Faculty of Science

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A Comparative Study of Natural Radioactivity and Associated Radiological Hazards of Imported Sanitary Ware Products Sold in Kenya
(IRESPUB Journal of Natural & Applied Sciences, 2024-08-25) Natang’ah, Edwin Chemos; Waswa, Michael Nakitare; Khakina, Peter Nyongesa; Kibe, Horace Eyinda
Natural radioisotopes are present in all ceramic products used in building construction at varying rates. The primary source of outdoor radiation that residents of homes or workplaces are exposed to is these radioisotopes. Determining the radiation levels of ceramic items used in buildings is crucial. In this investigation, Thallium doped sodium iodide detector NaI(Ti) was used to measure the natural radioactivity levels (226Ra, 232Th, and 40K) in twelve ceramic sanitary ware products manufactured in India, China and Uganda imported and used in Kenya. For the studied samples, the average activity concentrations of 226Ra, 232Th, and 40K radionuclides were 19.5±0.99Bq/kg, 89.75±4.49Bq/kg and 405.75±20.29Bq/kg for 226Ra, 232Th and 40K respectively. With the exception of the average 232Th concentration of studied samples, these results are lower than the global average values (50, 50, and 500 Bq/kg).Values for radium equivalent activity (Raeq), gamma index (Iγ), external hazard index (Hex), internal hazard index (HIn), absorbed dose rate (ADR), annual effective dose (AED), and excess lifetime cancer risk (ELCR) were also computed in order to assess the radiological risks resulting from naturally occurring radionuclides of the ceramic sanitary ware samples under examination. The mean of the radioactive hazard parameters (Raeq, Iγ, Hex, HIn ,D, and AEDE,) computed for every sample of ceramic sanitary equipment was discovered to be below the upper bounds suggested by global organization safe for ELCR which registered slightly higher values.
Adsorption of Cadmium Ions on Geopolymers Derived from Ordinary Clay and Rice Husk Ash
(International Journal of Materials and Chemistry, 2018-10-07) Maingi, Francis M.; Mbuvi, H. M.; Ng’ang’a, M. M.; Mwangi, H.
The presence of heavy metals in water is of growing concern. One crucial global strain is the existing disparity in water distribution resulting into millions of people lacking access to safe clean water. This is exasperated by the looming climate change and increased pollution impendence posed by industrialization and population growth. Consequently, pursuance of sustainable materials and technologies for wastewater remediation is critical. Adoption of adsorbents for water treatment is desirable due to their simplicity and cheap materials involved. Geopolymers are prepared hydrothermally using alumina and silica gleaned from clay and rice husks waste materials respectively. These materials are locally attainable and environmentally benign. This work reports synthesis of geopolymers GP-1, GP-2 and GP-3 prepared using clays from three different regions. The XRD diffraction patterns obtained revealed the presence of quartz (SiO2), albite (NaAlSi3O8), vermiculite (Mg,Fe,Al)3((Al,Si)4O10)(OH)2.4H2O), microcline (KAlSi3O8), analcime (NaAlSi2O6•H2O) and natrite (Na2CO3) among other crystalline phases. The initial adsorption rates were found to increase as the Si/Al ratio of the geopolymers increased. The adsorption rates were found to fit into the second order kinetic model. This implies that Cd (II) ions adsorb on geopolymer adsorbents through chemisorption.
Aluminophosphates Derived from Tea Leaves and Pumpkin Seeds Ashes Adsorb Lead Ions from Contaminated Water
(Frontiers in Science, 2018-10-08) Maingi, Francis M.; Mbuvi, H. M.; Ng’ang’a, M. M.
One major global challenge is the existing disparity in water distribution resulting to millions of people lacking access to safe clean water. This will certainly be exacerbated by the impending climate change and increased pollution threats posed by industrialization and population growth. Therefore pursuing sustainable materials and technologies for water remediation is crucial. Adsorbents use for water treatment is preferable owing to its simplicity and cheap materials involved. Aluminophosphates molecular sieves have open-framework structures that possess a wide range of pore openings and large surface area for use as adsorbents that can be synthesized hydrothermally using alumina and phosphates. Literature reports indicate that accumulation of aluminum in tea leaves correlates positively with leaf age. The EDXRF analysis showed that tea leaves ash used contained 30.09% of Al2O3. Similarly, literature findings indicate that pumpkin seeds contain relatively large amounts of phosphorous with the pumpkin seed ash used containing 37.01% of P2O5. Consequently, aluminophosphate APA and APB were synthesized using tea leaves to pumpkin seeds ash ratios of 1:1 and 1:2 respectively. XRD characterization and lead ions batch sorption experiments were done. Turbidity column experiment was done. Data for adsorption of Pb (II) ions data on the adsorbents best fitted into the Langmuir isotherm model. Adsorption capacities obtained from the linearized graphs were 90.91 and 50.0 mg/g for APA and APB respectively. This shows that tea leaves and pumpkin waste can synthesize aluminophosphate adsorbents. Aluminophosphates have shown good potential of removing Pb (II) ions from wastewaters.
