Circular chemistry (CC) is an approach for establishing chemical processes to become truly circular and sustainable. It adopts the principles of circular economy (CE), employing life cycle approaches and systems thinking, which help to understand and address the sustainability issues of chemical processes and products. Within this whole context, it is possible to identify some problems of the current lifestyle, such as plastic waste disposal, CO2 emission, e-waste, among others, which need to be addressed accordingly. The reuse provided, well-structured within the context of circular chemistry, can bring benefits in all spheres: social, environmental and economic. Thus, the purpose of this revision is to present CE and CC as the pillars for a sustainable development, bringing discussions about: CE and CC systems; sustainable chemistry; and chemistry 4.0, which embeds digitization, sustainability, and circular economy in industrial chemical processes. Through the knowledge of chemistry, both CC and CE can contribute with innovative methods and processes which maximize benefits, eliminating, or, at least, reducing adverse impacts, thus contributing to construct a mutually beneficial relationship between science and society, its surroundings, and the environment. Therefore, implementing this new model is an opportunity that challenges the human imagination in building a better world.

Green hydrogen is a fuel capable of promoting sustainable energy development and is gaining attention in the current global energy transition framework. The global shift toward decarbonization has triggered a substantial boost in the hydrogen industry. This study presents an overview of the current status of hydrogen production, regulation of the green hydrogen segment, hydrogen storage, distribution, and transportation, and final use and application. We also critically discuss the viability of adopting green hydrogen in terms of possible economic and environmental impacts as well as the main challenges and opportunities it represents for the Chemical Sciences.

Analytical methods for determining 14 endocrine-disrupting compounds (EDCs) in coastal waters, suspended particles, and sediment samples were successfully performed by ultrafast liquid chromatography with photodiode array and fluorescence detections (UFLC-PDA-FLD). Solid phase extraction (SPE) and ultrasound-assisted extraction (USE) were used for sample preparation. Two chromatographic methods have been developed. An isocratic separation method was used to separate bisphenol A (BPA) and steroids and another gradient elution method to separate phthalates and alkylphenols. The detection by fluorescence was used for alkylphenols, BPA, and steroids and photodiode array (PDA) for phthalates. Limits of detection (LOD) ranged from 0.41 (4-tert-octylphenol (4tOP)) to 63 ng L-1 (dibutylphthalate (DBP)), 0.41 (4tOP) to 63.2 ng g-1 dried weight (dw) coastal waters, and solid samples (suspended particulate matter (SPM) and sediment samples), respectively. Recoveries ranged from 52 (diethylphthalate (DEP)) to 116% (DBP) for water, from 54 (DEP) to 108% (estrone (E1)) for SPM, and from 62 (4-n-nonylphenol (4nNP)) to 117% (4-n-octylphenol (4nOP)) for sediment samples. Finally, with the minimization of reagents and energy, the proposed methods were applied to samples collected from Todos os Santos Bay (BTS), Bahia, Northeastern Brazil.

The crescent number of scientific articles published per year shows that research on biodiesel continues to play an important role to support the growing demand for this biofuel. The second edition of Biodiesel: An Overview presents the worldwide research in the last 15 years. Microalgae biomass is the most studied raw material alternative in this period and several studies have been carried out to develop basic heterogeneous catalysts for biodiesel production. Concerning to production technologies, supercritical conditions and intensification process have been extensively investigated. The development of new antioxidants additives has focused mainly on biomass-derived formulations and there are few studies on biocide candidates. In terms of pollutant emissions, in general, the studies showed that the addition of biodiesel generates lower concentrations of polycyclic aromatic hydrocarbons (PAH), CO and n-alkanes pollutants, but carbonyl compounds, major ions and NOx are emitted in a higher concentration compared to pure diesel.

