Layered double hydroxides (LDH) with the composition Zn2Cr, intercalated with acetate and chloride ions were synthesized by co-precipitation with increasing pH and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). The samples synthesized at optimized pH showed XRD patterns with basal diffraction peaks typical of layered structures, with basal distances of 7.88 and 12.69 Å for intercalated chloride (Zn2Cr/Cl) and acetate (Zn2Cr/Ac), respectively. After optimization experiments, exchange reactions were performed with different anions, using an excess of five times the anions to be intercalated. Zn2Cr/Cl was exchanged with CH3COO-, F-, Br-, I-, SO42- and NO3-, and Zn2Cr/Ac was exchanged with F-, Cl-, Br-, I-, SO42- and NO3-. Not all reactions were effective, indicating that among the evaluated anions, CH3COO- was preferred for exchange, mainly attributed to the pre-expansion with bigger anions, facilitating the exchange with smaller anions.

The ubiquity of microplastics ecosystems has gained global attention. In this context, Latin America, which is responsible for 8% of the world’s consumption of plastic material and has a small recycling rate (4.5%), does not have enough data on microplastics contamination in its environmental matrices. This systematic review analyzed 196 studies from 16 territorials in Latin America and provided information about the current state of knowledge regarding the abundance, distribution, and associated impact of microplastics in different matrices. This review also describes the analytical procedures of sampling, extraction, identification, and characterization methodologies adopted by the literature review. The analysis shows that most of the studies that investigate microplastics abundance were carried out in the marine environment (59%), and there is an insufficient investigation on microplastics abundance in freshwater bodies (16%). Among all the studies, the highest microplastics concentration was observed in regions with high population density and/or in locations without proper sanitation and solid waste management. Additionally, the difference among microplastics abundance in the studies might be associated with the different analytical procedures employed to investigate microplastics. Lastly, knowledge gaps are identified, and recommendations are proposed to guide future studies on microplastics contamination.

A hybrid imprinted polymer (HMIP) was synthetized via sol-gel technique in aqueous solution for caffeine separation from environmental waters samples. The optimal conditions of synthesis were stablished by application of a 23 full factorial experimental design with three factors: ratio of functional monomer and cross-linker reagent, and acid or basic catalyst (HCl or NH4OH). The HMIP obtained with the factorial designs was 22.5 times more selective for caffeine than control polymer, with an adsorption mechanism of pseudo-second order with two sorption sites. The maximum equilibrium adsorption capacity was 1.91 mg g−1 that was maintained until ten cycles of reuse, indicating their excellent stability. The material was 21 times more selective for caffeine than for its analogous molecules (theophylline and theobromine). HMIP was applied in solid phase extraction (SPE) procedure and caffeine extraction of surface water had good recoveries (93.0%). These results demonstrated that the factorial experimental design resulted in an efficient and selective sorbent for caffeine with a reduction of number of synthesis and problems of trial-and-error protocol as well as reagents consumption decrease.

Samplers based on the diffusive gradients in thin films for organics (o-DGT) were developed and applied in Brazilian aqueous matrices for the determination of four emerging contaminants (EC): 4-octylphenol, 4-nonylphenol, triclosan, and bisphenol A. The OASIS HLB resin used as the binding phase presented a high sorption capacity and the extraction associated with sonication, using a mixture of acetonitrile and methanol (2:1, v v-1) as the solvent, provided a higher desorbed mass of the compounds. The diffusion coefficients determined experimentally were in the range of the values found in the literature and the pH and ionic strength influenced the sorption of some compounds by the binding phase. The substances were detected and quantified in tap and river water samples after 7 days of deployment using gas chromatography tandem mass spectrometry (GC-MS/MS). Finally, the results indicate deficiencies in the current wastewater, as well as water treatment systems, and could contribute in the future to the improvement of public policies on basic sanitation in Brazil.

Layered double hydroxides (LDHs) of Cu:Al in the molar ratio of 2:1, intercalated with sulfate, sulfate/(Li+, Na+, K+ or NH4+), NO3- and CO32-, were synthesized by co-precipitation with increasing pH. The materials were submitted to exchange reactions using B2SO4 (B = Li+, Na+, K+, NH4+) solutions in an attempt to replace previously intercalated cations or incorporated cations without removing intercalated sulfate. X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra were consistent with the expected intercalated species and scanning electron microscopy (SEM) images indicated submicrometric platelet-like particles, typical of LDHs. The chemical compositions of all phases were confirmed by inductively coupled plasma optical emission spectrometry (ICP OES) and thermogravimetric analyses (TGA). In the exchange reactions, only in [Cu6Al3(OH)18][Na(H2O)6(SO4)2]·6H2O the sodium cations were almost totally replaced with lithium, potassium and ammonium, without removing the intercalated sulfate.

