Theses and Dissertation

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Browsing Theses and Dissertation by Author "Mng’onya, Angel"

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    Development And Evaluation Of Agricultural Wastes As Alternative Binders For Coconut Husk-Based Bio-Briquettes
    (NM-AIST, 2025-10) Mng’onya, Angel
    Excessive reliance on traditional energy sources in many African nations has significantly contributed to deforestation and increased carbon emissions. Agricultural waste offers a promising alternative to traditional energies, However, there is limited available information on the effectiveness and comparison of these materials as a raw materials and binder in the production of bio-briquettes. In this study, briquettes were produced using carbonized coconut husks with potato, cassava and banana peels serving as binders. For each binder type, three binder-to-char ratios were used: 80:20, 70:30 and 60:40. The briquettes were then evaluated for their combustion and mechanical properties. Briquettes bound with potato peels for a ratio had a higher calorific value, ranging from 28.563 ± 0.172 MJ/kg to 25.177 ± 0.23 MJ/kg while briquette bound with banana peels had lower calorific values ranging from 26.495 ± 0.464 MJ/kg to 24.375 ± 0.507 MJ/kg. Among them, briquettes prepared with potato peel binders exhibited the highest impact resistance, measuring 96.55%, 96.43% and 95.26% for binder-to biomass ratios of 80:20, 70:30 and 60:40, respectively. In comparison, briquettes bound with cassava peels demonstrated moderate impact resistance, increasing to 87.71% at a 60:40 binder-to-biomass ratio. Conversely, banana peel binders showed the lowest impact resistance, with a maximum value of 76.72%. A similar pattern was observed for abrasion resistance: potato peel-bound briquettes reached up to 88.69% at the 60:40 ratio, whereas those with banana peel binders exhibited the lowest abrasion resistance of 70.09% at the same ratio. Water penetration resistance improved as binder concentration increased, potato peel-bound briquettes attained 79.82% resistance at 60:40, while briquettes with cassava and banana peel binders completely disintegrated at the 80:20 ratio. Ignition times ranged from 1.9 ± 0.3 to 3.6 ± 0.32 minutes, with briquettes bound using potato peel at an 80:20 ratio exhibiting the shortest ignition time. Both the burning rate and water boiling time were influenced by the density of the bio-briquettes, varying between 0.03 ± 0.003 and 0.08 ± 0.043 g/s, and 11.67 ± 0.58 to 17.67 ± 1.15 minutes, respectively. Overall, the findings demonstrate that agricultural waste can serve as an effective binder in briquette production, promoting sustainable energy use in households. This study contributes to renewable energy innovation, waste valorization and climate change mitigation by promoting sustainable alternatives to traditional biomass energy.