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Kamau JM, Mbui DN, Mwaniki JM, Mwaura FB. "Application of microbial fuel cells in the degradation of 2, 4, 5, 6-tetrachloroisophthalonitrile (chlorothalonil)." Journal of Bioscience and Biotechnology Discovery. 2019;4(2):28-35. Abstract

Pesticide’s persistence in the environment due to the relatively slow degradation mechanism leads to their bio-accumulation which in turn has adverse impacts on human health. Bio-remediation involves utilization of microbes from nature to the breakdown of organic molecules. The purpose of this study is to investigate the potential of microbes in degrading chlorothalonil. Aerobic-anaerobic combined conditions in an H-shaped double chamber microbial fuel cell (MFC) were employed for the breakdown of chlorothalonil. Decomposing tomatoes were used as the major substrate with their proximate properties being analyzed using standard method. Glucose loaded with different concentrations of chlorothalonil was introduced to the cells on day 10 when voltage production had stabilized. The voltage and current generated were monitored using a digital multi-meter while pesticide concentrations were obtained using a UV-Vis spectrophotometer. The highest voltage readings were obtained on day 9 of degradation, with values ranging from 0.463 to 0.537 V. The current ranged from 0.002 to 0.076 mA. Higher voltage and current values were recorded in solutions with lower pesticide concentration. The obtained degradation level was highest in 10 g glucose at 95.95 and 98.75% for day 10 and 20 respectively. The lowest breakdown was observed in the cells without glucose at 10.54 and 31.04% on day 10 and 20 respectively. The results demonstrate that MFC technology can be employed in mineralization of chlorinated pesticides as an alternative for incineration and photo-degradation.

Kamau JM, Mbui DN, Mwaura FB. "Utilization of rumen fluid in production of bio–energy from market waste using microbial fuel cells technology." J Appl Biotechnol Bioeng. 2018;5(4):227-231. Abstract

Environmental Protection Agency classifies slaughter house waste as one of the most toxic environmental pollutants due to high pathogen content. Composting and anaerobic digestion are among the most common methods used for its disposal. In this study, utilization of rumen fluid as bio–catalyst in microbial fuel cells is investigated. Different market wastes were converted to electricity by loading them in anodic anaerobic chamber and then adding rumen fluid from Dagoretti slaughterhouse. 0.584 V was obtained on day 19 from avocado fruit waste while the maximum voltage for tomato waste was 0.701 V on day 20. Water melon and fruits mixture produced the least voltage. The maximum power from the tested substrate was obtained from tomato wastes. The power and current density were in the range of 1.825 to 60.041 mW/m2 and 6.762 and 99.174 mA/m2 respectively for tomato wastes. A maximum voltage of 0.584 V was obtained from tomato wastes when 500ml rumen fluid was used while 0.248 Vwas obtained for avocado fruit waste with the same amount of rumen fluid. Electrode surface area of 0.006666 m2 gave the highest voltage and power amongst 0.00399 m2 and 0.01331 m2. When the influence of external resistors was investigated, power, voltage and current obtained across a 45kΩ were 0.385 V, 0.038 Ma and 0.01463 mW on day 7 respectively for tomato wastes.

Kamau JM, Mbui DN, Mwaniki JM, Mwaura FB. "Cow Dung to Kilo Watt using Double Chamber Microbial Fuel Cell." IJSRSET. 2017;3(5):70-79. Abstract

In the current study, voltage is generated from cow waste at varying time duration of 6 to 11 days. PVC pipe was used to make a salt bridge using agarose and potassium chloride and Sodium chloride. The performance of microbial fuel cells was evaluated by characterizing the generated voltage, current, power and surface power density. It was observed that despite the high impedance of the substrate, all the generated parameters have shown maximum values at day 6 and then a decline in trend was observed on 7 days onwards. The highest values of voltage, current, power, current density and power density obtained were 0.5090V, 0.28μA, 0.0093μW, 0.05181mA/m2 and 0.0000006 W/m2 respectively. The study concluded that microbial fuel cells technology can be used to generate electricity from cow dung.
Keywords: Microbial Fuel Cells, Voltage, Current, Power Density

Kamau JM, Mbui DN, Mwaniki JM, Mwaura FB. "Microbial Fuel Cells: Influence of External Resistors on Power, Current and Power Density." Journal of Thermodynamics & Catalysis. 2017;8(1):1-5. Abstract

The effect of external resistance on voltage, current, power, power density and current density is investigated in a microbial fuel cells using cowdung is investigated. This involves use of varying resistance resistors. The fuel cells were operated under anaerobic condition for 9 days. PVC pipe was used to make a salt bridge using lamp wicks and potassium chloride. The obtained results indicated that the maximum voltage was on day 7 with 0.153 V across 33 kΩ resistor. The power was in the range of 0.000001 to 0.01 mW, current density was in the 0.1 to 23.29 mA/m2
range while the power density was in 7.5 × 10-7 to 3.1036 mW/m2 range.

