Resumo em Inglês:

Given the extensive use of pesticides in modern times, residues are frequently detected in water samples. Therefore, this study developed and validated a method utilizing solid-phase extraction (SPE) with a polymeric sorbent for sample preparation in combination with ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The aim was to determine a variety of current-use pesticides (CUPs) in different types of water. The preconcentration step, employing the polymeric sorbent Oasis HLB (60 mg), combined with the high selectivity and sensitivity of the UHPLC-MS/MS analysis, enabled the multiclass determination of pesticide residues in water samples at very low concentrations. The proposed method underwent validation, demonstrating satisfactory linearity, precision, and accuracy. The accuracy results, determined through recovery assays at varying spike levels (0.04-0.4 μg L-1), ranged from 71 to 117%, with precision expressed as relative standard deviations consistently below 19%. The practical limits of detection and quantification for most compounds were 0.01 and 0.04 μg L-1, respectively. This method was effectively employed to analyze drinking water, artesian well water, dam water, and river water, leading to the detection of various pesticides at concentrations of up to 2.24 μg L-1.

Resumo em Inglês:

Mixed oxides of pyrochlore structure of the type La2Zr2O7 and La2M0.3Zr1.7O7 (M = Fe or Ni) were synthesized through the modified proteic method and calcined at 900 °C for 2 h, this is a synthesis route not yet explored for materials with this structure and were characterized by X-ray diffraction, scanning electron microscopy images, point of zero charge (PZC) and specific surface area. Its abilities to remove pollutants from aqueous media by adsorption process were investigated using a model compound. Data analysis revealed that the synthesized materials correspond to the pyrochlore phase (La2Zr2O7). They present particulate morphology with grains of different sizes and pores in their structure. The results of the adsorption studies show that the materials are efficient adsorbents for the removal of model compound in aqueous media, with efficiency above 90%. The adsorption kinetics of the compound in the adsorbents was studied. The materials were applied in reuse studies five times and maintained high efficiencies, highlighting the better performance presented by the material without doping. The obtained adsorbents were also submitted to removal of contaminants of industrial effluent tests and compared with the silica gel and activated carbon materials and also proved to be promising materials.

Resumo em Inglês:

Polybrominated diphenyl ethers (PBDEs) are persistent flame retardants widely used in everyday materials, with the potential to leach out and contaminate indoors and receiving waters. Despite their well-documented ecological risks, there has been limited reporting on PBDE levels in sediments from Brazilian freshwaters, motivating the monitoring of sediments from Paranoá Lake, in the Brazilian capital. After sampling, extraction, and analysis of congeners BDE-28, -47, -66, -85, -99, -100, -138, -153, and -154 by gas chromatography with electron capture detection, Σ9PBDE levels ranged from 3.9 ± 0.2 to 19 ± 1 ng g-1 dw, with higher concentrations attributed to effluent discharge from wastewater treatment plants (WWTPs), followed by the influence of storm drainage water contamination. The distribution of PBDE congeners suggested a predominant influence of the commercial pentaBDE formulation, likely DE-71. However, in points influenced by WWTPs, the prevalence of BDE-66 suggests biotic reductive debromination of high-brominated PBDE, possibly BDE-209, indicating the possible influence of the decabrominated formulation. The distribution of PBDEs in the environment, estimated using the EQC (equilibrium criterion) model, level I, indicated low concentrations in the water column, but also noteworthy levels in biota and sediment precursor materials. Finally, preliminary ecological risk assessment indicated the need for future further surveys.

Resumo em Inglês:

In recent years, the Brazilian government has authorized several agricultural pesticides, increasing the possibility of pollution of different ecosystems and the food consumed by a large part of the population. The analytical determination of pesticides can be carried out using different techniques associated with various methods. Their development and validation have been based on obtaining better reliability, meeting the requirements of environmental legislation, and adapting to the principles of Green Chemistry. Thus, a chromatographic method was developed for the separation and determination of eight agricultural pesticides (aldicarb, ametrine, atrazine, bendiocarb, carbaryl, hexazinone, methiocarb, and methomyl) in compliance with Green Chemistry criteria, using ethanol as the mobile phase, which it is an ecologically less aggressive solvent. The developed method showed efficient separation and excellent results for green analysis metrics with high scores on the Eco-scale and good presentation in the National Environmental Methods Index (NEMI), Green Analytical Procedure Index (GAPI), and Analytical Greenness Calculator Metric (AGREE) pictograms. The validation parameters indicated the linearity of the method with good precision, selectivity, and sensitivity with detection and quantification limits in the ranges of 0.50 to 0.94 mg L–1 and 0.74 to 1.81 mg L–1, respectively.

