1. Department of Chemistry, Haramaya University, P.O.Box 138, 138 Dire Dawa, Ethiopia
2. Instituto de Catálisis y Petroleoquímica (ICP), CSIC, C/Marie Curie 2, 28049 Madrid, Spain
3. Department of Chemistry, Debre Berhan University, P.O.Box. 445, 445 Debre Berhan, Ethiopia