Mwaniki JM, Ogutu H, Gituauki K. "A study of Elemental composition of Biomass fuel from Kenyan grown Chamomile flowers extract." Kenya Chemical Society. 2017;10(1):14-23.
Awas E, Omosa LK, Midiwo JO, Ndakala A, Mwaniki J. "Antioxidant Activities of Flavonoid Aglycones from Kenyan Gardenia ternifolia Schum and Thonn." IOSR Journal of Pharmacy and Biological Sciences (IOSR-JPBS). 2016;11(3):136-141. Abstract

Phytochemical investigation of surface exudates of the leaves of Gardenia ternifolia resulted to
characterization of four flavonoids; 3,5,3′-trihydroxy-7,4′-dimethoxyflavone (1), 5,7-trihydroxy-4′-
methoxyflavone (2), 5,7-dihydroxy-3,4′-dimethoxyflavone (3), 5,4′-dihydroxy-7-methoxyflavanone (4) and two
tritepenoids; β-sitosterol (6) and stigmasterol (7). Compound 1 exhibited the highest antioxidant activity with
IC50 = 40.3± 1.55 μΜ. The rest of the flavonoids showed minimal activities with IC50 values of 75.5±1.75,
89±0.22, 94±0.11 μΜ for 2-4, respectively. The antioxidant activities of 1 was substantially lower than the
standard, quercetin (IC50 = 20.1±1.34 M). Methoxylation of quercetin at 7 and 4′-position in 1 substantially
reduced antioxidant potential. Lack of oxygenation at 3′ position, as observed for kaempferol derivatives was
responsible for further reduction in the radical scavenging potential as observed for 2 and 3. Furthermore,
methylation of 3-OH position in kaempferol derivatives further reduced the antioxidant activities as exhibited by
3 with an oxygenation pattern similar to 2 except for the methylation at 3-position. The results of this study are
consistent with previous findings that revealed that flavonols, exhibited better anti-oxidant activities as
compared to 3-methoxyflavones. Acetylation of 3 at the 5 and 7 positions resulting to 3,4′dimethoxy-5,7-
diacetylflavone (5), substantially reduced the activity of this compound. The triterpenoids exhibited were
inactive as expected.
Keywords: Antioxidant activities, Gardenia ternifolia, surface exudates

Mwaniki JM, Kali AM, Mbugua JK, Kamau GN. "A New Variant of the Hydraulic Stirring Mechanism for Pilot Scale Wet Thermophilic Anaerobic Digester." Journal of Kenya Chemical Society. 2016;Vol. 9(1):135-155. Abstract

A new variant of stirring mechanism for agitating contents of an anaerobic digester that makes
use of vertical and horizontal directed jets of liquid reactor content being re-circulated by and
electric pump, is reported. In order to demonstrate its working, a thermophilic pilot scale reactor
using waste water is described and various parameters analysed. As a sample run, raw
(untreated) waste water from the treatment works in Nairobi was used as the nutrient source,
while sludge from an anaerobic pond in the same treatment works was used as source of bacteria.
Measurement of various parameters like organic loading rate and characteristics of feed
wastewater (BOD, COD, pH, TS), biogas production rate in thermophilic anaerobic digester,
maximum gas yield and biogas quality were undertaken. The reactor was fed at a controlled
organic loading rate of 0.5 L/min. The reactor contained substrate to inoculums in the ratio 3:1
with the temperature was controlled using a thermostated heating coil. Digestion was carried out
in a pilot scale digester (with a capacity of 210 litres) under thermophilic (at 55 0C) anaerobic
conditions for a period of 15 days. The final average yield of biogas was 1.225 x 10-2 m3.
Average percentage composition of biogas produced by thermophilic digester was 66.6 vol. %
CH4, 30.4 vol. % CO2.

