Browsing by Author "Kapiamba, Kashala Fabrice"

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    Synthesis of bimetallic FeMn nanoparticles using rooibos tea extract: characterization and application
    (Springer, 2023) Böke, Nuran; Kapiamba, Kashala Fabrice; Kimpiab, Elyse
    Bimetallic FeMn nanoparticles based on a ferromanganese wad were successfully synthesized employing an entirely green approach. South African rooibos tea (RTea) extract was used as an environmentally friendly reducing and capping agent for preparing the Fe and Mn nanoparticles (nFeMn). The obtained nFeMn suspension and freeze-dried RTea capped nFeMn powder were characterized using several techniques. Elemental analysis conducted using XRF combined with ICP analysis revealed a metallic loading of 1.08 wt% of Fe and 0.25 wt% of Mn. The ultraviolet–visible spectroscopy (UV–vis) showed a broad shoulder in the UV region where the peaks of RTea and FeMn are located, implying bond formation during the reaction between RTea polyphenols and nFeMn. TEM analysis depicted a core–shell architecture for the nFeMn with an average size of 20 nm while the FTIR revealed that specific peaks observed in the spectrum of RTea extract were visible on that of the nFeMn powder, indicating the capping of nFeMn particles by the RTea extract. Finally, the reactivity of nFeMn powder as a Fenton-like reagent was probed for the decoloration of methylene blue (MB) from an aqueous solution. Fenton-like oxidation of MB followed a pseudo-first-order reaction kinetics with a rate constant of 0.23 A− 1 min− 1. The results showed that nFeMn removed MB dye with an efficiency of over 95% in the MB concentration range of 50–250 mg/L. Overall, the finding herein is unique because we directly used readily available raw material as a source of metals and a safe, practical reagent to prepare bimetallic FeMn nanoparticles that can be used to remove the color from dye wastewater, thus, creating a circular green process.
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    Synthesis of stabilized iron nanoparticles from acid mine drainage and Rooibos tea for application as a Fenton-like catalyst
    (American Chemical Society, 2022) Kimpiab, Elyse; Kapiamba, Kashala Fabrice; Petrik, Leslie
    Intensive mining activities generate toxic acid mine drainage (AMD) effluents containing a high concentration of metals, including iron. The chemical synthesis of iron nanoparticles from this waste could lead to further environmental concerns. Therefore, the green synthesis of nanoparticles using plants has gained significant interest because of several benefits, including being eco-friendly. The current study reports a novel approach involving the synthesis of stabilized iron nanoparticles from AMD using rooibos tea extract. An aqueous solution of rooibos tea was prepared and titrated with AMD to reduce Fe2+/Fe3+. The samples synthesized under optimum conditions were characterized by TEM, XRD, FTIR, UV−Vis, and EDS. The results revealed that the nanoparticles had an average particle size of 36 nm with a spherical shape. These particles showed promising application as a Fentonlike catalyst for the degradation of textile dye (orange II sodium salt) with a removal efficiency of 94% within 30 min. Thus, the stabilized iron nanoparticles synthesized here performed in higher ranges than the currently reported Fenton-like catalysts regarding dye removal efficiency and reaction time.