Studies on Sorption of Cadmium on some Soils of India

Chemical Laboratories, D. S. College, Aligarh-202 001 Manuscript received 25 November 1985, revised 19 June 1987, accepted 7 January 1988 Adsorption of cadmium has been studied on eight agricultural soils having pH range 6.0 - 9.2 and total cadmium content 0.45 - 0.95 µg Cd g-1 soil. The equilibrium was attained within 3 h. The adsorption Isotherms followed the Freundlich adsorption equation and isotherms were of 'L' type as defined by Giles et al. Desorption was also studied on three soils with variable pH; with the soil ot lowest pH (soil no. 1; equilibrium pH 5.6), Cd desorbed by repeated washings with 0.002 M CaCI2 was >85% while In soils 8 and 4 with equilibrium pH values 6.4 and 7 9 it was only 49 and 30%, respectively. The amount of Cd desorbed from the three soils by 125 or 500 µm ml-1 solution of heavy metal chlorides varied from 35 to 85%. The results indicate that Cd Is strongly sorbed by soils of high pH (>7.0) when it Is added in amounts comparable to additions as sewage