MST-Department of Chemistry

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    Hydrogeochemical Analysis and Modeling of Groundwater in South Kinangop, Nyandarua County, Kenya
    (Kenyatta University, 2023-04) Macharia, Chege Robert; G. Kibe Macharia; Paul Njihia Gichuhi
    Abstract
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    Bacterial Contamination of Water Used in the Household for Domestic Purposes in Mombasa County, Kenya
    (Kenyatta University, 2023-11) Abdallah Bakari, Bibi; Juddy Mwaura; Shadrack Yonge
    It is essential to determine the microbial content of water since it is essential to sustain human life. Unsafe drinking water and inadequate sanitation account for 4% of all elobal disabilities. Due to the water scarcity experienced in developing countries, people forced to rely on water sources of unknown quality. The United Nations has classified Kenya a country which frequently faces water scarcity. Approximately 56% of its citizens are able to access safe drinking water, with up to 50% of the reported illnesses being waterborne diseases. In Mombasa County, only 24% of the residents have access to safe drinking water. An acute water shortage makes most people adopt alternative water sources whose quality is doubtful. An average of 24% of Kisauni, Nyali and Mvita residents use unimproved water sources. The study's objective was to determine the bacterial quality of 55 water samples, where 35 water samples and 20 water samples collected in the household (HH) storage containers were either from borehole water (case) or other sources (controls), respectively. The research also determined the relationship between bacterial quality and diarrhoeal. The association between the type of water sources and diarrhoeal cases reported was determined. Three hundred and eighteen HHs for the cases and one hundred and sixty four HHs for controls were interviewed to determine risk factors that affect water quality at the HH level. Total coliform, faccal coliforms, Heterotrophic Plate Count (HPC), Salmonella and Shigella were isolated. The APHA standards methods were adopted to analyse water and a structured questionnaire was used 1o collect data at the HH. The study design adopted was analytical descriptive cross sectional study. Stratified sampling and random sampling methods were used to identify HHs which were interviewed in case and controls respectively Total coliforms from the two groups had a combined mean of £1039.98 CFU, t =0.000. Faecal coliforms (FC) had a combined mean of +634.74 CFU, t= 0.0006. The results showed significant difference in TC and FC in the two groups. HPC had combined means of +4519.66. 1=0.0891. Boreholes and other sources of water were contaminated with Salmonella at 34.3% and 20%, respectively. None of the water samples collected had Shigella. The study showed a significant relationship between the microbial quality and diarrheal cases for the two groups (t=0.93, df= 53, and 1=0.006). It was also found that there was no relationship between the diarrheal reported diarrheal cases and the type of water consumed in the houschold, t= 0.076. Risk factors associated with water quality were water treatment, other water sources. hand-washing with soap, water storage period, cleaning of containers, income and the number of under-fives in households. Borehole stored water at the HH was found to be unsafe for human consumption. Improving water quality is essential to reduce cases of diarhhoea. Type of was consumed at the HH cannot be associated with diahhoea cases reported in the HH. Interventions that help to improve water quality by targeting the community, like safe drinking water storage and appropriate handling at the HHs need to be strengthened. Water sanitation and Hygiene activities targeting the HH need 1o be intensified. Water sampling at the HH needs to be initiated.
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    Geoplolimer Filters Derived from Geopolimers and activated Carbon for the removal of lead2 and Copper 2 in acquois Solution
    (Kenyatta University, 2023-11) Mwaura Dominic Munyu, Dominic Munyu; Harun Mbuvi and Francis maingi
    ABSTRACT Heavy metals pose serious environmental and health effects in the society since they are toxic and non-biodegradable. Removing aqueous heavy metals from solution especially wastewater has become an area of study in the recent past. Various methods like ion exchange, reverse osmosis, coagulation, and adsorption among others have been put forth in the removal of heavy metal ions. There is little information in the literature on the use of geopolymer filters in adsorption. This study focused on the removal of heavy metal ions of Pb(II), and Cu(II) from an aqueous medium using geopolymer filters fabricated from geopolymer and activated carbon. Geopolymers were used for the adsorption of the heavy metal ions, while activated was to increase porosity in the filter. Geopolymers are easily synthesized using locally available materials, are easy to use, and are environmentally friendly. Common clay was used as a source of alumina, and silica which are important ingredients of geopolymerization, and sugarcane bagasse ash was to provide extra silica. The activated carbon that was used in this study was derived from saw dust. The raw materials for the geopolymerization process and activated carbon process were sourced locally. Characterization of the geopolymer and activated carbon was done using XRF, XRD, and FT-IR.XRF identified the mineral composition of the raw materials, geopolymer, and activated carbon. FT-IR was used to find out the functional groups in both the geopolymer Al-O, Si-O, and activated carbon. XRD was used to identify that both the geopolymer and activated carbon were amorphous broad peaks between 20° 34° in 2-theta hence adsorption of heavy metal ions would occur and, carbon would have good porosity. Adsorption application of the geopolymer filter was done using an aqueous medium while varying geopolymer: activated carbon ratio where a 2:1 ratio was used, filter thickness of 4 cm was used for 50ml solution, pH the optimum range was 4-6.5 for both metal ions, and initial metal ion concentration; adsorption was above 85% for both metal ions when the concentration range was 15-150mg/L, above this concentrations, the adsorption efficiency reduced but not below 50%. The experimental data obtained were treated using Freundlich and Langmuir adsorption isotherm models to understand if the adsorption sites were homogenous or heterogeneous. Based on the correction coefficient (R2), Freudliuch isotherm was best fitted to predict the adsorption capacity of the geopolymer adsorbent for both Pb(II) metal ions, and Cu(II) metal ions with the heterogenous index being between 0-1. This illustrates that the geopolymer filter has a multilayer adsorption sites on its surface. From the adsorption data, it is clear that geopolymers and activated carbon can be used to fabricate water filters that can adsorb heavy metal ions and maintain good porosity. The filters are potential adsorbents for heavy metals from water treatment.
