A Study of the Kinetics of Adsorption of Zinc(II) Ions by a Natural Aluminosilicate of Eastern Transbaikalia

摘要

The adsorption of zinc ions by a natural aluminosilicate of Eastern Transbaikalia has been investigated. The effect of the grain size of aluminosilicate on the adsorption of zinc ions has been studied. It has been determined that, along with the decrease of the grain size from 5 to 0.1 mm, the adsorption value increased by 3.8 times and reached a value of 0.075 mmol/g. The kinetics of zinc adsorption at pH 5.4 in the temperature range from 298 to 318 K have been studied using pseudo-first- and -second-order models. It has been determined that the adsorption of zinc ions decreases along with the increasing temperature. It has been shown that the adsorption kinetics are best described by the second-order model. The values of the correlation coefficients were 0.998-0.999. The maximum value of the adsorption rate constant of 0.446 g/(mmol min) corresponded to the temperature of 298 K. The value of the thermodynamic equilibrium constant decreased along with the increasing temperature. The studied adsorption process was followed by a small change in the enthalpy of ion exchange. The calculated values of increment H and & UDelta;G indicate an exothermic adsorption process with the formation of thermodynamically stable surface compounds of zinc(II) ions.