Journal Articles

Effects of Adsorbent Dosage and Particle Size on Fluoride Removal Using Calcium-Spiked Moringa oleifera Seed Powder

Mon, 01 Sep 2025 00:00:00 GMT

Effects of Adsorbent Dosage and Particle Size on Fluoride Removal Using Calcium-Spiked Moringa oleifera Seed Powder Chavaregi, Geoffrey,; Lusweti, John; Keronei, Pius Access to safe drinking water remains a major challenge in fluoride-endemic regions, where excessive fluoride concentrations can lead to dental and skeletal fluorosis. This study evaluated the effects of adsorbent dosage, particle size, and particle size classification (mesh size) on the fluoride removal performance of Moringa oleifera seed powder (MOSP) in both calcium-spiked and non-spiked forms. A three-factor factorial batch adsorption experiment was conducted using initial fluoride concentration of 1ppm, dosages of 0.25–2.0 g/100 mL, particle sizes of <250 μm, 250–500 μm, and >500 μm, and mesh classifications of 20 (850 μm), 40 (425 μm), and 60(250 μm). Response variables included fluoride removal efficiency, residual fluoride concentration, and adsorption capacity (qe), measured using a fluoride ion-selective electrode. ANOVA and linear regression were applied to evaluate the dose and size response relationships. Results showed that calcium-spiked MOSP consistently outperformed non-spiked MOSP across all parameters. Fluoride removal efficiency increased with dosage, reaching 88.95% for spiked and 70.34% for non-spiked MOSP at 2.0 g. Finer particle sizes and smaller mesh fractions significantly enhanced removal efficiency and reduced residual fluoride levels, with spiked MOSP at ≤250 μm achieving 89.80% removal and residual fluoride below WHO guidelines. Regression analysis confirmed strong inverse relationships between particle size/mesh size and fluoride removal performance, and positive correlations with dosage. The improved performance of calcium-spiked MOSP is attributed to increased surface-active Ca2+ sites enabling precipitation of CaF2 and enhanced adsorption via electrostatic attraction and ion exchange. These findings indicate that calcium-spiked MOSP, optimally prepared at fine particle size and moderate dosage, is a viable, locally sourced defluoridation medium suitable for rural water treatment systems.

Fluoride Removal Efficiency of Calcium-spiked and Non-spiked Moringa Oleifera Seed Powder

Wed, 01 Oct 2025 00:00:00 GMT

Fluoride Removal Efficiency of Calcium-spiked and Non-spiked Moringa Oleifera Seed Powder Chavaregi, Chavaregi; Lusweti, John; Keronei, Pius Fluoride contamination in drinking water remains a widespread public health concern, particularly in arid and semi-arid regions where groundwater is the primary source of potable water. Chronic exposure to elevated fluoride levels—commonly above the World Health Organization’s (WHO) recommended limit of 1.5 mg/L—can result in dental and skeletal fluorosis, affecting millions of people globally. Affordable and effective defluoridation technologies are urgently needed, especially in low-income rural settings. In this study, the fluoride removal efficiency of calcium-spiked and non-spiked Moringa oleifera seed powder was investigated through controlled laboratory batch adsorption experiments. Biosorbents were prepared by treating ground seed powder with 1% calcium chloride solution and characterised based on their performance across five fluoride concentrations (1-20 ppm). Key parameters such as removal efficiency, residual fluoride levels, and adsorption capacity (qe) were evaluated under consistent operating conditions (pH 7, 2 g/50 mL dose, mesh 40, 120 minutes). Results indicated that calcium-spiked Moringa oleifera powder significantly outperformed its non-spiked counterpart. At 1 ppm, the spiked adsorbent achieved 94.35 ±1.15% removal efficiency, compared to 81.45 ±1.35% for the non-spiked. At the highest tested concentration (20 ppm), the spiked biosorbent still removed 72.31 ±1.80% of fluoride, while the non-spiked removed only 54.21 ±1.95%. Linear regression models showed strong inverse correlations between fluoride concentration and removal efficiency (R2 > 0.99, p < 0.001). The spiked adsorbent also resulted in significantly lower residual fluoride concentrations, with final values closer to the WHO guideline. One-way ANOVA confirmed significant differences in adsorption capacity and efficiency between treatments (p < 0.001). These findings highlight the effectiveness of calcium modification in enhancing biosorption performance and suggest that calcium-spiked Moringa oleifera seed powder is a promising, low-cost, and environmentally friendly solution for mitigating fluoride contamination in drinking water.

