Pyrolysis kinetics of a hardwood representative, beech ( Fagus sylvatica ), was investigated by two different kinetic approaches: model-free isoconversional method and model-fitting method. The model-free isoconversional method was used for the determination of apparent kinetic parameters, i.e. the activation energy and pre-exponential factor. The model fitting method was used for the optimization of kinetic parameters of the reaction pathways of three selected reaction mechanisms: one-step, two-step, and three-step one. In both approaches, thermo-gravimetric data were used at five heating rates: 2°C min −1 , 5°C min −1 , 10°C min −1 , 15°C min −1 and 20°C min −1 . As the most suitable mechanism, the three-step mechanism containing the intermediate degradation step was chosen. This selection was supported by experimental results from the 13 C NMR analysis of solid residues prepared at the key temperatures within the range of 230–500°C. The progress of mass fraction values of each component in this mechanism was simulated. Conclusions from the simulation were confronted with experimental results from the 13 C NMR.

Activated sewage sludge samples obtained from two different waste water treatment plants were investigated by thermogravimetric analysis. Due to a very high content of water in the sludge samples, these had to be dried at 160°C in an electrical oven in order to remove all adsorbed water. To ensure pyrolysis conditions, nitrogen atmosphere was applied. The pyrolysis decomposition process was carried out in the temperature range from ambient temperature to 900°C at three different heating rates: 2 K min−1, 5 K min−1, 10 K min−1. TGA and DTG curves of the decomposition processes were obtained. Temperature of onset decomposition, final temperature of decomposition, maximum decomposition rate, and decomposition temperature were determined by thermogravimetric analysis for both sludge samples used. The main decomposition process takes place at temperatures in the range from 230°C to 500°C. Above this temperature, there are only small changes in the mass loss which are often attributed to the decomposition of carbonates present in the sewage sludge samples. To determine the apparent kinetic parameters such as the activation energy and the preexponential factor, the so called Friedman isoconversional method was used. Because of the requirements of this method, initial and final parts of the decomposition process, where crossings of the decomposition lines occurred, were cut off. Obtained dependencies of the apparent activation energies and preexponential factors as a function of conversion were used backwards to calculate the modeled decomposition process of sewage sludge and the experimental data were in good accordance with the data obtained by simulation.

The synthesis, spectral measurements and theoretical study of simple model oligothiophenes terminated symmetrically or asymmetrically by (10H-anthracen-9-one) methylene chromophore are presented. The electron absorption spectra of these novel molecules were measured in polymer matrices and chloroform solution. The absorption spectra of investigated systems measured in chloroform are characterised by a broad low energy band with partially distinguished vibrational structure. Theoretical calculations of electronic ground state structures have been performed at the density functional theory (DFT) level of the theory. The vertical excitations energies were calculated using the time-dependent version of DFT (TD-DFT) and semiempirical Zerner's Intermediate Neglect of Differential Overlap methods. The role of the termination group upon the vertical excitation was estimated from the localisation of highest and lowest occupied orbitals. This analysis showed that the excitation energy transfer upon the optical excitation leads from the thiophene chromophores into the central part of (10H-anthracen-9-one) methylene unit.