1. School
of Chemical and Metallurgical Engineering, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein, Johannesburg 2000, South Africa
2. MaPS
Research Unit, University of South Africa (UNISA), Fifth Floor
Pha-Pha Building, Corner of Pioneer and Christian De Wet Roads, Private
Bag X6, Florida, Gauteng 1710, South Africa