Browsing by Author "Amedalor, R."
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Item Ag2CO3-halloysite nanotubes composite with enhanced removal efficiency for water soluble dyes(Heliyon, 2019-06-13) Nyankson, E.; Agyei-Tuffour, B.; Annan, E.; Yaya, A.; Mensah, B.; Onwona-Agyeman, B.; Amedalor, R.; Kwaku-Frimpong, B.The release of water soluble dyes into the environment is an utmost concern in many countries. This paper presents the effects of Ag2CO3-halloysite composites on the efficient removal of water soluble dyes. In this study, NaHCO3 solution was added dropwisely to halloysite nanotubes (HNTs) dispersed in aqueous AgNO3 to form Ag2CO3-HNTs composite. The synthesized Ag2CO3-HNTs composite was characterized with Diffused Reflectance Spectroscopy (DRS), X-ray Diffraction (XRD), Thermogravimetric analysis (TGA), Scanning Electron Microscopy- Energy Dispersive Spectroscopy (SEM-EDX) and Fourier Transform Infra-Red (FT-IR) spectroscopy. The photocatalytic activity and the adsorption capacity of Ag2CO3-HNTs on methylene blue and rhodamine b dyes were dependent on pH and the amount of HNTs used in the synthesis. The photodegradation efficiency of Ag2CO3 was lower when compared with that of the composite material. This observation is due to the reduction in the electron-hole recombination with the HNTs acting as electron trapping site and the enhanced aqueous dispersity of Ag2CO3-HNTs. The enhanced adsorption of water soluble dyes by the Ag2CO3-HNTs resulted from the electrostatic attraction of cationic dyes to the surface of the HNTs (negatively charged). The Ag2CO3-HNTs therefore removed dye pollutants through a combination of photocatalytic and adsorption processes. The results obtained during the study confirmed the potential application of Ag2CO3-HNTs composite in water treatment technologies.Item Characterization and Evaluation of Zeolite A/Fe3O4 Nanocomposite as a Potential Adsorbent for Removal of Organic Molecules from Wastewater(Journal of Chemistry, 2019-07-28) Nyankson, E.; Adjasoo, J.; Efavi, J.K.; Amedalor, R.; Yaya, A.; Manu, G.P.; Asare, K.; Amartey, N.A.In this work, zeolite (Z) and Z-Fe3O4 nanocomposite (Z-Fe3O4 NC) have been synthesized. The Fe3O4 nanoparticles were synthesized using the extract from maize leaves and ferric and ferrous chloride salts and encapsulated into the zeolite framework. The nanocomposite (Z-Fe3O4 NC) was characterized using X-ray diffractometer (XRD), Fourier-transform infrared (FT-IR) spectroscopy, energy-dispersive X-ray (EDX) spectroscopy, and scanning electron microscopy (SEM). The potential of Z-Fe3O4 NC as an adsorbent for removing methylene blue molecules (MB) from solution was examined using UV-Vis and kinetic and equilibrium isotherm models. The adsorption data fitted best with the pseudo-second-order model and Weber and Morris model, indicating that the adsorption process was chemisorption, while the Weber and Morris described the rate-controlling steps. The intraparticle diffusion model suggests that the adsorption processes were pore and surface diffusion controlled. The Langmuir isotherm model best describes the adsorption process indicating homogeneous monolayer coverage of MB molecules onto the surface of the Z-Fe3O4 NC. The maximum Langmuir adsorption capacity was 2.57 mg/g at 25°C. The maximum adsorption efficiency was 97.5%. After regeneration, the maximum adsorption efficiency achieved at a pH of 7 was 82.6%.Item Microwave- and Formaldehyde-Assisted Synthesis of Ag−Ag3PO4 with Enhanced Photocatalytic Activity for the Degradation of Rhodamine B Dye and Crude Oil Fractions(ACS Omega, 2020-06-01) Nyankson, E.; Amedalor, R.; Chandrabose, G.; Coto, M.; Krishnamurthy, S.; Kumar, R.V.The release of crude oil and water-soluble dyes into our marine environment is a major global problem. An efficient semiconductor Ag–Ag3PO4 photocatalyst was synthesized using formaldehyde as a reducing agent to form surface active Ag on Ag3PO4 under microwave radiation for heating, and its potential in destroying environmental pollutants has been examined. The diffuse reflectance spectroscopy of Ag–Ag3PO4 revealed an enhanced absorption in the visible light region. The rate of photocatalytic degradation of rhodamine B by Ag–Ag3PO4 was over 4-fold compared to Ag3PO4. The potential application of Ag–Ag3PO4 in oil spill remediation was also examined through photocatalytic degradation of benzene, n-hexane, and 1:1 v/v benzene/methanol crude oil-soluble fractions. UV–vis and gas chromatography–mass spectrometry analysis of the crude oil components after visible light irradiation showed excellent degradation. The photocatalytic efficiency enhancement of Ag–Ag3PO4 is attributed to the excellent electron trapping of silver nanoparticles deposited on the surface of Ag3PO4. This work will motivate future studies to develop recyclable visible light photocatalysts for many applicationsItem Nanowires for Photonic Applications(Taylor and Francis Group an Informa Business, 2023) Agyei-Tuffour, B.; Adzo, E.; Amedalor, R.; et al.Nanowires have the potential to be easily integrated into nanoelectronics and nanophotonic systems, which could lead to improved industry performance. Their chemical compositions, lengths, and diameters (structural properties) significantly influence their electronic and optical characteristics. Based on their applications, plasmonic and photonic devices often use dielectric and metallic nanowires. For sensing and light-emitting devices, semiconducting nanowires are used. These characteristics are due to the fact that there are quantum restrictions of the electron in nanowires, which results in inhibition in the energy levels different from in bulk materials. This chapter presents the theory, synthesis, and fabrication of nanowires for use in the photonic industry. Also presented are efforts being made to integrate nanowires as components in photonic structures while highlighting the scientific and technological challenges with their possible solutions. Finally, a projection into the future direction of nanowire application in the photonic industry is also presented and discussedItem Potential Application of Dioctyl Sodium Sulfosuccinate Salt (DOSS)–Saponin Binary Dispersant in Oil Spill Remediation: Synergistic Interaction Between DOSS and Saponin(Water, Air, & Soil Pollution, 2020-02-03) Nyankson, E.; Agyei-Tuffour, B.; Efavi, J.K.; Yaya, A.; Onwona-Agyeman, B.; Konadu, D.S.; Amedalor, R.; Frimpong, B.K.The interfacial activity of dispersants can be enhanced by combining two or more surfactants to formulate the dispersant. This paper examines the effects of Bio-Saponin (BS), a phytogenic surfactant on the interfacial activity of synthetic dioctyl sulfosuccinate sodium salt (DOSS) usually adopted as a suitable surface-active agent in dispersants used in dealing with large-scale oil spills. The o/w emulsion created with the binary DOSS-BS was very stable and recorded the least average droplet size compared with that of DOSS only and BS only. Lower surface and interfacial tension values were also obtained from the DOSS-BS binary formulation. The dispersion effectiveness was also higher compared with that of DOSS and BS. However, they were dependent on the salinity and type of crude oil. These observations were attributed to the moderation of the interaction between the anionic head group of DOSS by the polysaccharide hydrophilic group of BS. The results revealed the potential application of DOSS-BS binary dispersant in oil spill remediation and in other processes that would require an effective emulsifier.