PHD-Department of Chemistry

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ADH/ADLH polymorphism as biochemical and genetic markers in study of alcohol tolerance in selected Kenyan populations
(2011-08-16) Korir, Elena Doudoladova
Excessive alcohol consumption is a major health hazard worldwide. Alcohol is commonly used and often abused in Kenya, especially by the youth. For European, Asian, Australian and American populations, studies have shown linkage between polymorphisms of the alcohol dehydroggenase (ADH) and aldehyde dehydrogenase (ALDH), the ethanol metabolizing enzymes, with the increase of alcohol intake. For Africans, no studies on heterogeneity of ADH and ALDH and its relationship to alcoholism, alcohol intake and alcohol drinking behaviour have been reported. The aim of this study was to find out the distribution of alleles of ADH 2, ADH 3, and ALDH 2 loci in the selected Kenyan populations namely the Kolweny, Siaya, Longisa, Limuru and Rugunga and to investigate the association of these ADH/ALDH alleles with alcohol drinking and alcoholism. These five Kenyan populations represent two major African groups namely the Bantu and Nilotes. Different gender and age groups of the selected Kenyan communities were screened for ADH 2, ADH 3 and ALDH 2 polymorphisms via phenotyping of hair lysates using high resolution isoelectric focusing.. In addition, information on education, marital status, occupation, drinking behaviour, alcohol sensitivity, alcohol intake, age of regular alcohol drinking, alcohol drinking experience, alcohol dependence, emotional response to alcohol and preference of alcoholic drinks was collected via a questionnaire. The data obtained on ADH 2, ADH 3 and ALDH 2 polymorphism and alcohol drinking behaviour was statistically analyzed using chi-square, t-test and Fisher's exact test. Three hundred and seventy one adult volunteers participating in the project from all Kenyan study groups were divided into groups on the basis of alcohol tolerance. Alcohol-drinking parameters of alcohol use were analyzed with respect to alcohol tolerance. The significant difference in alcohol intake, alcohol drinking experience, alcohol sensitivity, emotional response to alcohol, the role of ADH 3*1 allele in the drinking behaviour and preference of alcoholic drinks were determined among individuals with high and low alcohol tolerance. ADH 2, ADH 3 and ALDH 2 polymorphism showed significant relation to alcohol intake (among alcoholics), alcohol drinking experience (among nonalcoholics), sensitivity to alcohol, alcohol drinking behaviour, mode of alcohol drinking, and preference of alcoholic drinks. ADH and ALDH heterogeneity was not associated with the difference in alcohol intake (among nonalcoholics), age of regular drinking and emotional response to alcohol. The role of different socio-demographic, biochemical and genetic factors in alcohol drinking and spread of alcoholism were identified for each Kenyan study group. The Kolweny, Siaya, Limuru and Rugunga populations have dominance of individuals with high alcohol tolerance and relatively low spread of alcoholism in the populations. The Longisa population had relatively high proportion of individuals with low alcohol tolerance and high occurrence of alcoholism in the community. The research findings may be used to formulate ethnically adequate methods of diagnosis, treatment, and management of alcoholism in relation to alcohol tolerance in the studied Kenyan populations
Antimicrobial efficacy of selected medicinal peanuts used by Kenyan herbal doctors
(2012-05-07) Okemo, P. O.
Herbal medicine is practiced by many countries of the world including Kenya, but scientific data to support the efficacy of herbal preparations has been lacking. Sixteen indigenous plants used by herbal doctors in Kenya were chosen from seven provinces and screened for antimicrobial activities using the disc diffusion method for preliminary selection. The most active plants, Entada abssyinica (Stem bark), Terminalia spinosa (Stem bark), Harrizonia abyssinica (roots), Ximenia caffra (roots), Azadirachta indica (stem bark and laves), and Spilanthes mauritiana (flowers and roots), were chosen for subsequent analysis, to determine efficacy and to identify a source of new possible antimicrobial agents. These plants were soxhlet extracted with methanol and tested for bioactivity. In the bioassay, the microtitre broth dilution method and the agar dilution method were compared to determine suitability for use. The microtitre method was found superior with a mean of 0.856 mg/ml compared to 2.958 mg/ml for the agar dilution method. Subsequently 110 strains of pathogenic bacteria from six genera were tested for activity using the microtitre broth dilution method. Their minimum inhibitory concentration (MICs) in mg/ml and minimum bactericidal concentrations (MBC's) in mg/ml were determined as a measure of their efficacy. The extracts had a bacteriostatic effect on Gram-negative bacteria and bactericidal effect on Gram-positive bacteria. Bacteria with special significance and some protozoa were examined separately. Mycobacteria species which were tested because of tuberculosis upsurgence in Human Immunodeficiency virus victims were found to be resistant to the extracts. Helicobacter pylori no known cure was killed by T. spinosa extracts (MIC range 62.5 - 500 g/ml). A protozoa, Acanthamoeba castellanii which causes granulomatous brain lesions has no known cure but responded to extracts of E. abyssinica, T. spinoss, X. caffra, A. indica and S. mauritiana when tested in vitro. Strains of pathogenic fungi from 2 genera Candida and Aspergilus were tested and found to be sensitive to more than 60% of the extracts used. As a result of this evaluation, four plant extracts E. abyssinica (stem bark), T. spinosa (stem bark), X. caffra (roots), and A. indica (stem bark) were found substantially bioactive. Candida albicans (ATCC 90873), E. coli (ATCC 29213) and a potent -lactamase producing organism, Pseudomonas aeruginosa (ATCC 27853), were used to perform time kill kinetics studies, in an effort to assess the rate and extent of the destruction of the said microorganisms by the above plant extracts. The mode of action was investigated by the kill kinetics experiments using an electron microscope. By this technique, any morphological changes in the microbial cell structure with continued exposure to the extracts would be detected. Results showed cell wall malfunction leading to failure to form septa and lysis of several microbial cells. Finally, the plant extracts were screened for the presence of coumarins, tannins saponins and other classes of compounds, which were considered active plant constituents. T. spinosa contained 75% of the classes of compounds screened, S. mauritiana 60%, H. abyssinica 56.3% and A. indica 56.3%.
