Inorganic Particulates in Removal of Toxic Heavy Metal Ions: Efficient Removal of Cadmium Ions from Aqueous Solutions by Hydrous Manganese Oxide

Abstract

Adsorption of cadmium ions from aqueous solutions of Cd(NO3)2 on hydrous manganese oxide (HMO) has been studied as a function of the contact time, concentration (10-2-10-7 M), temperature (303-333 K) and pH (2.80-11.80) of the Cd(II) solution employing 'radiotracer technique'. The results on adsorption of Cd(II) on HMO show that the removal process is essentially complete in ca. 2 h and the steady state values of adsorption at various concentrations agree well with the classical Freundlich adsorption isotherm. The temperature and pH of the bulk solution markedly affect the extent of adsorption and the process is thermodynamically irreversible. The exposure of HMO to neutrons and γ-radiations from a 11.1 GBq (Ra-Be) neutron source having 1.72 Gy/h dose rate or to a high radiation γ-cell (having mean dose rate 4.66 kGy/h) has practically no significant effect on the adsorption capacity of HMO.