Optimization and characterization of biochar obtained from weedy biomass of Calotropis gigantea by vacuum pyrolysis

Abstract

Abstract In the present study, response surface methodology (RSM) was employed to optimize the preparation conditions of biochar to obtain better quality biochar. The maximum fixed carbon, carbon, surface area, pore volume and pore size were predicted at the optimised preparation parameters of 450°C temperature and 50-100mm particle size. The objective of the present study is to evaluate and characterized the application of biochar of invasive weed Calotropis gigantea obtained under optimized parameters by vacuum and slow pyrolysis for one hour of reaction time. The biochar was characterized with the presence of high carbon content of 64.65%, and; low H/C and O/C molar ratio of 0.08 and 0.15 respectively. The surface of biochar was observed porous constituting mesoporous pore structure with remarkable high surface area of 99.91m2/g and pore volume of 0.0398cm3/g along with traces of minerals fractions such as K- 1.33%, Na- 1.17%, Mg- 1.05%. Strong FTIR bands observed at 1994.1 cm-1, 1110 cm-1, and 745 cm-1, representing allenes (R 2C=C=CR 2) , aryl alkyl ethers (R − O – R) and aromatic (C–H) bending. All these parameters indicate its potential in the application for carbon sequestration, climate change mitigation, environment pollutants adsorption (both organic and inorganic) and soil improvement.