Eduardo Monteiro Martins

A produção de sabão a partir de óleo de cozinha usado representa uma alternativa sustentável que contribui para a preservação do meio ambiente. Essa prática evita a contaminação da água, reduz a geração de resíduos e incentiva o reaproveitamento de materiais. Além disso, promove a conscientização ambiental e fortalece a economia circular no cotidiano. Este artigo apresenta seis testes realizados na produção de sabão a partir de óleo de cozinha residual, comparando o desempenho dos processos a frio e a quente, também variando o tempo da mistura. O objetivo final é identificar qual abordagem oferece os melhores resultados em termos de consistência, estabilidade e tempo de solidificação.

Emission inventories are essential tools for air quality management. However, the state of Rio de Janeiro lacks a comprehensive inventory. Consequently, global models such as EDGAR (Emission Database for Global Atmospheric Research) become an attractive alternative. This study aims to analyze data on nitrogen oxides (NOx) and volatile organic compounds (VOCs) and compare them with existing data. To achieve this, a 3 × 3 km simulation grid centered on the state of Rio de Janeiro was constructed. Meteorological fields were generated using the Weather Research and Forecasting model, while emission data were obtained from EDGAR. The simulation period spanned 34 days in 2018. Emissions were analyzed for NOx and VOCs, and compared to mobile source inventory data from the State Environmental Institute of Rio de Janeiro. Sectoral contributions to NOx emissions revealed that industry, navigation, and energy were the dominant sources. For VOCs, the primary contributors were industry, residential sources, and transportation. The comparison with State Institute for the Environment of Rio de Janeiro (INEA-RJ) data indicated that the model underestimated NOx and VOC emissions by approximately 38 and 48%, respectively. Despite the underestimation, the model effectively captured the regional emission characteristics, highlighting its potential as a tool for emission analysis without a comprehensive local inventory.

Brazil’s significantly large fleet of ethanol-powered vehicles makes it unique with regard to mobile source emissions. An accurate estimation of emission rates is best obtained from studies reflecting real-world vehicular conditions, such as tunnel investigations. Although laboratory-based estimations are standardized, they may not reflect reality. This study evaluates two methods for estimating emission factors that arise from the circulating fleet of vehicles that travel through the Rebouças Tunnel in Rio de Janeiro. The two monitoring points were located in the L1 gallery of the tunnel. Thirteen sampling campaigns took place between 2017 and 2020. The Pierson correlation method yielded emission rates for total aldehydes of 22.1 ± 6.9 mg km⁻¹, while the fuel consumption testing method resulted in rates of 17.7 ± 7.8 mg km⁻¹. Acetaldehyde predominated in both methods, as it is a major constituent of the exhaust emissions using ethanol as fuel, which is one of the major component fuels in the Brazilian fuel matrix. Benzene emerged as the most abundant BTEX compound, with 3.7 ± 3.2 mg km⁻¹, when the Pierson method was used, and 2.5 ± 0.3 mg km⁻¹ with the fuel consumption testing method. Naphthalene, which was mainly collected in the gas phase, showed rates of 1.4 ± 1.0 mg km⁻¹ (Pierson) and 0.9 ± 0.4 mg km⁻¹ (fuel consumption). Despite these methodological variations, our findings converge, which suggests that the choice of method should depend on available resources. The Pierson method, which requires a vehicle counting method for traffic flow, obviates the need for CO and CO₂ concentration measurements, that are essential for determining fuel consumption.

Ozone (O3) is a secondary pollutant, and modeling studies used to assess its behavior play a role in facilitating regulatory and decision-making processes in public policies. Thus, the Community Multiscale Air Quality (CMAQ), a chemical transport model, was specifically designed to simulate and forecast O3 concentrations. This critical review includes publications between 2016 and 2023 showing the most used configurations. The research was carried out in the Scopus and Web of Science databases, and the articles were filtered using determined criteria. With this, it was observed that the most used model arrangements are Weather Research and Forecasting as a meteorological model, carbon bond 2005 as the chemical mechanism, 36 × 36 km with 35 vertical layers as grid resolution, CMAQ standard profiles as a boundary condition, Multi-resolution Emission Inventory for China, due to the high number of publications by Chinese researchers, and Model of Emissions of Gases and Aerosols from Nature as inventory and processor of biogenic emissions, respectively. It is concluded that this arrangement of configurations is the most widespread in the literature but shows that nowadays the publications predominantly lie over China and with greater prominence of this country in studies of influence on ozone simulation.

