Publications

Use of microwaves as an alternate heat source to replace conventional heating has been studied in organic synthesis. Microwave irradiation results in faster reaction rates, cleaner production, thereby reducing energy consumption. This also leads to better environmental impacts and is considered green chemistry. This Paper reviews application of microwave irradiation in transesterification reactions for production of biodiesels. Transesterification of Croton Megalocarpus oil using homogeneous sodium hydroxide catalyst was carried out using conventional heating in a water bath, and in a microwave oven. Synthesis of fatty acid methyl ester (FAME) was studied for the reaction variables catalyst concentration, methanol to oil molar feed ratio and reaction time. Results indicated that reaction time was reduced to about 2% for a similar yield when microwave irradiation was employed instead of convective heating. During convectional heating, a FAME yield of 96% corresponded to a methanol-to-oil molar ratio of 6:1, catalyst of 1 %, temperature of 70oC, and reaction time of 60 minute. During microwave irradiation, a yield of 92% was obtained when methanol-to-oil molar ratio was 9:1, catalyst concentration 0.5 %, and reaction time 1 minute. FAME was analyzed through gas chromatography.

Groundwater contamination by pesticides is an
environmental health concern throughout the world. Many
pesticides do not leach because they are adsorbed on the
soil particles or organic matter even though they may have
a relatively high solubility. The objective of this study was
to determine the relationship between soil permeability
and organic carbon in the transport of pesticides into
groundwater along the shore of Lake Naivasha, using
regression analysis of soil permeability and organic carbon
data collected along the shore. The results showed that the
soil organic carbon (foc) positively affected the soil
permeability (k) and were related by the equation k=
80.724(1.726)foc. It was concluded that organic carbon
increased soil permeability by 30%, thereby recharging the
aquifer while at the same time reducing pesticide transport
into groundwater. Based on these findings the study
recommended that the use of compost (organic
amendments) should be increased in place of inorganic
fertilizers.

Adolescents living in HIV endemic settings face unique sexual health risks, and in the context of abject poverty, orphanhood, social marginalization, and discrimination, adolescents may be particularly at-risk of horizontal HIV transmission. Street-connected children and youth are a particularly vulnerable and marginalized population and therefore may be a key population at-risk.

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 …