72 / 2021-06-30 15:14:52

Biochar prepared from biogas residue Effects of residue types and pyrolysis temperature on yields and physicochemical properties of biochars

Biogas residue; Biochar; Pyrolysis temperature; Yield; Physicochemical property

Shifted biogas residue to biochar is a win-win strategy to sustain the biogas industry and protect the environment. Four biogas residue types including sludge residue (SR), mushroom residue (MR), straw residue(STR) and distillery lees (DL) were used to prepare biochar with different pyrolysis temperature of 300℃, 500℃ and 700℃. The effects of residue types and pyrolysis temperature on the yields and physicochemical properties of biochar were investigated. Results indicated that the biochar yield was SR > MR > DL > STR, decreased gradually with the increase of temperature. The content of C in STR-biochar and DL-biochar increased under higher temperature, while a decrease was observed in SR-biochar and MR-biochar treatments. What’s more, with pyrolysis temperature increasing, P, K content, pH value, specific surface area and pore volume of biochar increased, while peaks of functional groups (e.g. -OH, C=C, C-O) were weakened analyzed by FTIR. Especially, the functional groups of STR-biochar decreased significantly, and the aromatic compounds were decomposed. The results of TGA confirmed that except SR-biochar, the structures of other biochars were more stable under high pyrolysis temperature, and the morphological structure of DL-biochar at 700℃ was most stable. Overall, biochar prepared by STR at 700℃might be a better biogas residue choice for biochar preparation.