Programme: Industrial Chemistry

Permanent URI for this collectionhttp://itsupport.cu.edu.ng:4000/handle/123456789/28781

Here you will find works strictly related to Industrial Chemistry.

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Author: search.filters.author.Covenant University, Dissertation

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    SYNTHESIS OF Cu–Mn–S TERNARY METAL CHALCOGENIDE QUANTUM DOTS AS POTENTIAL HIGH-PERFORMANCE OPTICAL NANOSENSORS
    (Covenant University, Ota, 2026-07) LASISI, Bolatito Lateefat; Covenant University, Dissertation
    The detection of environmentally relevant pollutants and biomedical biomarkers by traditional analytical techniques is often time-consuming, invasive, and insufficiently sensitive, underscoring the need for advanced optical nanosensor materials. In this study, the synthesis and characterisation of ternary metal chalcogenide quantum dots (TMC-QDs) of Cu-Mn-S were carried out as candidate materials for advanced optical nanosensors in environmental and biomedical applications. Eight Cu-Mn-S QDs (TMC-1 to TMC-8) were successfully synthesised via the modified solvothermal method. CuCl2, Mn(CH3COO)2, and thiourea were employed as precursors and sulfur source, respectively, in a 1:1 deionised water/ethylene glycol solvent, with two stoichiometries (CuMn2S2 and CuMn1.7S2), three varied temperatures (180 to 190 °C), and two reaction times (10 and 12 hrs). The synthesised QDs were characterised. The UV-Vis absorption measurements revealed a controllable wavelength range from 205 nm to 556 nm and visible-region excitonic absorption, indicating the optical activity of the CuS sub-phase in the samples at low temperatures. The XRD pattern of the resultant particles showed crystalline QDs with particle sizes ranging from 14.97 to 16.19 nm. The product is found to be of a single hexagonal CuS covellite phase except for TMC-6 and TMC-7, which are binary composites of hexagonal CuS covellite and cubic MnS alabandite. FTIR confirmed the presence of both phases, with CuS and MnS stretching. Thus, this work established, for the first time, the synthesis of ternary metal chalcogenide Cu-Mn-S QDs with controlled structural and optical properties. The ternary system conditions for phase segregation of a dual CuS covellite and α-MnS alabandite composite were also found to depend on reaction temperature and time, rather than just the stoichiometric ratio.
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    COMBUSTION PERFORMANCE OF PALM KERNEL SHELL BIOCHAR BRIQUETTE MODIFIED WITH ACID-LEACHED NEEM LEAF ASH
    (Covenant University, Ota, 2026) ADEYEYE, PEACE IFEOLUWA; Covenant University, Dissertation
    Wood fuel contributes significantly to air pollution and deforestation. Agro-waste briquetting as solid fuel has emerged to reduce the burden on forest resources, but its adoption is hindered by poor combustion performance and high pollutant emissions. This study developed biomass briquettes from Palm Kernel Shell (PKS) biochar modified with Acid-Leached Neem Leaf Ash (ALNLA) and rendered beef tallow. This is to target improved combustion efficiency and reduced harmful emissions, for household cookstove applications. Neem leaves were calcined at 750°C and then leached with 2M HCl at 45°C for 2 hours, thereby achieving a leachability percentage of 91.24% and producing a silica-enriched residue (SiO₂ = 57.86 wt%; Fe₂O₃ = 8.20 wt%; CaO = 7.52 wt%). PKS biochar was produced by slow pyrolysis at 550°C. Six briquette formulations (B1–B6) were prepared and characterized using XRF, FT-IR, XRD, TGA, and proximate analysis. Water boiling test (WBT), and measurement of burn duration, combustion temperature and some Toxic Air Pollutants (TAP) (CO, SO₂, NO₂ and particulate matter) emission, heating value and fixed carbon, were carried out. All formulations outperformed commercial charcoal in burn duration by factors of 1.97 – 4.02%. Formulation B6 (90% biochar, 1.0% ALNLA, 10% starch) achieved the longest burn duration (378 minutes), highest combustion temperature (1109°C), and lowest stabilized TAP emissions. Formulation B5 recorded the highest estimated higher heating value (5.78 MJ/kg) and fixed carbon (15.59%). These results demonstrate the viability of acid-leached neem leaf ash as a low-cost, waste-derived modifier for producing cleaner-burning briquettes suited to Sub-Saharan African household energy needs.