Synergetic effect of microwave heated alkali pre-treatment on densification of rice (Oryza sativa) husk biomass grinds

Abstract

ABSTRACTExperiments on pelletization of pre-treated rice (Oryza sativa) husk grinds were performed to study the effect of pretreatment processes on compression characteristics and quality of rice husk pellets. Pre-treatment of rice husk was carried out by microwave-heated sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH)2) solutions. During the pre-treatment process, rice husks were immersed in distilled water, NaOH or Ca(OH)2 solutions (1% and 2% w/v) and heated using microwaves at power levels of 603 W and 713 W. Measured quantity of pre-treated rice husks were compressed at 4000 N force in a plunger-die system maintained at 95⁰C. Compression and relaxation test data were recorded and specific energy was calculated. Pellet quality parameters such as tensile strength, durability and bulk density were determined. Chemical composition, gross calorific value, bulk density and particle density of untreated and pretreated rice husk were measured. Chemical analysis results confirm that the microwave exposure with alkali pre-treatments significantly affected the chemical composition of rice husks which subsequently enhanced the quality of pellets. The results concluded that the sodium hydroxide with microwave-treated rice husk samples have shown excellent compression characteristics and delivered high-quality pellets when compared to all other treated and untreated samples tested. Microwaves exhibit positive impacts on the quality of pellets along with NaOH treatments in the production of rice husk pellets.