Combustion characteristics and gasification kinetics of Brazilian municipal solid waste subjected to different atmospheres by thermogravimetric analysis.

This study examines the gasification kinetics of Brazilian municipal solid waste (MSW) and its components under air, CO2, and air/CO2 (70/30 vol%) atmospheres. The ignition indices of paper and plastic are 6 and 3 times that of food waste, which are 38.6 × 10-3 %/min3 and 19.6 × 10-3 %/min3, respectively, implying a faster separation of volatile compounds from the paper and plastic. The minimum Eα values of 132 kJ/mol and 140 kJ/mol have been obtained for paper waste under air and air/CO2, respectively. On CO2 condition, MSW has an average Ea value of 96 kJ/mol. Under an air/CO2 atmosphere, a high synergistic ΔW of -4.7 wt% has been identified between individual components. The presence of air and CO2 improves the oxidation and char gasification process, thus resulting in better combustion. Hence, the gasification of MSW under an air/CO2 atmosphere would improve the waste-to-energy plant's performance and minimize the CO2 emission.

Entropy: From Thermodynamics to Information Processing.

Entropy is a concept that emerged in the 19th century. It used to be associated with heat harnessed by a thermal machine to perform work during the Industrial Revolution. However, there was an unprecedented scientific revolution in the 20th century due to one of its most essential innovations, i.e., the information theory, which also encompasses the concept of entropy. Therefore, the following question is naturally raised: "what is the difference, if any, between concepts of entropy in each field of knowledge?" There are misconceptions, as there have been multiple attempts to conciliate the entropy of thermodynamics with that of information theory. Entropy is most commonly defined as "disorder", although it is not a good analogy since "order" is a subjective human concept, and "disorder" cannot always be obtained from entropy. Therefore, this paper presents a historical background on the evolution of the term "entropy", and provides mathematical evidence and logical arguments regarding its interconnection in various scientific areas, with the objective of providing a theoretical review and reference material for a broad audience.

The Mutagenic Potential Caused by the Emissions from Combustion of Crude Glycerin and Diesel Fuel

This study evaluated the use of crude glycerin as an alternative of energy generation to replace the traditional fuels. The Tradescantia stamen hair mutation assay (Trad-SH) was applied to study the mutagenic effects caused by the emissions generated in the direct combustion of diesel oil and glycerin in a flame tube furnace. Tradescantia inflorescences were exposed to gaseous emissions from the combustion tests in a fumigation chamber for 30-40 min. The analysis of variance and the Tukey test were applied to compare the differences between six test groups (intoxicated with emissions from glycerin and diesel oil combustion) and a control group. Only one glycerin group showed statistical differences (0.05), possibly due to the complexity of the burning process and impurities, besides the acrolein present in its emissions. The high heating value (HHV) of crude glycerin (25.5 MJ/kg) was lower than diesel oil (45.19 MJ/kg), but it was comparable to other fuels. Although the use of glycerin as a biofuel could be an important aspect to be considered, the results showed that the glycerin had a substantial mutagenic potential similar to that of diesel oil.

Thermal decomposition kinetics of Brazilian limestones: effect of CO2 partial pressure.

The influence of the partial pressure of carbon dioxide (CO2) on the thermal decomposition process of a calcite (CI) and a dolomite (DP) is investigated in this paper using a thermogravimetric analyser. The tests were non-isothermal at five different heating rates in dynamic atmosphere of air with 0% and 15% carbon dioxide (CO2). In the atmosphere without CO2, the average activation energies (E(alpha)) were 197.4 kJ mol(-1) and 188.1 kJ mol(-1) for CI and DP, respectively. For the DP with 15% CO2, two decomposition steps were observed, indicating a change of mechanism. The values of E(alpha) for 15% CO2 were 378.7 kJ mol(-1) for the CI, and 299.8 kJ mol(-1) (first decomposition) and 453.4 kJ mol(-1) (second decomposition) for the DP, showing that the determination of E(alpha) for DP should in this case be considered separately in those two distinct regions. The results obtained in this study are relevant to understanding the behaviour changes in the thermal decomposition of limestones with CO2 partial pressure when applied to technologies, such as carbon capture and storage (CCS), in which carbon dioxide is present in high concentrations.