Radiotracer technique in adsorption study. Pt. 8

Adsorption of microamounts of phosphate ion on alumina-supported copper oxide from aqueous solutions of sodium dihydrogen phosphate has been studied as a function of contact time, concentration (10-7-10-2 M), temperature (303-323 K) and pH (2.10-9.60) of the adsorptive solution using radiotracer technique. The uptake is found to increase with the concentration of adsorptives as well as temperature. The adsorption kinetics of phosphate ions is quite dependent on the pH of the adsorptive solution. The stepwise growth of phosphate adsorption follows first-order kinetics. The experimental results show that the adsorption in the system under study obeys the classical 'Freundlich isotherm' in the entire range of adsorptive concentration. Pre-treatment of oxide adsorbent with neutrons - and γ-radiations from a 11.1 GBq (Ra-Be) neutron source having an integral neutron flux of 3.85x106 neutrons/cm2/sec and associated with a nominal γ-dose of ca. 1.72 Gy/hour, enhances the adsorption capacity up to certain periods and then reduces it upon further irradiation. Desorption experiments support the 'Chemisorption' nature of the process involved. (orig.)