1. Department of Chemical Engineering, University of South Africa (UNISA), Cnr Christiaan de Wet and Pioneer Street, Florida Johannesburg, 1710, South Africa
2. Department of Chemical and Life Science Engineering, Virginia Commonwealth University (VCU), Richmond, Virginia, USA
3. Institute for the Development of Energy for African Sustainability (IDEAS) research unit, University of South Africa (UNISA), Cnr Christiaan de Wet and Pioneer Street, Florida, Johannesburg, 1710, South Africa