Abstract: Cow dung has been investigated as metal adsorbent for lead and Zinc ions from aqueous solution for its availability as animal waste and its cellulosic matrix rich in potential metal binding active sites. The effect of various parameters on adsorption process such as contact time, initial metal ion concentration and solution pH were studied at room temperature, 25±2^oC to optimize the conditions for maximum adsorption. Adsorption process revealed that the initial uptake was rapid and equilibrium was established in 90 minutes for both metal ions. The results obtained indicated that the amount of metal ion adsorbed per gram of the adsorbent increased with increasing initial metal ion concentration for both Zn²⁺ and Pb²⁺ ions. However, there was a decline in percentage removal despite increase in metal ion concentration. Sorption was observed to increase as the solution pH was increased. Optimum metal ion removal occurred at pH 5 for Zn²⁺ and pH 6 for Pb²⁺.It is shown that cow dung can bind substantial amount of heavy metal ions, percentage removal of 63.8 was recorded for Zn²⁺ and 60.8 for Pb²⁺.Zinc showed higher affinity and adsorption rate compared to lead under all experimental conditions. The equilibrium data were satisfactorily fitted to Freundlich isotherm.

 

Keywords: Adsorption, cow dung, heavy metals, wastewater.