Publications

Biodiesel is currently mostly produced by homogeneous catalysis. Recently, however, heterogeneous catalysis is being considered as a cheaper alternative to the homogeneous process. Heterogeneous transesterification is considered a green process. The process requires neither catalyst recovery nor aqueous treatment steps and very high yields of ethyl esters can be obtained, close to the theoretical value. However, heterogeneously catalyzed transesterification generally requires more severe operating conditions, and the performance of heterogeneous catalysts is generally lower than that of the commonly used homogeneous catalysts. This study seeks to address this problem by studying the production of biodiesel using eggshells as heterogeneous catalysts. Heterogeneous catalysts can make biodiesel production more energy efficient, and therefore less expensive, by eliminating the need for expensive purification processes that separates the catalyst from reaction products typical in the use of homogeneous catalysts. Matlab was employed for the experimental design, statistical analysis and process modeling. Fatty acid ethyl ester was produced by transesterification of sunflower oil and ethanol using calcined eggshells as a heterogeneous catalyst. To optimize the process, some important variables such as reaction temperature, molar ratio of ethanol to oil and mass weight of catalyst were selected and studied. At the following conditions: 343K of reaction temperature, ethanol to sunflower oil ratio of 9: 1 and 1 mass wt% of catalyst, an optimum fatty acid ethyl ester yield of 92% was obtained, indicating that eggshells have the potential of …

{Purpose The objectives of this study were to characterise the sexual health of street-connected adolescents in Eldoret, Kenya, analyse gender disparity of risks, estimate the prevalence of sexually transmitted infections (STIs), and identify factors associated with STIs.Methods A cross-sectional study of street-connected adolescents ages 12–21 years was conducted in Eldoret, Kenya. Participants were interviewed and screened for Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, herpes simplex virus-2, syphilis and HIV. Descriptive statistics and logistic regression were used to identify factors associated with having any STI.Results Of the 200 participants, 81 (41%) were female. 70.4% of females and 60.5% of males reported sexual activity. Of those that participated in at least one STI test, 28% (55/194) had >=1 positive test, including 56% of females; 14% (28/194) had >1 positive test. Twelve females and zero males (6% overall, 14.8% of females) were HIV positive. Among females, those with HIV infection more frequently reported transactional sex (66.7% vs 26.1%