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    Physico-Chemical Parameters, Levels of Selected Heavy Metals and Nutrients during Wet and Dry Seasons Along River Ewaso Narok, Laikipia County, Kenya
    (Kenyatta University, 2023-10) Maisa, Thadius Nyamweya; Alphonse Wanyonyi; Silvanus Shisia
    River water pollution is a growing problem especially in developing countries where population growth and urbanization are never adequately checked. Effluents from chemical industries and dumping of toxic solid wastes from urban settlements find their way into rivers. Run-offs from agricultural fields downstream and other anthropogenic activities result in heavy pollution of rivers. Downstream most urban areas live huge communities of humans and animals who rely on water from these rivers for survival. There are reports of environmental degradation, water related discases in both animals and humans all of which are cvidence of water pollution. The objective of this study was to assess the extent of water pollution by determining the levels of selected heavy metals namely: Pb, Cu, Mn & Cd and selected nutrients (NO3 and PO3~) along river Ewaso Narok, Laikipia County, Kenya, during wet and dry seasons. Sampling was done along the river to obtain samples of water, sediment and soil in both seasons, and each sample was analyzed for the concentrations of each parameter along with determination of selected Physico-chemical parameters of water including pH, T, Ce, TDS and TSS. Soil and sediment samples were digested using nitric and hydrochloric acid. Samples were then analyzed for heavy metals using FAAS and for nutrients using UV-vis Spectrophotometry. Data was analyzed using ANOVA and t-tests. The results obtained were as follows: The mean pH varied downstream across the two scasons; 7.46 1.02 wet, 8.56 + 0.51 dry, with a lower pH in the wet season, an indication of presence of heavy metals. Temperature was generally lower than the set limit by WASREB (20-35°C) in both seasons; 13.91 + 1.96°C wet, 15.57 £ 2.13°C dry. The same trend was observed with electrical conductivity Ce; 153+ 198.5pS/em wet, 164 + 206.23pS/cm dry, and TDS; 113.6 = 133.5mg/L wet, 122.8 + 144.5mg/L dry. Noticeably, T, Ce and TDS were generally higher in the dry season albeit falling below set limits by WHO. Ce, just like TDS, is a factor of temperature. TSS was slightly above set limit by WASREB in the wet season; 30.4 + 17.36mg/L wet, 224 = 14.74mg/L dry. Pb concentration was higher in the wet season; 0.0529 0.0830mg/L, being significantly higher than set limit by WHO (p<0.05). The same trend was noted with Cu; 2.6057 + 3.2705mg/L in the wet season The wet season is associated with run-offs and heavy agricultural activities. Mn was not detected in the wet season. Manganese Carbonate, a fertilizer, is insoluble in water thus not easily detectable. However, in the dry season a mean of 0.06524 = 0.03666mg/L was recorded falling within the limit set by WHO. Cd was higher in the wet season (0.0051 £ 0.0044mg/1) than in the dry season (0.0002 = 0.0006mg/l), but was within WHO limit (0.003mg/1). The concentration of nitrate was significantly higher in the wet season; 1 10.3122 + 62.1294mg/L, than in the dry season (25.5787 £ 1.4487mg/l) being significantly higher (p<0.05) than standard WHO value in both seasons. Similarly the concentration of phosphate was significantly higher than WHO set limit in both seasons: wet season; 0.1068 + 0.07249mg/L, dry season; 0.1376 = 0.0957mg/L. This is because of wash-off of agricultural residues during downpour. These results signify clevated levels of heavy metals and nutrients in R. Ewaso Narok, especially in the wet scason, potentially from urbanization, agriculture and other anthropogenic activities along the river, which may lead to health and environmental implications. NEMA, WRA, KFS and other relevant bodies need to combine effort to control human activities along the river which will lead to availability of clean drinking water for residents in order to protect the river and lives.
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    Determination of the Physicochemical Properties of Honey from Suba Region, Homa Bay County-Kenya
    (kenyatta university, 2023) Ondogo, Linet Kwamboka; Daniel Okanga' Oyoo; Robert Motari Bichang'a
    Honey is a naturally sweet substance produced by honeybees from plant flowers' nectar and honeydew. Examining the physicochemical properties of honey is crucial for assessing its quality. The primary economic activities in Homa Bay County Suba Region, Suba South Sub-County, Gwassi North, and Gwassi South divisions are subsistence farming and fishing. The divisions of Gwassi North and Gwassi South have lately embraced commercial apiculture as a new economic enterprise. The physical and chemical characteristics of this honey were examined to assess its quality, determining whether it meets both local and global honey standards. To enable farmers to process and increase the value of their honey, plans are being made to build a facility that would process honey. This study aimed at evaluating the physicochemical properties of honey to determine its compliance with international honey standards. The famous bee, Apis mellifera, was the only kind of honeybee studied. The Gwassi North and Gwassi South divisions' four regions, Nyandiwa (Western), Tonga (Northern), Magunga (Eastern), and Nyancha (Central), were the sampled regions of the study's forty honey samples. To achieve its objectives, the study used an experimental technique. The Codex Alimentarius Commission's defined methods were used to analyze each property. A pH meter, UV-visible spectrophotometer, and HPLC instruments were used to measure the pH, free acidity, HMF content, proline content, fructose content, glucose content, and sucrose content of the honey, respectively. Utilizing an Abbe refractometer, a conductivity meter, an oven, and density bottles respectively, the following parameters were assessed: moisture content, refractive index, electrical conductivity, ash content, and density. The levels of mineral elements were assessed using atomic absorption spectroscopy (AAS) for sodium (Na) and potassium (K), while calcium (Ca), zinc (Zn), magnesium (Mg), manganese (Mn), and iron (Fe) were measured using a flame photometer. An analysis of variance was used in the statistical analysis, which was performed using SPSS version 21. The investigation's results showed that the physical and chemical properties had the following mean values for the honey sample: pH = 4.01± 0.03, free acidity = 35.83±0.45 mEq/kg, HMF = 19.95±1.76 mg/kg, proline = 629.77±9.80 mg/kg, sum of glucose and fructose = 68.37±0.51%, moisture content = 21.53±0.13%, refractive index = 1.4745±0.0083, ash content = 0.55±0.01, electrical conductivity = 0.54±0.01 and density was 1.41±0.02g/cm3. According to the mineral study of the honey samples, manganese was the least common mineral and potassium was the most common. The concentration increased in the order Mn < Zn < Fe < Ca < mg < Na
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    Phytochemical and mosquito larvicidal studies of stachytarpheta urticifolia (sims)
    (Kenyatta university, 2022-10) Agola, Faith Caroline; Alphonse W. Wafula; Ram Manohar
    Malaria is one of the most common and severe tropical diseases on the planet, transmitted by the Anopheles gambiae mosquito. Malaria affects more than 300 million people each year, according to the World Health Organization. Each year, these diseases are estimated to kill between 1.5 and 3 million people worldwide, with nearly 90 percent of all illnesses affecting pregnant women and children under the age of five. Chemotherapy, vaccine development, and vector control are currently used to prevent and control malaria. Vector management has been hailed as a critical tool in the fight against malaria transmission in light of the plasmodium species' increasing resistance to currently available antimalarial medications. Controlling mosquitoes during their larval stage is an additional effort made by humanity in an attempt to combat malaria. The use of natural compounds derived from plants to control the insect pests is a non-toxic and environmentally friendly strategy. Research has shown that compounds from the Vebenaceae family have been identified and shown to have larvicidal activity. The phytochemical and mosquito larvicidal properties of crude extracts and fractions derived from Stacytarpheta urticifolia, a member of the Vebenaceae family, were investigated in this work. The dry powdered stems of S. urticifolia were extracted using hexane, DCM, EtOAc and methanol for a total of 48 hours, with each extraction utilizing a different solvent. Phytochemical screening showed presence of terpenoids, alkaloids, tannins, steroids and flavonoids in the plant. For bioassay investigations, different concentrations of extracts were used. The larvicidal activity of the polar crude extracts was much greater than that of the non-polar extracts; MeOH LC50=0.08, Hexane LC50=10.59. The cytotoxicity tests also revealed that the EtOAc and methanol extracts were the more toxic to brine shrimp eggs; MeOH LC50= 6.48x10-8, EtOAc LC50=0.0015. Column chromatography and repeated PTLC on the bioactive crude extracts from Hexane, DCM, EtOAc and MeOH gave a white amorphous solid (EtOAc:MeOH, 7:3). Upon use of 1H NMR, 13C NMR, DEPT, HMBC and HSQC led to SUS 1 an oleanane tritepene, 1,2,3,4,4a,5,6a,7,8a,9,10,11,12,12a,13,13a,14,14a,14b-icosahydro-2,3,11,12,13apentahydroxy-4,4,6a,12,14b-pentamethyl-10-oxobenzo[α]tetracene-12a-carboxilic acid. A white amorphous solid (EtOAc:MeOH, 7:3). Another oleanane tritepenoid with a sugar moiety, 8a-acetyloctadecahydro-6b,8,12-tihydroxy-4,4,6a,11,12b,14b-hexamethyl-2(tetrahydroxo-3, 4, 5trihydroxy-6- (hydroxymethyl) - 2H- pyran - 2-yl oxy) picen - 6 (6aH, 6bH ,14Bh)-one, SUS 3 was also obtained as white crystalline solid (EtOAc:MeOH, 7:3). In addition, two common plant sterols were also isolated from Chloroform: EtOAc (1:1); 3β-stigmasterol, SUS 2 as white powder and 3β-sitosterol, SUS 4 as colourless needlike crystals. The results from this study provides a basis for further research in malaria control.