Antibacterial Activity of the Tender Leaf, Stem Bark and Root Extracts of Guizotia Scabra against Streptococci Bacteria Using Bioassay

Mon, 01 Sep 2025 00:00:00 GMT

Antibacterial Activity of the Tender Leaf, Stem Bark and Root Extracts of Guizotia Scabra against Streptococci Bacteria Using Bioassay Paul, Anjeline Jepchumba; Lagat, Grace; Lutta, Samuel Dental caries remains a major public health concern globally, largely attributed to bacterial pathogens such as Streptococcus mutans and Streptococcus sobrinus. The search for plant-based alternatives to synthetic oral care products has intensified in recent years. This study evaluated the antibacterial activity of ethanol and acetone extracts of Guizotia scabra leaf, stem bark and root against these key oral pathogens in comparison with commercial toothpastes. The ethanol leaf extract exhibited the highest activity against Streptococcus mutans with an inhibition zone of 5.0 mm (62.5%), followed by the root extract (3.0 mm, 37.5%) and stem extract (2.0 mm, 25.0%). Against Streptococcus sobrinus., the ethanol leaf extract recorded 4.0 mm (50.0%), root extract 2.5 mm (31.25%), and stem extract 1.5 mm (18.75%). Similarly, the acetone leaf extract demonstrated the highest inhibition against Streptococcus mutans (4.6 mm, 57.5%) and Streptococcus sobrinus. (4.3 mm, 53.75%), compared to the root extract (2.8 mm, 35.0%; 2.3 mm, 28.75%) and stem extract (1.9 mm, 23.75%; 1.7 mm, 21.25%). In contrast, commercial toothpaste brand 1 produced inhibition zones of 6.0 mm (75.0%) against both pathogens, while brand 2 showed 7.0 mm (87.5%) against Streptococcus mutans and 6.0mm (75.0%) against Streptococcus sobrinus. These findings demonstrate that Guizotia scabra extracts possess significant antibacterial activity, with leaf extracts showing the greatest potential. Although commercial toothpastes were more effective likely due to fluoride and other active ingredients. The results highlight the potential of Guizotia scabra as a natural complementary agent for dental caries prevention. Future research should explore its integration with fluoride or other natural antibacterials to enhance its efficacy. Keywords: Antibacterial Activity, Guizotia scabra, Streptococcus mutans & Streptococcus sobrinus bacteria, Bioassay.

Fluoride distribution in selected foodstuffs from Nakuru County, Kenya, and the risk factors for its human overexposure

Sun, 01 Jan 2023 00:00:00 GMT

Fluoride distribution in selected foodstuffs from Nakuru County, Kenya, and the risk factors for its human overexposure Nelima, Delphine; Wambu, Enos W.; Kituyi, John L. Critical data on the impacts of fluoride (F) in food systems along the Eastern Africa Rift Valley System (EARS) is needed for public health risk assessment and for the development of strategies for ameliorating its deleterious effects among the affected communities. Long-term F overexposure causes dental and skeletal fluorosis, and leads to neurotoxicity, which impacts several important body functions. Investigating F exposure pathways is of essence to inform and safeguard public health of the affected communities. The current study assessed the F levels in potatoes (Solanum tuberosum L.), beans (Phaseolus vulgaris L.) and garden peas (Possum sativa) from Nakuru County, Kenya, by potentiometric analysis using F ion-selective electrodes. It then evaluated the risk factors for excessive human exposure to F through contaminated foodstuffs. The mean F levels in the potatoes (8.50 ± 4.70 mg/kg), beans (8.02 ± 4.12 mg/kg) and peas (4.99 ± 1.25 mg/kg) exceeded recommended dietary allowances (RDA) level of 4 mg/kg endorsed by US Institute of Medicine for the different categories of people. The F distribution trends in beans and potatoes reflected the environmental patterns of F contamination of the study area but the spatial extent Fin the peas indicated existence of partial resistance of the pea plants to environmental F uptake. The results indicated that both the beans and the potatoes were more liable to accumulating greater amounts of F from the environment than garden peas and that all the three foodstuffs contained high F levels that posed greater risk of F overexposure and its deleterious impacts among the young children, male populations, and in people of greater body weight and high physical activity levels.

