Pyrolysis kinetic evaluation by single-step for waste wood from reforestation.

The objective of this study was to evaluate the kinetic parameters of pyrolysis of waste wood from reforestation: Eucalyptus benthamii (EB), Eucalyptus dunnii (ED) and Pinus elliottii (PN). The kinetic study was performed using the Friedman, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Starink, and Vyazovkin methods from the experimental data at four heating rates (5, 10, 20 and 30 °C min-1). The Friedman method presented higher activation energy values (Ea) when compared to the other methods (EaEB = 142.98 kJ mol-1, EaED = 147.71 kJ mol-1, EaPN = 155.46 kJ mol-1). The KAS, Starink and Vyazovkin methods resulted in approximate values of activation energy (EaEB = 132.83-133.31 kJ mol-1, EaED = 137.51-137.98 kJ mol-1, EaPN = 145.24-145.70 kJ mol-1) due to the approximation equations with lowest relative errors. The simulation of curves using the kinetic parameters obtained with the Vyazovkin method showed that the decomposition process of EB and ED occurs as a multi-step process resulting in an unsatisfactory result for the simulation. On the other hand, for PN a satisfactory fit to the experimental data was obtained, which demonstrates its suitability for application to the modeling of thermochemical systems.

Combustion of pistachio shell: physicochemical characterization and evaluation of kinetic parameters.

The study of different renewable energy sources has been intensifying due to the current climate changes; therefore, the present work had the objective to characterize physicochemically the pistachio shell waste and evaluate kinetic parameters of its combustion. The pistachio shell was characterized through proximate analysis, ultimate analysis, SEM, and FTIR. The thermal and kinetic behaviors were evaluated by a thermogravimetric analyzer under oxidant atmosphere between room temperature and 1000 °C, in which the process was performed in three different heating rates (20, 30, and 40 °C min-1). The combustion of the pistachio shell presented two regions in the derivative thermogravimetric curves, where the first represents the devolatilization of volatile matter compounds and the second one is associated to the biochar oxidation. These zones were considered for the evaluation of the kinetic parameters E a , A, and f(α) by the modified method of Coats-Redfern, compensation effect, and master plot, respectively. The kinetic parameters for zone 1 were E a1 = 84.11 kJ mol-1, A 1 = 6.39 × 106 min-1, and f(α)1 = 3(1 - α)2/3, while for zone 2, the kinetic parameters were E a2 = 37.47 kJ mol-1, A 2 = 57.14 min-1, and f(α)2 = 2(1 - α)1/2.

Recovery of iron oxides from acid mine drainage and their application as adsorbent or catalyst.

Iron oxide particles recovered from acid mine drainage represent a potential low-cost feedstock to replace reagent-grade chemicals in the production of goethite, ferrihydrite or magnetite with relatively high purity. Also, the properties of iron oxides recovered from acid mine drainage mean that they can be exploited as catalysts and/or adsorbents to remove azo dyes from aqueous solutions. The main aim of this study was to recover iron oxides with relatively high purity from acid mine drainage to act as a catalyst in the oxidation of dye through a Fenton-like mechanism or as an adsorbent to remove dyes from an aqueous solution. Iron oxides (goethite) were recovered from acid mine drainage through a sequential precipitation method. Thermal treatment at temperatures higher than 300 °C produces hematite through a decrease in the BET area and an increase in the point of zero charge. In the absence of hydrogen peroxide, the solids adsorbed the textile dye Procion Red H-E7B according to the Langmuir model, and the maximum amount adsorbed decreased as the temperature of the thermal treatment increased. The decomposition kinetics of hydrogen peroxide is dependent on the H(2)O(2) concentration and iron oxides dosage, but the second-order rate constant normalized to the BET surface area is similar to that for different iron oxides tested in this and others studies. These results indicate that acid mine drainage could be used as a source material for the production of iron oxide catalysts/adsorbents, with comparable quality to those produced using analytical-grade reagents.