Characterization and ammonia adsorption of biochar prepared from distillers' grains anaerobic digestion residue with different pyrolysis temperatures

BACKGROUNDIncreasing attention is being paid to find an alternative way to handle biogas residue from biogas production which is important for sustainable development of biogas project. In this study, biochars from distillers' grains anaerobic digestion residue (BRC) in the pyrolysis temperature range of 300 to 800 degrees C were prepared. Subsequently, elemental analysis, thermal stability, specific surface area (SSA), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and the performance of ammonia (NH4+) adsorption were studied. RESULTSBRC produced at 700 degrees C exhibited the highest SSA (251.47 m(2) g(-1)). Generally, the pH (6.2-8.4), ash (17.58-36.93%), carbon (48.09-56.18%) and the NH4+ adsorption capacity (1.95-5.86 mg N g(-1)) of BRC increased with increasing pyrolysis temperature (300-700 degrees C). However, for pyrolysis yield (76.39-40.44%), volatile matter (48.72-4.69%), phenolic (0.85-0.01 mmol g(-1)), total acidity (1.39-0.21 mmol g(-1)) and the contribution of H (4.92-1.13%), O (29.41-5.76%), O/C (0.61-0.10), H/C (0.10-0.02), (O+N)/C (0.65-0.13), an opposite trend was found. CONCLUSIONSPyrolysis temperature has a significant effect on the physicochemical properties of BRC and thus on the quantity of NH4+ adsorbed. The BRC produced at 700 degrees C could serve as a highly efficient material for NH4+ removal, therefore presenting a high value-added application for biogas residues. (c) 2017 Society of Chemical Industry