1. Department of Chemical Engineering, University of Pretoria, Pretoria 0028, South Africa
2. Institute for Nanotechnology and Water Sustainability (iNanoWS), College of Science, Engineering and Technology, University of South Africa, Florida Campus, Roodepoort, Johannesburg 1710, South Africa
3. Transdisciplinarity Laboratory Sustainable Mineral Resources, University for Continuing Education Krems, 3500 Krems, Austria