Mwaniki JM, Mwazighe F, Masimba DM. "Optimization of C/N Ratio For Mesophilic Anaerobic Digestion From Food Wastes Found In Nairobi A Lab-Scale Case Study." Journal of Kenya Chemical Society. 2016;Vol. 9(1):63-81. Abstract

Extensive work has been done on Anaerobic digestion of single substrates and using codigestion.
In a number of cultures around the world, the wastes that are discarded as
household waste may not easily fit in the biogas models that have been developed so far. It is
therefore necessary to analyse the biogas produced from food mixtures found in unique
settings and compare them with literature values of individual substrates. In the current study,
food mixture found at waste bin at a cafeteria used by StudentsofUniversity of Nairobiwas
analysed. The purposes of this study were to investigate adjusted modes of substrate pretreatment
(Mechanical, thermal and thermo-chemical) and their role in maximizing the
process of anaerobic digestion through speeding up hydrolysis. The experiments were carried
out on waste samples consisting of carbohydrate food waste (ugali+Rice),potato peels, banana
peels and a mixture of the substrates mixed with rumen slurry in the ratio 3:1 under controlled
mesophilic anaerobic conditionsin the lab scale digester. Thermo-chemical pre-treatment was
the most effective for speeding up hydrolysis with the co digested substrates producing
maximum biogas. The desired C:N ratio of 31 was obtained when all the four substrates were
combined. Similarly, the biogas produced from the mixture of the four substrates was higher
than from any of the substrates.

Mwaniki JM, Mwazighe FM, Gitura DW, Gakuo SM, Kamau GN. "Useful Products from Microalgae: Case Study of Ruai Wastewater Treatment Plant in Nairobi." Journal of Kenya Chemical Society. 2016;Vol. 9(1):15-34. Abstract

Microalgae has had a number of applications. This study explores the formation of biodiesel from lipids and
formation of charred biomass fuel from the algae species found at Ruai Wastewater facility at Ruai, Nairobi. The resulting biomass after solvent extraction was carbonized and the gross calorific value determined using a constant volume bomb calorimeter. The bio-oil obtained from the algae was transesterified and the calorific value determined. In one of the cases, carbon dioxide was bubbled through fresh algae from the waste water facility and the biodiesel from this sample which was later sun-dried, crushed, then subjected to solvent extraction and subsequent transesterification had the highest calorific value of 27,620 KJ/g compared to 22,758KJ/g in algae sample which was not subjected to such a treatment. In the case of the charred biomass fuel, the gross calorific value was found to be approx 23,132 KJ/g which makes it a medium calorific value fuel. GC-MS analysis was performed on one of the transesterification samples and methyl esters of the isolated fatty acids were identified as methyl esters of polyunsaturated fatty acid α-linolenic acid (18:3, n-3; ALA), Hexadecanoic acid and cis-9-hexadecenoic acid. In addition an alkane heptadecane was also isolated. This study shows that algae, which is present in many water systems in Kenya can be used as a valuable source of fatty acids that are taken in diet by animals and humans thus building a healthy nation.

Mwaniki JM, Mwazighe FM, Kamau GN. "Analysis of Blue Chamomile Essential Oil produced by multi-solvent Solvent Extraction Clevenger Distillation Method." Africa Journal of Physical Sciences. 2015;Vol 2(1):1-10. AbstractWebsite

Blue colored essential oil samples were obtained from chamomile flowers by a Solvent Extraction Clevenger Distillation (SECD) method and by the standard Clevenger distillation of Chamomile flowers. The solvents used were hexane, acetone, dichloromethane (DCM), ethyl acetate and methanol. The solvents were evaluated in terms of the yield of extract, and the quality of extract (determined by Gas Chromatography-Mass Spectrometry). Of all the SECD extracts, the DCM extract gave the highest yield of the essential oil while the hexane extract gave the lowest yield of the blue essential oil

Mwazighe FM, Kamau GN, Mwaniki JM. "Anaerobic Digestion of Sewage Wastewaters with Sludge and Rumen Fluid." European International Journal of Science and Technology. 2014;Vol 3(6):61-66. Abstract

Anaerobic digestion was conducted at mesophilic (37oC) and thermophilic (55oC) conditions using sewage
wastewaters as the substrate and sludge and/or rumen fluid as the inoculum, with a view to optimize biogas
production. The substrate and inoculum were mixed in the ratios 1:1, 1:3, and 3:1 (volume by weight (where
sludge was used) or volume by volume (where rumen fluid was used).At mesophilic conditions for both
inocula, the 3:1 substrate/inoculum mixture produced the most biogas in a 24 hour period, with the rumen
mixture producing the highest yield (20 ml). At thermophilic conditions the 3:1 wastewater/sludge mixture
had the highest biogas yield (58 ml), whereas when rumen fluid was used as inoculum, the 1:3 mixture
produced the most biogas (66 ml). The thermophilic experiments using rumen as the inoculum were
repeated for a 10 day period and the 3:1 mixture achieved the maximum yield (140 ml) faster than the other
two (1:1 and 1:3 mixtures) indicating that the 3:1 substrate/inoculum ratio is the best.