Codes, designs and graphs obtained from some projective symplectic group
(KIBU, 2019-11) Kananu, Rukaria Lydiah
After the classiﬁcation of ﬁnite simple groups, there is still much work to be done to give a clear geometric identiﬁcation of the ﬁnite simple groups. There are also many problems in enumerating and characterizing a structure which either has a particular group acting on it or which has some degree of symmetry from a group action. It has been shown that there exists interplay between ﬁnite simple groups and codes. In this thesis we construct and enumerate binary linear codes for the projective symplectic group S8(2) from the permutation representations of degree 120, 136, 255, 2295, 5355, 5440 and 11475. We ﬁnd that the support of codewords of a given weight in a code hold a combinatorial design, or represent points of a projective space PG(2m−1,q), or represent the rows of the adjacency matrix of a graph or equivalently are the incidence vectors of the blocks of a design. Through coding theory, the interplay between the combinatorial objects is enhanced and the internal structures of the group characterized.
Measurement of Radiological Parameters in Harvested Sand in Bungoma County Rivers, Kenya
(Journal of Engineering and Technology for Industrial Applications, 2022-02-08) Waswa, Michael Nakitare; Maingi, Francis M.; Wanyama, Conrad Khisa; Sindani, Lazarus
Samples of sand were collected along the course of ten selected rivers two from each river through random sampling. Activity concentration of 238U, 232Th and 40K were measured using high resolution NaI(Ti) gamma ray spectrometer. Activity concentration of the three primordial radionuclides obtained were used to calculate, absorbed dose rate, annual effective dose rate, interna and external hazard indices and radium equivalent. The average activity concentration for the three primordial radioactive nuclides were; 2±0.1Bq/kg with a range of 0± 0.03Bq/kg to 4±0.24Bq/kg for 238U, 55±2.78Bq/kg with a minimum value of 32±1.6Bq/kg and a maximum value of 87±4.38Bq/kg for 232Th and 51±2,56Bq/kg with a minimum value of 27±1.37Bq/kg and a maximum value of 76±3.8Bq/kg for 40K. The mean activity concentrations for 238U and 40K were below the world averages of 33Bq/kg and 420Bq/kg respectively. The indoor and outdoor annual effective dose rate varied from 0±0mSv/y to 0.2±0.01mSv/y with an average of 0.1±0 mSv/y and 0±0.003mSv/y to 0.1±0.009mSv/y with a mean of 0.1±0.006 mSv/y respectively. The annual effective dose rates were below the safe limits of 1mSv/y. Therefore, use of sand from the selected rivers in Bungoma County, Kenya for construction has minimal health risks to the inhabitants.
Physical-Chemical Characterization of Soils in Selected Potato Growing Areas of Molo, Nakuru County Kenya
(SSRG International Journal of Agriculture & Environmental Science, 2020-08-07) Maingi, Francis M.; Mbuvi, Harun Mbatha; Abdulhameed, Adamu
Characterization of soils in selected potato growing farms of Molo, Nakuru County in Kenya was compelled by the decline in potatoes acreage yields observed in the study area over the years. In the pursuit of reasons behind the decline, this study determined levels of some key soil fertility indices in soil samples obtained from selected farms. Four farms that have been in intensive potatoes farming were used. The soil was randomly collected from a depth of 0-10 cm separately for all the investigated sites. Collected site-wise samples were air-dried, ground, and passed through a 2 mm sieve and stored in plastic containers ready for analysis. Analytical techniques employed were Walkley black for carbon, Kjeldahl for nitrogen, standard wet chem soil analysis, saturation method for water porosity, glass electrode determined soil pH, bulk density, particle density, water holding capacity were determined by methods of Keen box. The mean levels of essential soil fertility indices obtained were; soils pH (5.46 ± 0.43), soil bulk density (g/cm3) (1.03 ± 0.01), particle density (2.51 ± 0.08), water holding capacity (%) (36.07 ± 2.57), porosity (0.59 ± 0.01), exchangeable cations (uS/cm) (83.63 ± 14.22), cation exchange capacity (meq/100g) (18.48 ± 0.89), organic carbon (%) (3.50 ± 0.24), total nitrogen (%) (0.17 ± 0.03). Mean micro and macronutrients available (mg/Kg) were; phosphorous (7.11 ± 2.77), potassium (100.27± 8.32), calcium (198.2 ± 35.1), magnesium (20.97 ±4.28), manganese (15.26 ± 1.12), sulphur (2.31 ± 1.88), copper (0.59 ± 0.12), boron (0.38 ± 0.07), zinc (12.96 ± 2.04), sodium (8.61 ± 0.51), iron (147.92 ± 4.10). These findings reveal the extent of some fertility indices depletion in the soils and will form a base for decreased acreage yield of potatoes in this region. The results further form the baseline for future research on the working acreage of key soil fertility indices required for remediation.
