Characterisation of Magnetised and Non-Magnetised Coconut Shell Biochars

Coconut shell as biomass with little use constitutes a source of pollution. This biomass material was utilized to produce three biochars, CSB400, CSB600 through carbonisation (at 400 and 600 °C), and magnetisation (MCSB600) through the chemical wet co-precipitation method respectively; to assess the effects of temperature and magnetisation on their physicochemical properties. Results showed that temperature decreased the biochar yield from 44.54 to 25.04% for CSB400 and CSB600 respectively. The specific surface area (SSA) increased with temperature from 122.2 to 135 m²/g while magnetisation (MCSB600) resulted in a 33.81% decrease in SSA compared to its pristine precursor (CSB600). The Fourier transform infrared spectroscopy (FTIR) showed a decrease in functional groups with temperature increase while it increased for magnetised biochar (MCSB600). Results also showed a decrease in both moisture and volatile contents from CSB400 to CSB600 while the ash and fixed carbon contents increased across CSB400 to CSB600 and CSB600 to MCSB600 respectively. The pH increased with carbonisation and magnetisation. Higher cation exchange capacity value, 7.5 cmol/kg was recorded for CSB400 compared to 5.4 cmol/kg for CSB600. The oxygen and carbon contents increased with temperature while the carbon content decreased with magnetisation. The biochars are expected to have different adsorption and soil amendment characteristics based on these variations in the measured properties.