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    Phytochemical and Mosquito Larvicidal Studies Of Stachytarpheta Urticifolia (Sims
    (Kenyatta University, 2022) Agola, Faith Caroline; Alphonse W. Wafula; Ram Manohar
    Malaria is one of the most common and severe tropical diseases on the planet, transmitted by the Anopheles gambiae mosquito. Malaria affects more than 300 million people each year, according to the World Health Organization. Each year, these diseases are estimated to kill between 1.5 and 3 million people worldwide, with nearly 90 percent of all illnesses affecting pregnant women and children under the age of five. Chemotherapy, vaccine development, and vector control are currently used to prevent and control malaria. Vector management has been hailed as a critical tool in the fight against malaria transmission in light of the plasmodium species' increasing resistance to currently available antimalarial medications. Controlling mosquitoes during their larval stage is an additional effort made by humanity in an attempt to combat malaria. The use of natural compounds derived from plants to control the insect pests is a non-toxic and environmentally friendly strategy. Research has shown that compounds from the Vebenaceae family have been identified and shown to have larvicidal activity. The phytochemical and mosquito larvicidal properties of crude extracts and fractions derived from Stacytarpheta urticifolia, a member of the Vebenaceae family, were investigated in this work. The dry powdered stems of S. urticifolia were extracted using hexane, DCM, EtOAc and methanol for a total of 48 hours, with each extraction utilizing a different solvent. Phytochemical screening showed presence of terpenoids, alkaloids, tannins, steroids and flavonoids in the plant. For bioassay investigations, different concentrations of extracts were used. The larvicidal activity of the polar crude extracts was much greater than that of the non-polar extracts; MeOH LC50=0.08, Hexane LC50=10.59. The cytotoxicity tests also revealed that the EtOAc and methanol extracts were the more toxic to brine shrimp eggs; MeOH LC50= 6.48x10-8, EtOAc LC50=0.0015. Column chromatography and repeated PTLC on the bioactive crude extracts from Hexane, DCM, EtOAc and MeOH gave a white amorphous solid (EtOAc:MeOH, 7:3). Upon use of 1H NMR, 13C NMR, DEPT, HMBC and HSQC led to SUS 1 an oleanane tritepene, 1,2,3,4,4a,5,6a,7,8a,9,10,11,12,12a,13,13a,14,14a,14b-icosahydro-2,3,11,12,13a-pentahydroxy-4,4,6a,12,14b-pentamethyl-10-oxobenzo[α]tetracene-12a-carboxilic acid. A white amorphous solid (EtOAc:MeOH, 7:3). Another oleanane tritepenoid with a sugar moiety, 8a-acetyloctadecahydro-6b,8,12-tihydroxy-4,4,6a,11,12b,14b-hexamethyl-2-(tetrahydroxo-3, 4, 5trihydroxy-6- (hydroxymethyl) - 2H- pyran - 2-yl oxy) picen - 6 (6aH, 6bH ,14Bh)-one, SUS 3 was also obtained as white crystalline solid (EtOAc:MeOH, 7:3). In addition, two common plant sterols were also isolated from Chloroform: EtOAc (1:1); 3β-stigmasterol, SUS 2 as white powder and 3β-sitosterol, SUS 4 as colourless needlike crystals. The results from this study provides a basis for further research in malaria control
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    Cooking Effects on Folate and Ascorbic Acid Levels in Selected African Indigenous Vegetables from Githurai Market, Nairobi City County, Kenya
    (Kenyatta University, 2022) Mumbi, Janety; Ruth Wanjau; Jane Murungi
    Folate (vitamin B9,5-methyltetrahydrofolate) and ascorbic acid (AA) (vitamin C), play a key role in human health and wellbeing. It is greatly established that AA is beneficial in preventing scurvy while folate helps in the prevention of neural tube defects and congenital malformations. The main sources of these vitamins are fruits and vegetables and especially green leafy vegetables, including the African indigenous vegetables (AIVs). However, these vegetables are consumed after cooking which leads to loss of the vitamins through oxidation, thermal degradation and leaching. Main cooking methods in Kenya include boiling in unspecified amounts of water and discarding the boiling effluents leading to high nutrient loss. There is also the addition of additives such as bicarbonate of soda, lye (traditional salt), milk, cream, sesame and groundnuts paste whose effect on nutrient levels especially folate and AA levels in AIVs are yet to be explained, thus the need for investigation. The study aimed at determining the effect of different cooking methods on the retention of AA and folate in cowpea [Vigna Unguiculata (L.) Walp], saget (spider plant) [Cleome gynandra (L.)] and pumpkin leaves (Cucurbita moschata) as affected by different cooking methods. The vegetables were bought from Githurai market then sorted, prepared and cleaned using tap water then rinsed with distilled water on arrival in the laboratory. Both raw and cooked samples were analyzed. A portion of 100.000 g of the edible portion of vegetable samples including leaves and young shoots, was used in each of the cooking methods. During extraction, mortar and pestle were used to grind 10.000 g of sample then mixed with 50 mL of extraction solution containing; 20 mM KHCO3 (for vitamin B9 extraction) and 3 % Metaphosphoric acid, MPA, and 8 % acetic acid (for vitamin C extraction). The mixture was then filtered and put in a 100 mL volumetric flask and topped to the mark using the extraction solution. All samples were extracted in triplicates. Folate and AA were determined using high-pressure liquid chromatography with ultra-UV-visible detection, after extraction of the vitamins from raw and cooked samples. Analysis of Variance (ANOVA) was used to determine the difference in nutrient retention by various cooking methods. Significance was imputed at p<0.05. The AA and folate levels in raw vegetables ranged from 9.36±0.12 mg/100g to 60.28±0.32 mg/100 and 35.83±0.23 μg/100g to 258.08±0.58 μg/100g respectively. The cooked samples of the vegetables contained folate levels ranging from 15.59±0.19 μg/100g to 258.08±0.58 μg/100g. The AA mean concentration levels in cooked vegetables were found to be ranging from 1.36±0.02 mg/100g to 39.53±0.40 mg/100g. Therefore, it was determined that cooking the vegetable significantly reduced both folate and AA concentration compared to the raw vegetable samples, p<0.05. Steaming vegetables resulted in significantly higher retention of vitamins compared to other cooking methods. Significant losses of the vitamins were found in vegetables boiled in lye. Therefore, this study recommended that AIVs should be cooked by steaming which leads to higher retention of both folates and AA. The addition of lye and sodium bicarbonate should be avoided during the cooking of AIVs since they cause significant losses of vitamins. The results will be availed to relevant authorities and also used to sensitize vegetable consumers and cooks.