Biomass-Based Fertilizer Formulation Using Chemically Decomposed Agricultural Wastes and Evaluation of Its Efficacy in Growing Maize
(Kenyatta University, 2020-11) Echessa A.C., Peter
Utilization of the conventional fertilizers such as NPK, DAP, CAN and Urea by smallholder farmers in developing countries like Kenya has remained dismal due to high retail prices as well as environmental and soil related concerns such as P-fixation, leaching and volatilization. Organic fertilizers generated using traditional composting methods come in handy despite own challenges of long composting periods, imbalanced nutrients and environmental impacts of pathogens. The long composting period can be shortened through chemical decomposition of selected farm wastes that can provide balanced nutrients. The objective of this study was to utilize chemically decomposed agricultural wastes to formulate a biomass-based fertilizer and evaluate its efficacy in growing maize. Selected agricultural waste (maize cobs, maize stalks, sugar cane bagasse, sisal leaf pulp and cattle horns/hoofs) were analyzed for nutrients N, P, K and Ca to determine their suitability for formulating a Biomass-Based Fertilizer (BBF). Results indicated that the agricultural wastes had varied levels of macronutrients sufficient to support use in fertilizer formulation. The acidic sisal leaf pulp required basic conditions to decompose. The lye from burned maize cobs was used to digest sisal leaf pulp to give a basic cobs ash sisal digest (CASD) product while cattle horns and hoofs soaked in peracetic acid gave an acidic horns and hooves digest (HD) product. HD (acidic) was mixed with CASD (basic), (HD: CASB) in varying ratios to give different fertilizer formulations namely, BBF0 (0:1), BBF1 (1:1), BBF2 (2: 1), BBF3 (3:1), BBF4 (1:2) and BBF5 (1:0). The formulations had pH varying from 6.82±0.15 to 8.41±0.27 and would provide macronutrients in the ranges of 1.0-3.9 g (N), 0.002-0.17 g (P), 0.001-6.30 g (K) and 0.08-9.20 g (Ca) per plant environment. Fertilizer formulation BBF1, with pH above 7.5 and macronutrients 2.31% N, 0.08% P, 2.5% K and 3.46% Ca, was used in efficacy study carried out in Lugari, Kakamega county because of the acidic nature (pH<7.0) of the field soils. Plant height and yield of maize under the BBF1/BBF1 and that under the DAP/CAN schedules were comparable, but differed significantly from those of maize in the plots without fertilizer schedule. Side dressing maize whose leaves developed purple coloration (phosphorus deficiency) with freshly prepared BBF1 cleared P-deficiency symptoms in ≤ 7 days. Chemical decomposition of agricultural wastes produces digests that blend into a BBF formulation that is effective in promoting growth and yield of maize crops.
Biomass-Based Fertilizer Formulation Using Chemically Decomposed Agricultural Wastes and Evaluation of Its Efficacy in Growing Maize
(Kenyatta University, 2020) Echessa, A.C. Peter
Utilization of the conventional fertilizers such as NPK, DAP, CAN and Urea by smallholder farmers in developing countries like Kenya has remained dismal due to high retail prices as well as environmental and soil related concerns such as P-fixation, leaching and volatilization. Organic fertilizers generated using traditional composting methods come in handy despite own challenges of long composting periods, imbalanced nutrients and environmental impacts of pathogens. The long composting period can be shortened through chemical decomposition of selected farm wastes that can provide balanced nutrients. The objective of this study was to utilize chemically decomposed agricultural wastes to formulate a biomass-based fertilizer and evaluate its efficacy in growing maize. Selected agricultural waste (maize cobs, maize stalks, sugar cane bagasse, sisal leaf pulp and cattle horns/hoofs) were analyzed for nutrients N, P, K and Ca to determine their suitability for formulating a Biomass-Based Fertilizer (BBF). Results indicated that the agricultural wastes had varied levels of macronutrients sufficient to support use in fertilizer formulation. The acidic sisal leaf pulp required basic conditions to decompose. The lye from burned maize cobs was used to digest sisal leaf pulp to give a basic cobs ash sisal digest (CASD) product while cattle horns and hoofs soaked in peracetic acid gave an acidic horns and hooves digest (HD) product. HD (acidic) was mixed with CASD (basic), (HD: CASB) in varying ratios to give different fertilizer formulations namely, BBF0 (0:1), BBF1 (1:1), BBF2 (2: 1), BBF3 (3:1), BBF4 (1:2) and BBF5 (1:0). The formulations had pH varying from 6.82±0.15 to 8.41±0.27 and would provide macronutrients in the ranges of 1.0-3.9 g (N), 0.002-0.17 g (P), 0.001-6.30 g (K) and 0.08-9.20 g (Ca) per plant environment. Fertilizer formulation BBF1, with pH above 7.5 and macronutrients 2.31% N, 0.08% P, 2.5% K and 3.46% Ca, was used in efficacy study carried out in Lugari, Kakamega county because of the acidic nature (pH<7.0) of the field soils. Plant height and yield of maize under the BBF1/BBF1 and that under the DAP/CAN schedules were comparable, but differed significantly from those of maize in the plots without fertilizer schedule. Side dressing maize whose leaves developed purple coloration (phosphorus deficiency) with freshly prepared BBF1 cleared P-deficiency symptoms in ≤ 7 days. Chemical decomposition of agricultural wastes produces digests that blend into a BBF formulation that is effective in promoting growth and yield of maize crops.
Bioprospecting for Anti-Mosquito Phytochemicals Associated with Olfaction and Larvicidal Activities from Selected Kenyan Plants
(Kenyatta University, 2020-01) Ochola, John Bwire
Mosquitoes are of high public health concern since they are significant disease vectors of different tropical and subtropical life-threatening diseases like malaria, dengue, yellow fever, chikungunya, zika virus and encephalitis. Use of synthetic insecticides for control of mosquitoes causes development of resistance in vector species and have negative effects to the environment and human. This study aimed to find alternative, effective tools against these vectors from plant essential oils. Plant-based products are promising alternatives of low-toxicity, eco-friendly and low-cost. Oils from air-dried aerial parts of Satureja biflora, Satureja abbysinica, Conyza newii and Plectranthus marrubioides from Aberdare and Ocimum kilimandscharicum from Kakamega in Kenya were extracted using Clevenger apparatus. Oil yields were determined and analyzed by Gas Chromatography/Mass Spectrometry. Repellency of the oils was assessed on adult mosquitoes in ‘WHO arm in the cage’ method, while 3rd instar larvae were used to assess larvicidal activities based on WHO protocol. Oil with better larvicidal activity was formulated into a water-miscible solution for laboratory and semi-field testing. GC linked to EAG detector was used to determine the constituents that elicited chemosensory responses from the antenna of An. gambiae. Individual constituent contribution to mosquito repellence was established through a subtractive-combination bioassay. From the results, oils from different habitats and seasons showed