Browsing by Author "Awudza, Johannes A. M."

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    Growth Kinetics of Zinc Sulphide Nanocrystals Synthesized by Colloidal Thermolysis of Fatty Acid Carboxylates
    (Hindawi, 2022) Mensah, Michael Baah; Boadi, Nathaniel O.; Awudza, Johannes A. M.; 0000-0002-8080-4812
    Zinc sulphide (ZnS) is an important semiconductor with widespread electronic and catalytic applications. e growth kinetics of ZnS nanocrystals synthesized by the thermal decomposition of zinc ricinoleate carboxylates in an oleylamine:dodecanethiol (1 :1) solvent mixture isreported. Crystalline sphalerite ZnS nanocrystals with quantum dot sizes of 2.3–5.3 nm were obtained at temperatures higher than 240° C. e p-XRD patterns showed a clear relationship between the crystallite sizes and the peak broadness at a temperature range of 250–300°C. e optical bandgap energies of the ZnS nanocrystals reduced from 4.27 eV to 3.73 eV as the time of reaction increased from 20 to 60 min at 250°C. e activation energy for the growth kinetics of the ZnS nanocrystals was determined to be 36.24 kJ/mol which compares closely to those reported in the literature for aqueous systems.
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    Heavy metal pollution and the role of inorganic nanomaterials in environmental remediation
    (Royal Science Society, 2021) Mensah, Michael Baah; Lewis, David J.; Boadi, Nathaniel O.; Awudza, Johannes A. M.; 0000-0002-8080-4812
    Contamination of water and soil with toxic heavy metals is a major threat to human health. Although extensive work has been performed on reporting heavy metal pollutions globally, there are limited review articles on addressing this pernicious phenomenon. This paper reviews inorganic nanoparticles and provides a framework for their qualities required as good nanoadsorbents for efficient removal of heavy metals from water. Different inorganic nanoparticles including metals, metal oxides and metal sulfides nanoparticles have been applied as nanoadsorbents to successfully treat water with high contaminations of heavy metals at concentrations greater than 100 mg l−1 , achieving high adsorption capacities up to 3449 mg g−1 . It has been identified that the synthesis method, selectivity, stability, regeneration and reusability, and adsorbent separation from solution are critical parameters in deciding on the quality of inorganic nanoadsorbents. Surface functionalized nanoadsorbents were found to possess high selectivity and capacity for heavy metals removal from water even at a very low adsorbent dosage of less than 2 g l−1, which makes them better than conventional adsorbents in environmental remediation