https://repository.seku.ac.ke/handle/123456789/19 2026-03-17T11:15:33Z 2026-03-17T11:15:33Z Mungwari, Chakanaka P. King'ondu, Cecil K. Sigauke, Placxedes Obadele, Babatunde A. https://repository.seku.ac.ke/handle/123456789/8299 2026-03-12T08:48:31Z 2025-03-01T00:00:00Z

Title: Conventional and modern techniques for bioactive compounds recovery from plants: Review Authors: Mungwari, Chakanaka P.; King'ondu, Cecil K.; Sigauke, Placxedes; Obadele, Babatunde A. Abstract: New extraction techniques are being developed in response to the growing interest in bioactive compounds found in nature. The goal of these novel procedures is to extract these chemicals from a range of biomasses and natural sources. In contrast to the conventional extraction methods that have been employed historically, these newer approaches are meant to be more ecologically friendly. On the other hand, phytochemicals, bioactive compounds derived from plant sources, have garnered extensive interest due to their diverse health benefits and industrial applications. The efficient extraction of these phytochemicals is a fundamental step in harnessing their potential. Emerging technologies, such as supercritical fluid extraction, microwave-assisted extraction, and ultrasound-assisted extraction, instant controlled pressure drop, pressurized liquid extraction and negative pressure cavitation have demonstrated improved yields, reduced solvent usage and enhanced sustainability. The integration of phytochemical extraction with biorefinery concepts further showcases the potential for circular economy approaches and zero-waste valorization of plant biomass. The review explores recent advancements in phytochemical extraction, highlighting their impact on human health, environmental sustainability, and industrial applications. It provides a critical analysis of current green extraction procedures in natural product chemistry, aimed at providing insights into strategies to improve both extraction efficiency and eco-sustainability, including innovative techniques, emerging solvents and sustainable approaches. Description: https://doi.org/10.1016/j.sciaf.2024.e02509

2025-03-01T00:00:00Z Khao, Tsholofelo Gembo, Robert O. Odisitse, Sebusi King'ondu, Cecil K. https://repository.seku.ac.ke/handle/123456789/8298 2026-03-12T08:25:37Z 2025-04-01T00:00:00Z

Title: Fabrication of ZnO nanoparticles using marula (Sclerocarya birrea) leaf extract for catalytic degradation of rhodamine 6 G and methylene blue dyes under UV light irradiation Authors: Khao, Tsholofelo; Gembo, Robert O.; Odisitse, Sebusi; King'ondu, Cecil K. Abstract: This study investigated the synthesis of zinc oxide nanoparticles (ZnO NPs) using marula leaf extract. Boiling water was used to extract the active marula ingredients, which were then processed hydrothermally with zinc precursor to synthesize ZnO NPs. Under UV light irradiation, the produced ZnO NPs were used to simultaneously degrade two dyes: methylene blue (MB) and rhodamine 6 G (R6G) in a binary dye mixture. The XRD analysis showed that pure and crystalline structures of ZnO NPs were fully formed after calcination at 350 ℃. Raman spectroscopy was employed to determine the materials’ molecular functional groups using the fingerprint regions on the spectra. The distinctive peaks at 318, 429, and 566 cm−1 were used to identify ZnO NPs. SEM showed that ZnO NPs had both sphere-like and agglomerated nanorod structures and BET analysis showed that the ZnO materials had a an average pore size of 2818.35 (Å) with a pore volume of 0.008846 cm3/g and a surface area of 21.29 ± 0.07 m2/g. CT350-ZnO NPs afforded simultaneous MB and R6G degradation efficiencies of 99 and 98 %, respectively, after a time interval of 75 min. The degradation efficiency increased with the catalyst amount, contact time, and reaction temperature and decreased as the original concentration was raised. This study shows that ZnO NPs have a great deal of promise for environmental and public health protection because of their high effectiveness in degrading binary dye combinations when exposed to UV light. Description: https://doi.org/10.1016/j.nxmate.2024.100366