qualitative and quantitative differences. Thirty three (33) compounds were identified in S. biflora oil with 3 chemotypes based on location: geranial(31%)/neral (24%)/linalool (12%) of Kinale, linalool (28%)/neridol (21%)/β-pinene (7.4%) of Nyahururu, and geranial (27%) neridol (Z) (21%)/linalool (16%) of Kieni-Gakoe. S. abyssinica had also 33 compounds comprising majorly menthone (44.1%) and pulegone (33.3%). C. newii had 19 components forming 2 chemotypes p-mentha-1,8-dien-7-yl acetate (24%)/limonene (23%)/5-methyl-2-phenyl-2-hexenal (21%) associated with Nyahururu, and p-mentha-1,8-dien-7-yl acetate (27%)/ limonene (38%). P. marruboides and O. kilimandscharicum had 35 and 41 components respectively. The major compounds in P. marrubioides were carene-2-δ (18.7%) and camphor (17.9%), whereas for O. kilimandscharicum was camphor (36.6%) and limonene (18.6%). C. newii (Nayahururu) S. biflora (Kieni) and S. biflora (Nyahururu) gave a high repellence of ED50 at < 1.95 ppm, whereas S. biflora (Kinale) had ED50 at < 2.35 ppm against Ae. aegyptei and An. gambiae. Besides, C. newii had strong repellence with ED50= 0.5 ppm against An. gambiae. Comparatively DEET gave the highest protection time of 389 min against An. gambiae, followed by C. newii (cream) against the 3 mosquito species; 241, 206 and 60 minutes for An. gambiae, Cx. quinquefasciatus and Ae. aegyptei respectively . S. biflora cream gave 208, 180 and 56 minutes against An. gambiae, Cx. quinquefasciatus and Ae. aegypti respectively. Addition of vanillin to the cream formulation resulted in a longer protection time of 382 min against An. gambiae. Nine EAG-active constituents were identified. Perillyl alcohol and α-pinene increased repellency, while neral, geraniol, perill aldehyde and cinnamaldehyde-α-pentyl reduced the repellency of the respective blends. Limonene and linalool interchangeably increased or decreased the repellence based on the resulting blend. O. kilimandscharicum oil showed the highest larvicidal effect against 4 mosquito species, with LD50 of 0.292 and 0.41ppm at 24 and 48 hrs respectively against An. gambiae larvae. The O. kilimandscharicum water miscible formulation recorded a LC50 of 0.13, 0.14, 0.16 and 0.13ppm against larvae of An. gambiae, Ae. aegypti, Cx. quinquefasciatus and An. arabiensis respectively. In a semi-field setup, the larvicidal formulation at 0.5ppm on day 8 attained 100% larval reduction when B.ti had 96.5%. The larvicidal and repellent results of the plant formulations generated in this study have demonstrated high potential for practical application in control of mosquito vector borne diseases and need to be deployed for large scale field trials and registered with the relevant bodies for adoption for control of mosquitoes
Bioprospecting for Anti-Mosquito Phytochemicals Associated With Olfaction and Larvicidal Activities From Selected Kenyan Plants
(Kenyatta University, 2020) Ochola, John Bwire
Mosquitoes are of high public health concern since they are significant disease vectors of different tropical and subtropical life-threatening diseases like malaria, dengue, yellow fever, chikungunya, zika virus and encephalitis. Use of synthetic insecticides for control of mosquitoes causes development of resistance in vector species and have negative effects to the environment and human. This study aimed to find alternative, effective tools against these vectors from plant essential oils. Plant-based products are promising alternatives of lowtoxicity, eco-friendly and low-cost. Oils from air-dried aerial parts of Satureja biflora, Satureja abbysinica, Conyza newii and Plectranthus marrubioides from Aberdare and Ocimum kilimandscharicum from Kakamega in Kenya were extracted using Clevenger apparatus. Oil yields were determined and analyzed by Gas Chromatography/Mass Spectrometry. Repellency of the oils was assessed on adult mosquitoes in ‘WHO arm in the cage’ method, while 3rd instar larvae were used to assess larvicidal activities based on WHO protocol. Oil with better larvicidal activity was formulated into a water-miscible solution for laboratory and semi-field testing. GC linked to EAG detector was used to determine the constituents that elicited chemosensory responses from the antenna of An. gambiae. Individual constituent contribution to mosquito repellence was established through a subtractive-combination bioassay. From the results, oils from different habitats and seasons showed qualitative and quantitative differences. Thirty three (33) compounds were identified in S. biflora oil with 3 chemotypes based on location: geranial(31%)/neral (24%)/linalool (12%) of Kinale, linalool (28%)/neridol (21%)/β- pinene (7.4%) of Nyahururu, and geranial (27%) neridol (Z) (21%)/linalool (16%) of KieniGakoe. S. abyssinica had also 33 compounds comprising majorly menthone (44.1%) and pulegone (33.3%). C. newii had 19 components forming 2 chemotypes p-mentha-1,8-dien-7-yl acetate (24%)/limonene (23%)/5-methyl-2-phenyl-2-hexenal (21%) associated with Nyahururu, and p-mentha-1,8-dien-7-yl acetate (27%)/ limonene (38%). P. marruboides and O. kilimandscharicum had 35 and 41 components respectively. The major compounds in P. marrubioides were carene-2-δ (18.7%) and camphor (17.9%), whereas for O. kilimandscharicum was camphor (36.6%) and limonene (18.6%). C. newii (Nayahururu) S. biflora (Kieni) and S. biflora (Nyahururu) gave a high repellence of ED50 at < 1.95 ppm, whereas S. biflora (Kinale) had ED50 at < 2.35 ppm against Ae. aegyptei and An. gambiae. Besides, C. newii had strong repellence with ED50= 0.5 ppm against An. gambiae. Comparatively DEET gave the highest protection time of 389 min against An. gambiae, followed by C. newii (cream) against the 3 mosquito species; 241, 206 and 60 minutes for An. gambiae, Cx. quinquefasciatus and Ae. aegyptei respectively. S. biflora cream gave 208, 180 and 56 minutes against An. gambiae, Cx. quinquefasciatus and Ae. aegypti respectively. Addition of vanillin to the cream formulation resulted in a longer protection time of 382 min against An. gambiae. Nine EAG-active constituents were identified. Perillyl alcohol and α- pinene increased repellency, while neral, geraniol, perill aldehyde and cinnamaldehyde-α- pentyl reduced the repellency of the respective blends. Limonene and linalool interchangeably increased or decreased the repellence based on the resulting blend. O. kilimandscharicum oil showed the highest larvicidal effect against 4 mosquito species, with LD50 of 0.292 and 0.41ppm at 24 and 48 hrs respectively against An. gambiae larvae. The O. kilimandscharicum water miscible formulation recorded a LC50 of 0.13, 0.14, 0.16 and 0.13ppm against larvae of An. gambiae, Ae. aegypti, Cx. quinquefasciatus and An. arabiensis respectively. In a semi-field setup, the larvicidal formulation at 0.5ppm on day 8 attained 100% larval reduction when B.ti had 96.5%. The larvicidal and repellent results of the plant formulations generated in this study have demonstrated high potential for practical application in control of mosquito vector borne diseases and need to be deployed for large scale field trials and registered with the relevant bodies for adoption for control of mosquitoes.