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    Adsorption of Selected Heavy Metals Using Modified Pennisetum Purpureum Plant Stalks: A Case Study of River Ruiru, Kiambu County, Kenya
    (Kenyatta University, 2022) Murage, Daniel; Eric Masika; Alphonse Wanyonyi
    Water pollution is a global problem affecting the welfare of humanity. Availability of clean water is a fundamental prerequisite to public health safety and the survival of the human race as well as animals. However, pollution of river water by heavy metal ions deposition is a grave ecological problem especially in developing countries. Previous research work on analysis of fish, soil sediments and water samples obtained from Nairobi and Ruiru river confirmed the presence of heavy metals. These metal ions which include lead, chromium, and iron are mainly from industrial effluents discharged into the rivers. Presence of the heavy metals in the water, pose a serious health risk particularly to rural populations which rely majorly on the river water for domestic purposes. Several methods for elimination of the heavy metal pollutants from river waters have been previously employed. However, most of these methods have proved to be expensive and cumbersome, hence not sustainable. Simpler methods are, therefore, needed for better sustainability. This research explored the potential of modified Pennisetum purpureum plant adsorbent in eradication of lead (II), manganese (II) and chromium (VI) ions from Ruiru river water by adsorption process. Sampling was done at three different locations along the river, that is, Ruiru Town, Juja Farm and Fourteen Falls. The mean concentration of heavy metal ions was determined before and after the adsorption process in triplicates using Atomic Absorption Spectroscopy (AAS). Effect of changes in pH on adsorption was investigated by conducting adsorption at pH of 5, 7 and 9. Data was organized in excel worksheets before it was transferred into SPSS software for analysis. The results show high chromium and lead pollution of the Ruiru river. Average concentrations of chromium and lead were 1.495±0.09 ppm and 1.610±0.1 ppm respectively. Average Manganese levels were 0.05±0.01 ppm which was within the permissible level (0.5 ppm). Modification of the adsorbent surface improved its adsorption capacity. The modified adsorbent achieved greater % adsorption in all the three metals. Increase in the pH of adsorption from 5 to 9 had a reducing effect on the percent adsorption of metal ions from water samples with significant reductions in % adsorption being recorded for lead and manganese ions but not for chromium ions. These results show the potential of the Pennisetum purpureum plant in the purification and detoxification of river water by adsorption. This adsorbent presents a more readily alternative to many current adsorbents and adsorption methods in use. However further research is needed to ascertain the best set of conditions as well as the most suitable modification treatment for maximum adsorption.
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    Antimicrobial Activities and Bioassay Guided Identification of Bioactive Constituents of Selected Kenyan Medicinal Plants
    (Kenyatta University, 2022) Kagika, Mary Wanjiku; Sumesh Chander Chhabra
    The relationship between man and plants has been very close in almost all generations. Egyptians, around 1500 B.C. discovered that oil from beans of castor tree would bring relief when applied to burns and septic wounds. In this study the focus was to investigate the potential of Trimeria grandifolia (Hochst.) Warb Flacourtiaceae and Capparis fascicularis DC. ( Cappaaraceae used traditionally to manage microbial infections. This is due to the current infectious disease burden and the increasing rate of antimicrobial resistance to existing antibiotics. This creates the need to look for alternative antimicrobials in which pathogens have lower or no resistance. The study aimed to carry out antimicrobial activities of the constituents of different parts of T. grandifolia and C. f ascicularis and characterize the most active constituent. Leaves, root bark and stem bark of the two plants were sampled from Nyandarua County in Kenya, dried, ground and sequentially extracted using solvents of increasing polarity petroleum ether, ethyl acetate, methanol and water )). Twenty four extracts were obtained, screened against selected strains of bacteria and fungus Staphylococcus aureus, Bacillus subtilis, Salmonella typhi, Escherichia coli and Candida albicans respectively) using disc diffusion and tube dilution methods. The results were analysed by analysis of variance (ANOVA). The ethyl acetate extract of C. fascicularis root bark (CFR2) showed a significant inhibition against S. aureus, B. subtilis and S. typhi, compared to those extracted using other solvents (F = 18.84, P = 0.0001, F= 18.84, P = 0.0001 and F = 9.27, P = 0.0001 respectively). Minimum inhibitory concentration (MIC) of CFR2 against S. tyhpi and B. subtilis was at 500 μg/mL (F = 14.38, P = 0.0001) and 250 μg/mL (F = 4.82, P = 0.0001) respectively, which was significantly lower than other concentrations of plant extract. Therefore, CFR2 was considered the most active crude extract. Fractionation of CFR2 by column chromatography yielded s even fractions that were screened against t he selected bacterial strains. Fraction 2 (F2), had the lowest MIC values and was considered the most active fraction It inhibited B. subtilis , E. coli and S. typhi at 250 μg/mL (F = 14.38, P = 0.0001), 500 μg/mL (F = 3.23, P = 0.003) and 500 μg/mL (F = 6.58, P = 0.0001) respectively. F2 was further fractionated and four sub fractions obtained . They were screened against the selected strains of bacteria. However, F2 (mean= 13.250 mm) was the most bioactive fraction compared to the four sub-fractions (F = 66.79, P = 0.0001). This suggested that, constituents of F2 worked in synergy. F 2 was then s creened for phytochemicals where p henols, ter penes and flavonoids were present . In addition, F2 was analysed by GC MS T wo bioactive compounds were identified as , 2,4-Di-tert-butylphenol (14) and (E,E) -2,4-Decadienal (18) . F 2 was also analysed by LC ESI MS and three reported bioactive compounds wer e identified as Tanshinone II A (21), Cryptotanshinone (22) and Danshensu (23). Better antimicrobial activities were displayed in C. fascicularis compared to T. grandifolia . CFR2 was the most active extract on bacteria and this suggested that m ost antimicrobial compounds are concentrated i n the roots of C. fascicularis . Therefore, we recommend that further chromatographic separation be done to obtain all the chemical constituents and screen them against various strains of bacteria and fungi, t oxicity studies of isolated compounds from T. grandifolia and C. fascicularis be carried out to determine their efficacy, blending and structure-activity relationships of isolated compounds with known antifungal and antibacterial drugs be carried out in order to determine if there is synergy or antagonism and derivitization of the isolated compounds be done so as to improve their bioactivity.
