1. Nanotechnology and Water Sustainability Research Unit, College of Science, Engineering and Technology, University of South Africa, Florida, 1709 Johannesburg, South Africa
2. SabiNano Research and Innovation and the DSI/MINTEK Nanotechnology Innovation Centre, Mintek, 200 Malibongwe Drive, Strijdom Park, Randburg, 2194 Johannesburg, South Africa
3. Department of Chemical, Metallurgical and Material Engineering, Tshwane University of Technology, Private Bag x680, Pretoria 0001, South Africa
4. HySA Infrastructure Centre of Competence, Centre for Nanostructures and Advanced Materials (CeNAM), Chemicals cluster, Council for Scientific and Industrial Research (CSIR), Meiring Naude Road, Brummeria, Pretoria 0001, South Africa