Research Articles

Cobalt(II) removal from synthetic wastewater by adsorption on South African coal fly ash

Evans T. Musapatika, Maurice S. Onyango, Ochieng Aoyi
South African Journal of Science | Vol 106, No 9/10 | a167 | DOI: | © 2010 Evans T. Musapatika, Maurice S. Onyango, Ochieng Aoyi | This work is licensed under CC Attribution 4.0
Submitted: 08 April 2010 | Published: 01 October 2010

About the author(s)

Evans T. Musapatika, University of the Witwatersrand, South Africa
Maurice S. Onyango, Tshwane University of Technology, South Africa
Ochieng Aoyi, Vaal University of Technology, South Africa


Advanced wastewater-treatment techniques such as adsorption are essential in the removal of non- biodegradable toxic wastes from water. In this study, the use of South African coal fly ash, an industrial byproduct, has been investigated as a potential replacement for the current costly adsorbents used for removing heavy metals from wastewater. We utilised coal fly ash for the adsorption of cobalt(II) ions from synthetic petrochemical wastewater and characterised its performance. A two-level three-factor full-factorial design was successfully employed for experimental design and analysis of the results. The combined effects of pH, initial concentration and adsorbent dose on cobalt(II) removal were assessed using response surface methodology. Although the focus was on removal of cobalt(II), the adsorption was carried out in the presence of phenol and other heavy metal ions using the batch technique. The applicability of the Freundlich and Langmuir models to the equilibrium data was tested. Consequently, the equilibrium data was found to conform more favourably to the Freundlich isotherm than to the Langmuir isotherm; in this case, the coal fly ash had a maximum adsorption capacity of 0.401 mg/g for cobalt(II). We conclude that South African coal fly ash, as a natural, abundant and low-cost adsorbent, might be a suitable local alternative for elimination of cobalt(II) from aqueous solutions.


adsorption; coal fly ash; cobalt (II); isotherm; response surface methodology; wastewater


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Crossref Citations

1. Nano-Adsorbents for Cobalt Removal from Wastewater: A Bibliometric Analysis of Research Articles Indexed in the Scopus Database
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