to the physico-chemical properties of the solids. The solids were characterized by powder X-ray diffractometry, N2 adsorption-desorption isotherms, temperature-programmed NH3 desorption, infrared and ultraviolet–visible diffuse reflectance spectroscopies, scanning electron microscopy connected with energy dispersive X-ray analysis, dynamic light scattering and thermal analysis. The detailed structural study of the as-received samples was supplemented by exploring the effect of mechanochemical treatment. It was found that beside specific surface area and pore volume, the amount of the Lewis acid sites proved to be the most important factors, and the picture was found to be modulated by the degree of aggregation of the primary particles. On mechanochemical treatment (60 min milling in a mixer mill), the number of the acid sites increased significantly (from 0.004–0.013 to 0.055–0.066 mmol/g), and largely as a result of this, the dissolution of all raw kaolinites became practically instantaneous and source-independent.
Graphical abstract Display Omitted
Highlights Dissolution of kaolinite was studied in hot and highly alkaline aluminate solution. Dissolution behavior of kaolinites from five different sources was compared. Physico-chemical data of the initial, milled and calcined solids were determined. Increased dissolved silica concentration is due to the formation of metakaolinite. The number of Lewis-acid centres plays important role in the kaolinite dissolution.
The dissolution kinetics of raw and mechanochemically treated kaolinites in industrial spent liquor – The effect of the physico-chemical properties of the solids
Kása, Eszter (Autor:in) / Szabados, Márton (Autor:in) / Baán, Kornélia (Autor:in) / Kónya, Zoltán (Autor:in) / Kukovecz, Ákos (Autor:in) / Kutus, Bence (Autor:in) / Pálinkó, István (Autor:in) / Sipos, Pál (Autor:in)
Applied Clay Science ; 203
17.01.2021
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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