Antioxidant and Antidiabetic Effects of Mondia whitei Root Extract in Streptozotocin-Induced Diabetic Wistar Rats

Wed, 01 Jan 2025 00:00:00 GMT

Antioxidant and Antidiabetic Effects of Mondia whitei Root Extract in Streptozotocin-Induced Diabetic Wistar Rats Gitau, Kennedy K.; et. al... Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia and is a major contributor to global morbidity and mortality. Although Mondia whitei has been traditionally used for its antidiabetic and antioxidant effects, scientific evidence supporting these claims remains limited. This study aimed to evaluate the therapeutic potential of Mondia whitei root extract in a streptozotocin (STZ)-induced diabetic Wistar rat model. Phytochemical screening of M. whitei root extract revealed the presence of saponins, phenols, flavonoids, tannins, alkaloids, glycosides, coumarins, steroids, and terpenoids. Antioxidant activity was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays. DM was induced with 65 mg/kg body weight STZ. Rats were grouped into normal control, diabetic control, 200 mg/kg extract, 400 mg/kg extract, and 100 mg/kg metformin treated groups. Treatments were administered orally for 21 days. Fasting blood sugar (FBS) and body weight were measured weekly. At termination, blood and liver tissues were collected for analysis. M. whitei extract exhibited strong antioxidant activity in vitro. The 400 mg/kg dose significantly reduced FBS levels, nearing metformin’s hypoglycemic effect when compared to diabetic control. The extract also significantly lowered serum gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lipids, and malondialdehyde (MDA), while increasing FRAP values in liver and plasma while serum creatinine and urea levels were reduced, though not significantly. The phytochemical-rich M. whitei root extract showed significant antidiabetic, antioxidant, hypolipidemic, and hepatoprotective activities, supporting its potential as a natural alternative for managing DM and its complications.

Removal of Selected Heavy Metals from the Water of the River Sosiani in Uasin Gishu County Using Cynodon dactylon (Couch Grass)

Sun, 01 Sep 2024 00:00:00 GMT

Removal of Selected Heavy Metals from the Water of the River Sosiani in Uasin Gishu County Using Cynodon dactylon (Couch Grass) Lelei, Kiptoo Richard; Kipkemboi, Pius; Lutta, Samuel The management of heavy metal pollution in rivers is a growing concern due to the rapid pace of industrialization and urbanization. Rivers are especially susceptible to heavy metal contamination due to various human activities, such as industrial processes, agricultural runoff, mining operations and improper waste disposal. Several studies in Kenya have documented the alarming presence of elevated heavy metal levels in various rivers, raising concerns about environmental and public health impacts. A variety of methods and techniques have been developed and implemented to remove heavy metals from contaminated water however, several of these techniques are expensive. The potential of plants to serve as a bio adsorbent offers a sustainable solution for addressing heavy metal pollution in rivers. This research therefore investigated the efficacy of modified Cynodon dactylon grass as an adsorbent for removing lead (Pb²⁺), manganese (Mn²⁺), cadmium (Cd²⁺) and chromium (Cr⁶⁺) ions from Sosiani River water. Water samples were collected from three purposively selected sites along the Sosiani River in Uasin Gishu County, Kenya and the mean heavy metal concentrations were analysed using Atomic Absorption Spectroscopy (AAS). The batch adsorption experiments were conducted in triplicates for untreated and treated grass. The study also examined the impact of pH levels on adsorption by testing at pH levels of 5, 7 and 9. Data was coded into SPSS software version 20 and analysed using descriptive and inferential statistics. The results indicate that the mean concentration of Cr⁶⁺ and Pb²⁺ in the water samples were 1.49 mg/L and 1.61 mg/L respectively. Both metals ions exceeding the NEMA guideline. However, the concentration of Cd²⁺ and Mn²⁺ was found to be 0.002 mg/L and 0.05 mg/L which is below the NEMA recommended level. Further, the heavy metal concentrations in Sosiani River water samples varied significantly (p<0.05) across different locations. Also, the chemically treated Cyanodon dactylon grass exhibited a higher percentage of adsorption across all tested heavy metals compared to the untreated Cyanodonat pH 5 compared to pH 9. These findings demonstrate the potential of Cynodon dactylon grass as an effective and more accessible alternative for river water purification. Further research is needed to optimize the conditions and modifications for enhanced adsorption performance. dactylon grass. Lastly, there was a higher adsorption efficiency for treated adsorbent

