• Energy Research

Abstract In this study, rice husk was used as a biomass raw material as a substitute for commercial silica in glass making. The mass fraction of silica in rice husk ash (RHA) derived from rice husk powder by combustion at 1000 °C for 2 h was found to be as high as 96%, comparable to that of commercial silica. To make the rice husk glass a more value-added product, the addition of green photoluminescent (PL) pigments into rice husk glass was attempted. Green PL pigment was found to withstand high temperatures while maintaining its photoluminescent properties. Experiments were performed to add the PL pigment using two different methods, namely layering and mixing techniques. For the layering technique, the PL rice husk glass was produced by spreading the PL pigment between two layers of casted rice husk glass, resulting in a sandwich-like structure. On the other hand, through the mixing technique, the PL pigment was mixed directly into the molten glass. PL rice husk glass produced using the layering technique yielded a more preferable product. Some PL pigments were decomposed at high temperature during the glass making process, causing the pigment to lose its PL properties. As a result, the layering technique, which involved a lower level of decomposition of the PL pigment, was preferred to produce a PL rice husk glass with better PL properties compared to the mixing technique, which exposed more PL pigment to high temperature attack.

Thermochemical reactions viz. combustion and pyrolysis are important processes in the conversion of biomass from agricultural wastes into functional materials activated carbon fibre (ACF). Acid treatment during combustion and pyrolysis leaves a major impact which affects quality and properties of the resulting ACF such as pore size control and surface area enlargement. In this study, carbonisation and activation of empty fruit bunch (EFB) fibre into ACF was carried out using acid treatment assisted combustion and pyrolysis followed by CO2 gas flow. The effects of acid treatment on the physicochemical properties and pore characteristics was studied by applying sulphuric acid and switching the sequence of acid treatment before and after combustion and pyrolysis. Intercalation of sulphuric acid and exfoliation reactions on the acid-treated EFB fibre resulted in a higher thermal degradation rate compared to raw EFB fibre without acid treatment. Higher BET surface area and total pore volume were obtained for ACF samples treated with acid. The higher pore volume is due to the intercalated sulphuric compound which facilitated the removal of volatile matter and generated more pores for adsorption. However, severe acid oxidation could also lead to pore blocking with excess oxygen complexes and creation of limited porosity. The results show that properties of the ACF can be affected by the sequence of the acid treatment depending on the thermochemical process applied.