REMOVAL OF CADMIUM (II), COBALT (II) AND  NICKEL (II) IONS FROM AQUEOUS SOLUTION  USING CORNCOB WASTE

Onwordi, C.T., Okwuolise, C.H., Osifeko, O. L; B K Oguntade; L F Petrik; A. D Wusu

Onwordi, C.T., Okwuolise, C.H., Osifeko, O. L Chemistry Department, Lagos State University, P. O LASU 0001 Ojo, Lagos, Nigeria.
B K Oguntade Chemistry Department, Rhodes University, Grahams town 6140, South Africa.
L F Petrik Environmental and Nano Sciences Group, Department of Chemistry, University of the Western Cape, Bellville, 7535, South Africa.
A. D Wusu Biochemistry Department, Lagos State University, P. O LASU 0001 Ojo, Lagos, Nigeria.

Keywords: adsorption

Abstract

The rapid spate of development of many industries has led to wastes containing heavy metals being directly or indirectly discharged into the environment. This study employed the use of corncob an agricultural waste for adsorption of cadmium (II), cobalt (II), and nickel (II) in batch mode at room temperature. The residual metal was determined with flame atomic absorption spectrophotometer. The study investigated the influences of adsorbent dosage, solution pH, contact time, and initial metal concentration on the removal of metal ions. The Langmuir and Freundlich isotherm models were used to fit the equilibrium adsorption data. The reaction kinetics of the cadmium (II), cobalt (II) and nickel (II) removal from the aqueous solution were identified and correlated to the pseudo first and second order kinetic models. The results showed an increase in adsorption by metal ions studied with an increase in adsorbent dosage. Metal uptake showed a pH-dependent profile with optimum at pH values 4.0 for Cd (II) as well as Ni (II), and 8.0 for Co (II) ions. The Freundlich adsorption isotherms model fitted the experimental data best with the regression coefficient ranging between 0.837 and 0.989 for the metal ions. A kinetic study of the adsorption process showed that adsorption of cadmium (II), cobalt (II), and nickel (II) on corncob was observed to follow closely to the pseudo-secondorder. It was concluded that corncob exhibited rapid adsorption capabilities and high efficiency in removal of cadmium (II), cobalt (II) and nickel (II) ions from aqueous solution.