1. Department of Physics, College of Science, Engineering and Technology University of South Africa Johannesburg 1710 South Africa
2. Department of Pure and Applied Physics Ladoke Akintola University of Technology Ogbomoso PMB 4000 Nigeria
3. Department of Mechanical and Industrial Engineering University of South Africa Johannesburg 1710 South Africa
4. Institute for Nanotechnology and Water Sustainability (iNanoWS), College of Science, Engineering and Technology University of South Africa Johannesburg 1710 South Africa