RADIOTRACER TECHNIQUE IN ADSORPTION STUDY .16. AN EFFICIENT REMOVAL OF CADMIUM IONS BY SODIUM TITANATE FROM AQUEOUS-SOLUTIONS

The uptake of Cd(II) ions on synthesized sodium titanate at different pH values (3.5-10.2), adsorbate concentrations (10(-2)-10(-8) M) and t emperatures (303-333 K) has been studied using the radiotracer techniq ue. The results show that the uptake follows first order rate law and equilibrium data fitted well for Freundlich adsorption isotherm. A cha nge in temperature does not affect markedly the uptake of Cd(II) ions; however, it is greatly influenced by the presence of diverse ions lik e Ba2+, Ca2+, Sr2+, Hg2+, Zn2+, Na+, K+ and complexing agents like ace tate, phosphate, oxalate and EDTA. Radiation stability of sodium titan ate was also assessed by exposing it to neutrons and gamma rays from a 11.1 GBq (Ra-Be) neutron source having an integral neutron flux of 3. 85 x 10(6) n/cm(2)/s associated with gamma-dose of 1.72 Gy/h as also u sing a Gamma cell (4.66 kGy/h). The increasing presence of acids (HCl and H2SO4) decreases the uptake of Cd(II) ions, however, practically n o desorption takes place into the bulk at the studied pH (5.2) and tem perature (303-333 K) which suggest irreversibility of the uptake of Cd (II) ions. (C) 1997 Elsevier Science Ltd.