The Study of Kinetics of Potassium Release by Ammonium acetate and Sodium tetraphenylborate Extractants from Selected Micaceous Minerals

The objectives of this study were to compare the capability of ammonium acetate (NH4OAc) and sodium tetraphenylborate (NaBPh4) in the release of potassium from micaceous minerals including biotite, phlogopite and muscovite. Non-linear regression of pseudo second-order, power function, Elovich and parabolic diffusion equations models inspected to describe potassium release from those minerals in a period of 5 to 11520 minute. The results indicated that the amount of NaBPh4-extractable K was s higher than NH4OAc-extractable K. NaBPh4 extractant released 56.15, 60.14 and 10.78% of total potassium from phlogopite, biotite and muscovite respectively, while those values were 0.81, 0.84 and 0.62% for NH4OAc extractant. The results also showed that the potassium released from minerals in two different phases. The rapid phase occurred at the beginning of experiment and the second phase with lower rate release happened until to the end of experiment. Parabolic diffusion and exponential function equations reasonability described the potassium release from micaceous minerals very well according to R2 and SE indexes. Kinetics of potassium release from biotite and phlogopite minerals were described very well by power function equation (R2=0.98-0.99 and SE=1.20-2.43). The best-fitted kinetic models for the phlogopite (R2=0.98 and SE=2.23) and muscovite (R2=0.87 and SE=1.26) minerals were Elovich and parabolic diffusion equations respectively. Therefore, it may be concluded that the release of potassium is controlled by diffusion process from the surface of the studied minerals.