Soil and underground water is being contaminated on daily basis by heavy metals present in wastes indiscriminately discharged by industries which lack financial ability to invest in conventional waste treatment methods, hence, the need for the development of low cost adsorbents which can effectively reduce concentration of these metals before such wastes are discharged. Aldrich bentonite with CEC of 95 meq/100g known to be high swelling clay was modified with goethite and humic acid which are also phases in the soil and known to act as sink for heavy metals in the soil. Various operating parameters such as the effect of pH, contact time, initial metal ion concentration etc. were optimised on bentonite. Adsorption was then carried out on modified and unmodified bentonite, goethite and humic at these optimised conditions. The results from the optimisation of various operating parameters on bentonite showed that pH of maximum adsorption of Cu2+ and Cd2+ where 5 and 6, while optimised contact time were 4 hours and 8 hours respectively. The general order of effectiveness of the adsorbents (i. e. modified and unmodified) is shown in full details in the book.