Occurrence and environmental risks of contaminants of emerging concern across the River Athi Basin, Kenya, in dry and wet seasons

Mon, 01 Jan 2024 00:00:00 GMT

Occurrence and environmental risks of contaminants of emerging concern across the River Athi Basin, Kenya, in dry and wet seasons Chebii, Faith; et. al... Globally, the environmental occurrence of Contaminants of Emerging Concern (CECs) including pharmaceuticals (PhACs), personal care products (PCPs) and modern polar pesticides has raised ecological and human health awareness. However, as the developed world races against time to establish regulatory measures to mitigate their effects, developing nations including Kenya are lagging behind, partly due to unavailability of adequate data. In this work, a multi-residue analysis of 86 CECs was carried out on 198 surface water and 18 effluent samples collected at 24 sites across the River Athi basin area, Kenya, in both dry and rainy seasons. Overall, 57 CECs comprising 31 PhACs (0.4 ng L− 1 –142 μg L− 1 ), 6 PCPs (0.7–570 ng L− 1 ) and 20 pesticides (0.3 ng L− 1 –8.3 μg L− 1 ) were detected. The maximum loads varied from 217 g day− 1 (PCPs) to 46 kg day− 1 (PhACs). Individually, carbamazepine, nevirapine, sulfamethoxazole and DEET were the most ubiquitous CECs, with detection frequencies (DF) higher than 80 %. The highest concentrations were observed at river sites that are heavily impacted by informal settlements, highlighting the critical role of slums in urban rivers pollution. At least 8 CECs including acetamiprid, alachlor, atrazine, diuron, nevirapine and paracetamol show potential risk to algae, Daphnia magna and fish, as exemplified by Risk Quotients (RQ) up to 174. Similarly, potential risk of antibiotic resistant bacteria development is evident (RQ up to 64), being driven by metronidazole, sulfamethoxazole and trimethoprim. Ultimately, further studies on the occurrence and distribution of antibiotic resistant bacteria within the basin and among the communities consuming untreated river water for drinking is merited.

A systematic review of Datura stramonium as a potential biocide for mosquito control

Tue, 01 Oct 2024 00:00:00 GMT

A systematic review of Datura stramonium as a potential biocide for mosquito control Okumu, Naomi; et. al... Global burden of malaria reduction has been significantly slowed down by malaria vectors developing resistance to conventional chemical pesticides currently in use. Anopheles mosquitoes, which are malaria vectors, have over time developed coping mechanisms which can enable them to detoxify poisonous chemical pesticides meant to kill them consequently threatening the effectiveness of such control measures. Coupled with the danger of the chemical pesticides on the environment, attention is shifting to natural products that would successfully control malaria vectors particularly those that have developed bacteria-mediated resistance to conventional pesticides currently in use. A web-based literature search using scientific databases was explored to find data on the insecticidal and antibacterial properties of Datura stramonium. This was prompted by a dearth of information on alternative bio-pesticides that are cost-effective, eco-friendly, and with high toxicity on vectors. This review evaluated the potential of extracts of D. stramonium in different solvents as a biocide. A lot of research on D. stramonium extracts has focused more on its potential as a medicinal plant rather than as a biocide. This review outlines research evidence that D. stramonium has phytochemicals and bioactive compounds which are antibacterial, insecticidal, and anti-malarial. Not much studies have been done with Anopheles gambiae of confirmed resistance and its inhibition effect on mosquito bacterial community is not fully understood.

