2.2 Combustion calorimetry
The heat of combustion of the samples was determined in an e2k Bomb calorimeter (Digital Data Systems Pty Ltd, South Africa) in triplicates as described in [26]. Briefly, a pre-cut firing cotton (Part No. CAL2K-4-FC) was looped over the firing wire (Part No. CAL2K-4-FW) and twisted at the ends. A crucible containing 0.30 g of dried biomass was inserted into the outside electrode’s crucible holder, with the firing cotton touching the sample. The electrode assembly was loaded into the vessel body and filled with 3000 kPa oxygen. The vessel was removed from the filling station and allowed to stabilize for 1 min prior to insertion into the calorimeter. The analytical grade Benzoic acid (Part No. CAL2K-BA) was used for calorimeter calibration.