Characterisation of Kenyan honey and a design model for processing equipment
(2011-07-26) Bichang'a, R.M. Robert
Honey production potential in Kenya is estimated to be 100,000 metric tonnes which can earn the country between Ksh 15-20 billion in foreign exchange. This production potential is not met because of poor apiculture practices. Lack of appropriate honey extraction and processing equipment which is affordable and accessible has resulted into production of low level and poor quality honey. Honey produced in Kenya is from different regions and botanical sources and have different physicochemical and biochemical properties. There has been no study on these important properties in order to characterise and regulate the honey quality. The purpose of this study was to investigate the physicochemical and biochemical properties of Kenyan honey from different regions and design a model to fabricate and construct a processing equipment to improve the quality of local honey. Honey from the four regions of Kenya; Rift Valley, Central, Eastern and Coast was analysed for moisture content, electrical conductivity, ash content, mineral content, pH, HMF, water insoluble. The mean moisture content for the four regions was 19.48 ± 0.11% varying from 1 x.44-29.60%. Coast region had the highest mean moisture content (20.77 ± 0.46%) while Rift Valley had the minimum (18.84 ± 0.10%). The mean electrical conductivity for the four regions was 0.549 ± 0.029 mS ranging from 0.020-2.25 mS. Rift Valley honey had the lowest mean value (0.059 ± 0.015 mS) while Eastern had the highest. The mean viscosity for the four regions at 30 *c was 4342.98 ± 314.08 centipoises, varying from 1000-7700 centipoises. Rift Valley had the most viscous honey with a mean of 5607.75 ± 393 centipoises whereas central had the least viscous with mean of 3335.00 ± 152.53 centipoises. The mean apparent reducing sugars for the four regions before and after hydrolysis were 69.41 ± 0.17 and 71.39 ± 0.17% respectively, ranging from 54.43-78.27% in the same order. Fructose was the dominant specific sugar in honey for the four regions followed by glucose, sucrose and maltose. The mean values of pH, HMF, density, diastase enzyme activity, and hygroscopicity for the four regions were 4.32 ± 0.02, 17.54 ± 1.46 mg/kg, 1.41 ± 0.00 g/cm3, 15.04 ± 0.460 DN, and 8.67 ± 0.01% respectively. In the design of extractor warmer equipment, the overall mean of density and viscosity were used to determine the dimensions and heat transmission of the vessels. The pH was used for the selection of material for construction. Moisture content, HMF, hygroscopicity and diastase were used to set the processing and storage conditions. Kenyan honey was identified as floral (blossom), honeydew honey, compound or mixed honey with Newtonian behaviour. No thixotropic honey was found in these regions. The moisture content of Kenyan honey was found to be below the maximum permitted limit of (21%) and therefore stands no risk of fermenting. Most of the Kenyan honey had matured with acceptable levels of proline and diastase number. The physicochemical parameters of Kenyan honey were successfully used to design honey extraction and processing equipment which can be used to process honey in any part of the country.
Computational chemistry studies of (1,7) sigmatropics hydrogen shiftd in Z,Z-1,3,5- heptatrien systems and esterification reactions
(2011-07-19) Macharia, Godfrey Kibe; Rajab, M.S.; Muthakia, G.K.
Density functional theory has been used to study mechanisms of the reactions involving [1,7]-sigmatropic hydrogen shift in Z,Z-1,3,5-heptatriene systems, esterification of acetyl chloride with methanol and acid-catalyzed esterification of carboxylic acids with methanol. The calculations employed the B3LYP functional, with 6-31+G(d) basis sets. Mechanism routes were computed, with complete optimization of all intermediates and transition states. The effect of electron-donating and electron-withdrawing substituents in Z,Z-1,3,5heptatriene systems was investigated. Analysis of the geometries, energies and electronic characteristics of the sigmatropic transposition compared to those of the unsubstituted cases provided insights into substituent effects of the reactions. The study revealed that the inductive and mesomeric effects of heteroatoms or heterosubstituents are of great importance in the energetics of the transformation. Steric effects also play an important role due to the geometrical constraints of the reaction.Generally increasing the electron density of the system, decreases the electron density on the protropic proton resulting in the decrease of the activation energy. For the esterification of acetyl halides with methanol, the calculations suggest that the reaction proceeds through a loose transition state with a concerted SN2 mechanism. The nucleophilic methanol attacks the carbonyl carbon at Biirgi-Dunitz trajectory and the interaction is subject to general base catalysis, either by a second molecule of methanol or a solvent molecule. This explains the mixed reaction kinetics observed from experimental data. The calculations suggest that the acid-catalyzed esterification of carboxylic acids with methanol involve interaction of both the proton and the counter ion. The calculated activation parameters in the solvent model are in excellent agreement with experimental results. The computational results for the methanolysis of acetyl chloride and acid-catalyzed esterification reactions call for a re-evaluation of some commonly accepted classical mechanistic pathways. For the reactions investigated in this study, the calculations revealed a new mechanistic insight of the reaction pathway
Concentration of iron in laterites using in-situ carbonized biomass
(2014-08-28) Njoroge, Peter Waithaka
Iron occurs in more than 85 minerals. However, among these, only a few are important ores of the element. For economical extraction of iron, the iron ore must contain over 55% iron. These ores must be concentrated before putting them in a blast furnace. Kenya has widespread documented huge volumes of laterites. However the country spends huge amounts of money in importation of iron and iron products despite having these laterites that are rich in iron. This thesis describes the results of a study undertaken with the aim of finding out whether the level of iron in laterites (murram), can be increased to a level above 55% which can placed in a blast furnace for iron extraction. Samples for this study were obtained from selected murram quarries in, Kamahuha and Juja located in Murang‟a and Kiambu Counties respectively, in the Republic of Kenya. Total elemental analysis was carried out with particular interest on the levels of iron in both the raw and treated samples using Atomic Absorption Spectroscopy (AAS), X-Ray Flourescence Spectroscopy (XFRS) and EthylenediaminetetraaceticAcid (EDTA) Titrations. The mineralogical composition of both the raw and treated materials was determined using a Brucker D2 PhaserDiffractometer. The results of this study show that levels of iron in the raw laterites from Kamahuha ranged between 24-39% while those form Juja ranged between 12-17%. The iron in the raw laterites is present predominantly as the minerals goethite, FeO.OH and haematite, Fe2O3, as shown by presence of peaks at diffraction angles of 2θ = 21.51˚ and 2θ = 54.11˚respectively, which are attributed to these minerals. The concentration of iron in the laterites was done by heating a laterite/charcoal mixture in the temperature range 500-700oC in a ceramic container, under a slow current of air (0.5-0.7cm3/sec) from a compressed air cylinder. On cooling this mixture, the iron-containing mineral was readily picked with a permanent horse-shoe magnet (about 92milliteslas). The experiment was repeated using carbonized saw dust, leaves and dried potato peelings obtained from solid municipal waste in place of charcoal. The optimum ratio of biomass: laterite was found to be 1:20 by mass. After magnetic-separation iron was present predominantly as the mineral, magnetite Fe3O4, and had a broad diffraction peak at 2θ = 36˚.Furthermore, the percentage of iron in the magnet-separated product from both Kamahuha and Juja had increased to 55-62%. These results show that iron in the laterites can be increased to a level that can be used for iron extraction. Biomass from solid municipal waste can be used as a source of carbon monoxide to reduce goethite and hematite to magnetite. The use of biomass from the solid municipal waste also impacts positively on the environment. From the results obtained this process should be scaled up by setting up a pilot plant to concentrate iron laterites and determine the economic viability of the process.
Determination of heavy metals in Kenyan cigarettes, tobacco leaves and intercropped plants by atomic absorption spectrophotometry.
(2012-05-07) Mitei, Yulita C.
