[1] Univ Pretoria, Dept Chem, ZA-0002 Pretoria, South Africa
[2] Ladoke Akintola Univ Technol, Dept Pure & Appl Chem, PMB 4000, Ogbomosho, Oyo State, Nigeria
[3] Ladoke Akintola Univ Technol, Dept Elect & Elect Engn, PMB 4000, Ogbomosho, Oyo State, Nigeria
[4] Landmark Univ, Dept Phys Sci, Ind Chem Programme, Omu Aran, Nigeria