Utilisation of cement brick waste as low cost adsorbent for the adsorptive removal of copper, nickel and iron from aqueous solution: Batch and column studies

Abstract

The pollution of surface and groundwater by heavy metals from industrial effluents is of great concern to the environment. In this study, the adsorptive removal of iron, nickel, and copper from the aqueous solution was investigated through batch and fixed-bed column mode using Cement Brick Waste (CBW) as an adsorbent with particle size in the range between 0.6 and 1.18 mm in diameter. The chemical and physical characterisation of media was conducted through X-ray Diffraction (XRD), X-ray Fluorescence (XRF), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The XRD pattern showed the presence of both amorphous and crystalline phases before and after adsorption, and no notable changes were observed as the patterns were similar. The experimental maximum adsorption capacities were 3.953, 3.937 and 3.938 mgg−1 media copper, iron, and nickel ions achieved with an adsorbent dosage of 5.0 g/100 mL. The pH 4 was optimum with adsorption capacities of 8.5, 8.7 and 5.6 mg g-1 media were observed for copper, iron, and nickel ions, respectively. The adsorption process was best described by the Pseudo Second Order kinetic model and the Freundlich isotherm model, suggesting that both chemisorption and physisorption occurred and the adsorbent was heterogeneous. Thermodynamic studies have shown the process to be exothermic. Reusability studies revealed that CBW adsorption capacity decreased with each regeneration cycle. The results analysis of the column studies showed less removal of Nickel as compared to other heavy metals. The Yoon-Nelson kinetic model best describes the adsorption process. In addition, the results analysis shows that CBW can be used as an effective adsorbent to remove iron, copper and nickel from aqueous solutions, but there is a need to consider further studies using real wastewater.