1. Department of Chemistry, University of Zululand, X1001, KwaDlangezwa, KwaZulu-Natal, South Africa
2. Department of Applied Chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein, Johannesburg 2028, South Africa
3. Centre for Nanomaterials Science Research, University of Johannesburg, Johannesburg, South Africa
4. Department of Chemistry, University of Kwazulu Natal, Kwazulu Natal, South Africa