Analysis of rice husk biochar characteristics under different pyrolysis temperature

Abstract

Rice is the main food for Indonesian. In production, it produces rice husk in huge amounts as waste. Rice husks have tough fibers, so their natural decomposing takes a long time. One strategy to take advantage of and add value to rice husk waste is to convert it into biochar. Biochar is a material that produced by a pyrolysis process of organic material, which is beneficial for the soil. The quality of biochar is influenced by pyrolysis temperature. This research aimed to analyze the biochar characteristics under various pyrolysis temperatures. The results showed that increasing the pyrolysis temperature will increase the element concentration of SiO2 (ash fraction). On the other hand, increasing the pyrolysis temperature decreases the biochar yield, calorific value, carbon and hydrogen content, and K2O, CaO, P2O5, MnO, and TiO2 concentration. The dominant elemental content of biochar (ash fraction) is SiO2 with a concentration of 85.35-89.47%. Biochar yield was 37.4-68.18%. The carbon, hydrogen, and nitrogen content ranged from 31.77-38.11; 1.67-3.61; and 0.63-0.73%, respectively. The calorific value of the biochar ranged from 14.48 to 11.61 MJ/Kg. The highest biochar yield, with the highest carbon, hydrogen, and calorific value content, was obtained using the lowest pyrolysis temperature of 250 °C. Fourier transform infrared (FTIR) analysis showed that the functional groups in the biochars were O-H, C=O, and C-OH. Following the X-Ray diffraction (XRD) analysis result, the amorphous biochar of rice husk decreases with increasing pyrolysis temperature and vice versa. The rice husk biochar has excellent potential to produce silicate crystals.