[1] Univ Johannesburg, Fac Sci, Dept Appl Chem, Johannesburg, South Africa
[2] Univ Johannesburg, Fac Sci, Fac Engn & Built Environm, Mineral Proc & Technol Res Ctr,Dept Met, Johannesburg, South Africa
[3] Univ Johannesburg, Fac Sci, Dept Chem, Johannesburg, South Africa