Cd2+ ions removal by silica, iron hydroxide and their equimolar mixed oxide from aqueous solution

 

S. Mustafa^a,*, M. Waseem^a, A. Naeem^a, K. H. Shah^a, T. Ahmad^a

 

^a National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar ? 25120, Pakistan

 

Summary

In this study, all the adsorbents were prepared in the laboratory and the adsorption of cadmium ions on the prepared adsorbents was studied. The adsorption of cadmium ions on silica, iron hydroxide and a mixture of cadmium and iron hydroxide with equal molar amounts were studied. The concentration range of cadmium ions was in the range of 8.89 and 88.96 mol L^?1. Experiments were performed in the temperature range of 288?318 K and a pH value of 5 was selected. The adsorption curves show that the amount of cadmium ions on mixed oxide is higher than on silica and iron hydroxide. The increased adsorption results show that surface groups FeO? and SiO? are involved in adsorption. Further, the cadmium ions sorption increased with the increase of temperature.

It was concluded that the mixture of silica and iron hydroxide was highly effective in adsorption of cadmium ions. Langmuir isotherm was found to be applicable for cadmium ions sorption. The thermodynamic parameters showed that adsorption was spontaneous and endothermic because of which adsorption increased with increase of temperature. Since the surface groups of both the adsorbents were found responsible for increased adsorption. So, it was concluded that electrostatic forces between opposite ions of surface groups and cadmium ions play their role in adsorption. The curves for adsorption are shown in the figure below.

 

 

Aamir Alaud Din

aamiralauddin@gist.ac.kr