Assessment of the bioenergy potential and fuel properties of biochar solid briquettes of alkaline pretreated tapioca sago
摘要
This paper assesses how tapioca sago processing waste can be used to achieve the high-quality biochar briquettes by means of alkaline pretreatment and controlled carbonization. A 3% solution of sodium hydroxide (NaOH) was used to pretreat the biomass, and then carbonized at 400–500 °C under low oxygen conditions. The resulting biochar was pressed into briquettes through hydraulic press and another batch of briquettes was made without alkaline pretreatment as the control. The pretreated briquettes were found to have very good fuel properties as opposed to the untreated samples. The moisture content and volatile matter decreased to 3.5% and 12.4% respectively, whereas the carbon content (78.5%) and the fixed carbon (82.1) also increased significantly. Higher heating value of the untreated briquettes was 24.7 MJ/kg, whereas it was 28.5 MJ/kg with the pretreated samples, which was a sign of a better energy density. The TGA-DSC thermal analysis had indicated increased thermal stability and reduced rates of decomposition of the treated briquette. The emission analysis showed a decrease in the amount of pollutants discharged in combustion as well as the amount of particulate matter, sulfur dioxide and nitrogen oxide which dropped to 95 mgN/m3, 12 ppm and 38 ppm respectively. Moreover, mechanical performance was enhanced, and bulk density as well as compressive strength were 1.12 g /cm3 and 13.2 Mpa, respectively. These findings show alkaline pretreatment can produce biochar briquettes that are both environmentally friendly and can improve the fuel quality and combustion activity of biochar briquettes made of tapioca sago waste.