Academic qualifications: I am currently undertaking my PhD research in chemistry in the University of Nairobi, Kenya. My research title is: Experimental - Synthetic Design and Characterization of Biodegradable Polymers from Cellulosic Biomass: Grevillea Robusta Leaves as a Potential Economic Input in Local Plastic Industry
Masters in Environmental Chemistry Degree (2014), University of Nairobi, Kenya. Thesis title: Electrocatalytic Decomposition of Captan and Methoxychlor Pesticide Residues using Cyanocobalamin
Bachelor Degree in Education Science(1997), Kenyatta University, Kenya.
Teaching experience: I have teaching experience of 10 years in high school and 9 years in university, a total of 19 years.
My area of research is Environmental Chemistry.
Electrocatalytic reduction of (3aR,7aS)-2-[(trichloromethyl)sulfanyl]-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione (Captan) pesticide residue was carried out in homogenous medium (acetonitrile/water 1:1). Cyanocobalamin was used as a catalyst to lower the reduction potentials. The studies were carried out by use of cyclic voltammetry method. A three electrode system was used with Glassy carbon as the working electrode, Platinum wire as the counter electrode and the Saturated Calomel Electrode (SCE) as the reference electrode. Potassium ferricyanide was used as a standard for instrument calibration. Preliminary work also involved cyclic voltammetric study of cyanocobalamin. Direct reduction of (3aR, 7aS)-2-[(trichloromethyl) sulfanyl]-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione (Captan) pesticide was carried out using glassy carbon electrode. Captan exhibited a 1- electron reduction peak under these conditions. The observed reduction potentials were -1.282 ± 0.104 V at 0.02 V/s versus SCE. The calculated formal potential was 1.043 V and the diffusion coefficient was 3.029 x 10-5cm2s-1. The current density calculated was 3.330x10-4 ± 0.0001 A/cm2. The electrocatalytic reduction of captan gave lower reduction potential of -0.745 ± 0.045 V in 0.1 M KNO3 in acetonitrile/water (1:1). Therefore, a lowering of over potential for reduction of captan of about 0.54 V was achieved, which is an indication of energy saving. The pesticides were then decomposed in the presence of cyanocobalamin by bulk electrolysis method for four hours at constant potential of 1.0 V. The product yield was determined by UV/Vis Spectrophotometry. The UV/VIS spectrum for captan gave an intense absorption peak at 278 nm. The decomposed substrate gave three peaks at 260.5 nm, 223.6 nm and 214.9 nm which indicated the presence of decomposed products. The captan sample after decomposition was also analysed by Thin layer chromatography, which indicated the presence of two decomposition products with different Rf values of 0.727 and 0.636 respectively, while captan standard gave Rf value of 0.152. This confirmed the decomposition reaction. The study demonstrated effective lowering of the reduction potentials of captan in the presence of cyanocobalamin. The method is therefore economical and environmentally friendly and can greatly contribute in alleviating the levels of captan pesticide residues in the water bodies and in contaminated swimming pools and improve their quality.
Audience Take away:
1. The audience will understand the concept of cyclic voltammetry, which is an electrochemical method of analysis and be able to apply the technique in analysis in various areas of study.
2. The audience will understand how cyanocobalamin used as a catalyst, helps in lowering reduction potentials of the substrate hence saving energy.
3. They will appreciate the use of environmentally friendly catalysts to solve environmental problems associated with non biodegradable pesticide residues.
4. The audience will also be sensitized on the importance of using greener pesticides and greater emphasis on alternative methods of controlling pests, for instance biological controls such as resistant plant varieties and Integrated Pest Management (IPM) which establishes chemical use on a need basis only.