Organic elemental analyzer flash 2000 chns o

Elemental analysis was carried out using an Organic Elemental Analyzer Flash 2000 CHNS-O (Thermo Scientific, Milan, Italy) coupled with EAGER experience software, version 1.2. The elemental composition was determined in triplicate for one representative sample of each condition, and the oxygen content was calculated using the difference method. Before carrying out the elemental analysis, the preparation of samples of SOPRAW and biochars involved drying at 105 °C for 24 h to reduce the possible effects of moisture content, in this way obtaining the elemental composition on a dry basis.

Pelletized sunflower husks were made using a flat die pellet-making machine. The nominal size of the pellets was 8 mm in diameter and about 10 mm in length. Pellets were made without the use of any external additives.
Proximate and ultimate analyses of sunflower husk, sunflower husk pellets, and hardwood pellets are presented in Table 1. Analyses were carried out using a S8 TIGER 1 kW-High Performance Wavelength Dispersive XRF spectrometer (Bruker Scientific Instruments, Billerica, MA, USA) and an Organic Elemental Analyzer Flash 2000 CHNS/O (Thermo Scientific, Waltham, MA, USA). The moisture content was determined using a Moisture Analyzer MAX 50 (Radwag, Radom, Poland; max capacity 50 g, readout accuracy 0.0001%), and calorific value was determined using a calorimeter (EkotechLAB, Gdańsk, Poland).
To evaluate the combustion characteristics of these fuels, sunflower husk and sunflower husk pellets (shown in Figure 1) were compared with commercial hardwood pellets (8 mm in diameter and 10–15 mm in length). The measured bulk density of HP was 669 kg/m³, while for SHP and SH the respective values were 478 kg/m³ and 139 kg/m³. All of the materials had a similar HHV value and composition (the analysis of HP shows a slightly higher fixed carbon content at the cost of the volatiles fraction).