Department of Biological and Environmental Sciences

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    Effective Microorganisms and their Influence on Growth and Yield of Pigweed (Amaranthus Dubians)
    (ARPN Journal of Agricultural and Biological Science, 2010-01-01) Muthaura, Chrispaul; Musyimi, David M.; Ogur, Joseph A.; Okello, Samuel Victor
    Pigweed (Amaranthus dubians) plants grow widely in many parts of the world. It is a very popular indigenous wild vegetable and is usually utilized by many communities as a nutritional additive. Pigweed is becoming very popular nowadays because of its high nutritive value and simple growth habits. However there is very little information about growth of this plant, using effective microorganisms, thus this study is designed to evaluate the effect of inoculation of effective microorganism on growth and yield of pigweed. The experiment was performed in five liter pots representing various conditions in the field. It comprised of four treatments, replicated, five times and arranged in a complete randomized design. One set of the treatments consisted of soil collected from the field, while the other treatments consisted of soil and organic manure prepared using effective microorganisms, sterilized soil treated with effective microorganisms, and sterilized soil plus organic manure without application of effective microorganisms respectively. Shoot height, stem diameter, leaf number per plant, leaf area, leaf fresh weight, leaf dry weight, root fresh weight, root dry weight and chlorophyll a and b contents were determined. Inoculated pigweeds with effective microorganisms recorded highest values in all the parameters measured except the root dry matter accumulation. There were significant differences (p≤0.05) in shoot height growth, stem diameter, leaf numbers per plant, leaf area, leaf fresh and dry weight and root fresh and dry weights among treatments. There were no significant differences in leaf chlorophyll content among the treatments even though chlorophyll a and b contents were slightly higher in plants inoculated with effective microorganisms. The three other treatments had significantly lower values of the parameters determined. The results from this study demonstrated that growth and yield of pigweeds may be improved by inoculating the plants with effective microorganisms, and as a result reduce the use of fertilizers in production of this vegetable hence promoting sustainable agriculture. More studies would be needed to determine the effects of effective microorganisms’ inoculation on other amaranthus species.
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    Equilibrium, Kinetic, and Thermodynamic Studies of Pb (II) ions Adsorption onto Modified Tamarind Fruit Pulp
    (American Journal of Chemistry, 2026-10) Mukhalisi, Stellah Nelima; Maingi, Francis M.; Kowanga, Keno
    The challenge of accessing clean drinking water in urban Kenya is compounded by contamination from heavy metals, leading to serious health risks such as kidney and brain damage. Industrialization and technological advancement have exacerbated the problem of increase of Pb (II) ions and other heavy metals in water ecosystem through industrial effluents. This study investigated the use of modified tamarind fruit pulp (MTFP) for the adsorption of (Pb II) ions from synthetic wastewater. Characterization techniques like XRF and FT-IR were utilized, and adsorption experiments were conducted by varying pH, contact time, temperature, dosage, and initial concentrations of the metals. The results were analysed statistically using ANOVA, with significant differences at P ≤ 0.05. The equilibrium studies indicated that the adsorption of Pb (II) ions was best represented by the Freundlich model, with adsorption capacities of 1.30 and 1.67 mg/g for unmodified tamarind fruit pulp (UTFP) and modified tamarind fruit pulp (MTFP), respectively. Thermodynamic study showed that the adsorption process was thermodynamically spontaneous and endothermic. Kinetic studies revealed that chemisorption was the rate limiting step in the adsorption of Pb (II) ions. This information revealed the enhanced capabilities of MTFP to effectively remove Pb (II) ions from wastewater, showcasing its potential as an eco-friendly adsorbent.
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    Green superabsorbent hydrogel derived from activated charcoal and glycerol with maleic acid as a cross-linker
    (Journal of Experimental Sciences, 2024-02-16) Kasimu, Titus M.; Mbuvi, Harun M.; Maingi, Francis M.
