Dissolution kinetics and mechanisms of reaction of Udi clay in nitric acid solution

The dissolution kinetics and mechanisms of reaction of Udi clay in nitric acid have been studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It was observed that the dissolution rate increased with decreasing particle size and solid-to-liquid ratio and increased with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is chemical reaction controlled via hydrogen ion [H+] action, with reaction order of 0.31 and the reaction kinetics can be expressed as: 1 – (1 – X) 1/3 = 1.7275 x 10 4 C [HNO3] 0.3113 (dp) -0.4102 (S/L) -0.3104 (w) 0.2709 exp (-2621/T) t. The activation energy of the process was determined to be 21.791kJ/mol. The experimental data were tested by graphical and statistical methods and it was found out that the above model best fitted the data.