1. Department of Chemical Sciences, Faculty of Science, University of Johannesburg, P.O. Box 17011, Doornfontein, 2028Johannesburg, South Africa
2. DSI/Mintek Nanotechnology Innovation Center−UJ Water Research Node, University of Johannesburg, P.O. Box 17011, Doornfontein, 2028Johannesburg, South Africa
3. Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Florida, 1709Johannesburg, South Africa