1. Department of Chemistry; University of Fort Hare; Alice Campus South Africa
2. Department of Chemical; Metallurgical and Material Engineering, Tshwane University of Technology; Pretoria South Africa
3. DST/CSIR National Centre for Nanostructured Materials; Council for Scientific and Industrial Research; Pretoria 0001 South Africa
4. Department of Applied Chemistry; University of Johannesburg; Doornfontein 2028 Johannesburg South Africa