1. Graduate Student, Sustainable Materials Research and Technology Center, Jomo Kenyatta Univ. of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.
2. Associate Professor, Sustainable Materials Research and Technology Center, Jomo Kenyatta Univ. of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya (corresponding author).
3. Director, Sustainable Materials Research and Technology Center, Jomo Kenyatta Univ. of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.