Effect of Citric Acid on Aluminum and Silicon Release from Kaolinite

The experiments was conducted to investigate the effect of citric acid on aluminum and silicon release from water-eluviated kaolinite with batch method. The results showed citric acids enhanced significantly both Al and Si release from kaolinite, and release of Al and Si from kaolinite increase with concentration of citric acids compared with deionised water. Dissolution stoichiometry of kaolinite was related to concentration of citric acids, dissolution stoichiometry of kaolinite increase with concentration of citric acids, and preferential Al-release was observed initially but after reaction anaphase, Al and Si showed stoichiometric release. The rate of kaolinite dissolution obtained in citric acid solution was almost 1 order of magnitude as large as that of inorganic acid, and the dissolution rate behave the character of saturation with the concentration of citric acids.