Investigation of Nickel Ion Removal by Means of Activated Clay

Abstract

Natural and activated clays have been investigated as adsorbents for the removal of nickel from wastewater. Analysis of the natural clay under test showed that it was composed, approximately of 51% kaolinite, 46% montmorillonite and 3% illite, having a specific surface area of 65 m²/g.

The natural clay was treated with different activators (HCl, NaCl and H₂O₂) to enhance its adsorption capacity towards nickel. The efficiency of such activation was greater by 16.0% and 23.2% in the case of NaCl and H₂O₂, respectively, relative to untreated clay. No significant increase in the adsorption capacity was brought about by HCl treatment.

A limited comparison has been made between clay and activated carbon by performing isotherm studies under similar conditions. The results indicate that the adsorption capacity of clay activated with H₂O₂, clay activated with NaCl and natural clay is 216.9%, 204.2% and 176.1% that of activated carbon, respectively.

Based solely on the adsorption capacity, an economic analysis demonstrates that natural clay is the cheapest material, followed by clay activated with NaCl and clay activated with H₂O₂. The relative costs of removing nickel using natural clay, clay activated with NaCl and clay activated with H₂O₂ were found to be 2.8%, 5.4% and 25.4%, respectively, that of activated carbon.