Current Research Paper The behaviour of cadmium adsorption on some Egyptian surface soils KEYWORDS Cadmium; NaCl, Na 2 SO 4; Langmuir; Freundlich; Egyptian soils. ABSTRACT Adsorption of cadmium on two different soils from Egypt (clays and sandy loam soils) was studied. Data on adsorption isotherms, competitive effects and/or inorganic complex formation of NaCl and Na 2 SO 4 are presented. The adsorption was described by a Langmuir or a Frendlich equation. The maxi- mum adsorption derived from the Langmuir equation was taken to measure the adsorption capacity, while the Langmuir parameter was taken to point out the relative degree of affinity or energy at different cadmium adsorption conditions. In particular, the clay soil had higher adsorption capacities in all cases than the sandy loam soil. The higher clay content, CEC, OM and the surface area of the clay soil may account for the higher capacity. It appears likely that the existence of NaCl decreases the maximum adsorption of cad- mium in both soils and also reduces the bonding energy coefficients less than those in presence of Na 2 SO 4 apparently favoring the dissociation of adsorbed Cd complex. Due to this behavior, cadmium adsorption in case of NaCl salt matrix was about three times less than for Na 2 SO 4 . This effect is important since relatively moderate concentration of Cl in soil solution will greatly reduce the adsorption of Cd on soil surface. Thereby relatively high Cd concentrations in soil solutions will be maintained especially under surface irrigation conditions, which increase the probability for ground water pollution with this harmful and toxic metal.  2011 Trade Science Inc. - INDIA INTRODUCTION Cadmium is probably the heavy metal of most con- cern associated with soil pollutants. It is a potentially dangerous inorganic pollutant ion. The major question here is the ability of the soil to act as an attenuate and perhaps even a sink for cadmium. The answer of this question could be through knowledge concerning cad- Elmetwaly M.Selim 1 , Faiz F.Assaad 2 , Mohamed E.EL-Hefnawy 3,4,* 1 Department of Biology, Rabigh College of Sciences and Arts, King Abdulaziz University, P.O. BOX 344, Rabigh 21911, (SAUDI ARABIA) 2 Soil and Water Use Department, National Research Centre, Cairo, (EGYPT) 3 Chemistry Department, Rabigh College of Sciences and Arts, King Abdulaziz University, P.O. BOX 344, Rabigh 21911, (SAUDI ARABIA) 4 Department of Chemistry, Faculty of Science, Tanta University, Tanta 31527, (EGYPT) E-mail : mhefnawy46@yahoo.com Received: 22 th July, 2011; Accepted: 22 th August, 2011 Environmental Science An Indian Journal Trade Science Inc. Volume 6 Issue 6 ESAIJ, 6(6), 2011 [313-319] Environmental Science ISSN : 0974 - 7451