Kinetic Study for Adsorption of Chromium tri-Oxide 3 CrO on Kaolinite Surface

Abstract

The removal of 3 CrO by using kaolinite have been investigated, as a function of initial
concentration, pH and temperatures.
Adsorption process, was attained to equilibrium within 60 minutes which indicated by
uv-visible absorption spectroscopy technique at wave length 390 nm.
The best results which are used in this study were achieved at pH of 4, and 290 K, in
this range of pH and temperature, the chromium tri oxide transformation hydro-chromate into
bi-chromate takes place.
The equilibrium data for adsorption are fitted to the Freundlich, Langmuir and Dubinin-
Radushkevich (D-R) isotherm equations. Values of parameters for theses isotherms equations
were calculated.
The mean energy of adsorption Eads, was also calculated from the adsorption energy
constant Keng, its value determined from the D-R isotherm equation. The temperature
thermodynamic parameters like ΔG , ΔH and ΔS have been calculated. Values of enthalpy
ΔH showed that the adsorption process is exothermic.