Browsing by Author "Njagi, Eric"

Now showing 1 - 5 of 5

ADSORPTION OF LEAD (II) IONS FROM AQUEOUS SOLUTIONS USING MANGROVE ROOTS (Rhizophora mucronata) CHARCOAL-CARBON NANOTUBES NANOCOMPOSITE
(Chuka University, 2021) Ngugi, Fidelis; Mwangi, Joel; Njagi, Eric
Providing clean and affordable water to meet human needs is a grand challenge of the 21st century. Worldwide, water supply struggles to keep up with the fast growing demand, which is exacerbated by population growth, global climate change, and water quality deterioration. Nanotechnology holds great potential in advancing water treatment to improve water treatment efficiency. In this study, Mangrove Roots Charcoal and Carbon Nanotubes (MRC- CNTs) nanocomposite was synthesized and utilized as a novel adsorbent for the removal of lead ions from aqueous solutions. The efficacy of MRC-CNT nanocomposites was investigated in batch mode which involved the effects of pH, temperature, concentration of the lead ions, adsorbent mass and contact time on adsorbates removal. Characterization of the adsorbent was carried out by Scanning Electron Microscopy (SEM) to observe the morphology of the adsorbent and surface area analysis and Energy Dispersive X-ray spectroscopy (EDX) to determine the elemental composition of the adsorbent. Adsorption isotherm models and adsorption kinetic studies were used for data analysis. It was observed that the removal efficiency of Pb (II) ions depended on pH of solution and the maximum efficiency was noticed at pH 7 with adsorption capacity of 3.629 mg/g which was calculated by the Freundlich isotherm model. Kinetic studies were well suited and found in good agreement with pseudo-second order. The results indicated that MRC-CNT nanocomposites would be a promising adsorbent for adsorption of Pb (II) ions from aqueous solutions.
Adsorption of Lead (II) Ions from Aqueous Solutions Using Mangroves Roots (Rhizophora Mucronata) Charcoal-Carbon Nanotubes Nanocomposite
(Journal of Multidisciplinary Engineering Science and Technology (JMEST), 2021) Ngugi, Fidelis; Mwangi, Joel; Njagi, Eric; Ombaka, Ochieng
Providing clean and affordable water to meet human needs is a grand challenge of the 21st century. Worldwide, water supply struggles to keep up with the fast growing demand, which is exacerbated by population growth, global climate change, and water quality deterioration. Nanotechnology holds great potential in advancing water treatment to improve water treatment efficiency. In this study, Mangrove Roots Charcoal and Carbon Nanotubes (MRCCNTs) nanocomposite was synthesized and utilized as a novel adsorbent for the removal of lead ions from aqueous solutions. The efficacy of MRC-CNT nanocomposites was investigated in batch mode which involved the effects of pH, temperature, concentration of the lead ions, adsorbent mass and contact time on adsorbates removal. Characterization of the adsorbent was carried out by Scanning Electron Microscopy (SEM) to observe the morphology of the adsorbent and surface area analysis and Energy Dispersive X-ray spectroscopy (EDX) to determine the elemental composition of the adsorbent. Adsorption isotherm models and adsorption kinetic studies were used for data analysis. It was observed that the removal efficiency of Pb (II) ions depended on pH of solution and the maximum efficiency was noticed at pH 7 with adsorption capacity of 3.629 mg/g which was calculated by the Freundlich isotherm model. Kinetic studies were well suited and found in good agreement with pseudo-second order. The results indicated that MRC-CNT nanocomposites would be a promising adsorbent for adsorption of Pb (II) ions from aqueous solutions.
Adsorption of rhodamine b from aqueous solution using mangroves (Rhizophora mucronata) carbon nanotubes nanocomposites
(www.allsubjectjournal.com, 2021) Ngugi, Fidelis; Mwangi, Joel; Njagi, Eric; Ombaka, Ochieng
The use of dyes has increased dramatically and uncontrollably in last few decades. Different types of dyes are frequently employed in plastics, paper, cosmetics, leather, and textile industries for coloring purposes. These dyes are released in water as effluents, which are of low Biological Oxygen Demand (BOD) and high Chemical Oxygen Demand (COD). Some of these dyes also are toxic and carcinogenic in nature. This study report on the synthesis of Mangroves Roots-Carbon Nanotubes (MRC-CNT) nanocomposite as an adsorbent for efficient removal of Rhodamine B (Rh. B) dye from aqueous solution. Effect of contact time, initial concentration of dye, pH, and shaking speed on adsorption behavior were systematically investigated. The data obtained were fitted into Langmuir, Freundlich, Dubinin-Rudishkevich (D-R), and Temkin adsorption isotherm models for evaluation of adsorption parameters. The results indicated that MRC-CNT nanocomposite would be a promising adsorbent for adsorption of Rh. B from aqueous solutions.
Facile one-step template-free synthesis of uniform hollow microstructures of cryptomelane-type manganese oxide K-OMS-2
(2010-08) Galindo, Hugo M.; Carvajal, Yadira; Njagi, Eric
Hollow microstructures of cryptomelane-type manganese oxide were produced in a template-free one-step process based on the fine-tuning of the oxidation rate of manganese species during the synthesis. The tuning of the reaction rate brought about by a mixture of the oxidants oxone and potassium nitrate becomes apparent from the gradual physical changes taking place in the reaction medium at early times of the synthesis. The successful synthesis of the hollow uniform structures could be performed in the ranges 120-160 degrees C and 8.2-10.7 for temperature and mass ratio oxone/potassium nitrate, respectively. Independent of the conditions of the synthesis, all of the complex microstructures showed the same pattern for the array of very long nanofibers in which some of these elongated around the surface confining the cavity and the other fibers grew normal to the surface created by the previous arrangement. A mechanism based on the heterogeneous nucleation of the cryptomelane phase on the surface of an amorphous precursor and the growth of the nanoscale fibers by processes such as dissolution-crystallization and lateral attachment of primary nanocrystalline fibers is proposed to explain the formation of the hollow structures.
A review of green synthesis of nanophase inorganic materials for green chemistry applications.
(2012-04-15) Genuino, Homer; Huang, Hui; Njagi, Eric; Stafford, Lisa; Suib, Steven L.
The sections in this article are Introduction Green Synthesis of Nanophase Inorganic Materials Metal Oxide Nanoparticles Hydrothermal Synthesis Reflux Synthesis Microwave‐Assisted Synthesis Green Synthesis of Metallic Nanoparticles Green Chemistry Applications of Inorganic Nanomaterials Manganese Oxides Titanium Dioxide Environmental Applications of Nanomaterials Background Titanium Dioxide Nanomaterials Zinc Oxide Nanomaterials Iron‐Based Nanomaterials Conclusion and Future Perspectives Acknowledgment