Flame retardants are substances mixed with numerous materials to inhibit the combustion process, reducing risks and damages caused by fires. Among these substances, polybrominated diphenyl ethers (PBDEs) have been widely used for decades due to their low cost and high efficiency. However, since they are mixed and not chemically bonded to the materials, PBDEs can be released over time being transported through numerous pathways until they reach soils and aquatic systems, where they can accumulate in sediments and biota. Due to their high chemical stability, an essential feature for flame retardants, they are considered persistent contaminants. Several studies report the presence of PBDEs in atmospheric and aquatic particulate matter, sediments, soils and biological matrices such as marine animals, tissues and human fluids. In Brazil, little is known about the use and commercialization of PBDEs, as well as their levels in different environmental compartments. Thus, this review provides an overview of the origin of PBDEs in the environment as well as information inherent to the understanding of the behavior and presence of this contaminants of recent interest in different environmental compartments. Finally, the manuscript also brings state-of-the-art analytical approaches used for environmental sampling, preservation, preparation and sample analysis.

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.

Soils that had received successive applications of retorted oil shale (ROS) in an experiment under field conditions were used in this study, aiming to evaluate the availability of trace elements. In the batch tests, we observed that toxic elements present in the ROS are not desorbed from the matrix in significant amounts to contaminate soil and groundwater. The element Ca represents the greatest nutrient contribution, which has high mobility and ease release into the soil solution. Concerning the results obtained from the soil extracts analysis; we observed that the undesirable elements released into the extracts are not directly related to the presence of ROS in the soil samples. Comparing the behavior of soil samples with and without ROS it is possible to infer that many of the trace elements are derived from soil constituents, from previous fertilizer and pesticides applications. The study suggested that the ROS can be used as a soil conditioner for agricultural purposes without adding harmful elements to the environment.

The main objective of the present work was to validate a chromatographic method to determine herbicides commonly applied in the irrigated rice farming. For this, matrix-matched calibration was employed along with the extraction and clean-up of the samples by quick, easy, cheap, effective, rugged and safe (QuEChERS) method and determination of the analytes by high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) with electrospray ionization in the positive mode. By this method, it was possible to achieve the ionization and detection of a total of 18 herbicides, with quantification of 12 of them. The method presented adequate precision and accuracy according to the European Commission and the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines for analytes in low concentrations. The limits of quantification ranged from 0.015 μg g-1 for oxadiazon to 0.165 μg g-1 for imazapyr. The method showed good linearity with R2> 0.99 and recovery values from 92 to 103%. The proposed protocol is adequate for monitoring bispyribac-sodium, cyclosulfamuron, cycloxydim, clomazone, ethoxysulfuron, fenoxaprop-p-ethyl, imazapic, imazapyr, imazethapyr, metsulfuron-methyl, oxadiazon and thiobencarb in rice grains in concentrations up to 109 times lower than the maximum residue limits established by the Brazilian Health Surveillance Agency (ANVISA) for these compounds in rice samples.

The use of MT-K10 Montmorillonite immobilized onto agarose was investigated in this work as an alternative binding phase in Diffusive Gradient in Thin Film (DGT) devices for the determination of metallic labile species. In addition, agarose itself was also used as the diffusive phase. The percentage of sorption of Zn2+, Cu2+, Cr3+, Mn2+, Cd2+, Pb2+, and Ni2+ onto the binding phase was higher than 80% and the desorption process for all elements was also greater than 75%. Elution factors were determined experimentally, ranging from 0.74 for Zn2+ and 0.90 for Cr3+ and Pb2+. The accumulation of all species was linear with time, in agreement with the Fick's 1st law of diffusion. The deployment of the alternative devices in natural waters was compared to commercial devices. Labile concentrations determined by the alternative devices were slightly superior compared to results obtained with the deployment of original DGT devices due to the less restrictive pores of agarose.

Neste trabalho foi proposto um procedimento para a extração do herbicida atrazina (AT) e dos principais metabólitos desetil-atrazina (DEA) e desisopropil-atrazina (DIA) de uma amostra de latossolo vermelho proveniente da região sudoeste do estado do Paraná no Brasil, onde a AT está entre os herbicidas mais amplamente utilizados. Foi conduzida uma comparação usando extração por agitação e por ultrassom, sendo obtido um procedimento de extração simples e rápido, seguido pela quantificação por cromatografia em fase líquida de alta eficiência. Cabe ressaltar que foi utilizado um estudo por planejamento fatorial, o qual foi decisivo para determinar as melhores condições de extração por agitação. Foram obtidos percentuais de recuperação e desvios padrão relativos adequados, para amostras de solo de três diferentes profundidades, o que sugere a possibilidade de empregar o método de extração proposto para a quantificação de AT, DEA e DIA em amostras de latossolo vermelho.