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    Repellency and Toxicity of Commiphora Africana Resin Extract and It’s Constituents against Cimex Lectularius and Characterization of its Active Constituents
    (Kenyatta University, 2022) Wairagu, Norman Wachira; Margaret Mwihaki Ng’ang’a; Ahmed Hassanali
    Bedbugs (Cimex lectularius Linnaeus) pose a great menace in many homes, hotels, public transport and institutions where they obtain blood meal from humans, chicken and domesticated animals. They cause physical and mental problems to the affected humans, on heavy and frequent feeding on the host leading to anemia. Bedbug control has not been successful due to their resistance to conventional insecticides, environmental pollution of the insecticides and the high costs involved. There is need to explore natural herbal-based insect control phytochemicals in control methods due to their environmental friendliness as compared to synthetic pesticides. Commiphora africana (A. Rich.) Engl. resin has been used traditionally to control blood-feeding insects and other arthropods such as lice, bedbugs, fleas, honey beetles and ticks. This research sought to extract bioactive compound(s) from C. africana resin, evaluate the repellency and toxicity of the extracts/compounds/selected blends against bedbugs. The isolated compounds were characterized using conventional spectroscopic techniques. The resin was tapped from the stem of mature C. africana trees in their natural habitat. The plant resin was extracted with H2O and in a separate set up sequentially extracted with CH3(CH2)4CH3, CH2Cl2, EtOAc and MeOH. The extracts were evaluated for insecticidal activity against C. lectularius. The CH2Cl2 crude extract proved to be the most effective against bedbugs with mean repellency of 98.5% and LC50 of 4.96 mg/L after 24- and 72- hrs exposure respectively. The extract was subjected to chromatographic separation and purification where the eluents (fractions) were evaluated at different doses for repellency and toxicity against bedbugs. The most active chromatographic fraction against bedbugs was analyzed by Gas Chromatography Mass Spectrometry (GC-MS) and identified 20 compounds in the class of esters, carboxylic acids, alkanes, alkenes, heterocyclics, aromatics, alcohols, amine and alkyne. Among the identified compounds, cedrol and citronellyl formate had significantly (p < 0.05) higher mean repellency (80.5% and 77.0% respectively after six hours of exposure) and toxicity (27.43 and 37.01 mg/L respectively after 24 hours exposure) against bedbugs than the rest. Selected blends of these compounds showed synergistic repellency and toxicity effects as compared to individual compounds. A six-constituent blend comprising of 9-octadecenoic acid, ethyl ester + octadecadien-1-ol + citronellyl formate + cedrol + hexadecanoic acid + 1,2-dihydro-6-methoxy-Naphthalene had the highest mean repellency (93.4 ± 6.61 % after 12 hours exposure) and toxicity (8.83 mg/L after 72 hours exposure) against bedbugs. The isolation of compounds from the CH2Cl2 resin crude extract gave five triterpenoid compounds (taraxasterol, pseudo-taraxasterol, beta-sitosterol, fungisterol and guggulsterol) which were characterized by conventional spectroscopic techniques and evaluated for repellency and toxicity against bedbugs. Fungisterol showed highest mean repellency (100%) and toxicity (14.40 mg/L) after 12 and 72 hours of exposure respectively. This study proves that the resin of C. africana contains compounds that can be used as an insecticide in bedbug control.
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    Physical and Chemical Integrity of Long Lasting Insecticidal Nets (Llins) Used in Control of Malaria Vector in Kirinyaga County, Kenya
    (Kenyatta University, 2022) Wanjiku, Nyangi Mary Sofia; Margaret Mwihaki Ng’ang’a; Elizabeth Mumbi Kigondu; Beatrice Njeri Irungu
    The use of treated nets specifically long-lasting insecticidal nets (LLINs) has greatly reduced morbidity and mortality due to malaria. Mosquito is the vector which is responsible for malaria transmission. One of the most effective strategies of controlling the vector is the use of treated nets by majority in a community in malaria prone areas. In order to achieve a high coverage of households with the treated nets, free mass net distribution was introduced in all malaria endemic areas in Africa by the World Health Organisation. In Kenya the first free mass net distribution was carried out in the year 2006 and there after every five years. Washing of the nets causes a decline in chemical efficacy of nets. Due to this factor, both physical integrity and insecticidal concentration of distributed nets in Kirinyaga County, Kenya was assessed. The study was carried out on an area which had received treated nets from the Ministry of Health, during the 2016 mass net distribution. Most studies that have been carried out in the area focused on the rate of net survival but little is known about the physical state and chemical content of LLINs after their distribution. The objective of the study was to evaluate use, care, physical and chemical integrity of the distributed long-lasting insecticidal nets used in control of malaria in Kirinyaga County. A total of 420 households were systematically sampled with a random start, and consent to participate in the study was sought from the household heads/spouses. A structured questionnaire assessed use, care and physical integrity while chemical content of the LLINs was analysed in the laboratory by gas chromatography mass spectroscopy (GCMS). Data was analysed using Statistical Package for Social Sciences (SPSS) version 19. Eighteen months after the November 2016 nets distribution 97.9% (95% CI: 96.4% – 99.3%) of the distributed nets were still present. Regarding the net utilization, 94.1% of household heads reported sleeping under an LLIN the previous night. On visual examination of the nets, 49.9% (95% CI: 43% - 52.8%) of the nets had at least one hole. The median number of holes of any size was 2 [inter-quartile range (IQR) 1-4], with most holes located on the lower parts of a net, [median 3 (IQR 2-5)]. Of the nets with holes, only 15% had been repaired. The mean insecticidal content for baseline nets was 40.38 ± 0.86 mg/g and 9.05 ± 2.13 mg/g for α-cypermethrin and permethrin treated nets respectively. The mean concentration of sample nets was 16.29 ± 4.08 and 1.55 ± 0.41 mg/g for α-cypermethrin and permethrin treated nets respectively. Based on proportionate hole index Chi-square test results show that net physical integrity varied significantly with the manufacturer (X (6, N = 389) = 29.124, p < 0.05). The proportion of households with good LLINs was 69% .There was no association between the extent of net damage and the location (X (2, n = 336) = 40.42, p > 0.05). There was no notable difference in mean concentration of insecticide remaining between α-cypermethrin (X2 (2) = 3.83, p > 0.05) and permethrin (X2 (2) = 4.55, p > 0.05) in nets with different number of washes. The mean concentrations of α-cypermethrin and permethrin were significantly lower than the manufacturer’s label claim, and a significant difference in physical integrity of LLINs from different manufacturers was observed (X (6, N = 389) = 29.124, p < 0.05).
