Browsing by Author "Matthews, Tatum"

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    Biogenic silica derived from sugarcane bagasse as a precursor material for unmodified SBA-15: physicochemical properties and their use in biodiesel production from spent oil
    (John Wiley and Sons Ltd, 2025) Matthews, Tatum; Seroka, Ntalane Sello; Khotseng, Lindiwe
    Sustainable energy production requires innovative approaches to decrease the dependence on nonrenewable resources and reduce environmental impacts. In this proof-of-concept study, we investigated green Santa Barbara Amorphous 15 (SBA-15) catalysts using sugarcane bagasse ash (SCBA) as a silica source and incorporating organic acids and bases to create an eco-friendly synthesis pathway. These catalysts were applied in the transesterification of waste sunflower oil (WSO) to produce biodiesel. Although the overall biodiesel yields were relatively low, peaking at 5.603% FAME with the L-cysteine-modified SBA-15 catalyst (Lcys-500), the main objective of this study was to establish the feasibility of employing green SBA-15 materials as effective catalysts, rather than to optimise reaction parameters or maximise yield. Catalyst characterisation was carried out using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA), confirming that the green SBA-15 retained key structural properties of conventional SBA-15, including ordered mesoporosity (p6mm symmetry) and spherical morphology with some variation in pore structure and thermal behaviour. Gas chromatography–mass spectrometry (GC–MS) was employed solely for biodiesel product analysis. FTIR spectra of the biodiesel confirmed successful transesterification, as indicated by characteristic C=O and C–O stretching bands. However, issues such as solidification of the CA-500-derived biodiesel and the low yield from the OP-after calcination sample (0.178%) underscore the need for further refinement. Importantly, catalyst modification strategies, such as surface functionalisation or metal doping, were beyond the scope of this initial study. Overall, the results support the feasibility of producing functional mesoporous SBA-15 catalysts from agricultural waste through green chemistry approaches. This study lays the groundwork for the development of environmentally friendly silica-based catalysts, with future research focussed on surface functionalisation to improve catalytic performance ecologically.