Resumo em Inglês:

It is essential to diversity energy sources for ensuring sustainability. While hydrogen is considered a promising energy storage medium, its potential hinges on the development of efficient photocatalysts for green production. In addressing this challenge, we evaluated the performance of a heterojunction system composed of non-stoichiometric molybdenum oxides (MoO3−x) and cadmium sulfide (CdS) quantum dots (QDs) for water splitting. MoO3−x were synthesized via gamma irradiation of the MoO3 in the presence of formic acid (FA), while CdS-MPA QDs were electrosynthesized. The heterojunction was formed through adsorption. The structural and electronic characterization revealed a progressive transformation from MoO3 to MoO3−x and MoO3−x/CdS-MPA QDs, demonstrating enhanced water-splitting performance. Upon evaluation, the study revealed a charge transfer mechanism, highlighting the significance of relative band positions between MoO3−x and CdS-MPA QDs in promoting eco-friendly hydrogen evolution and methanol processing. Thus, we suggest that the synergism between MoO3−x and CdS-MPA QDs semiconductors makes the heterojunction system a promising solution for photocatalytic production of hydrogen and oxygen.

Resumo em Inglês:

In the present work, we developed an experimental class for undergraduate students concerning the linear synthesis of 2-phenylimidazo[1,2-α]pyridine through mechanochemical techniques. This approach aims to conceptualize the green chemistry principles through a safe, robust, atom-economic, energy-efficient, and solvent-free method for preparing these classes of compounds by manual grinding and vortex mixing. The methodology was easily applied in experimental classes for chemistry students and could be easily expanded to other courses such as pharmacy and biotechnology.

Resumo em Português:

The Sustainable Development Goals (SDGs) provide a comprehensive framework to guide actions towards a more sustainable future, emphasizing the need for sustainable production and consumption patterns (SDG 12), urgent measures to combat climate change and its impacts (SDG 13), and ensuring inclusive, equitable, and quality education (SDG 4). In this context, environmental education (EE) becomes crucial to empower present and future generations to address complex environmental challenges. Promoting EE can be enhanced through Chemistry education, encouraging the use of biomass as a primary energy source, a significant ally in addressing the SDGs. This study integrates experimental and educational chemical knowledge on the pyrolysis reaction of black pepper waste, aiming at higher education in Chemistry in an Environmental Chemistry class at Federal University of Espírito Santo. It aims to provide an in-depth understanding of chemical kinetics, connected to sustainable development through the theoretical-methodological strategy of problematized experimental activity (PEA). The developed PEA comprised five theoretical-experimental classes, including thermogravimetric analysis (TGA) simulation and pyrolysis furnace testing. The results indicate significant learning in Chemical Kinetics and themes related to the pyrolysis process associated with sustainable development, highlighting the contribution of the utilized PEA.

Resumo em Inglês:

(S)-Pyroglutamic acid is a heterocyclic amino acid derivative which was easily synthesized in undergraduate laboratory through a solvent-free environmentally friendly method involving controlled heating and agitation. This preparation allowed teaching stereochemistry in undergraduate levels, which entails the synthesis of (S)-pyroglutamic acid and the assessment of its optical purity using the simple and rapid technique of melting point measurement, corroborated by polarimetry. The reasons why the solid-state properties of enantiomeric mixtures can differ from those of enantiopure compounds are also discussed, with optical rotation not being the sole distinguishing property.

Resumo em Inglês:

The interconnectedness between sustainability, sustainable development, sustainable chemistry, and green chemistry is evident in the pursuit of innovative solutions that can balance economic, environmental, and social needs, thereby building a more sustainable future for present and future generations. Although these are topics that have been widely discussed in recent years, there are many controversies regarding the exact definition and scope of these terms. The term “Green Chemistry” was defined with the Twelve Principles of Green Chemistry, but in recent years, aspects of environmental and social costs need to be incorporated into the definition. Historically, green chemistry has tended to focus on the process, i.e., how a product is made, rather than the properties of the product. So, we generally talk about a process being green or not. This contribution aims to discuss the parallels, interconnections and differences that exist among the concepts within the realms of “Sustainability”, “Sustainable Development”, “Sustainable Chemistry”, and “Green Chemistry”. Additionally, it discusses how these topics play a crucial role in mitigating environmental impacts, conserving natural resources, generating employment, and promoting safer and more sustainable products and processes.