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    Determination of Arsenic Concentration and Contamination Factor in Water from Selected Boreholes in Nairobi City County, Kenya
    (Kenyatta University, 2022) Kiplangat, S. Alice; Wilson Njue; Lucy Kiruri
    Arsenic is a metalloid, which may be found in surface water, ground water, plants and rocks. In high concentrations, its compounds are considered to be genotoxic and carcinogenic. Arsenic enriched minerals and bearing rocks have been the chief source of arsenic (As) in the ground water. Anthropogenic activities such as improper waste disposal and landfill, excessive use of fertilizers, pesticides and herbicides has also contaminated the groundwater quality to a larger extent. In Nairobi City County, there has been increased number of drilled water boreholes “in thousands,” to meet the demand of the scarcity of water resources. However, there is a high possibility of having some of these boreholes in contaminated sites. Thus there is increased concern on the safety and quality of these borehole water due to possible contamination with toxic heavy metals such as mercury, cadmium and in particular arsenic. The objective of study was to determine the concentration and contamination factor of arsenic in water from selected boreholes in Nairobi City, County. Water was randomly sampled from a total of sixty three (n-63) boreholes in five (5) zones (Central, Eastern, Northern, Western and Southern) during the dry and wet seasons. The arsenic was analyzed by Hydride Generation Atomic Absorption Spectrometer (HG-AAS). The results showed that the arsenic content in borehole water during the dry and wet seasons ranged from 0.00455 0.0022 - 0.01007 0.0060 and 0.002057±0.0008 0.00744±0.0051 mg/L respectively . There was a significant difference (P˂0.05) in arsenic content in borehole water samples in Central zone compared to the other zones. The a rsenic content in water from ten bor eholes (16 %%) during the dry season and four boreholes (6%) during the wet season was found to be above the WHO recomm ended and NEMA regulatory limit of 0.01 mg/L. During the dry season, the calculated contamination factor (CF) for the borehole water ranged from moderately contaminated to very severely contaminated (CF 0.26 – 1.0). On the other hand during the wet season, it ranged from slightly contaminated to severely contaminated (CF 0.10 - 0.74). Therefore, the borehole water for domestic purposes requires monitoring in order to mitigate the effect on human health.
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    Customized Potassium Foliar Feed for Optimum Yield of Maize (Zea Mays L) in Nyeri County, Kenya
    (Kenyatta University, 2022) Mutahi, Wachira Samuel; Harun Mbatha Mbuvi; Eric Masika
    In Kenya, Maize is a very vital cereal crop and a major staple food to many Kenyan families. Majority of farmers apply Nitrogenous and Phosphorous fertilizers to boost maize productivity in the country and Nyeri County in particular. Despite all this, acreage yield has been declining. Potassium (K) and micro nutrients fertilizers application in this region is limited yet potassium is required by maize in large quantities. There is also limited report on foliar feed application in this region. This study aimed at determining the nutrients levels in various farm soils of more intensive agricultural areas of Nyeri County in Kenya and formulates a customized potassium foliar feed. Grid sampling technique was used in soil sampling. Four farms under intensive cultivation were selected for the study. Customized Potassium Foliar feed was formulated and analyzed. Maize was grown in 12 plots of 5m by 5m with spacing of 50cm between the adjacent plots at each of the 4 selected farm sites. The 12 plots received the same N and P basal fertilizer dosage of 70kg/ha. In addition, 3 plots in each farm received commercial foliar feed (20mg/l), 3 plots received half dosage (10mg/l) of customized K foliar feed while the other 3 plots received a full dosage (20mg/l) of customized K foliar feed while the other 3 plots were used as control. Plant height, stem girth, length of leaf and grains yields were compared with the treatment applied. Soil analysis found that the total nitrogen ranged between 0.06- 0.06% as opposed to the recommended level of 0.25%, phosphorous levels ranged between 1.6-1.9mg/L below the recommended value of 10mg/L. The available Potassium had a mean of 7.76±1.10 mg/L; Calcium and Magnesium had a mean value of 6.28±0.16mg/L and 10.164±0.19 mg/L respectively. However, these levels are below the recommended values of 160 mg/L, 15mg/L and 25mg/L respectively. The study also indicated micro nutrients were. Micro nutrients such as Zn(0.14±0.06mg/L),Cu(0.15±0.01mg/L),Fe(0.11±0.03mg/L) and Mn (0.10±0.03mg/L), as opposed to the recommended critical values of 5mg/L, 5mg/L, 6mg/L and 2mg/L respectively. Customized K foliar feed contained nutrients such as Potassium, Phosphorous, Nitrogen, Magnesium and Calcium with concentration level of 13±0.13mg/L, 6.64±1.02mg/L, 0.75±0.001%, 6.19±0.18 mg/L, and 23.94±1.10 mg/L respectively. In addition, levels of zinc, copper, iron and manganese were determined. These nutrients registered 0.15±0.05mg/L, 0.66±0.008 mg/L, 0.34±0.18 mg/L and 0.46±0.003 mg/L respectively. The data obtained from the study found that farms treated with full dose customized K foliar feed fertilizer had increased plant height (45.5±42.23 %), ear length (76.7±21.05 %), stem girth (44.4±15.63 %) and maize yields (132.4±23.92%). Thus, the study established that customized foliar feed significantly improved the maize yield in the region. There is need to supplement nutrients to the soil for optimum yield of maize. Farmers and policy makers should put a lot of efforts to correct the soil nutrients deficiency by applying 20mg/l of customized K foliar feed for optimum yield of maize in this region.
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    Antimicrobial Activities and Bioassay Guided Identification of Bioactive Constituents of Selected Kenyan Medicinal Plants
    (Kenyatta University, 2021) Kagika, Mary Wanjiku; Sumesh Chander Chhabra; James Nonoh
    The relationship between man and plants has been very close in almost all generations. Egyptians, around 1500 B.C. discovered that oil from beans of castor tree would bring relief when applied to burns and septic wounds. In this study the focus was to investigate the potential of Trimeria grandifolia (Hochst.) Warb (Flacourtiaceae) and Capparis fascicularis DC. (Cappaaraceae) used traditionally to manage microbial infections. This is due to the current infectious disease burden and the increasing rate of antimicrobial resistance to existing antibiotics. This creates the need to look for alternative antimicrobials in which pathogens have lower or no resistance. The study aimed to carry out antimicrobial activities of the constituents of different parts of T. grandifolia and C. fascicularis and characterize the most active constituent. Leaves, root bark and stem bark of the two plants were sampled from Nyandarua County in Kenya, dried, ground and sequentially extracted using solvents of increasing polarity (petroleum ether, ethyl acetate, methanol and water). Twenty-four extracts were obtained, screened against selected strains of bacteria and fungus (Staphylococcus aureus, Bacillus subtilis, Salmonella typhi, Escherichia coli and Candida albicans respectively) using disc diffusion and tube dilution methods. The results were analysed by analysis of variance (ANOVA). The ethyl acetate extract of C. fascicularis root bark (CFR2) showed a significant inhibition against S. aureus, B. subtilis and S. typhi, compared to those extracted using other solvents (F = 18.84, P = 0.0001, F= 18.84, P = 0.0001 and F = 9.27, P = 0.0001 respectively). Minimum inhibitory concentration (MIC) of CFR2 against S. tyhpi and B. subtilis was at 500 µg/mL (F = 14.38, P = 0.0001) and 250 µg/mL (F = 4.82, P = 0.0001) respectively, which was significantly lower than other concentrations of plant extract. Therefore, CFR2 was considered the most active crude extract. Fractionation of CFR2 by column chromatography yielded seven fractions that were screened against the selected bacterial strains. Fraction 2 (F2), had the lowest MIC values and was considered the most active fraction. It inhibited B. subtilis, E. coli and S. typhi at 250 μg/mL (F = 14.38, P = 0.0001), 500 µg/mL (F = 3.23, P = 0.003) and 500 μg/mL (F = 6.58, P = 0.0001) respectively. F2 was further fractionated and four sub-fractions obtained. They were screened against the selected strains of bacteria. However, F2 (mean= 13.250 mm) was the most bioactive fraction compared to the four sub-fractions (F = 66.79, P = 0.0001). This suggested that, constituents of F2 worked in synergy. F2 was then screened for phytochemicals where phenols, terpenes and flavonoids were present. In addition, F2 was analysed by GC-MS. Two bioactive compounds were identified as, 2,4-Di-tert-butylphenol (14) and (E,E) -2,4-Decadienal (18) . F2 was also analysed by LC-ESI-MS and three reported bioactive compounds were identified as Tanshinone II A (21), Cryptotanshinone (22) and Danshensu (23). Better antimicrobial activities were displayed in C. fascicularis compared to T. grandifolia. CFR2 was the most active extract on bacteria and this suggested that most antimicrobial compounds are concentrated in the roots of C. fascicularis. Therefore, we recommend that further chromatographic separation be done to obtain all the chemical constituents and screen them against various strains of bacteria and fungi, toxicity studies of isolated compounds from T. grandifolia and C. fascicularis be carried out to determine their efficacy, blending and structure-activity relationships of isolated compounds with known antifungal and antibacterial drugs be carried out in order to determine if there is synergy or antagonism and derivitization of the isolated compounds be done so as to improve their bioactivity.
