1. Department of Chemistry, Faculty of Science & Agriculture, University of Fort Hare, Alice, South Africa
2. Department of Biological and Environmental Sciences, Faculty of Natural Sciences, Walter Sisulu University, Mthatha, South Africa
3. Department of Chemistry, University of Zululand, KwaDlangezwa, South Africa
4. Department of Chemical & Physical Sciences, Faculty of Natural Sciences, Walter Sisulu University, Mthatha, South Africa
5. Centre for Nanomaterials Science Research, University of Johannesburg, Johannesburg, South Africa
6. Department of Applied Chemistry, University of Johannesburg, Gauteng, South Africa