Recent studies have indicated an increasing concern for the role that cadmium and lead play or are suspected to play in biological and physiological disorders such as emphysema of the lungs, renal tubular damage, cancer and cardiovascular diseases. Studies have revealed that cigarettes contain some heavy metals and that smoking involves the inhalation of small amounts of metals such as cadmium and lead. Since absorption from the lungs is usually complete, heavy smokers tend to absorb more of these metals. Given that both metals are accumulative in nature with long biological half-lives, smokers accumulate twice the amount accumulated by non-smokers. The study set out to find out whether Kenyan Smokers (Passive and active) are exposed to high levels of these heavy metals, to compare the levels in the cigarette tobacco with those in fresh tobacco leaves and to compare the levels in the fresh tobacco leaves with those in other crop plants grown in the same locality. In this study levels of cadmium, lead and Zinc were determined in fresh, cured/processed tobacco leaves, soil and other crop plants growing in the same locality. Levels in eight Kenyan cigarette brands currently in the market were also determined. For this the Spectr AA-10 Varian Atomic Absorption Spectrophotometer (AAS) (Varian Techtron Pty. Ltd. Australia) was utilized. The results reveal that the cadmium levels in Kenyan cigarettes compare well with those reported in the literature; However, the levels of lead and zinc were found to be higher than those reported in the literature. Also evident are higher than in the fresh tobacco leaves. This may indicate contamination during processing. The results also show that there is no significant differences in cadium and lead levels in fresh tobacco leaves and in the cured/processed leaves, thus the curing process does not seen to affect the metal levels in the tobacco leaves. This is however not the case with zinc. On the contrary the levels of zinc in fresh leaves are significantly higher than in the cured/processed leaves. Therefore the curing process seems to lower its levels. The levels of these heavy metals in other crop plants either higher or lower than those in tobacco leaves.
Diammonium Phosphate Fertilizer from Bone–Phosphate Enriched Phosphoric Acid and Ammonia from Lithium Nitride and its Efficacy in Tomato Growing
(Kenyatta University, 2021) Makhanu, Mutenyo Maxmilla; Evans Changamu Ogwagwa; Dickson Andala
obtained from finite rock phosphate is one of the essential elements for food production and modern agriculture. Therefore, for sustainability of food supply and development in agriculture, management of phosphorus is key. The estimated periods within which the finite rocks might be depleted range from 30 to 300 years. There is a general agreement that there is a decrease in accessible reserves of phosphorus. Among the alternatives to rock phosphorus are animal bones disposed as waste from abattoirs in large cities and towns. Animal bones have a high concentration of phosphate that can be harvested and used in fertilizer production but they take many years to decompose and release the phosphate. The objective of this was to prepare bone-phosphate enriched phosphoric acid from discarded animal bones and use it to prepare DAP fertilizer and determine its efficacy in tomato growing in a greenhouse. Animal bones (predominantly cattle bones) were collected from Kachok Municipal dump site, Kisumu West District, Kenya. They were washed, dried and crashed to smaller particles using a hammer after which they were ground in a mill. The ground bones were extracted with 0.275M H3PO4 to give a 4.58 M bone phosphate-enriched phosphoric acid solution. Nitrogen was extracted from air by passing the air over heated copper filings and reacted with lithium to form lithium nitride. The lithium nitride was later hydrolysed to form ammonia which was reacted with the bone-phosphate enriched phosphoric acid to generate the diammonium phosphate (NH4)2HPO4) fertilizer. Lithum metal was recycled by electrolysis of LiCl using electricity generated by a hybrid solar – wind system in a cell fabricated at Kenyatta University‟s Engineering Workshop. The percent composition of nitrogen (Kjeldahl) in the diammonium phosphate was found to be 17.14 % N while that of the phosphate was found to be 44.58 % P2O5. The process realized 98.87 % N2 separation from air, 94.74 % lithium conversion to lithium nitride and 94.75% lithium nitride conversion to ammonia. The percentage yield of (NH4)2HPO4) obtained from the reaction of ammonia with 4.58 M H3PO4 was 48.06 %. The efficacy of diammonium phosphate in the growing of tomatoes in a greenhouse was determined with the commercially obtained diammonium phosphate as the positive control and no fertilizer as the negative control. Growth parameters of the tomatoes including plant heights, leaf length, leaf width and root length were obtained over a period of twelve weeks. The results showed that the growth parameters recorded for tomato plants grown with synthesized fertilizer were not significantly different from those recorded for tomato plants grown with commercial fertilizer (p-values = 0.000 <0.05). However, growth parameters of tomato plants grown without any fertilizer were significantly different (lower in value) from those grown with fertilizer. Based on the results obtained, it can be concluded that the bone phosphate based fertilizer prepared in this study was as efficacious as the commercial fertilizer.this is a significant finding in that it shows that it shows that animal bones can be converted into readily available phosphatic fertilizer. A pilot study on production of the same is recommended
Diversity and distribution of the afroalpine flora of Eastern Africa with special reference to the taxonomy of the genus pentaschistis (poaceae)
(2013-08-14) Ahmed, Abdikadir Abdi
The African tropic−alpine system, consists of a number of geographically separated ‘sky−islands’ and constitutes an excellent system in which to investigate the interaction between the geographical and ecological components of differentiation. The mountain systems harbouring the Afroalpine zone act as giant water towers that are source of almost all rivers that are an important source of water for domestic, industrial and agricultural use. Due to inaccessibility caused by extreme isolation and harsh conditions little research has been done on the diversity, species richness and evenness among other aspects in the Afroalpine zone. For effective conservation of these important zones it is important to understand their ecology. and the conservation status of the species of these zones. The aim of this study was to carry out ecological analysis of Afroalpine species in general and addresses species delimitation in the genus Pentaschistis. The vegetation of Afroalpine zone of Mount Kenya, Elgon, Kilimanjaro, Ruwenzori, Bale and Simen were sampled for ecological analysis and taxonomic revision of the genus Pentaschistis. A total of 75 plots (100 × 100 m) from five vegetation types were analysed using both univariate and multivariate analyses. From the study a total of 46 families, 124 genera and 278 species were recorded from rock outcrops, bogs, grassland, Dendrosenecio forest/woodland and Alchemilla vegetation communities. Six families, namely Asteraceae, Poaceae, Caryophyllaceae, Lamiaceae, Cyperaceae and Rosaceae constitute 56% of all the species sampled. Five communities were described from the vegetation types studied: Carex−Deschampsia bogs, Festuca−Pentaschistis grassland communities, Dendrosenecio−Alchemilla forest/woodland, Alchemilla communities and Helichrysum−Festuca−Koeleria−Pentaschistis rock outcrop communities. The species richness and diversity is higher in older mountains such as Mt. Simen, Bale and Elgon (over 20 MYBP) compared to younger mountains such as Mt. Kenya (3.5 MYBP), Kilimanjaro and Rwenzori (less than 3 MYBP) mountains. Similarly Ethiopian Mountains were more species rich and have higher diversity than mountains of East Africa. Simen was the most species rich as well as exhibiting highest species diversity while Rwenzori was the most species poor and with the least species diversity. The East Africa Mountains were similar both in their species composition and community structure, as were the Ethiopian Mountains. Factors such as the geographical distance, age, geological history, and position of the mountains along the Rift Valley, climatic and edaphic factors are thought to be responsible for the observed patterns. The five vegetation communities were recognizable from each other though rock outcrop and grassland communities were barely separable (R< 0.25). The rest of the vegetation communities were overlapping but separable especially between bogs vs. Dendrosenecio (R > 0.5). The mainly southern African grass genus Pentaschistis was represented on all Afro−alpine mountain systems but due to the complex ecological and geographical variation patterns, the number of species recognized is widely disputed. A classification based on a well–supported evolutionary hypothesis for the genus is necessary. In order to obtain this, morphological studies of both natural populations and herbarium specimens have been conducted during this study. A total of 38 characters were used to carry out phenetic analysis of 37 specimens from nine taxa. The results from morphological observation as well as the cluster and principal component analysis produced two main groupings viz. (1) the two widely distributed species P. borussica and the P. pictigluma species complex, and (2) two narrow endemics P. dolichochaeta and P. chrysurus. Similarly, phylogenetic analysis of three gene regions (TrnL-F, rpL-16 and ITS) based on 83 sequences were done in this study to infer the phylogeographic history of this genus. The results from this study indicate two independent events of colonization each corresponding roughly to the two broadly distributed species and the two narrow endemics. The morphological, phenetic and phylogenetic analysis of this study support the current taxonomic classification of the tropical species of the genus Pentaschistis.
