Removal of cadmium, lead, zinc, copper and iron from their aqueous solution by kaolinite clay

This study includes the removal of some heavy metals such as Cd (?), Pb (?), Zn (?), Cu (?) and Fe (???) in aqueous solution using kaolinite clay. The adsorption of these metals on kaolinite conformed to linear form of Langmuir adsorption equation.Langmuir Cm constant for each metal were found as 35.7mg/g (Pb) ,16 mg/g(Cd) ,24.4mg/g(Fe),12.5mg/g(Zn) and 8mg/g(Cu) at 25 ºc respectively .The effect of contact time (5-90min),pH (2-12),temperature(25-60ºc),amount of adsorbent(0.05-1.4g) and metal ion concentration(0.5-12ppm), were studied .The optimum conditions were recorded in each case and the adsorption was in the order Pb (?)>Fe (???)>Cd (?) > Zn (?)>Cu (?).The thermodynamic parameters such as ?H, ?G and ?S were calculated and these values shown that the adsorption of heavy metals on kaolinite was an endothermic process, and the adsorption was of physical type, which increase by temperature rises. Also the kinetic parameter such as adsorption rate constant (k) was calculated. The desorption process was studied for each metal, and the effect of regeneration time on efficiency of the uptake percentage was represented and discussed.