Since the 1950s, pesticides have been used in agriculture. The increase in their consumption has been observed in recent years. In this work, it was determined the concentration of pesticides in the atmosphere of São Paulo and Piracicaba cities (sugarcane plantation site) and the hazard quotients and cancer risk caused by inhalation of these compounds were calculated. Twenty-three samples were analyzed and 34 pesticides associated to atmospheric particulate matter (with diameter equal to or less than 2.5 (PM2.5) and 10 µm (PM10)) were investigated by gas chromatograpy-mass spectrometry (GC-MS). Fourteen compounds including organochlorines, organophosphorus, and pyrethroids pesticides, were determined in these samples. The concentrations in the particulate matter ranged from 17 pg m−3 (tebuconazole) in Piracicaba, to 166 pg m−3 (endrin aldehyde) in São Paulo. The highest values of daily inhalation exposure for heptachlor were 9.0 × 10−5mg kg−1 day−1 at Piracicaba, and 6.5 × 10−5 mg kg−1 day−1 at São Paulo, in both cases registered in infants. The values of the hazard quotients are lower than 1.0, indicating that there is no danger to the exposed population, it is health protective. On the other hand, the cancer risk calculations for heptachlor resulted in values above those recommended by US Environmental Protection Agecy (EPA).

In this work, the redox activity of fine diesel/biodiesel particulate matter (PM2.5) was studied in order to approach its toxicity from reactive oxygen species, due to adverse effects it may cause to human health. The oxidative potential was measured by the dithiothreitol (DTT) assay in order to study the relative contribution of water-soluble transition metals, polycyclic aromatic compounds (PAH), nitro-PAH, and quinones. It was analyzed a total of 24 samples collected from primarily diesel/biodiesel-exhausted particles from buses. The rate concentrations of PM2.5 redox activity ranged 0.020-0.069 nmol min-1 μg-1, with median at 0.040 nmol min-1 μg-1 (on average, 0.042 ± 0.005 nmol min-1 μg-1 for morning, 0.033 ± 0.007 nmol min-1 μg-1 for afternoon and 0.045 ± 0.009 nmol min-1 μg-1 for night). The transition metals appear to dominate the DTT response, since they were responsible up to 89% of redox activity measured in the samples. Apparently, the metal fraction contained in PM2.5 demonstrated a greater ability to catalyze reactions that promote the formation of reactive oxygen species when compared to organic compounds. It was observed that the oxidative potential of PM2.5 particles emitted from diesel/biodiesel (B7) is similar to diesel-emitted particles.

In this study, it is reported the fractal dimension and morphology of ultrafine particles emitted by a diesel engine run with B4, B50, and B100. Transmission electron micrographs evidenced two main groups of particles with characteristic and distinct morphological behaviors: (i) particle agglomerate structures self-organized within a fractal-like geometry, and (ii) amorphous and irregular particles with diffuse edges in a liquid-like particle appearance, mainly associated with some sub-fractions of samples collected from B50 and B100 combustion. Particles from (i) showed typical diesel soot morphology and fractal dimension. Primary particle diameter (Dpp) was 24 ± 4 nm, 23 ± 4 nm, and 20 ± 4 nm for B4, B50, and B100, respectively. Mean aggregate gyration diameters (Dg) ranged from 242 ± 140 nm for B4, 210 ± 135 nm for B50, and to 232 ± 140 nm for B100. In turn, fractal dimensions (Df) were 1.94, 1.89, and 1.99 for B4, B50, and B100, respectively. On the other hand, particle from (ii) had their morphology impaired from the addition of biodiesel to petrodiesel in a way it did not follow a fractal geometry.

Considerando com as exigências de economia de energia e redução de emissões de carbono, o nexo água vs. energia vem alcançando destacado interesse em todo o mundo. O Brasil ocupa uma posição singular na matriz energética mundial. A maior parte das habitações brasileiras tem eletricidade; e a expansão da matriz energética que, a princípio, possui meios adequados para sustentar o crescimento econômico, pode experimentar transformações. A determinação do Brasil pelos combustíveis alternativos foi uma escolha natural, dado seu potencial hidrelétrico e a extensão de terras agriculturáveis. No setor de transportes, o Brasil desenvolveu sua matriz energética com importante contribuição do etanol e do biodiesel. Embora esses combustíveis sejam baixos emissores de carbono, não são alternativas acessíveis quando considerados o uso da terra, segurança alimentar e water footprint. Desta forma, considerando os recentes avanços na exploração de petróleo do Pré-Sal (9-15 milhões de barris) e as recentes descobertas de jazidas de gás de xisto (245 tcf), juntamente às questões sociais e ambientais desfavoráveis dos biocombustíveis, a matriz energética brasileira poderá voltar a ter como foco os combustíveis fósseis. Estes desafios deverão ser resolvidos nas próximas décadas, refletindo não só no Brasil, mas também em todo o mundo.

