Department of Mechanical Engineering

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Start date: 2023Subject: search.filters.subject.Technology

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    Inhibition potential of silver-gold nanoparticles on mild steel in 3.5% NaCl solution
    (Engineering and Applied Science Research, 2023-01-01) Peter Pelumi Ikubanni; Adekunle Akanni Adeleke; Jamiu Kolawole Odusote; Tesleem B. Asafa; Sharafadeen K. Kolawole; Victor O. Ogbesanya; Jude A. Okolie
    This study investigates the corrosion behaviour of silver-gold nanoparticles as an inhibitor on the degradation of mild steel in 3.5% NaCl (saline environment) using gravimetric analysis and potentiodynamic measurement. The inhibitor Ag-AuNPs was synthesized from Kola nut pod. Five different concentrations of the Ag-AuNPs solution (0, 5, 10, and 20 μg/ml) were added to the saline environment. The gravimetric result showed that inhibition efficiency of 83.33% was the highest at 20 μg/ml of Ag-AuNPs inhibitor concentration. The Tafel polarization result showed that the solution with 20 μg/ml of Ag-AuNPs had the highest inhibition efficiency of 99.465%. At 0 μg/ml of Ag-AuNps, the surface morphologies of the mild steel sample did not show the existence of Ag-AuNps constituent in the saline environment containing the nanoparticles. The outcome showed that the saline environment with 15 and 20 μg/ml of Ag-AuNPs could successfully limit the corrosion of the mild steel.
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    Production of bioplastic films from wild cocoyam (Caladium bicolor) starch
    (Elsevier, 2024-10-15) Chinaza Enwere; Ikechukwu Okafor; Adekunle Akanni Adeleke; Petrus Nzerem; Khaleel Jakada; Adebayo Isaac Olosho; Peter Pelumi Ikubanni; Prabhu Paramasivam; Ayuba Salihu
    This study tackles the pressing environmental challenges resulting from the rapid and ongoing use of conventional plastics by investigating biodegradable alternatives derived from wild cocoyam starch. The bioplastics developed from various formulations, incorporating gelatin, glycerine, vegetable oil, and vinegar, were systematically evaluated for their mechanical, chemical, microstructural and biodegradability properties. The addition of glycerine and gelatin enhanced the moisture content and flexibility of the films while vegetable oil improved water resistance, reducing water absorption. Th sample that contains 3 g of gelatin and 3 ml of glycerine exhibited the best overall performance with a tensile strength of 6.5 MPa and an elongation at break of 77 %. This sample also achieved an impressive biodegradation rate of 70 % within 7 days. Scanning Electron Microscopy revealed a uniform and smooth morphology, while Fourier Transform Infrared Spectroscopy confirmed the presence of key functional groups responsible for the material's performance. These results establish wild cocoyam starch as a promising resource for producing biodegradable bioplastics with considerable potential in various industries, particularly in packaging and agricultural applications. The excellent mechanical properties and biodegradability of the materials along with its natural abundance, offer an eco-friendly solution to the plastic waste problem. The study also opens new avenues for optimizing bioplastic formulations to enhance specific properties like thermal stability and moisture resistance, further broadening their practical applications. This research contributes to the sustainable materials landscape and represents a step toward reducing reliance on fossil-based plastics, advancing the global effort to mitigate environmental pollution.
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    Scanning and transmission electron microscopy examinations of composite hybrid chromate and chromate phosphate conversion coatings exposed in hot 100% relative humidity environments
    (Elsevier, 2023-07-20) Peter Pelumi Ikubanni; Makanjuola Oki; Adesoji A. Adediran; Sarah A. Akintola; Adekunle Akanni Adeleke
    Conversion coatings are sine qua non in the finishing of aluminium alloys. They may be put into service without coating of paints. However, for aesthetics in architectural applications, paint overcoat is common. Chromate phosphate coatings are relatively less toxic than chromate which gained the pride of place until recently. Thus, aluminium specimens coated with hybrid chromate/phosphate conversion coatings have been subjected to 100% relative humidity for 480 h at 313K in comparison to chromate coatings and bare aluminium. Scanning electron microscopy examination revealed that initial dried river bed morphologies on coated specimens were obliterated. The friable outer coatings collapsed into the cracks/environment leaving a relatively smooth surface after exposure. Additionally, transmission electron microscopy of sections before and after exposure revealed similar texture and morphological striations nearly parallel to each other throughout the length of the coatings to the metal/coating interface. These were not disrupted as well as the metal/coating interface which remained relatively smooth with no visible corrosion products after exposure. Thus, the coatings formed effective barrier between the substrate and the relatively harsh environment. From EDS, elemental compositions were the same albeit, spectral intensities remained relatively constant after humidity exposure regimes. The coatings are made up of either Cr, O and Al for chromate and Cr, P, O and Al for chromate/phosphate. At deliberately breached regions, the coatings prevented spread of corrosion and paint delamination over the substrates. On the other hand, bare aluminium was decorated with mounds of hydrated aluminium oxide/hydroxide after exposure as revealed in the SEM/TEM.