Characterization of biochars produced from residues from biogas production

In the present study an evaluation of the properties of biochars produced from residues from biogas production (RBP) at a temperature range of 400-800 degrees C was investigated. RBP originated from three different biogas plants using different biogas production methods. Physico-chemical properties (pH, electrical conductivity - EC, elemental composition - CHN, the X-ray fluorescence - XRF, X-ray diffractometer - XRD, Raman spectroscopy) and surface properties (Surface area - S-BET, Fourier Transform Infrared Photoacoustic Spectroscopy - FTIR-PAS) of RBP and RBP - derived biochars were studied. The values of the individual parameters were primarily dependent on the type of residue used (separated/unseparated). Furthermore, the temperature conditions (thermophilic/mesophilic) in these biogas plants and the type of substrates used for biogas production were observed to affect the specific surface area of the biochar. Generally, the pH (10.42-12.76), EC (2.91-23.80 mScm(-1)), ash (14.12-43.56%) and macro- and micronutrient content as well as aromaticity of the biochars increased with increasing pyrolysis temperature. For pyrolysis yield (45.27-27.16%), contribution of H (3.22-0.71), N (2.55-1.40%) and 0(16.73-8.07%), O/C (polarity of the biochars), (O+N)/C mole ratios, an opposite trend was found. (C) 2015 Elsevier B.V. All rights reserved.