According to the demands of energy saving and carbon emission reduction, the water vs. energy nexus has become a major concern worldwide. Brazil occupies a singular position in the global energy system. A major portion of the Brazilian occupancies has electricity and the energy system expansion that, at first, possesses adequate means for supporting the economic growing may experience some turnovers. The Brazil determination through alternative fuels was a natural choice, given its large hydropower potential and land agricultural base. In the transportation sector Brazil has developed its energy matrix towards an important rate of ethanol and biodiesel. Although those fuels are low carbon emitter, they may probably not be an affordable alternative regarding land use, food security and water footprint. In this way, considering the recent advances in the exploration of oil from Pre-salt (9-15 million barrels) and the discovery of shale gas wells up to 245 tcf, together to unfavorable social and environmental issues associated to biofuels, the Brazilian energy matrix might turn back to the fossil fuels again. These represent challenges to the Brazilian policymakers and how they will be solved will reflect not only in Brazil but also to the world at large.

A atmosfera de regiões costeiras adjacentes a regiões urbanas podem ser afetadas pela emissão de diferentes poluentes atmosféricos, dentre eles, os íons majoritários. Nesse estudo foram estudadas a composição química e as fontes de carboxilatos e íons solúveis em água em partículas finas e grossas bem como as estimativas de fluxo de deposição seca em um sítio em uma região costeira tropical afetada por uma Região Metropolitana. As concentrações médias de carboxilatos totais foram 78 ng m–3 na fração fina e 81 ng m–3na fração grossa do material particulado (MP). Os valores correspondentes de concentração para os íons inorgânicos foram 2143 ng m–3 e 4880 ng m–3, respectivamente, para as frações fina e grossa. As principais fontes para as partículas finas foram: (i)formação fotoquímica de ácidos carboxílicos na fase vapor e posterior conversão gás-partícula sobre partículas de sal marinho, (ii) emissões de fontes antrópicas envolvendo processos de transporte de longas distâncias; e(iii) a interconversão de espécies voláteis entre fases atmosféricas. Por sua vez, as fontes predominantes para as partículas grossas foram:(i) espécies gasosas ab/adsorvidas em partículas pré-existentes, (ii)emissão primária de partículas grossas de fontes antrópicas, e (iii) spray marinho e/ou ressuspensão do solo. Finalmente, a deposição seca de partículas representa o fluxo de íons majoritários na interface ar-oceano.

The coastal atmosphere adjacent to large urban areas can be strongly affected by the emission of air pollutants, among them, major ions species. In this study, the chemical composition and sources of carboxylates and other water-soluble ions in fine and coarse aerosols as well as estimates of particle dry deposition fluxes were studied at a tropical coastal site affected by an urban environment. The mean concentrations of the total carboxylates were 78 ng m–3 in fine fraction and 81 ng m–3 in coarse fraction of particulate matter (PM). The corresponding values for the total inorganic ions were 2143 ng m–3 and 4880 ng m–3 respectively. Main sources for fine particles were:(i) photochemical formation of carboxylic acids in vapor phase and a posterior gas-to-particle conversion onto sea salt particles; (ii) emissions from anthropic sources with long range transportation processes; and (iii) the interchanging of volatile species among atmospheric phases. In turn, for coarse particles, the predominant sources were: (i)gas-phase species and ab/adsorbed onto pre-existing particles afterwards;(ii) primary emission of coarse particles from anthropogenic sources; and (iii) sea salt spray and/or soil resuspension. Finally, particle dry deposition was a very important mechanism representing air-to-sea fluxes of major species.

A sensitive spectrophotometric method was developed for sulphate determination in automotive ethanol fuel. The method based on the reaction of the analyte with barium-dibromosulphonazo(III) complex lead to a decrease in the magnitude of the absorbance signals monitored at 649 nm. No sample pretreatment is required and the proposed method allows sulphate determination in the 0.45 - 6.50 mg L-1 range with R.S.D. < 2% and limit of detection of 0.14 mg L-1. The method has been successfully applied for sulphate determination in automotive ethanol fuel and the results agreed with the reference chromatographic method.

