Chromium and nickel metal ions removal from contaminated water using Nigerian bentonite clay

Abstract

In this work, bentonite clay was characterized and investigated for the adsorption of chromium and nickel metal ions from aqueous solution. The clay, calcined at 650 °C, was characterized for physical, chemical and textural properties. Nickel sulphate hexahydrate (NiSO4.6H2O) and chromium tri oxide (Cr2O3) solutions were used as metal model compounds to evaluate the adsorption efficiency of the clay in a batch mode. The initial metal ions concentration ranged from 10 to 50 mg/L and the maximum removal efficiency was 99.40% for Cr (III) and 71.50% for Ni (II) metal ions. Langmuir and Freundlich models were utilized for the analysis of the adsorption equilibrium isotherm. The experimental data fitted well into the Freundlich model for Cr (III) with a regression coefficient (R2) of 0.996 and the Langmuir model for Ni (II) having an R2 value 0.994. The pseudo-second order kinetic model fitted well for both chromium and nickel and their adsorption from single metal solutions followed the order Cr > Ni. Highlight The local clay has not been reported in any scholarly journal or publication. The removal of nickel and chromium using this clay has been found to be effective. The data obtained will form a baseline for references and learning purposes.;

Keywords

• adsorption
• bentonite clay
• chromium
• isotherms
• kinetics
• nickel