Nchimbi, Hamisi, Yunus2019-11-012020-01-072019-11-012020-01-072013Nchimbi, H, Y (2013) Assessment of the variations in productivity of bark and phylloclade extracts of Euphorbia Tirucalli L. (African milk bush) as sources of liquid biofuel.Doctoral dissertation, University of Dar es Salaam, Dar es Salaam.http://localhost:8080/xmlui/handle/123456789/1927Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF QK495.E9N353)Variations in liquid biofuel quantity and quality of stem bark and phylloclade extracts of Euphorbia tirucalli L. were evaluated based stem diameters of the trees and agro-ecological zones: Dodoma, Dar es Salaam and Mbeya from which the samples had been collected. The effect of planting density on E. tirucalli growth rate and biofuel yield in different agro-ecological zones was also assessed. Soxhlet extraction method with different solvents was used to extract the oil and hydrocarbons. Amount of oil and hydrocarbons was measured by weighing the dried oil and hydrocarbons and results were expressed in grams of the total weight of sample used during the extraction. Oxidative stability (OS) and percent free fatty acid (%FFA) were used to determine the quality of the extracts. Also, the growth rate of E. tirucalli at different densities (i.e. 129,600, 40,000, 14,400 and 6,400 plants per hectare) in different agro-ecological zones and its relation to the quantity of biofuel yield were studied. Data analyses were done using Analysis of Variance and Minitab softwares. Results showed that high amounts of oil (> 16%) and hydrocarbons (> 15%) can be obtained by extraction from stem bark or phylloclade of E. tirucalli. However, significantly higher quantities were obtained from older trees, and at the closest planting densities for samples grown from test plots. Oil and hydrocarbon yields decreased in the order of Dodoma > Mbeya > Dar es Salaam. The study recommends further studies on liquid biofuel from E. tirucalli parts other than wildly grown stem bark and phylloclades in order to optimize their yields and quality at planting densities different from those used in the present study.enEuphorbia tirucalliPhyllocladeEuphorbiaceaeBiofuelHydrocarbon plantThesis