1. Department of Chemical Sciences University of Johannesburg Doornfontein Campus, P.O. Box 17011 Johannesburg 2028 South Africa
2. Department of Science and Innovation-National Research Foundation South African Research Chair Initiative (DSI-NRF SARChI) in Nanotechnology for Water University of Johannesburg Johannesburg, Doornfontein 2028 South Africa
3. Department of Chemistry University of Fort Hare Alice 5700 South Africa
4. School of Environmental Science and Engineering Nanjing Tech University Puzhu Nan Lu 30 Nanjing 211800 PR China