Biochars prepared from biogas residues: temperature is a crucial factor that determines their physicochemical properties

The quantity of biogas residues is continually increasing and causing a great threat to the environmental protection sustainable development bio-natural gas engineering. Thus, four (sewage sludge, SR; spent mushroom compost, MR; wheat straw, STR; distillers’ grains, DL) were collected prepare biochars at different temperatures (300 °C, 500 700 °C) in this study. functional groups, crystal structure, physical chemical properties characterized evaluate suitability preparing biochar from residues. results showed that yield ranged 45.13 66.42% 300 34.13 51.50% 30.33% 47.06% °C. carbon (C) content STR DL increased under higher temperatures. Further, with temperature, P K contents, pH, Brunauer–Emmett–Teller surface area (SBET), total pore volume (TPV) increased. groups decreased significantly, aromatic compounds decomposed. (except SR biochar) structures more stable high temperature. morphological structure °C was most stable. SBET 11.98- 33.43-fold compared And TPV 2.22 10.25 times STRB700 has SBET, because C–H bond stretching aliphatic formation C = hemicelluloses STRB relatively decomposed temperature °C), especially favourable smaller microporous.