1. School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
2. School of Chemistry, University of Leeds, Leeds LS2 9JT, UK
3. Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
4. Department of Physics, Chemistry and Material Science, University of Namibia, Windhoek, Namibia
5. Department of Chemistry, University of Botswana, Gaborone, Botswana
6. Department of Energy and Mineral Engineering, Pennsylvania State University, University Park, PA, USA
7. Department of Chemical and Forensic Sciences, Botswana International University of Science and Technology, Palapye, Botswana
8. Department of Chemistry, University of Johannesburg, Johannesburg, South Africa
9. Department of Earth Sciences, Utrecht University, 8a Princetonlaan, 3584 CB Utrecht, The Netherlands