Effect of Selected Bacterial Biocementation, Biodeterioration, Bioremediation on Selected Properties and Microstructure of Hydrated Cement Mortar
(Kenyatta University, 2023) Ngari, Reginah Wangui; Joseph Karanja wa- Thiong'o; Jackson Wachira Muthengia
Cement-made structures encounter durability and sustainability challenges. This is due to degradation by aggressive agents such as Cl-, SO42- and CO2. The presence of micro-organisms, such as Sulphur reducing bacteria (SRB) and Sulphur oxidizing bacteria (SOB), have been found to lead to production of cement degrading agents. On the contrary, there are micro-organisms that may benefit the mortar. Bacteria, for example that precipitate CaCO3, have found use in improving the performance or remediation of degraded concrete / mortar. In this study, the effect of Bacillus flexus, Bacillus cohnii and Thiobacillus thioparus on selected physico-chemical, mechanical properties and bioremediation of mortars was investigated. Growth of bacteria was done in a laboratory set-up. Bacteria concentration of 1.0 x 107 cells per mL of mix media was used. Mortar prisms were prepared using distilled water or bacteria solution as mix water and cured diistilled water or in bacteria solution. Control experiments had mortar prisms prepared using distilled water as mix and curing water. Pastes for setting time and soundness tests were similarly prepared using the above mix waters. Compressive strength, soundness, water absorption, setting time tests analyses were carried out for each category of mortars. Compressive strength test analyses were carried out on the 2nd, 7th, 14th, 28th, 56th and 90th day of curing of the mortars. Microstructural analyses of the hydrated mortars were conducted using Scanning Electron Microscopy (SEM). 28-day cured control and microbial mortars were subjected to water absorption analyses, chloride and sulphate ion ingress tests. From the results, the incorporated bacteria did not affect the soundness of cement significantly though setting time was significantly affected. Compressive strength was observed to increase with curing period for the Bacillus flexus and Bacillus cohnii with the highest gain observed at 90 days as 31.60 % for w/c of 0.4. On the contrary, there was a significant decline in compressive strength for all mortar where Thiobacillus thioparus was incorporated across all the curing regimes. The lowest percentage loss was observed as 44.38 % at 90 days for w/c of 0.6. Diffusivity of Cl- ions was highest for mortars subjected to Thiobacillus thioparus and lowest for Bacillus flexus. The same mortars exhibited Dapp of 2.5479 x 10-10 m2/s and 3.2977 x 10-10 m2 /s respectively. Dapp for SO42- showed a similar trend as Cl- ion. From the SEM images, microstructural analysis indicated presences of calcite (CaCO3), calcium silicate hydrate (CSH), ettringite, portlandite (Calcium hydroxide, CH) with the microbial mortars. A denser and a more refined microstructure with Bacillus flexus and Bacillus cohnii was observed as opposed to massive presence of voids, micro cracks and pores with Thiobacillus thioparus mortars. Generally, Bacillus flexus was a better CaCO3 precipitating bacteria than Bacillus cohnii. The results show that MICP was an effective method of remediating mortar that has been degraded by bacteria.
Effects of dehydration of dark-greenn, leafy vegetables on bioavailability and bioconversion of serum beta-carotene among preschool children
(2011-10-25) Oyugi-Nawiri, Mildred Pauline
Vitamin A, an essential micronutrient has its deficiency remaining as a major public health problem in developing countries. The deficiency is caused by insufficient intake of foods rich in vitamin A or pro-vitamin A carotenoids and its prevalence contributes substantially to morbidity and mortality among children. Carotenoids, with (b-carotene as the primary pro-vitamin A carotenoid in dark green leafy vegetables (DGLVs), are important for their various biological functions. The DGLVs are season dependent but can be preserved by dehydration to ensure their availability during the dry seasons to reduce cases of the deficiency. The R-carotene content and retinol (vitamin A) in serum of preschool children after consumption of dehydrated cowpeas and amaranthus leaves were quantified. Preschool children (study subjects) were involved in a 13-week intervention period. Extracts from vegetable and serum samples were analysed by High Performance Liquid Chromatography. Elution was performed isocratically with systems of methanol:dichloromethane:water (79:18:3, v:v:v), methanol:dichloromethane:water (83:15:2, v:v:v) and acetonitrile:water (85:15, v:v) for vegetable samples, serum (3carotene (S-BC) and serum retinol (S-R) analysis respectively. Fresh blanched vegetable leaves, contained high levels of the all-trans b-carotene; 779-827mg/g DM for cowpeas and 553-639mg/g DM for amaranthus. Although they reduced with dehydration and cooking, retentions for b-carotene were over 50% after dehydration and cooking. Thus, recipes provided sufficient amounts of retinol equivalents (RE)/day from both fresh and sun-dried vegetables to meet the recommended daily allowances for the study subjects. Serum beta-carotene concentrations were found to be within the normal range at baseline and increased significantly post-interventional for both study groups (p<0.000, df = 110, for fresh vegetable group and p<0.000, df = 38 for dehydrated vegetable group. There was a negative correlation between the baseline S-BC and change in S-BC for study subjects. However, the increase in S-BC of subjects in the fresh vegetable group was higher as compared to those of the sundried group. Although the control group for the fresh vegetable study group had an increase in S-BC, that of the dehydrated group had a decrease, but these changes were not statistically significant. The subjects in the fresh and dehydrated vegetable groups had marginally lower S-R concentrations at baseline but there was significant changes after intervention (p<0.000, df = 110, for fresh vegetable and p<0.000, df = 38 for dehydrated group). McNemars chi-square tests showed that at baseline, 55% and 70% of study subjects in the fresh and dehydrated vegetable study groups respectively had low S-R concentrations with the percentages reducing to 36% and 30% respectively post-intervention. Correlation analysis was negative between the baseline S-R and change in S-R for subjects in both the study and control groups. While data from individual subjects support the homeostatic regulation of vitamin A status, this study concludes that, intervention with the dehydrated vegetables improved the bio-availability of beta-carotene and bioconversion of beta-carotene to retinol. The findings contribute to the link between increased consumption of carotenoids from DGLVs and bio-availability of the same.
