A. Yusuf

Determination of Heavy Metals and Nutrients in Rivers Naka and Irigu, Chuka, (Kenya) Using Atomic Absorption Spectrometry and UV/Visible Spectrophotometry

Levels of concentration of heavy metals (lead, cadmium, arsenic and mercury) and nutrients in rivers Naka and Irigu were determined in the first three months (January, February and March, 2013) and variation downstream compared. Lead and cadmium were determined using Atomic Absorption Spectroscopy (AAS). Hydride generation method was used to determine concentration of arsenic while that of mercury was determined using cold vapour technique. Calorimetric methods were used to determine levels of nitrates and phosphates. Concentration levels of lead, cadmium and arsenic were found to be beyond the permissible levels stipulated by National Environment Management Authority (NEMA) and World Health Organisation (WHO) drinking water specifications. Lead had the highest concentration with a range of 0.0537±0.103 parts per million (ppm) to 0.765±0.782 ppm followed by cadmium with a concentration range of 0.035 ± 0.006ppm to 0.24±0.0084 ppm in both rivers Naka and Irigu. The high concentration levels of lead in River Naka could be attributed to disposal of wastes directly into the river from Chuka Town due to poor drainage systems. Mercury was found to be below the detection limit. On the other hand, phosphate had a concentration range of 8.31±0.429 ppm to 10.33±0.189 ppm. This was above the specified level of 2.2ppm in drinking water according to NEMA. Only nitrate was below the recommended levels of 50 ppm and 45 ppm NEMA and WHO guidelines respectively for drinking water.

In-Vitro Anthelmintic Bioactivity Study Of Eclipta prostrata L. (Whole Plant) Using Adult Haemonchus contortus worms A Case Study Of Migori County, Kenya

The aim of this study was to investigate the anthelmintic activity of Eclipta prostrata (Asteraceae) which is used by traditional medicine practitioners in Migori County using adult Haemonchus contortus worm as a model.50gm of ground powder of Eclipta prostrata (whole plant) was extracted separately with 300 ml methanol, acetone and water. The yields of the extracts were 3.53 gm, 4.19 gm and 4.02 gm for methanol, acetone and water respectively. The anthelmintic activity of 6.25 mg/ml, 12.5 mg/ml and 25 mg/ml concentrations of aqueous, acetone and methanol crude extracts of Eclipta prostrata (whole plant), were compared with the effect produced by the standard reference drug albendazole with Phosphate Buffered Saline (PBS) used as a negative control. Death of Haemonchus contortus worm was determined within a period of 24 hrs. Eclipta prostrata extract had mean mortality of 26.7-40.0 % at 6.25 mg/ml; 33.3-53.3 % at 12.5 mg/ml; 36.7-56.7 % at 25 mg/ml.All the extracts contained tannins and cardiac glycosides.

Determination of selected micro and macronutrients in sugarcane growing soils at Kakamega north district, Kenya

Kakamega North district is situated in Kakamega County in the western region of the Republic of Kenya. It is a major sugarcane producing area. The soils in the area were analyzed for selected macro and micronutrients. Macronutrients analyzed included potassium, sodium, calcium, phosphates and nitrates while the micronutrients analyzed were copper, iron and zinc. The techniques employed were Flame Atomic Absorption Spectrometry, Flame Emission Spectrometry and UV/Visible Spectrophotometry. The soil pH measurement was also taken. The average levels obtained in mg/kg for potassium, sodium, calcium, nitrates and phosphates were 110, 240.8, 540, 71 and 100 respectively. Recommended nutrient range levels in mg/kg as per Kenya Agricultural Research Institute (KARI) are: potassium 1 -100 mg/kg, sodium 20-300mg/kg, calcium 2- 400mg/kg, nitrates above 42 mg/kg and finally for phosphates 2000-5000mg/kg. The results indicate generally that macronutrient levels of phosphates and nitrates were low and below the required minimum required levels for normal plant. Micronutrients were within the limits for normal plant growth. The average soil pH was 5.48 which is acidic and within the limits for normal plant growth.

Electro-Characterization of Polypyrolle Electrosynthesized on a Montmorillonite Host-Matrix, in Aqueous Media Containing Sulphuric Acid as Supporting Electrolyte

In this paper polypyrolle has been electrosynthesised from an aqueous media containing the pyrolle monomer and sulphuric acid as the supporting electrolyte. The redox properties of polypyrolle on carbon graphite working electrode and on a clay montmorillonite host matrix has also been reported. The results obtained from plots of oxidative and reductive peak currents yield redox efficiencies above 95% for the polypyrolle redox process. The polypyrolle redox process is also shown to be diffusion limited. The reduction in the rate of electrodeposition of polypyrolle on a polyaniline loaded clay montmorillinite host- matrix, is a veiled confirmation of intercalation of the polyaniline in montmorillonite matrix.

