Effects of temperature and carrier gas on physico-chemical properties of biochar derived from biosolids

Abstract

This study investigated the influence of temperature (400 ºC, 500 ºC and 600 ºC) and –carrier gas (N2 and CO2) on biochar yields, physicochemical, and structural attributes. Higher temperatures resulted in less functional groups, higher surface area and lower H/C and O/C ratios. The biochar produced under N2 environment was more alkaline and showed higher salinity whereas the biochar produced under CO2 environment had higher surface area. The FTIR spectra of biochar produced in CO2 atmosphere indicated the decrease of functional groups such as –OH, CO, –CONH– and CC with increasing pyrolysis temperature. However, the band intensity for Si–O–Si or Si–O–C and aromatic and hetero-aromatic structures were more prominent in biochar obtained in CO2 environment than N2 environment. The presence of calcium carbonate (CaCO3), quartz (SiO2) and magnesium calcite (MgCO3) in biosolids and their biochars was confirmed by XRD spectrum. The outcomes from this research, particularly the stark contrast in biochar characteristics due to the variation in production conditions, inform the tailoring of biochars prepared under different conditions to environmental applications.