Posidonia oceanica (PO) is a marine plant endemic to the Mediterranean basin, forming extensive grasslands. Onshore residues represent a major environmental, economic, social and hygienic problem in all coastal zones of the Mediterranean basin due to the great disturbance they cause to bathers and beachfront populations. This work sought to evaluate the thermo-chemical properties of PO in pyrolysis and thermo-oxidative degradation processes. The investigations were carried out using a thermogravimetric analyser (TGA) coupled to a quadrupole mass spectrometer (MS) and an infrared spectrometer (FTIR). In addition, proximate, ultimate, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and biodegradability analyses were carried out on PO. The biodegradability analysis confirmed that residues of PO were a biodegradable material. Accordingly, the application of PO as a feedstock for combustion/co-combustion or biorefining is recommended.
The use of torrefied biomass as a substitute for untreated biomass may decrease some technological barriers that exist in biomass co-firing technologies e.g. low grindability, high moisture content, low energy density and hydrophilic nature of raw biomass. In this study the TG-MS-FTIR analysis and kinetic analysis of willow (Salix viminalis L.) and samples torrefied at 200, 220, 240, 260, 280 and 300 o C (TSWE 200, 220, 240, 260, 280 and 300), were performed. The TG-DTG curves show that in the case of willow and torrefied samples TSWE 200, 220, 240 and 260 there are pyrolysis and combustion stages, while in the case of TSWE 280 and 300 samples the peak associated with the pyrolysis process is negligible, in contrast to the peak associated with the combustion process. Analysis of the TG-MS results shows m/z signals of 18, 28, 29 and 44, which probably represent H 2 O, CO and CO 2 . The gaseous products were generated in two distinct ranges of temperature. H 2 O, CO and CO 2 were produced in the 500 K to 650 K range with maximum yields at approximately 600 K. In the second range of temperature, 650 K to 800 K, only CO 2 was produced with maximum yields at approximately 710 K as a main product of combustion process. Analysis of the FTIR shows that the main gaseous products of the combustion process were H 2 O, CO 2 , CO and some organics including bonds: C=O (acids, aldehydes and ketones), C=C (alkenes, aromatics), C-O-C (ethers) and C-OH. Lignin mainly contributes hydrocarbons (3000-2800 cm ). Hydrocarbons, aldehydes, ketones and various acids were also generated from hemicellulose (1790-1650 cm −1). In the kinetic analysis, the two-steps first order model (F1F1) was assumed. Activation energy (E a ) values for the first stage (pyrolysis) increased with increasing torrefaction temperature from 93 to 133 kJ/mol, while for the second stage (combustion) it decreased from 146 to 109 kJ/mol for raw willow, as well as torrefied willow at the temperature range of 200-260°C. In the case of samples torrefied at 280 and 300°C, the E a values of the first and second stage were comparable to E a of untreated willow and torrefied at 200°C. It was also found that samples torrefied at a higher temperature, had a higher ignition point and also a shorter burning time.
In this study, the combustion behavior of raw waste wood from furniture and samples torrefied at temperatures of 473, 513, 553 and 593 K was investigated. TG-DTG analysis showed that the mass loss in the first stage of the process decreased with the temperature of torrefaction, whereas the temperature in the second stage increased. The influence of torrefaction and combustion parameters on greenhouse gas emissions were investigated by the FTIR technique. The characteristic combustion parameters were also determined. The ignition temperatures for the furniture wood waste and samples torrefied at 473, 513 and 553 K from 549 to 559 K, whereas that of the sample torrefied at 593 K was significantly higher (600 K). All samples were completely burnt at 813-843 K, after 29-35 min, depending on the torrefaction temperature. Kinetic parameters are determined using a two-step firstorder reaction. The activation energy value for the first stage increased with the increasing temperature of torrefaction, from 68 to 125 kJ mol -1 , whereas the temperature in the second stage decreased from 108 to 47 kJ mol -1 . A similar correlation was observed for the pre-exponential value A. In the case of the torrefied furniture wood waste at 593 K, the combustion process runs as a single first-order reaction. The calculated data were fitted to the experimental data very accurately (R 2 [ 0.9992 and standard deviation \6.7 %), and the kinetic model was correctly founded. The linear relationship between logA and E a provides a way to predict the kinetic parameters of the combustion process. Keywords
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