THE STATE OF THE ART OF VOLATILE CARBONYL COMPOUNDS IN INTERNAL ENVIRONMENTS: IMPACTS TO HEALTH AND SAMPLING METHODOLOGIES AND ANALYSIS. The primary sources of emission of volatile carbonyl compounds (CCs) in indoor environments are chipboard panels, laminate floors, plywood, paints and solvents, household products, fiberglass, gas stoves, heaters and heating systems. Several studies have already confirmed an indoor/outdoor (I/O) ratio greater than 1 (one) for several CCs, indicating that these compounds are emitted mainly from internal sources. CCs (especially aldehydes and ketones) are easily absorbed into the airways, presenting a considerable mutagenic, teratogenic and carcinogenic risk to humans. Therefore, this study aimed to review the CCs found in different indoor environments, the effects and impacts of these compounds on human health and the national and international guidelines that establish their maximum exposure limits. The methodologies most used in the literature to analyze CCs in the air were reviewed directly (in real-time) or indirectly (using pre-treatment steps). A detailed review of the sampling techniques: with and without adsorption, with and without derivatization, with adsorption and derivatization simultaneously; using various methodologies employed during the last decades (cartridges, filters, tubes or liquid absorbent-impinger) was carried out. Finally, this work describes the instrumental methods and the advantages and disadvantages of determining CCs individually and simultaneously in the atmosphere.

This paper aims to present an overview of the ongoing of the Brazilian environmental chemistry over the last forty years inserted in the context of the Brazilian Chemical Society (SBQ). Initially, a brief history presents the main milestones and premise of its “birth” in the 1980s, as well as the set of major actions taken within the SBQ to consolidate and strengthen this area of research. Then, in a separated approach between atmosphere, hydrosphere and lithosphere, we present the evolution of the main topics covered in Environmental Chemistry in Brazil, as well as the contribution of the chemists in the interdisciplinary scenario that constitutes this area. Finally, an overview of the evolution of the teaching of Environmental Chemistry in Brazil is presented.

Among the various technologies for the production of hydrogen fuel, heterogeneous photocatalysis is one of the most promising, especially with the use of semiconductors, notably TiO2. However, the use of TiO2 is limited by hindrances for the photolysis of water, such as wide bandgap, a less negative conduction band reduction potential as compared to that of hydrogen evolution and the high electron/hole recombination rate. Deactivation of the semiconductor can be avoided by the addition of electron-rich compounds (sacrificial reagents) which react irreversibly with the hole, leading to a higher quantum efficiency. Another strategy is the Z scheme. In this system, two different photocatalysts (or photosystems) are combined using a suitable redox mediator. Furthermore, the bandgap can be adjusted by doping with transition metal oxides, with control of metal oxide valence band using p-orbitals of an anion, or s-orbitals of p-block metal ions, or by spectral sensitization. In view of these questions, the purpose of this review article is to describe and discuss recent studies that use a variety of materials for the photocatalytic generation of hydrogen.

Como alternativa aos relativamente complexos e dispendiosos métodos espectroscópicos, as propriedades redox dos ácidos húmicos, determinadas por titulação potenciométrica, vêm sendo usadas na avaliação da estabilidade do C do solo. O objetivo deste estudo foi estabelecer um índice redox de estabilidade do C (RICS) e correlacioná-lo com alguns atributos de diferentes solos modais brasileiros (distintos estádios de intemperismo ou manejo), a fim de mais facilmente comparar sistemas. O RICS foi eficiente para comparação de solos e variou similarmente com os métodos químicos e espectroscópicos usados na caracterização dos ácidos húmicos. Os valores de pH, ponto de efeito salino nulo zero, soma de bases, teor de cálcio trocável, índice de intemperismo, bem como de razão entre oxigênio e carbono, teores de quinonas e de radicais livres semiquinonas, carbono aromático e intensidade de fluorescência dos ácidos húmicos, mostraram estreitas relações com o RICS. Os solos menos intemperizados, com argilas mais ativas e mais alta fertilidade apresentaram maior RICS. Os solos sob longo tempo de manejo com cana-de-açúcar mostraram RICS seguindo a ordem decrescente: cana crua, cana queimada com vinhaça, cana queimada sem vinhaça.

As an alternative to the relatively complex and expensive spectroscopic methods, the redox properties of humic acids, determined by potentiometric titrations, have been used to evaluate the stability of soil organic C. The objective of the present study was to establish a Redox Index of C Stability (RICS) and to correlate it with some properties of the humic acids extracted from different modal soils in Brazil (distinct weathering stages or management) to facilitate system comparison. The RICS was efficient for soil comparison and variations were comparable to those of the chemical and spectroscopic methods used for humic acid characterization. The values of soil pH, point of zero salt effect, sum of bases, exchangeable Ca content, weathering index, as well as the humic acid O/C ratio, quinone and semiquinone free radical contents, aromatic C and fluorescence intensity were closely related with the RICS. The RICS was higher in less weathered soils, with more active clays and higher fertility. The RICS values of soils under long-term sugarcane management were ranked in decreasing order: unburned, burned with vinasse, burned without vinasse.