Mwaniki JM, Mbugua SN. "Combined Solvent Extraction – Clevenger Distillation method for producing blue essential oil from matricaria chamomilla flowers." Journal of the Kenya Chemical Society Vol 4 No 1, 2007, p12-26. 2007;Vol 4(1):12-26. AbstractWebsite

Ground chamomile flowers were mixed with distilled acetone in a large conical flask, kept under varying period of days without agitation/shaking, yielded an organic extract, which when concentrated, mixed with water and Clevenger distilled produced the blue essential oil. Thin layer chromatography, Nuclear Magnetic Resonance spectra and Gas Chromatography analysis of the oil obtained from the direct Clevenger distillation of chamomile flowers and that from the Solvent Extraction-Clevenger Distillation (SECD) revealed similar components of essential oil extracted, though in varying proportions. The SECD method offers a cheaper method of producing chamomile essential oil on large scale without the use of expensive high-pressure steam systems currently being used for the extraction of the essential oil on industrial scale. The yield of the essential oil produced on a 400 g scale of flowers after eight days of contact between solvent and flowers (extraction) is comparable with that of Clevenger distillation on a laboratory scale (1.1% yield).

Mwaniki JM. "SYNTHETIC TRANSFORMATION OF SELECTED FLAVONOIDS.". In: 12th NAPRECA SYMPOSIUM, Hotel Africana, Kampala Uganda, Tuesday 24th July 2007. Napreca; 2007. Abstract

Chalcones, flavanones and other flavonoids have been shown to have varied anti-plasmodium activity. In this work, chalcones were synthesized from corresponding flavanones  extracted from Senecio roseiflorus, Erythina abysinica and Polygonum senegalense, using conventional organic reagents and green chemistry approach.Dihydrochalcones were converted to homoisoflavones using the Kostanecki reaction. Characterization and bioassay on the synthetic derivatives was also undertaken.

Mwaniki JM. Heterocyclic Chemistry Volume 1. 2006: University of Nairobi; 2006.
Mwaniki DJM. Heterocyclic Chemistry Volume 2. Nairobi: University of Nairobi; 2006.
Mwaniki JM, Mbugua SN, Gituauki KM. "Biomass fuel from chamomile waste flowers." International Journal of BioChemiPhysics. 2005;Vol 14(1):1-9. Abstract

The waste chamomile flowers from solvent extraction of fresh chamomile flowers. were compacted into cylindrical shapes with and without added binder (Calcium Sulphate), then carbonised using an electric oven to avoid contamination. The gross fuel content of the carbonised biomass fuel determined using a constant volume bomb calorimeter was found to be 29,379 KJ kg-1, while the Net Calorific value was calculated as 26,661 KJ Kg-1.

Mwaniki JM, Kamau GN. "Factors affecting yield of essential oil from Clevenger distillation of chamomile flowers." International Journal of BioChemiPhysics. 2003;Vol.11&12(1&2):27-31. AbstractWebsite

Ground Flowers of Matricaria Recutita (German Chamomile) Banat Variety grown in Kenya, were subjected to Clevenger distillation under varying temperature, distillation, pressure conditions and the yields assessed. An inert solvent being present in the collecting column of the Clevenger apparatus increases the yield of the oil by reducing dispersion of the blue oil; its presence however, in the distillation flask inhibits the production of the essential oil. Distillation under reduced pressure leads to a decrease in the yield of the oil produced. A break in distillation time especially during the first three hours of distillation also leads to a decrease in the yield of the oil produced.

Fleming I, Mwaniki JM. "A synthesis of enantiomerically enriched propargylsilanes." J. Chem. Soc., Perkin Trans. . 1998;1:1237-1247. Abstract

Reduction of ethyl 3-methyl-, 3-isopropyl- and 3-n-pentyl-3-[dimethyl(phenyl)silyl]propanoates with DIBAL to the aldehydes, enol trifluoromethanesulfonate (triflate) formation using trifluoromethanesulfonic (triflic) anhydride and 2,6-di-tert-butylpyridine, and elimination using LDA, gives the propargyl silanes . The esters could also be prepared enantiomerically enriched, and the final products are the enantiomerically enriched propargyl (homochiral) silanes.

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