Neste trabalho, as distribuições sazonais de Al, Ca, Cu, Fe, K, Mg, Na, Pb, Zn e de íons majoritários (Cl-, PO4(3-), NO3-, SO4(2-), HCOO-, CH3COO-, oxalato, succinato, Na+, NH4+, K+, Mg2+ e Ca2+) foram estudadas na fração PM10 (material particulado menor que 10 mm) na cidade de São Paulo (abril de 2003 a maio de 2004). Os níveis atmosféricos mais elevados foram encontrados para os íons inorgânicos SO4(2-), NO3-, Cl- e PO4(3-), e dentre os íons orgânicos, oxalato e formiato. Os níveis atmosféricos para elementos foram: Fe > Al > Ca > K > at > Mg > Zn > Cu > Pb. As fontes relevantes foram: (i) queima de combustíveis e/ou queima de biomassa (NO3-, HCOO-, C2O4(2-), K+, Mg2+, Ca2+, Fe, Pb, Zn, Al, Ca, K e Mg), (ii) conversão gás-partícula (SO4(2-) e NH4+) e (iii) spray marinho (Cl-, Na+ e Na).

This study deals with the seasonal distribution of Al, Ca, Cu, Fe, K, Mg, Na, Pb and Zn and water soluble ions (Cl-, PO4(3-), NO3-, SO4(2-), HCOO-, CH3COO-, oxalate, succinate, Na+, NH4+, K+, Mg2+ and Ca2+) found in PM10 samples (particulate matter less than 10 mm in diameter) São Paulo City, Brazil, (April 2003-May 2004). Higher atmospheric levels were found for SO4(2-), NO3-, Cl- and PO4(3-) while the main organic anions were oxalate and formate. Atmospheric levels for elements were: Fe > Al > Ca > K > Na > Mg > Zn > Cu > Pb. Some sources were predominant for some species: (i) fuel burning and/or biomass burning (NO3-, HCOO-, C2O4(2-), K+, Mg2+, Ca2+, Fe, Pb, Zn, Al, Ca, K and Mg), (ii) gas-to-particle conversion (SO4(2-) and NH4+) and (iii) sea salt spray (Cl-, Na+ and Na).

Amostras de material particulado total e MP10 foram coletadas entre agosto de 2006 e fevereiro de 2007 na estação rodoviária Prefeito José Carlos Lacerda. Foram analisados os 16 HPAs considerados prioritários, emitidos pelos veículos pesados em condições típicas de operação, usando CG/EM. α ΣHPA correspondeu a 0,0018% da massa de MPT e 0,0012% da massa de MP10. O conteúdo total de HPAs foi de 3,57 ng m-3 e 2,59 ng m-3 para o MPT e o MP10, respectivamente. A contribuição dos compostos carcinogênicos, conforme a USEPA, (B[a]An, B[b]F, B[k]F, B[a]Py, IPy e DB[ah]A) foi 1,86 ng m-3 (52% do total de HPAs) e 1,40 ng m-3 (54% do total de HPAs), para as amostras de MPT e MP10, respectivamente. As relações características e a análise estatística multivariada deram, em geral, resultados similares aos obtidos para poeira de solos, exceto para a relação Flt/(Flt+Py), 0,34, compatível com emissões de diesel. Os fluxos de deposição seca estão no intervalo 0,022-0,603 e 0,016-0,436 μg m-2 dia-1 para os compostos contidos no MPT e MP10, respectivamente.

