1. Environmental Remediation and Nanoscience (EnviReN), Department of Geography and Environmental Sciences, Faculty of Science Engineering and Agriculture, University of Venda, Private Bag X5050, Thohoyandou, 0950, Limpopo Province, South Africa
2. School of Chemistry and Material Sciences, Technical University of Kenya, Haile Selassie Avenue, Nairobi. P.O. Box 52428 – 00200, Kenya