    Superabsorbent hydrogels characterize a set of polymeric materials with three-dimensional structures capable of absorbing large amounts of water due to their hydrophilic functional groups on their surface. Their application in industries, agriculture, and the environment is of primary significance. This study reports the synthesis and characterization of green superabsorbent hydrogels derived from activated charcoal. The process involved a polymerization reaction between activated charcoal (AC) with glycerol (G) using sodium hydroxide as an initiator in the absence and presence of maleic acid as a crosslinker to synthesize HCG-1 and HCG-2 superabsorbent hydrogel respectively. Characterization of the hydrogels was done using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and X-ray diffraction (XRD). Optimization conditions were done by synthesizing hydrogel with varying dosages of both activated carbon and maleic acid as well as swelling time. The FT-IR results showed the appearance of strong sharp peaks at 1591.34 cm-1 and 1400.28 cm-1 in HCG-1 associated with -COO¯ symmetric stretching and asymmetric bending vibrations, indicating interlink between reacting monomers. A new absorption band at 1639.48 cm-1 associated with -COO¯ bending in non-conjugated ester indicates ester-crosslink in HCG-2 hydrogel. XRD analysis showed a phase shift from semi-crystalline to crystalline structure upon crosslinking. SEM analysis showed a crystalline intact, rigid structure without voids and pores on its surface in HCG-1 compared to the smooth irregular pores and lamina structure observed in HCG-2 hydrogel. The dosage ratio of AC: G: maleic acid of 8:5:1 produced hydrogel with an optimal water absorption capacity of 1255.80±0.70%. Maleic acid was found to improve the water absorption capacity of the superabsorbent. The study is an eye opener towards the application of biodegradable hydrogels in agriculture, especially in semi and arid regions.
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    Oxalic Acid Functionalized Diatomite for Enhanced Lead (II) ions Adsorption from Wastewater
    (Physical Chemistry, 2026-06-08) Masai, Winny Chebeni; Maingi, Francis M.; Makhanu, Maximilla
    Increased global demand for batteries and paints has resulted in higher levels of heavy-metal contamination in waterways, harming aquatic life and human health. Lead is of particular concern due to its non-biodegradable nature and persistence at trace levels. Various technologies have been developed for heavy metal removal from wastewater, with adsorption being the most effective and resource-efficient. Information in literature shows that diatomite has the ability to adsorb heavy metal ions from aqueous media but suffers from a low adsorption capacity and specific surface area. This study therefore focused on enhancing the adsorption capacity of low-cost diatomite by functionalizing it with carboxyl groups via oxalic acid. Characterization techniques, including XRF, FT-IR, XRD, and Raman spectroscopy, confirmed the successful functionalization. Batch adsorption experiments demonstrated that functionalized diatomite effectively removed over 80% of Pb (II) ions, with an adsorption capacity of 8.00 mg/g. These findings suggest that functionalized diatomite is a promising potential adsorbent for remediation of heavy metal ions from wastewater.
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    Remediation of Water Contaminated with Cr6+ and Cd2+ Using Aluminophosphates Derived from Ashes of Tea Leaves and Pumpkin Seeds
    (Chemistry and Materials Research, 2016-10-07) Maingi, Francis M.; Mbuvi, H.M.; Nganga, M. M.
    Access to clean water is an ever increasing challenge that is not only fuelled by climate change and phenomenally growth in population but also by pollution by heavy metals arises from many sources that include automobiles, purification of metals, smelting industries, paint industries and textile industries. Water pollution is on the increase owed to industrial development and population increases. Commercial adsorbents frequently used as adsorbents in water remediation remain expensive out of reach to majority low income earners. It is therefore essential to develop cheap adsorbent materials capable of removing Cr6+, Cd2+ ions and turbidity from wastewaters. Tea leaves ash (TLA) and pumpkin seeds ash (PSA) was used to generate aluminophosphates materials by hydrothermal reactions for removal of selected heavy metals from contaminated waters. Two adsorbents A and B were also prepared by varying ratios of TLA and PSA. Material A, (APA) was prepared by mixing TLA and PSA as in ratio of 1:1 while material B, (APB) was prepared by mixing them in ratio of 1:2. XRay diffraction was used for phase identification and characterization of synthesized material. The effects of metal ion concentration, initial pH, contact time, temperature, shaking speed and dosage on percentage removal of Cd+2, and Cr+6 were determined. The equilibrium adsorption data fitted best in Langmuir isotherm model, as it had the highest value of correlation coefficient. Maximum monolayer adsorption capacities were 45.45 mg/g for cadmium and 50.00 mg/g for chromium using APA. Adsorption capacities of APB were 40.00 mg/g for cadmium and 41.67 mg/g for chromium. Based on adsorption capacities, APA was a better adsorbent than APB. The results from this study shows agro based aluminophosphates are potential adsorbents for remediation of heavy metals from waste waters.