An optimization procedure for the extraction of the herbicide atrazine (AT), and the main degradation products deethylatrazine (DEA) and deisopropylatrazine (DIA) from an oxisol soil sample was carried out, for a soil from the Southwest of Paraná State in Brazil, where AT is among the most largely employed herbicide. A comparison between shaking and ultrasound extraction was performed, to define a simple and fast extraction procedure, followed by the quantification using high performance liquid chromatography. It is important to inform that a factorial planning was employed, that was very important to define the best conditions of extraction by shaking. Appropriate recovery values were observed using soil samples from three different depths, as well as the relative standard deviation, suggesting the possibility to employ the proposed extraction method for quantification of AT, DEA and DIA in oxisol samples.

Neste trabalho foram aperfeiçoadas as etapas para determinação de hidrocarbonetos alifáticos e aromáticos em sedimentos. Durante as etapas de extração e concentração foram avaliados fatores determinantes como tempo, solvente extrator e sistema de resfriamento. Quanto ao cleanup, foram estudados diferentes volumes e misturas de solventes de eluição. Os resultados obtidos foram considerados aceitáveis (70-120%). A linearidade, limites de detecção e quantificação foram estudados construindo-se curvas analíticas (R > 0,99) com valores que demonstraram grande sensibilidade do método. A precisão e exatidão foram avaliadas com ensaios envolvendo material de referência certificado e adição e recuperação de analitos em sulfato de sódio. Nos testes de adição e recuperação os desvios ficaram abaixo de 20%, com recuperação dos alifáticos e aromáticos de 59-105% e 55-113%, respectivamente. Para os sedimentos de referência, os desvios obtidos foram inferiores aos valores certificados, com recuperações satisfatórias. O presente trabalho proporcionou a melhoria de um método já consolidado, possibilitando obter resultados com elevada confiabilidade analítica.

The main steps involved in the determination of aliphatic and aromatic hydrocarbons in sediments were evaluated in this work. In the extraction, factors such as the cooling system, time and solvent were evaluated. During the extraction and concentration, steps aspects such as time, extraction solvent and cooling system were evaluated. In the cleanup different solvents and elution mixtures were studied. The results were considered satisfactory (70-120%). Linearity and limits of detection and quantification were studied by means of calibration curves (R > 0.90) and the results demonstrated high sensitivity of the method. Precision and accuracy were studied by recovery tests using a certified reference material and sodium sulfate. In recovery tests, the standard deviations were below 20%, with percent recoveries for aliphatic and aromatics ranging from 59 to 105% and 55 to 113%, respectively. For the reference sediment, the standard deviations were lower than the certified values, with satisfactory recovery values. The present work provided a way of improving an already established method with high analytical reliability.

This paper describes the adsorption of 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) from aqueous solution by decomposed peat. The peat presented a good adsorption process, close to 76.2% for E2 removal and approximately 55.0% for EE2. Moreover, the results indicated a probable multi-layered process. Adsorption isotherms were well fitted by Freundlich model. The data were evaluated considering the pseudo-first-order and pseudo-second-order approaches, being the second more significant mechanism in the rate-controlling step. Thermodynamic data revealed that hormones adsorption onto peat is spontaneous under the employed experimental conditions. The results confirmed the potential of this adsorbent to be employed for effluents treatment.

Speciation of metals in a synthetic freshwater was comparatively evaluated using Anodic Stripping Voltammetry, Diffusive Gradients in Thin Films and a Chemical Equilibrium Model. The labile fractions of Cu and Zn quantified by DGT were similar to the ones measured by ASV. The labile species of Cd and Pb could not be determined by both experimental methods due to the formation of inert complexes with organic ligands in the sample. Despite the differences among the methods, the speciation results obtained by the use of DGT and ASV agreed well with predictions made by the chemical equilibrium model.

In this work a sulfide quantification protocol using voltammetric methods was developed to evaluate the effect of dissolved sulfides on copper complexation. On the basis of pH, sulfide release from the dissociation of specific metal sulfide complexes can be electrochemically measured and then removed (as H2S) by a N2 purge. Cathodic stripping square wave voltammetry (CSSWV) was conducted to quantify Cu sulfides complexes which dissociate at pH < 5.0 during the process of acid titration.