Bioethanol production from waste crops and crop residues

Rice straws and Husks were converted to reducing sugars by hydrolysis using concentrated sulphuric acid followed by fermentation using bakers yeast. After fractional distillation and purification, 52 ml (87 %) of ethanol was obtained from 480cm 3 of biomass which was blended with gasoline using different ratios. Physical constants of the bio-ethanol (density and distillation) conformed to Kenya Bureau of Standards specifications. The conclusion is that the bioconversion offers a cheap and safe method of disposing the agricultural residues and conversion of lignocellulosic wastes into ethanol.

Sodium Thiosulphate, a Novel Electrocatalyst in the Electrosynthesis of Electronically Conducting Polymer-Polythiophene

In this paper we report on the electrosynthesis of polythiophene from aqueous media with sulphuric acid as the supporting electrolyte. The redox features of polythiophene on a bare carbon graphite working electrode and on a clay montmorillonite host matrix is also reported. Co-polymerisation of polythiophene and polyaniline from an electrolyte media containing both aniline and thiophene monomers reveal that, the redox centres of the two polymers are independent, hence suggesting the formation of a bilayer, even though no charge rectification is observed.The role of sodium thiosulphate as a novel electrocatalyst which has led to a I. Introduction: Polyaniline, polythiophene, and polypyrrole are amongst the most well researched of electronically conducting polymers. They have received much in research because of their known unique properties such as low density, well behaved electrochemistry,versatility in methods of production, high anisotropy of electrical conduction, and non-metallic temperature dependence of conductivity . Electrochemical methods have played a significant role in the characterization and synthesis of these materials. The major advantage of these electrochemical techniques lies in the fact that, they are especially well- suited to the controlled synthesis of these compounds and for the tuning of a well-defined oxidation state. Despite all the advances made in the study of these novel materials, the preparation, characterization and application of these electronically conducting polymeric systems are still largely un-understood, hence still a major focus of research activity in electrochemistry. The key areas where gaps still exist include understanding the behavior of these systems, in particular on the mechanism of charge transfer and on charge transport processes that occur during redox reactions of conducting polymeric materials. On the applications frontier, research continues on how to perfect their use/application in the fields of energy storage, electrocatalysis, organic electrochemistry, bio-electrochemistry, photo-electrochemistry, electro-analysis, sensors, electrochromic displays, microsystem technologies, electronic devices, microwave screening and corrosion protection etc . The intensity of research geared towards understanding the electrosynthesis, charge transfer mechanism and possible applications domain for these polymers is captured in the litany of references listed (1- 61) and the references therein. In this paper we report on the electrosynthesis of polythiophene from aqueous media with the mineral acids as supporting electrolyte. This is in contrast to the much used non-aqueous media with large organic salts as supporting electrolyte. We also report on the novel role of sodium thiosulphate as an electro-catalyst in the polythiophene redox process leading to tremendous improvement in the film electrode transfer kinetics/faradaic process. II. Experimental Section: Analytical grade acids were used as received without further purification. The thiophene and aniline monomers were triply distilled until a colorless liquid was obtained prior to use. The liquids were purged using an inert gas and stored under nitrogen. Triply distilled water or de-ionised water from a Millipore-purification system was used, in preparation of the electrolyte solutions. The cyclic voltammograms were generated from a potentiostat/galvanostat used in conjunction with a universal programmer which generated the cyclical potential waves. The signals were then fed into an x-y recorder. The modification of the carbon graphite working electrode was achieved by cycling the potential of the working electrode within a given potential window in an electrolyte solution containing thiophene or aniline monomer. The clay montmorillonite modification of the carbon graphite working electrode surface was achieved as discussed by Orata and Segor (62-63).

Polyaniline and Polythiophene Modified Electrodes in Energy Storage Units with Hydrocarbon Gel/Bentonite/Sodium Chloride as Electrolyte gel

In this paper we present results obtained for energy storage units developed using polyaniline and polythiophene modified electrodes. The voltage potential profiles for recharge/discharge are either linear or exponential. Nucleation over-potential has been observed in some profiles where there is a phase transition. It is observed that hydrocarbon gel: bentonite electrolyte mixtures yielded relatively high initial voltages and that, this voltage also depended on the hydrocarbon: bentonite ratio. The potential decay profile for potential at Vo, 3/4Vo, 1/2Vo and 1/3Vo yielded linear and exponential curves for various hydrocarbon:bentonite mixtures. The capacity (C) were 0.0014 Ah, for the 2:1 energy unit and 0.00035 Ah for the 3:1 energy unit. The electric storage density (ESD) for the 2:1 and 3:1 energy units were 4.7 × 10 -4 Ah/g and 8.8 × 10 -5 Ah/g