2025-04-01T00:00:00Z Mungwari, Chakanaka P. Obadele, Babatunde A. King'ondu, Cecil K. https://repository.seku.ac.ke/handle/123456789/8297 2026-03-12T08:04:36Z 2025-09-01T00:00:00Z

Title: Application of response surface methodology (RSM) and artificial neural network (ANN) for bioactive compounds recovery from mimosa wattle tree (Acacia Mearnsii) bark using ultrasound-assisted extraction Authors: Mungwari, Chakanaka P.; Obadele, Babatunde A.; King'ondu, Cecil K. Abstract: Mimosa Wattle tree bark (MWTB) is a rich source of bioactive compounds known for their corrosion inhibition, medicinal properties, and use in leather tanning. The current study focuses on optimization of process parameters for extraction of these phytochemicals using ultrasound-assisted extraction (UAE), with the help of response surface methodology (RSM) and artificial neural network (ANN). The extraction process was optimized by varying three key factors: temperature (30–70 °C), extraction time (10–60 min), and solvent-to-solid ratio (0.075–0.125 mL/g). These parameters were evaluated based on extraction yield (EY) and total phenolic content (TPC). The optimum extraction conditions were determined to be 50 °C, 35 min, and a solvent-to-solid ratio of 0.1. Under these conditions, the RSM predicted an extraction yield (EY) of 27.61 % with a TPC of value of 81.84 mg GAE/g, while the Artificial Neural Network (ANN) model predicted a yield of 26.88 % and a TPC of 83.33 mg GAE/g. A multilayer perceptron (MLP) ANN model was developed and trained using the back propagation algorithm, and the predicted values from the ANN model showed closer agreement with experimental data compared to the RSM model. Phytochemical profiling was carried out using UV–Vis and FTIR spectroscopy. Description: https://doi.org/10.1016/j.sciaf.2025.e02934

2025-09-01T00:00:00Z Mungwari, Chakanaka P. Obadele, Babatunde A. King'ondu, Cecil K. https://repository.seku.ac.ke/handle/123456789/8296 2026-03-12T07:47:22Z 2025-10-01T00:00:00Z

Title: Synergistic corrosion inhibition of 304 stainless steel in 1 M HCl by methanolic Acacia mearnsii bark extract and KI: Thermodynamic, kinetic, and thermal analysis Authors: Mungwari, Chakanaka P.; Obadele, Babatunde A.; King'ondu, Cecil K. Abstract: This study evaluates the thermodynamic behavior and adsorption mechanism of methanolic Acacia mearnsii bark extract (MAMBE) as a green corrosion inhibitor for stainless steel (SS304) in synergy with KI in 1 M HCl solution. Using weight loss measurements, thermodynamic calculations, and adsorption studies, the study assesses both the individual and combined effectiveness of MAMBE and potassium iodide (KI). MAMBE alone achieved a maximum inhibition efficiency of 62.2 % at 1.2 g/L, which dramatically increased to 98.2% when supplemented with 0.3 g/L KI, indicating a strong synergistic effect (s > 1). Thermodynamic parameters, including activation energy (Ea), enthalpy change (ΔH°), entropy change (ΔS°), and Gibbs free energy change (ΔG°), were analyzed to understand the nature of adsorption and spontaneity. MAMBE and KI alone showed Ea values below 80 kJ/mol with positive ΔH°, indicating endothermic adsorption. The MAMBE and KI combination presented a higher Ea of 105 kJ/mol, suggesting a more robust corrosion barrier. The ΔG° values (-6.653 to −21.765 kJ/mol) confirmed spontaneous, predominantly physical adsorption. Adsorption followed the Langmuir isotherm model, and thermogravimetric analysis revealed MAMBE's thermal stability up to 110°C, highlighting its excellent thermal resistance and potential as an effective eco-friendly corrosion inhibitor. Description: https://doi.org/10.1016/j.ctta.2025.100233

2025-10-01T00:00:00Z