SBT 311:Plant biochemistry /biochemistry
(KIBU, 2025-01-23) KIBU
SBT 311:Plant biochemistry /biochemistry
SOME LINEAR CODES, GRAPHS AND DESIGNS FROM MATHIEU GROUPS M24 AND M23
(Kibabii University, 2019-05-01) Marani, Vincent
In this thesis, we have used four steps to determine G-invariant codes from primitive permutation representations of Mathieu groups M24 and M23 . We constructed all G-invariant codes from primitive representations of degree 24, 276, 759, and 1288 from the simple group M24. We found one self dual [24, 12, 8] code, three irreducible codes; [276,11,128], [759,11,352] and [1288,11,648]. There were several decomposable, self orthogonal and projective linear binary codes. There were two strongly regular graphs from a representation of degree 276 and 759. These graphs are known. We determined designs from some binary codes using codewords of minimum weight. All the designs constructed were primitive. We constructed symmetric 1-designs from the primitive permutation representations of degree 24, 276, 759, 1771, 2024 and 3795 deﬁned by the action of a group G on a set Ω = G/Gα. In most cases the full automorphism group of the design was M24 while in some cases the full automorphism group of the design was either S24 or S276. We also constructed all G-invariant codes from primitive representations of degree 23, 253, and 253 from the simple group M23. There was no self dual linear code. There were four irreducible codes [23,11,8], [253,11,112],[253,44] and [253,11,112] . There were several decomposable, self orthogonal and projective linear binary codes. There was no strongly regular graph from the three representations. We determined designs from some binary codes using codewords of minimum weight. All the designs constructed were primitive. We constructed symmetric 1-designs from the primitive permutation representations of degree 23, 253 and 253 deﬁned by the action of a group G on a set Ω = G/Gα. In most cases the full automorphism group of the design was M23 while in some cases the full automorphism group of the design was either S23, S253 or S506
Thermodynamic, Kinetic and Equilibrium Studies of Pb (II) Ions Adsorption Using Ordinary Clay/Rice Husk Ash Based Geopolymers
(IOSR Journal of Applied Chemistry, 2018-08-08) Maingi, Francis M.; Ng’ang’a, M. M.; Mwangi, H.; Mbuvi, H. M.; Abdulhameed, Adamu
One key global challenge is the existing disparity in water distribution resulting to millions of people lacking access to safe clean water. It is currently assessed that 1.1 billion individuals on the planet lacks access to improved quality water supplies. This is aggravated by the looming climate change and increased pollution threats posed by industrialization and population growth. Use of adsorbents for water treatment is preferable due to simplicity of the technique and cheap materials involved. Geopolymers can be easily synthesized hydrothermally using alumina and silica and possess amorphous surface for use as adsorbents. Clay minerals have been reported to contain alumina and silica and previous research show that rice husk ash as well contain substantial amounts of silica. Geopolymers can be easily synthesized hydrothermally using alumina and silica and possess amorphous surface that is useful for adsorption. Hence this work reports information on adsorption of Pb (II) using geopolymers GP-1, GP-2 and GP-3 synthesized with SiO2/Al2O3 ratios of 4.16, 4.18 and 8.29 respectively. Adsorption of metal ions was found to increase from 70.54%± 0.43 to 90.23% ± 0.04 with increase in Si/Al ratio from 4.16 to 8.29 in geopolymers. Equilibrium studies unveiled that experimental data for adsorption of Pb (II) ions best fitted in modified Langmuir Freundlich model. The adsorption capacities of 27.0, 79.58 and 209.9mg/g were obtained for GP-1, GP-2 and GP-3 respectively. Adsorption thermodynamics showed the process corresponded on spontaneous physiosorption activated by increase in temperature. Kinetic study on adsorption of Pb (II) ions onto clay based geopolymers was a Pseudo second order. This information may facilitate the development of optimized procedures for wastewater treatment, thus providing an alternative solution to environmental menace caused by heavy metal pollutants.

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