Total particulate matter and PM10 samples were collected from August 2006 to February 2007 in Mayor José Carlos Lacerda bus station. 16 priority PAHs compounds emitted by heavy-duty vehicles on typical conditions of operation were analyzed by using GC/MS. ΣPAH accounted for 0.0018% of the TSP mass and 0.0012% of the PM10 mass. Total PAH contents on the particle phase were 3.57 ng m-3 and 2.59 ng m-3 for TSP and PM10, respectively. Contributions of carcinogenic USEPA priority PAHs (B[a]An, B[b]F, B[k]F, B[a]Py, IPy and DB[ah]A) were 1.86 ng m-3 (52% of total PAHs) and 1.40 ng m-3 (54% of total PAHs), for TSP and PM10 samples, respectively. Diagnostic ratios and multivariate statistical analysis were, in general, similar to those reported for soil dust except for the Flt/Flt+Py) ratio, 0.34, compatible with diesel emissions. Dry deposition fluxes were in the range of 0.022-0.603 and 0.016-0.436 μg m-2 day-1 for compounds in TSP and PM10, respectively.

Emissões industriais são as fontes principais de poluição atmosférica no parque industrial de Cubatão, no sudeste do Brasil, onde a dispersão é limitada pela extensa faixa de montanhas na região. O transporte de veículos pesados é uma fonte importante de gases e aerossóis e pode influenciar nas concentrações de poluentes atmosféricos próximos à superfície, dependendo das condições meteorológicas. Este trabalho mostra que as fontes industriais foram predominantes nos fluxos de SO2, enquanto que o transporte veicular foi a principal fonte de NO2 para a atmosfera. A rápida remoção de NO2 e SO2 da atmosfera foi atribuída às reações na fase gasosa e reações heterogêneas, respectivamente. Concentrações médias de MP10 aumentaram cerca de uma ordem de magnitude durante a circulação da brisa do mar. Foi demonstrado que instrumentação de resposta rápida pode fornecer uma alternativa conveniente às medidas obtidas com equipamentos fixos para mapeamento espacial (horizontal e vertical) de poluentes atmosféricos.

Industrial emissions are a notorious source of atmospheric pollution in the Cubatão industrial park of Southern Brazil, where dispersion is restricted by surrounding mountain ranges. It is shown here that road transport is also a large source of gases and aerosols, which can dominate pollutant concentrations at ground level, depending on meteorological conditions. SO2 was released mainly by industry, while road transport was a major source of NOx. Rapid removal of NO2 and SO2 was attributed to fast gas phase and heterogeneous reactions, respectively. Average PM10 concentrations increased by an order of magnitude during sea breeze fumigation, and high particulate pollution events were associated with vehicular activity. It is demonstrated that fast-response portable instrumentation can provide a useful alternative to measurements at fixed network sites for spatial (horizontal and vertical) mapping of atmospheric pollutants.

O presente trabalho apresenta o estudo sobre 16 HPAs prioritários em material particulado atmosférico de três sítios próximos a Salvador-BA: (i) Estação da Lapa, estação de ônibus da Região Metropolitana de Salvador; (ii) Porto de Aratu, impactado por intenso movimento de matérias-primas e (iii) Bananeira, localizado na Ilha de Maré, vilarejo que tem como principais atividades a pesca e artesanato. Resultados mostraram que o BbF (0,130-6,85 ng m-3) foi o HPA com as concentrações mais elevadas em Aratu e Bananeira e CRY (0,075-6,85 ng m-3) apresentou nível mais elevado na Lapa. As fontes de HPAs nos sítios estudados foram principalmente de origem antrópica, tais como veículos de pequeno e grande portes, carregamentos do porto, ressuspensão de partículas do solo, queima de diesel das embarcações e a queima de carvão e madeira para produção de energia.

The present work has aimed to determine the 16 US EPA priority PAH atmospheric particulate matter levels present in three sites around Salvador, Bahia: (i) Lapa bus station, strongly impacted by heavy-duty diesel vehicles; (ii) Aratu harbor, impacted by an intense movement of goods, and (iii) Bananeira village on Maré Island, a non vehicle-influenced site with activities such as handcraft work and fisheries. Results indicated that BbF (0.130-6.85 ng m-3) is the PAH with highest concentration in samples from Aratu harbor and Bananeira and CRY (0.075-6.85 ng m-3) presented higher concentrations at Lapa station. PAH sources from studied sites were mainly of anthropogenic origin such as gasoline-fueled light-duty vehicles and diesel-fueled heavy-duty vehicles, discharges in the port, diesel burning from ships, dust ressuspension, indoor soot from cooking, and coal and wood combustion for energy production.