Preparation & characterization of biochar from rice husk by pyrolysis method

In nations where rice cultivation is prevalent, the responsible management of substantial quantities of rice waste is necessary to mitigate potential environmental concerns. This study aims to produce biochar from rice husks through the pyrolysis method, specifically without using inert nitrogen gas by utilizing a low-oxygen pyrolysis technique. The study employed many experimental parameters, including the process temperature, residence time, and heating rates. The FTIR results revealed a decrease in the stretching of O-H bonds in rice husk biochar at elevated temperatures (500°C), suggesting the degradation and disintegration of cellulose, hemicellulose, and lignin. Various bands associated with hydroxyl, carboxyl, aromatic bonds, amine groups, and other aromatic compounds were observed at lower pyrolysis temperatures. The observed functional group in rice husk biochar closely resembles the outcomes obtained from commercial biochar, except for the absence of C=O stretching. It was seen that the biochar structure exhibited an increase in pore size with increasing temperature. At higher temperatures, a decrease in pore size was observed on the surface of the biochar. It has been observed that when subjected to elevated pyrolysis temperatures, commercial biochar has a greater pore size compared to rice husk biochar, albeit fewer in number than the latter. Based on the findings, it can be inferred that the most favourable conditions for the rice husk biochar production by the low oxygen pyrolysis method are attained at temperatures of 300°C for durations of 60 and 90 minutes, as well as at 400°C for 90 minutes.