1. Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria 0183, South Africa
2. Water for Rural Communities (WARUC), Pretoria 0002, South Africa
3. Institut Européen des Membranes, IEM UMR-5635, Université de Montpellier, ENSCM, CNRS Place Eugène Bataillon, CEDEX 5, 34095 Montpellier, France