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    Determination of Physicochemical Properties of Sisal Honey from Taita Taveta County Kenya
    (Kenyatta University, 2021) Otieno, Linah Anyango; Robert M. Bichanga; Harun Mbatha Mbuvi
    Taita Taveta County hosts the largest sisal estates in the Kenyan coast and therefore has a high potential of sisal honey production. While most unifloral honeys such as acacia, citrus and eucalyptus have been characterized and hence their quality is known, no characterization has been done on sisal honey to determine its quality. This has therefore affected its marketing both inside and outside the country. The aim of this study was therefore to characterize sisal honey from Taita Taveta County in response to concerns raised by local consumers by ascertaining its quality according to the international honey standards set by Codex Alimentaruis which specify the acceptable limits for some of the physicochemical properties of honey. In this study, systematic sampling was used to collect 35 honey samples from four locations of Taita Taveta: Mwatunge, Landis, Kamtonga and Voi. The experimental procedures used to analyse physicochemical properties of honey samples followed the harmonized methods by the International Honey Commission. The results showed that the average Moisture content was, 19.62± 0.10%; Refractive index, 1.4877± 0.008; ash content 0.1512 ± 0.0087%; free acidity, 22.82± 1.28 mEqKg; pH, 4.293± 0.02; density 1.4083± 0.069 g/cm3; HMF, 15.223 ± 4.125 mg/Kg; Proline content 355.29 ±4.125 mg/Kg; Fructose, 40.19±1.9 g/100g; Glucose, 29.56 ± 4.60 g/100g; Sucrose, 3.36±1.34g/100g. The minerals found were K, 32.17 ± 1.28 mg/L; Ca, 0.8947± 0.32 mg/L and Zn 0.835± 0.354 mg/L. These values fulfilled the standards set by the Codex Alimentaruis commission. When the means of parameters of the four locations analysed using Anova (p= 0.05) were compared, no significant differences were noted in the means of all parameters except electrical conductivity. The results of this study indicate that sisal honey has good quality since it met the physicochemical specifications of Codex Alimentaruis. The data obtained from this study is not only important for the commercialization of sisal honey for both local and international honey market but can also be used as a guide to characterization of sisal honey in other parts of the world.
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    Physical and Chemical Characterization of Freshly Harvested and Factory-Processed Mangrove Honey from Kilifi County, Kenya
    (Kenyatta University, 2021) Kwamboka, Omori Nancy; Evans Changamu Ogwagwa; Robert M. Bichanga
    Mangrove honey from the mangrove forests at the Kenyan coastal region has been in production at the commercial level by beekeepers organized and registered in self-help groups for more than a decade now. The honey is said to have medicinal properties but it has not been fully characterized to determine whether it meets the Kenyan standards on Honey – Specification (KS EAS 36:2020), European Union (EU) Directive on Honey (2001/110/EC) and International Honey Commission (2009). The objective of this study was, therefore, to characterize Kenyan mangrove honey in terms of its physicochemical properties and volatile organic compounds present. It was also important to correlate the honey VOC profiles with the mangrove tree flowers extract profiles. Unprocessed honey sampling was done from selected beekeepers from the four mangrove forest regions of Kilifi County, namely, Mida, Kilifi, Watamu and Mtwapa creeks while processed honey samples were obtained from Kwetu Training Centre. Twenty (20) honey samples weighing approximately 250 g each were collected randomly from farmers and factory in different locations in Kilifi County, packed in 500 cm3 plastic bottles, ferried for refrigeration in the lab at a temperature of 4o C. Mangrove flower volatile organic compounds (VOCs) were collected by static headspace solid phase microextraction (HS-SPME) fiber while collection of VOCs in honey samples was done by ultrasound-assisted solvent extraction (USE) method. Mangrove honey was analyzed for moisture content (by refractometry), colour index, diastase, proline and hydroxymethylfurfural (by spectrophotometry), pH and electrical conductivity (by pH/conductivity meters), free acidity (by titrimetry), sugar content (high performance liquid chromatography) and volatile organic compounds (by GC-MS). Quantitative data was analyzed using the SPSS program version 21. The results showed that the mean moisture content ranged from 23.40±0.00 to 19.23±0.06%, mean pH from 4.45±0.05 to 4.00±0.00, mean electrical conductivity ranged from 0.54±0.00 to 0.32±0.00 MS/cm. The mean acidity ranged from 30.21±0.15 to 22.20±0.00 Meq/kg. The mean proline content ranged from 734.36±4.23 to 602.24±2.68 mg/kg. The mean HMF levels were in the range of 2.86±0.14 to 0 mg/kg. The mean invertase content ranged from 9.55±0.10 to 5.54±0.11 U/kg. The mean diastase content ranged from 11.48.47±0.06 to 8.11±0.64 S/units. In the VOCs profile of mangrove flower, factory and farm, 119, 90 and 70compounds were identified, respectively. Of the identified VOCs, 35 were found both in the honeys analyzed and in mangrove flower. Three compounds docosanoic acid, palmitoleic acid and n-hexadecanoic were found in large quantities in all samples analyzed and the mangrove flowers and can be considered to be chemical markers for mangrove honey. The HMF, diastase and invertase were found to be below the set limits suggesting that the mangrove honey studied was fresh and had not been heated by farmers during harvesting and extraction. The high proline content also revealed that nectar and pollen are produced in great quantities by mangrove plants. The rest of the physicochemical parameters were found to be within the limits set by the International Honey Commission, Codex Alimentarius and the Kenya bureau of standards (through the EAS).
