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Item Optimization of pyrolysis conditions for production of rice husk-based bio-oil as an energy carrier(Elsevier, 2023-11-09) Wakatuntu, Joel; Olupot, Peter Wilberforce; Jjagwe, Joseph; Menya, Emmanuel; Okure, MackayBio-oil is an eco-friendly energy source with potential to substitute fossil-derived fuels. This study optimized pyrolysis conditions for production of bio-oil from rice husks. Response surface methodology based on central composite design was employed to maximize bio-oil yield and high heating value (HHV) while minimizing water and ash contents. The pyrolysis process conditions were; temperature (400–650 ◦C), heating rate (6000–9750 ◦Ch-1), and holding time (600–1800 s). Analysis of variance revealed that the linear model best fits the responses of bio-oil yield and water content. On the other hand, the quadratic model best fits the responses of HHV and ash content. Pyrolysis temperature had the greatest influence on each of the studied responses, followed by holding time and lastly heating rate. Optimum pyrolysis conditions were found to be; temperature (650 ◦C), heating rate (9750 ◦Ch-1), and holding time (1800 s), leading to bio-oil yield, HHV, water, and ash contents of 38.13%, 23.40 MJ/kg, 18.27%db, and 0.16%db, respectively. These results fall in the range of standard quality values for bio-oil in published literature where >15 MJ/kg, 20–30%, 0.15–0.25% are the recommended ranges for HHV, water, and ash contents, respectively. Results from the FTIR spectroscopy revealed that phenolic compounds contributed the most to bio-oil composition. Phenolic compounds positively influenced the quality of bio-oil due to their high calorific values. Gas chromatograph and mass spectrometry results showed peaks continuing to spill up to the maximum retention time indicating good thermal stability and bio-oil quality.Item Effects of sawdust and adhesive type on the properties of rice husk particleboards(Elsevier, 2022-11-17) Olupot, Peter Wilberforce; Menya, Emmanuel; Lubwama, Festo; Ssekaluvu, Lawrence; Nabuuma, Betty; Wakatuntu, JoelThis study set out to investigate the effects of adhesive type, rice husk and sawdust proportions on the properties of composite particleboards. Specimens of 200 × 200 × 24 mm were made by blending 500 g of rice husks with each adhesive type at a mass ratio of 1:1. The rest of the specimens of similar dimensions were prepared with addition of sawdust in the range of 10–40 wt%, while maintaining the ratio of biomass particles to adhesive at 1:1. Three commercial synthetic adhesives Fevicol (FV), Ponal (PA) and woodfix (WF) were used. The particle adhesive mixtures were molded into a mat which was subsequently cold pressed at 10 MPa and left to dry in air. Density, water absorption (WA), linear expansion (LE), thickness swelling (TS), modulus of elasticity (MOE), modulus of rupture (MOR) and screw holding capacity of the specimens were evaluated. Adhesives were found to have over 42% solid content, with similar liquid constituents but in varying proportions. FTIR library search for the spectra of FV, PA, and WF revealed correlations of 82.5%, 78.6%, and 50.2%, respectively with polyvinyl acetate. The developed boards had a density of 510–610 kg/m3, MOE 13–26 MPa, TS 9–31%, and LE 3–7%. These properties suit them for furniture boards and soundproofing. The properties improved with the increasing proportion of sawdust. FV and PA-bonded particleboards exhibited higher stability and strengths than WF-bonded particleboards due to higher concentrations of polyvinyl-acetate in the latter. Blending 40 wt% sawdust, 10 wt% rice husk with 50 wt% of either FV or PA showed better prospects.