Evaluating Biochar Properties Derived from Various Agro-Residues Via Pyrolysis: A Comparative Study

Abstract

This study was designed to analyze the physicochemical characteristics and functional groups of biochar obtained from four agro-residues—sugarcane bagasse (SB), rice husk (RH), cotton stalk (CS), and orange peel (OP). Pyrolysis of agro-residues was performed at 450°C for two hours. Elemental analysis indicated carbon concentrations between 19.39% to 66.30%, whereas oxygen levels decreased due to pyrolysis, signifying increased aromaticity and biochar stability. Structural characterisation revealed a peak cellulose content in OP (55.89%) and the maximum lignin concentration in RH (26.1%), both of which influence the biochar's adsorption capacity and nutrient retention potential. FTIR analysis verified essential functional groups, such as O-H, C-H, C=O, and aromatic C=C bonds, which augment biochar's reactivity and nutrient-binding potential. The alkaline pH (9.2–11.2) and diverse electrical conductivity values indicate the appropriateness of biochar for enhancing soil quality, especially in acidic soils. The findings suggest that the distinctive characteristics of biochars formed from agro-residues render them advantageous for sustainable agricultural uses, including nutrient provision and soil enhancement.