1. Electrochemistry and Chemistry of Materials, Department of Chemistry, Faculty of Science, University of Dschang, P. O. Box 67, Dschang, Cameroon
2. Department of Chemical Sciences, Tezpur University, Tezpur, Assam 784028, India
3. Institute of Chemistry, Faculty of Process and Systems Engineering, Universitätsplatz 2, 39106 Magdeburg, Germany
4. Department of Chemistry, Higher Teacher Training College, University of Bamenda, Bambili P. O. Box. 39, Cameroon
5. Center for the Environment, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
6. University of Yaoundé 1, Faculty of Science, Department of Chemistry, Laboratory of Analytical Chemistry, P. O. Box 812, Yaoundé, Cameroon