Dissolution of Acid-Eluviated Kaolinite Induced by Different Concentrations of Oxalic Acid

Experiments were conducted to investigate the long-time dissolution effect of acid-eluviated kaolinite with batch method in oxalic acids solution. The results showed oxalic acids enhanced significantly Al³⁺and Si⁴⁺ release from kaolinite, compared with deionised water, and release of Al³⁺ and Si⁴⁺ from kaolinite increased with concentration of oxalic acids. The time of dissolution stoichiometry of kaolinite in the oxalic acids solution was later than the citric acids,and preferential Al³⁺-release was observed initially and after reaction anaphase, Al³⁺ and Si⁴⁺ showed stoichiometric release. The rate of kaolinite dissolution obtained in oxalic acid solution was almost one order of magnitude as large as that of inorganic acid, and which was higher than the citric acids, and dissolution rare did not reach saturation under the studied concentration of oxalic acids noted in this study, the dissolution rate presented an increasing character of linearity with the concentration of citric acids.