Effects of selected media on novel portland pozzolana cement
(2011-07-19) Muthengia, J. W.; Gerald Muthakia; Karanja Thiong'o
Cement is subject to degradation by aggressive media found in the environment. Durability tests are therefore necessary for any cementitious material in a given environment. The work reported in this thesis involved the study of the effects of selected aggressive media on a cement, made from inter-mixing Ordinary Portland Cement (OPC), dried acetylene lime sludge (DALS) and an incinerated mix of reject bricks (BB), spent bleaching earth (SBE) and rice husks. The cement was labelled Portland Combined DALS Cement (PCDC). Initial tests showed that PCDC met the Kenya Standard requirements for Portland Pozzolana cement (PPC). PCDC was subjected to various media which included sea water, distilled water, chloride and sulphate solutions in a laboratory set-up. The experiments were carried alongside OPC, 25 % Pulverised Fuel Ash substituted OPC (OPC + PFA) and commercial PPC. The study was carried out in two phases; cement mortar moulded into 100 mm cubes subjected to the media and reinforced mortar cubes subjected to a wet and dry alternate environment of 3.5 % sodium chloride solution. PCDC exhibited continued compressive strength gain in all media except in chloride solutions. PCDC exhibited comparable gain in compressive strength and selected ions intake/leach to PPC in sulphate solutions and distilled water. PCDC exhibited higher strength gain than OPC in distilled water. Except in chloride solutions, PPC exhibited higher strength gain than OPC. In Corrosion tests, the PCDC mortar rebars showed early attainment of active corrosion coupled with higher corrosion rates over a short period of time than OPC as w/c ratio was increased. The PCDC showed a decreased chloride penetration than OPC as w/c and depth of cover increased. PCDC showed the lowest apparent chloride diffusion coefficients. The resistivity of PCDC in the aggressive media suggested that it required greater depths of cover, where reinforcement was to be used, and long term curing to improve on its resistivity. The tests showed that PCDC can be used for general construction work in the tested media in a similar manner to PPC
Efficacy and kinetics of adsorption of single and multiple heavy metal cations from aqueous solutions by fruit waste products
(Kenyatta University, 2016-12) Nthiga, Esther Wanja
Removal of toxic heavy metals from water has been a major challenge, especially in rural areas. Various methods have been used for this purpose; among them is biosorption based technology. The technology has been recognized as an economical and eco-friendly method for removal of toxic anions and cations from wastewater. Moreover, the efficacy of biomass in adsorption of cations and anions can be improved by different modifications, including treatment with sulphuric acid. Numerous approaches have been developed for adsorption of single ions in solution. However, toxic metallic or non-metallic ions rarely occur singly in wastewater. The presence of multiple ions in solution may often have agonistic or antagonistic effect on the efficiency of an adsorbent, and there is insufficient information on the efficacy of different methods for removing multiple ions. This study assessed the efficacy and mechanism of acid treated (modified) and raw (unmodified) biosorbents (derived from lemon, sweet yellow passion, banana, watermelon peels, and avocado seeds) for removal of toxic cations (Cd, Pb and Cu) from water. Functional groups of adsorbents were identified by mid-infrared spectroscopy (MIR) and their surface morphology was probed by scanning electron microscopy (SEM). the efficacy of each adsorbent was evaluated by quantifying the kinetics and levels of cations adsorbed at different pH of the solution, initial concentrations, contact time and adsorbent dose. Desorption experiments were conducted to determine the possibility of recovering ions and reusing the sorbents for next cycle of deployment. Experimental data of each metal ion was described by either Freundlich isotherm or Langmuir isotherm. The acid treated fruit peels and avocado seeds recorded higher efficacy as compared to raw adsorbents. Generally, acid treated watermelon peels demonstrated the highest uptake of 130.23 mg/g of Pb (II), followed by 114.234 mg/g of Cu (II) and 97.14 mg/g of Cd (II) ions. Further adsorption trials with binary and ternary metal blends on showed significant reductions in metal uptake capacities of evaluated adsorbents as compared to single metal systems. On account of metal preference, the selectivity order for metal ions towards the all the studied biomass was Pb (II) > Cu (II) > Cd (II). Time-course measurements indicated involvement of pseudo-second-order kinetics in adsorptions. Desorption efficacies were high on acid-treated adsorbents: 99.97 % ofPb(II) ions from acid treated avocado seeds; and 99.79 % of Cu(II) and 99.23 % of Cd (II) from acid treated watermelon peels. The results show good performance of the fruit peels and avocado seeds in adsorbing single and multiple metal ions, and the potential of using such wastes for purifying drinking and cooking water at household level.
Fabrication and characterization of magneto responsive carbon nanotube-infused polysulfone (cnt-ipsf) nanocomposites for water purification
(2017-09) Silvanus, Shisia Kuboka
The search for materials for purification of polluted water is growing daily with the advent of nanoparticles. This is particularly important because many populations of people in the developing countries lack clean water due to water pollution. Water pollutants such as heavy metals and polycyclic aromatic hydrocarbons (PAHs) are known to have adverse effects on humans and environment. This work investigated the potential of synthesized magnetoresponsive CNT polysulfone infused polymeric nanocomposites (CNT-IPSF) in water purification against heavy metals and polycyclic aromatic hydrocarbons (PAHs) pollution. Adsorption mechanism was studied at constant initial Pb(II) ion concentrations, nanocomposite dosage, contact time, and pH. Carbon nanotubes (CNTs) with internal diameters in the range of 20-30 nm were prepared via chemical vapour deposition (CVD) process. Magnetite and silica coated magnetite nanoparticles (NPs) prepared by solvothermal and sol gel methods respectively exhibited UV-Visible spectrometric spectra at about 395 nm and 396 nm respectively. Successfully synthesized Fe3O4 nanoparticles exhibited FT-IR absorption bands at 460 and 521 cm-1 which ascribed for the vibrations of Fe-O bond. X-ray diffraction analysis of core shell NPs showed strongest peak at D(311) plane, characteristic of a cubic spinel structure. The core shell nanoparticles obtained displayed a thin hysteresis loop having saturation magnetization of 2.2 emu g-1 with ferrimagnetic property. Removal efficiency of the synthesized CNT-PSF/Fe3O4 nanocomposite for Pb(II) ions and phenanthrenes was 69 % and 63 % respectively compared to that for a commercially available activated carbon which recorded 54 % and 53 % respectively. Adsorption of Pb(II) ions and phenanthrenes followed pseudo-second-order while Freundlich adsorption isotherm gave the best-fit for the two pollutants. Regeneration for Pb(II) ions of above 60 % and a gradual decrease in desorption efficiency for phenanthrenes of up to 50 % after three desorption cycles confirmed the reusability of the fabricated magnetoresponsive CNT IPSF/Fe3O4 nanocomposites. This study has developed a novel CNT-IPSF/Fe3O4 nanocomposite material with higher removal efficiency for water pollutants than commercially available activated carbon for use in water treatment.