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    Kinetic, Equilibrium and Thermodynamic Adsorption Studies of Selected Heavy Metal Ions by Raw and Modified Jackfruit Seeds from Aqueous Media
    (Kenyatta University, 2021) Ng’ang’a, Ndung’u Samuel; Ruth N. Wanjau; Esther W. Nthiga
    Consumption of water contaminated with heavy metal ions compromise human and animal wellbeing even at permissible limits. Therefore, their removal from water is very important for the safety of consumers. Previously used conventional water treatment techniques were expensive and ineffective. Among them, adsorption has gained research interest because of its ease in design, environmentally friendly and availability of materials in large quantities, especially from agricultural wastes. Several chemical modification techniques are reported to have improved adsorbents removal capacity, including the use of modifying agents such as ethylene -1, 2- diamine. In this study, ethylene- 1, 2- diamine modified Jackfruit (Artocarpus heterophyllus Lam.) seeds were used. The raw adsorbent was chemically modified using thionyl chloride and ethylene -1, 2- diamine. Both raw and modified adsorbent were characterized using a Fourier transform infrared spectrophotometer (FT-IR) then employed in batch optimization, kinetic and thermodynamic adsorption experiments. The FT-IR results showed functional groups of hydroxyl (-OH), carbonyl (-C=O), carboxylate (-COO-) (raw adsorbent) and additional anchored amine (-NH2) groups (modified adsorbent) as important adsorption sites for metal ions removal. Batch results maximum adsorption capacity at optimal pH < 6.5; 20 minutes (raw) and 15 minutes (modified); optimal speed (150 rpm - 175 rpm), dosage (10 mg – 15 mg), temperature (310 K) and 30 mg/L. Adsorption of the three metal ions fitted Langmuir isotherm model (R2 > 0.98) with adsorption capacities in Pb2+ > Cu2+ > Cd2+ order. Kinetic data fitted pseudo-second-order (R2 > 0.91) which was more suitable in explaining the adsorption rate. Thermodynamic data showed that Gibb’s free energy (ΔG°) values for all metal ions were negative indicating feasibility and favorability of adsorption. Positive entropy change (ΔS°), enthalpy change (ΔH°) and activation energy (E𝑎) values which were > 40 kJ/mol and very low sticking probability (S*) values confirmed that chemisorption predominated adsorption of ions. The results showed good performance of modified Jackfruit seeds as a potential adsorbent for Cu2+, Pb2+ and Cd2+ ions removal from contaminated water. The study, therefore, recommends sachets of the modified adsorbent be made for water purification at the household level and also to scale up the applicability of the adsorbent to a pilot plant to cater for many communities considering its shelve life and regeneration.
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    Peanut Husks Functionalized with Citric Acid and Ethylene -1, 2-Diamine for Removal of Lead (Ii) Ions from Contaminated Water
    (Kenyatta University, 2021) Minda, Stephen; Harun Mbatha Mbuvi; Margaret Mwihaki Ng'ang'a
    Consumption of water contaminated with heavy metals poses a major risk. Consequently, safe and effective treatment of contaminated water remains a topic of global concern. Lead is among the most prevalent heavy metal contaminants as it is widely used in metallic form. It is easily absorbed by the body through water intake. In body, lead inhibits the enzymes and induces generation of reactive oxygen species that intensifies oxidative stress. This mechanism makes lead neurotoxic, mutagenic, teratogenic and carcinogenic. Studies reveal that some parts of Tanzania have higher levels of lead than the recommended level by World Health Organization and East African Community of 0.01mg/L in drinking water. Although several water treatment methods are available, adsorption offers an attractive method for the removal of heavy metal in terms of cost of adsorbent production, simplicity of design and operation. Cellulose-carboxylate ion and 6-(2-aminoethylamino)-6-deoxycellulose (or called celen) are thermally stable and can be easily employed for the adsorption of cations from aqueous medium. Hence, this study was aimed at modifying the peanut husks with citric acid and ethylene-1,2-diamine to synthesize cellulose-carboxylate ion and celen respectively to determine the adsorption capacity and efficiency in the removal of Pb(II) ion from contaminated water. Peanut husks were collected from Dodoma region in Tanzania, washed, ground and modified with citric acid and ethylene-1,2- diamine to prepare adsorbents. FTIR confirmed the peanut husks to contain cellulose and that the citric acid and ethylene-1,2-diamine are anchored onto the cellulose. XRF revealed that the peanut husks contained zero percent of Pb metal and XRD proved the amorphous nature of the cellulose present in peanut husks. Batch experiments were carried out to determine the effect of pH, contact time, temperature, initial concentration and adsorbent dose on adsorption process. The experimental data were fitted in Langmuir and Freundlich isotherms and were found to fit best in Langmuir isotherm as it had the highest value of correlation coefficient of 0.998, 0.959 and 0.997 for UMP, CMP and EMP respectively. The maximum monolayer adsorption capacities were 18.8 mg/g for UMP, 11.36mg/g for CMP and 19.23mg/g for EMP. Based on the adsorption capacities, EMP is a better adsorbent than the rest. These results indicate that peanut husks tethered with citric acid and ethylene-1,2-diamine constitute a promising material for the development of an adsorption technology for the removal of Pb(II) ion from aqueous systems.
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    Derivatization and Cross-Linking of Papyrus Reed for Use as Super Absorbent Mulch Substrate
    (Kenyatta University, 2021) Mwihaki, Josephine E.; Harun M. Mbuvi; Margaret Mwihaki Nganga
    Water is vital for the life and survival of plants. It is essential for transportation of plant nutrients from the soil; it maintains the plant posture and serves as a raw material for various chemical processes like photosynthesis, transpiration, as well as buffer the plant against wide temperature fluctuations. Lack of enough water to crops may lead to wilting and eventually death, some farmers have resulted to irrigation and mulching with plant remains and inorganic materials which lose water quickly. The study of application of hydrogel in agriculture is an area which has not been adequately empirically examined particularly in the African agricultural setup. Even though papyrus reeds have been found to have the ability to absorb and retain substantial amount of water, the study explores whether the papyrus reeds could retain more water when modified. The study, therefore, sought to enhance water retention of papyrus reed fibers through appropriate derivatization with ethylene diamine and phosphoric acid which was then cross-linked by the use of citric acid and urea respectively and it was then used as a mulching agent. The derivatized mulch was characterized by the use of Fourier Transform Infra-Red spectroscopy (FTIR) and Scanning Electron Microscopy (SEM); the swelling ratio was also calculated from the data collected from the laboratory. The modified mulch was applied in the field to evaluate the growth and yield parameters for growing kales and spinach. The FTIR peaks were observed for P-H at 2318 cm-1stretching vibration mode, P-OH at 788.90 cm-1stretching vibration mode of the phosphoric group, N-H at 3246.25 cm-1 bending vibration of primary amines, C-N at 1382 cm-1 stretching vibration mode, C-O at 875 cm-1 stretching and C=O at 1735 cm-1 stretching was attributed to a carboxyl group. The SEM images showed increase in the number of crevices and pores on the surface of the derivatized and cross-linked papyrus reed. The phosphate derivative absorbed 12 times its original weight while the ethylene diamine derivative absorbed 6.6 times its weight. The phosphate mulch with urea crosslink was the most optimal hence used for the field experiments. The cross-linked mulch had significantly higher yields of kales and spinach in terms of weight, where spinach had a mean of 2 kg, a mean length of 27.8 cm, mean width of 9.96 cm and a mean of 4 leaves. Kales grown with cross-linked mulch had a mean weight of 1.9 kg, a mean length of 24 cm, a mean width of 10.7 cm and a mean of 4 leaves. The study results conclude that modified papyrus mulch preserves more water; it is biodegradable, leads to high yield and helps to save labor and water by reducing frequency of irrigation. Based on the results of this study, it is recommended that the modified mulch be used in arid and semi-arid areas after the cost benefit analysis is done.