The objective of this work was to determine the trace element composition in the nanometric, ultrafine, fine, and coarse particulate matters (PM) found in the surrounding area of the UERJ Chemical Technology Applications Institute, using a MSP 120 MOUDI II cascade impactor. After acid extraction, the elements were analyzed via ICP–OES, and the results obtained were treated statistically. The average concentrations of the nanometric, ultrafine, fine, and coarse particles were 11.8, 8.2, 7.7, and 7.1 μg m⁻³, respectively. The total average concentration of Cd, Ni, Pb, Cr, and Fe complied with the air quality standards recommended by US EPA and WHO. When compared with other locations, the PM fractions found in this study were 1.1 to 346 times greater. Through the calculation of Pearson’s correlation coefficient, a high correlation was observed between most of the trace elements studied, especially in the ultrafine, fine, and coarse fractions, which suggests that they are probably caused by the same sources of vehicular emissions. The enrichment factor was calculated to estimate the possible sources. Since Cd, Cu, Pb, and Mo are enriched by anthropic sources, they are probably influenced by vehicular emissions, in particular the wear on tires and brakes, and the burning of fossil fuel.

This study investigates the potential factors that contribute to frequent high levels of ozone in Bangu, one of the most critical areas in the city of Rio de Janeiro, regarding ozone levels and air quality. Speciated non-oxygenated volatile organic compounds (VOCs) were measured using method TO-15 (US EPA). The measured concentrations and kinetic and mechanistic analysis of VOC reactivity showed that alkanes were the most important compounds. Ozone concentrations were simulated for a base case representing a day with high ozone levels. Simulated results and statistical multivariate analysis showed that the high ozone concentrations did not seem to be closely related to local emissions but rather were related to pollutant transport and low measured NO_x levels and were triggered by photochemical activity. The differences between weekdays and weekends were also investigated, showing that ozone concentrations were also higher during weekends, mainly on Sunday, when the diesel heavy vehicle fleet was reduced and lower NO emissions were observed. The VOC/NO_x ratios correspond to a VOC-limited process, which leads to higher ozone concentrations under low NO_x conditions.

Decomposition of formic acid (HCO₂H) proceeds via three unimolecular channels: dehydration, decarboxylation, and dissociation, the latter expected to be of minor contribution to the overall kinetics. In addition, despite the similar values reported for the individual activation energies for the dehydration and decarboxylation reactions, experimental works have shown that the former is dominant in the reaction mechanism. These reactions show pressure‐dependent rate coefficients, and the high‐pressure condition is not yet verified at atmospheric pressure. This work aims to investigate the influence of temperature and pressure on the rate coefficients. Hence, theoretical calculations at the CCSD(T)/CBS level have been performed to accurately describe the unimolecular reaction and Rice‐Ramsperger‐Kassel‐Marcus (RRKM) rate coefficients have been calculated and integrated for the prediction of k(T,P) rate coefficients, adopting both strong and weak collision models, over the intervals 0.5‐10 atm and 298‐2200 K. Our results suggest that the isomerization path is important and explains the preference for the (CO + H₂O) channel. Rate coefficients for the (CO₂ + H₂) and (CO + H₂O) formations are given, in s⁻¹, as exp(−34404/T) and exp(−33785/T), respectively. The dissociation limit of 107.29 kcal mol^–1, with respect the Z‐HCO₂H conformer, leading to OH + HCO, via a barrierless potential curve, with rate coefficients, in s⁻¹, expressed as k_HCO+OH(T) = 1.68 × 10¹⁷ exp(−56018/T). Temperature and pressure dependence for the HCO + OH → CO₂ + H₂ and HCO + OH → CO + H₂O reactions have also been estimated.

This study investigated the potential factors that contribute to frequent high levels of ozone as well as ozone episodes in Bangu, one of the most critical areas in the city of Rio de Janeiro regarding ozone levels. For 74 days in a two-year period (10.3%), the national air quality standard was exceeded. For the same period, a total of 378 days (51.8%) had ozone concentrations that were between 80 and 160 µg m⁻³. A statistical analysis of pollutant concentrations and meteorological data as well as a kinetic and mechanistic analysis of VOC reactivity showed that the high ozone concentrations did not seem to be closely related to local emissions but, rather, were related to pollutant transport and triggered by photochemical activity. The mountains in the southern and northern part of the district contribute to the increase of surface temperatures and the accumulation of pollutants. The VOC/NO_x ratios corresponded to a VOC-limited process.