Adsorption of Pb(II), Cd(II), Ni(II) and Cu(II) onto natural kaolinite clay

Kaolinite clay obtained from Longyan, China was investigated to remove heavy metal ions from wastewater. Thus, the present study includes the adsorption of Pb(II), Cd(II), Ni(II) and Cu(II) in aqueous solution on kaolinite clay through the process of adsorption under various conditions (with variable concentration of metal ion, amount of clay, pH and mixing time). Increasing pH favours the removal of metal ions till they are precipitated as the insoluble hydroxides. The uptake is rapid with maximum adsorption being observed within 30 min for Pb(II), Cd(II), Ni(II) and Cu(II). In addition, the results obtained from adsorption isotherm indicated that these data can be better fitted with the Freundlich equation than the Langmuir equation. Furthermore, the XRD patterns confirmed that this kaolinite clay sample is mainly a mixture of kaolinite and illite clays. The SEM images of samples showed irregular surface morphology. Finally, this kaolinite clay was used for removing metal ions from real wastewater such as Pb(II), where its concentration was reduced from 160.00 to 8.00 mg/L.