Phytochemical and Acute Toxicity Assessment of Syzygiumguineense (Willd.) DC.and Acacia hockii De Wild.Traditionally used for Female Contraception/fertility regulation in Baringo County, Kenya

Thu, 01 Aug 2024 00:00:00 GMT

Phytochemical and Acute Toxicity Assessment of Syzygiumguineense (Willd.) DC.and Acacia hockii De Wild.Traditionally used for Female Contraception/fertility regulation in Baringo County, Kenya Kiptisia, Richard. T; Nandwa, Anastasia A boiled stem bark mixture of Syzygiumguineense and Acacia hockii is traditionally used by the Tugen community in Baringo County, Kenya, for fertility regulation in women. This study aimed to validate the safety and eficacy of these plants through phytochemical screening and acute oral toxicity tests. Standard phytochemical tests were employed to identify the compounds present in the stem bark extracts. Acute toxicity was evaluated following the Acute Toxicity Class model based on the OECD 423 Guideline (2001). The study was conducted between April and July 2024 at the Department of Chemistry & Biochemistry for sample extraction and phytochemical analysis, and the Department of Biological Sciences, University of Eldoret, for toxicity testing. The stem bark extracts of both plants contained tannins, saponins, lavonoids, glycosides, alkaloids, terpenoids, steroids, and phenols, according to phytochemical screening conducted using established procedures. Rats were used in acute oral toxicity experiments, with each plant extract administered at a set dose of 2000 mg/kg body weight. The rats were split into test and control groups. Over the course of 14 days, signs of toxicity and death were noted every day, and body weights after fasting were recorded once a week. The fact that no deaths or changes in physiological indicators were noted during the trial suggests that the LD50 is higher than 2000 mg/kg. Furthermore, the rats fed with the extracts showed a consistent increase in their fasting body weights when compared to the control group (p = 0.05). This study concludes that the ethnobotanical use of Syzygiumguineense and Acacia hockii is safe based on acute toxicity results. The phytochemical compounds present may be responsible for the plants' pharmacological effects in traditional medicine. However, further long-term toxicity studies are recommended to fully assess the toxicological proile and reinforce the clinical signiicance of these indings

Optimisation of plutonium separations using TEVA cartridges and ICP-MS/MS analysis for applicability to large-scale studies in tropical soils

Tue, 01 Aug 2023 00:00:00 GMT

Optimisation of plutonium separations using TEVA cartridges and ICP-MS/MS analysis for applicability to large-scale studies in tropical soils Isaboke, Job; et al. The analysis of plutonium (Pu) in soil samples can inform the understanding of soil erosion processes globally. However, there are specific challenges associated for analysis in tropical soils and so an optimal analytical methodology ensuring best sensitivity is critical. This method aimed to demonstrate the feasibility of sample preparation and analysis of Pu isotopes in African soils, considering the environmental and cost implications applicable to low-resource laboratories. The separation procedure builds upon previous work using TEVA columns, further demonstrating their usefulness for the reduction of uranium (U) interference in ICP-MS analysis with enhanced selectivity for Pu. Here several steps were optimised to enhance Pu recovery, reducing method blank concentration, and improving the separation efficiency through the determination of the elution profiles of U and Pu. The elimination of the complexing agent in the eluent, increased the spike recovery by improving matrix tolerance of the plasma, and simplified the separation procedure, improving throughput by 20%. The subsequent method was validated through the analysis of Certified Reference Material IAEA-384, where high accuracy and improved precision of measurement were demonstrated (measured value 114 ± 12 versus certified value 108 ± 13 Bq kg−1). Optimisation of the column separation, along with the analysis of the samples using O2 gas in ICP-MS/MS mode to mass shift Pu isotopes away from interfering molecular U ions provided a simple, robust, and cost-effective method with low achievable method detection limits of 0.18 pg kg−1 239+240Pu, applicable to the detection of ultra-trace fallout Pu in African soils.