1. Thermodynamic Research Unit, School of Chemical Engineering, University of KwaZulu-Natal, Howard College Campus, King George V Avenue, Durban 4001, South Africa
2. Department of Chemical Engineering, National University of Science and Technology, P.O. Box AC 939, Ascot, Bulawayo, Zimbabwe
3. Department of Chemical Engineering, Faculty of Engineering, Stellenbosch University, Banhoekweg 7600, South Africa