The calculation and analysis of the kinetic parameters of the thermal decomposition of aluminum oxyhydrates obtained by the hydrolysis of aluminum nitrate in the presence of a non-inogenous surface-active substance (surfactant) - isooctyl ether of decaethylene glycol (IEDG) is presented. For comparison, samples of pure aluminum oxyhydrates were synthesized without the use of surfactants.
Thermogravimetric measurements were performed simultaneous thermal analyzer Netzsch STA 449 F3 Jupiter. As a result of the experiment for each sample, we obtained graphs of the TG/DTG mass loss in the temperature range from 400C to 1260°C with marking in sections and the corresponding tabular data.
The processing of tabular data of the corresponding thermograms recorded in increments of 0,5 degrees was carried out in two stages. At the first stage, according to the dependences of the form log[-log(1-∆m/∆mmax)] from 103/T, linear temperature ranges were determined. Each stage of thermolysis was processed according to the log[-log(1-α)] graph from 103/T [1]. The reliability of using the calculated trend model for describing experimentally observed dependencies was verified using the Fisher criterion. The apparent activation energy (Ea) and the value of the parameter (n) characterizing the appearance and development of crystallization centers are determined graphically. To find the rate constant (k), the Johanson – Melya – Arami – Yerofeyev – Kolmogorov equation was used [2].
At the second stage of processing the results of thermolysis, the Freeman–Carroll method was used [3]. TG/DTG curves are processed by temperature differentiation from the beginning to the end of the destruction process over the entire data array. As a result, characteristic peaks of mass loss are determined. According to this algorithm, the calculation and analysis of the values of the kinetic parameters describing the sequence and patterns of thermal transformations of aluminum oxyhydrates depending on the IEDG content during their synthesis were carried out.