Investigation of clay brick waste for the removal of copper, nickel and iron from aqueous solution: batch and fixed – bed column studies

Abstract

The adsorption of copper, iron and nickel ions from an aqueous solution using Makoro granite clay brick waste through batch and fixed – bed column modes was investigated. The adsorbent was characterised using X-Ray Fluorescence, X-Ray Diffraction (XRD), Thermogravimetric Analysis, and Scanning Electron Microscopy (SEM). XRD results revealed crystalline peaks of Quartz (51.28 %) and mullite (23.40%) in fresh and loaded adsorbent with unnotable changes before and after adsorption. SEM images indicate the presence of micro pores and irregularly distributed surfaces. Batch kinetic maximum adsorption capacities for iron, copper, and nickel are 7.60, 6.70 and 6.20 mg g−1 media respectively with 60 min as the optimum time. The maximum adsorption capacities at adsorbent dosage of 5 g L−1 were 10.0, 7.60 and 7.20 mg L−1 for iron, copper and nickel ions. The corresponding adsorption capabilities from the fixed-bed column reactor were 2.23, 2.22 and 0.74 mg g−1 media respectively. The thermodynamics parameters of enthalpy change (ΔH) were 5.21, 9.32 and 5.22 kJ mol−1 respectively for Copper, iron and nickel ions and the corresponding entropy change (ΔS) were -0.04, -0.05 and -0.03 kJmol−1K−1respectively and the process being non-spontaneous and exothermic. Thomas and Yoon-Nelson models yielded similar low coefficient of determination (R2) values (0.06 and 0.07) for copper and iron ions. Further investigations such as the use of real wastewater, competition of anions and further media characterisation and modifications are recommended.