Fabrication of Rapid Diagnostic Kit Casing Using Modified Biodegradable Paper Materials as an Alternative to Plastic
(Kenyatta University, 2019-07) Mwangi. James Njogu
The high population growth rate, emerging diseases and high cost of health care in developing countries has led to the high demand of rapid diagnostic test (RDT) kits. Rapid diagnostic test kits are medical devices used in early detection of diseases among the population living in areas with limited medical facilities. The portability and reliability of kits reduces medical cost incurred by inaccurate disease diagnosis. To meet this demand plastics are enormously produced as basic raw material in production of the kits. Plastics are often preferred because they are cheaper than their corresponding biopolymer. The most devastating menace from plastic is its high solid waste accumulation due to slow biodegradation. The study sought to modify selected paper materials and tree barks to mimic plastic properties to replace plastic in rapid diagnostic test kits. The selected papers were purchased from Nairobi County (Kenya) shops while selected tree barks were collected from farms within Kiambu County (Kenya). On modification with trichloro (lH, IH, 2H, 2H perfluorooctyl) silane at different reaction times insitu, the paper and polished tree barks surfaces displayed water contact angles between 90.14° to 144.60°, which indicated they were hydrophobic. The tree barks were however discontinued for further analysis due the limitation of cutting tools available. The modified paper did not attain superhydrophobicity since the water droplets placed on its tilted surface remained sticky rather than rolling as expected with superhydrophobic surfaces. The surface energy of modified paper materials displayed low critical surface energy values ranging from 27.9 to 40.0 dynes/em. The tensile strength of the unmodified and modified selected paper did not show any significant difference at P
Facile Remediation of Fluoride in Aquatic Media Using Modified Polyethylene Container
(Kenyatta University, 2020-07) Mbugua, Wachira Gerald
Development of environmentally friendly and economically viable water treatmet techniques for remediation of fluoride ions in drinking water has gained a huge research interest. Floridated water is associated with dental and skeletal disorders. Previously used water treatment methods encountered several limitations such as operational problems and are not regeneratable. Adsorption technique is easy to use and is regeneratable. Adsorbents used include activated carbon and bone char. However, activated carbon is expensive while bone char is not acceptable to some religions. Therefore there is need to search for cheaper and widely acceptable adsorbents. This research studied the use of polyethylene wastes from the enivironment `as a green water treatment technique. Polyethylene wastes were separately dispersed in 1, 2-dichloroethane or liquid vegetable oil. The dispersed wastes were each divided into two where one portion was chemically modified with ethylamine, diethylamine and triethylamine separately. Both modified and unmodified adsorbents were characterized using fourier trasnsform infra red spectroscopy (FTIR), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). The characterized materials were subjected to removal of fluoride ions and optimal parameters were applied. Liquid vegetable oil dispersed and activated with triethylamine adsorbent gave an adsorption capacity of 10.30 mg/g at pH 7. 0 fitting well in Langmuir model (R2 = 0.864) and was a pseudo first order (R2 = 0.726). When 1, 2 dicholoroethane dispersed and activated with triethylamine adsorbent was used, removal capacity of 0.17 mg/g at pH 4.0 was recorded. Using fabricated container, Lake Baringo water sample having a fluoride ion concentration of 2.5 mg/L had its fluoride concentration reduced to 1.5 mg/L. Thermodynamic parameter proved that fluoride ions removal was a spontaneous and exothermic process. This study presents an ecofriendly and cheaper method for water treatment and helps to curb polyethylene waste menace in the environment.
Flouride levels in water sources of Gilgil area in Kenya: Deflouridation using locally available geomaterials
(Kenyatta University, 2015) Wambu, Enos Wamalwa
ABSTRACT High prevalence of fluorosis resulting from consumption of drinking water containing excessive fluoride levels continues to affect many communities in Kenya. Low in come rural communities are most affected because of inadequate water treatment and high costs of necessary medication. As part of the on-going search for efficient and ffordable water defluoridation protocol, which has intensified in the most recent past, soil dsorbents have attracted a near-global acclaim as the most promising low cost media for water defluoridation. Nevertheless, it is still unclear whether certain Kenyan clays and soil minerals could be applied as inexpensive adsorbents in dcfluoridation of household water. The present study was, therefore, designed to assess the capacities of selected locally available geomaterials (LAGs) to remove fluoride from water with a view to develop an efficient and affordable water defluoridation technology. The adsorbent materials, which included a naturally occurring siliceous mineral (NSIM), a diatomaceous earth (DIME), a ferric polymineral (pEPM) and iron enriched lateritic soils (FELS) were sampled from their natural deposits in Bungoma and Nakuru counties of Kenya. The minerals were pulverized to pass through O.S-mm sieves and less than 1.0-J.lm fractions isolated by mechanical agitation and sedimentation of the pulverized samples in doubly deionized water (DDW). After the initial pre-treatment in dilute HCI solution, the chemistry and mineralogy of the LAGs were analyzed by atomic absorption spectrophotometry (AAS) and by X-ray Diffraction Analysis (XRD). The fluoride adsorption properties of the LAGs were then assessed with respect to changes in initial fluoride concentration, contact time, mixing ratios, presence of interfering ions, and solution pH and temperature. The efficacy of the LAGs to sorb fluoride from natural high-fluoride water was verified in batch and column tests. Fluoride adsorption onto the acidified LAGs was found to be controlled by the mineralogy and chemical composition of the adsorbents as well as by the solution parameters. The equilibrium fluoride adsorption onto the LAGs was adequately fitted by the Langmuir and the Freundlich adsorption isotherms indicating heterogeneity in the fluoride adsorption mechanisms. Acidified DIME had highest fluoride adsorption capacity (51.1 mg/g) and the capacities of NSIM, FEPM and FELS to sorb fluoride from simulated batch solutions were in range of 10-13 mg/g. The adsorption kinetic data showed that for fluoride adsorption by NSIM and FEPM followed both pseudo-first order and pseudo-second order kinetic models. The adsorption of fluoride onto DIME could, however, be described by intraparticle diffusion kinetics whereas that for FELS by both the pseudo-second order and intraparticle diffusion models. Highest fluoride removal from high-fluoride natural water was achieved using FELS. Fluorides desorption from the LAGs, which was assessed using aqueous solutions of NaCI and Na2C03, demonstrated the reversibility of the processes. The LAGs showed good fluoride adsorption capacities and they could be utilised as inexpensive adsorbents to defluoridate high fluoride drinking waters and help to alleviate endemic of fluorosis among the communities. Results of this study will be useful as a basis for future scale up using these inexpensive materials as low-cost adsorbents to develop affordable technology for easy and safe defluoridation and sustainable cleaning of drinking water.

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