Browsing by Author "Abrokwah, R.Y."
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Item Synthesis and characterisation of zeolite-A and Zn-exchanged zeolite-A based on natural aluminosilicates and their potential applications(Cogent Engineering, 2018-03) Nyankson, E.; Efavi, J.K.; Yaya, A.; Manu, G.; Asare, K.; Daafuor, J.; Abrokwah, R.Y.Zeolites have been hydrothermally synthesized using alumina and silica based deposits (kaolin, bauxite, silica and feldspar) sampled from three regions in Ghana and the chemical compositions of the zeolites varied by batch formulations. The as-synthesized zeolites were characterized using X-ray Diffraction, Fourier Transform Infra-Red and Porosimetry techniques. The morphology and elemental compositions were examined using Scanning Electron Microscopy and energy dispersive X-ray spectroscopy (EDX). The results indicate that zeolite A was formed with a cubic structure and structural variations depending on the batch formulations. By increasing the silica content (Si/Al ratio) through batch formulations, the crystallite sizes of zeolites increased forming Zeolite A with LTA structure and Zeolite A (K-exchanged dehydrated). Samples with higher alumina content produced Zeolite A (Hydrated), Zeolite-Na and Zeolite A (Na, Dehydrated) with lower crystallite sizes. The zeolite synthesized was then used in the synthesis of zinc exchanged Zeolite A (Zn-zeolite A). EDX analysis confirmed a complete exchange of Na in the Zeolite framework with Zn and the feasibility as an adsorbent for methylene blue tested. The synthesized Zn-exchanged Zeolite A showed strong adsorption for methylene blue dye. The adsorption kinetics of the MB onto Zn-exchanged Zeolite A was observed to follow pseudo-second-order model. Freundlich model better described the interaction among adsorbate molecules onto the Zn-exchanged Zeolite A adsorbent, suggesting a multilayer distribution of adsorbate molecules with some level of interaction between adsorbed molecules. The regeneration capacity of the adsorbent was low and calculated to be about 48% at pH of 12. © 2018 The Author(s). This open access article is distributed under a Creative Commons Attribution (CC-BY) 4.0 license.Item Synthesis and Kinetic Adsorption Characteristics of Zeolite / CeO2 Nanocomposite(Scientific African, 2019-11-23) Nyankson, E.; Adjasoo, J.; Efavi, J.K.; Yaya, A.; Manu, G.; Kingsford, A.; Abrokwah, R.Y.Adsorption is an effective method for treating polluted water bodies. In this study, Zeolite/Cerium oxide nanocomposite (Z/CeO2-NC) was hydrothermally synthesize and its adsorption capacity on methylene blue organic dye (MB) studied. The as-synthesized nanocomposite (Z/CeO2–NC) were characterized using X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FT-IR), Energy Dispersive X-Ray Spectroscopy (EDX) and Scanning Electron Microscopy (SEM). Kinetic models and sorption isotherms were used to predict the adsorption rate constants and process mechanisms. The synthesized Z/CeO2-NC showed an excellent adsorption kinetics of methylene blue and the characteristics of adsorption best fitted a pseudo-second-order model. The rate parameters of other models were evaluated and compared to establish the adsorption mechanisms. The Langmuir isotherm model best fitted the adsorption process indicating a homogeneous monolayer of the dye on the surface of the adsorbent. The thermodynamic Gibbs free energy (ΔG) parameter was determined to be negative, indicating a spontaneous adsorption process. The synthesized Z/CeO2-NCs showed strong adsorption for methylene blue dye with increasing amount of CeO2. The maximum adsorption efficiency was calculated as 93.9% and the maximum regeneration efficiency of the adsorbent was found to be 78.8% higher after it had been washed by alkaline solution of pH 13. The results reflect the feasibility of the nanocomposite as an adsorbent with a potential application in wastewater treatment technologies.