Resumo em Inglês:

Taking advantage of the energy contained in the biosolids generated in a wastewater treatment plant (WWTP) is one of the processes of greatest interest due to the opportunity to obtain an energy resources from a waste. The aim of this research was to analyze the environmental sustainability use of biosolids generated in a wastewater-treatment plant for energy-production by fluidized-bed gasification under exergy analysis. The energy-production system was based on previous studies of sustainable-emergy alternatives using biosolids. Sustainability of the process was evaluated by identifying stages in the energy-production system (from drying application to electricity generation) where it is possible to reduce useful energy losses as well as identifying the value of waste streams within the system through exergy analysis. It was illustrated the destroyed exergy and the efficiency by stage and by product in order to assess the effects of inefficiencies in the process sustainability. The mixture of biosolids with coal was identified as a highly sustainable stage of the process, as it presents the highest index of exergy sustainability (0.99), in contrast to the stages of energy-transformation (turbine) and gas-cleaning, which efficiencies are 0.17 and 0.4, respectively. Energy-transformation and gas-cleaning stages are of interest in terms of an improved energy recovery process, making it more efficient by applying new technologies and/or using the waste streams that have high energy potentials.

Resumo em Português:

NaA ZEOLITE SYNTHESIZED OVER FIBERGLASS AS A STRATEGY FOR OPTIMIZING HARD WATER SOFTENING. Zeolite NaA has been successfully synthesized over glass fiber surface previously activated by alkaline treatment. By varying the time of the treatment and the amount of silica and alumina precursors used in the reaction mixture, a sample with higher zeolite concentration could be obtained. This material was evaluated for water softening process as an alternative substitute for the use of the zeolite in its powder form, in which several drawbacks related to recovery and reuse limit its application. Water softening experiments, carried out in a continuous flow system, with a column containing the glass fiber-zeolite NaA, showed high performance in decreasing the Ca2+ ions, with complete removal achieved for 20 mL of simulated hard water (Ca2+ 100.0 mg L-1) by using 200 mg of the sample in form of column (10 mm diameter × 300 mm high). The sample maintained this performance in a wide range of pH (3.0-9.0), and also presented a feasible regenerability, with no decrease in its performance during the first four cycles of use, reaching 87.3% of efficiency over the tenth cycle.

Resumo em Inglês:

The pharmaceutical industries are focusing on Green Analytical Chemistry principles like miniaturization, eco-friendly solvent usage, waste recycling, and analyst safety for sustainable results. A simple, eco-friendly sensitive and effective extraction and multivariant green analytical method to estimate ketoconazole in bulk and cream formulation were developed and validated according to International Council for Harmonisation (ICH) guidelines. Based on the multivariant analytical technique, the developed method built in linear regression equations between concentration and absorbance with seven different wavelengths. The validation results represent the method has linear at a concentration of 12.8-19.2 μg mL-1 with calculated Limit of Detection (LOD) and Limit of Quantification (LOQ) of 0.338 and 1.026 μg mL-1, respectively. The method results representing a precise accuracy, inter-day, and intraday precision in all the wavelengths with percentage Relative Standard Deviation (RSD) under the limits as less than 2. Also, the method was tested with two different marketed ketoconazole cream formulations with a satisfactory result. The results of the proposed method replicated the novelty in classic approaches and proved statistically. This method was confirmed as greenest than previous methods reported by using assessing tools like National Environmental Method Index (NEMI), Green Analytical Procedure Index (GAPI), Analytical eco-scale, and Analytical Greenness (AGREE) metrics. As a result, the proposed approach could widely utilize for an efficient green analytical methodology for the estimation of ketoconazole.

Resumo em Português:

PROCESSING OF SPENT ULTRA-DEEP HYDRODESULFURIZATION CATALYSTS. This work discusses the recycling of spent NiMo/Al2O3 catalysts from ultra-deep hydrodesulfurization (HDS) units. They contain a refractory coke and fouling elements from the processed feedstocks. Samples were preoxidized (600 ºC) for 12 h using a very slow heating rate to eliminate coke and volatiles. Experiments were performed in the presence of HF + H2O2 mixtures under stirring at 25-60oC for 1-4 h. The amount of insoluble matter was the lowest (< 1 wt.% of the initial mass) after leaching for 2 h at 60oC using an excess of 50 vol.% HF and 20 vol.% H2O2. Leached molybdenum and vanadium were extracted together with Alamine 304 (tri-dodecylamine) in n-heptane at pH below 2. Aluminum and iron were precipitated from the raffinate as Na3AℓF6 (+ Na3FeF6) by adjusting pH at ~4 using 6 mol L-1 NaOH. Nickel was either recovered by solvent extraction using D2EHPA (bis-(2-ethylhexyl)phosphoric acid) in n-heptane at pH 6 or precipitated at pH 8 using 6 mol L-1 NaOH. The first method proved better as less contaminants were present. After slow evaporation of the final aqueous solution, a mixture of Na2SiF6 and NaF was recovered. Fluoride losses were very low (~0.10 wt.%).

Resumo em Inglês:

Understanding of the organomineral interactions in soil can elucidate the humic substances (HS) formation and the humification process. This study aimed to structurally characterize the humic acids (HA) formed in tropical soils with different pedogenesis degrees. The HA fraction was extracted from soil samples in the superficial horizons of an Inceptisol and a Mollisol in Rio de Janeiro state. The HA was characterized using spectroscopic techniques following by chemometric analyses: principal component analysis, descriptive analysis, and multivariate curve resolution. The results show that HA extracted from superficial horizon of Inceptisol and Mollisol are structurally different. The Inceptisol HA has a lower E4/E6 ratio than the Mollisol HA. The chemical groups show that most -CH groups belong to -CH2 and -CH3 and hydroxyls (-OH) for the Inceptisol HA, whereas the Mollisol HA predominantly contains aromatic C=C groups. The Inceptisol HA is mainly composed of CAlkyl-H,R and -C=O structures, whereas the Mollisol HA contains a higher quantity of CAlkyl-O,N, CAlkyl-O and CAromatic-H,R groups. The Inceptisol HA has a higher aliphatic content and hydrophobicity than the Mollisol HA. In Inceptisol, organic carbon stabilization can be facilitated by hydrophobic interactions, whereas in Mollisol, different interaction sites can stabilize proteinaceous compounds.

Resumo em Inglês:

A new fluorescent detection route for chloride ion was designed with Nitrogen-doped graphene quantum dots (N-GQDs), which were prepared by a traditional hydrothermal method with citric acid as carbon source and urea as nitrogen source. The prepared N-GQDs solution was light yellow, and the freeze-dried solid was black. It emitted blue light under ultraviolet light. Meanwhile, The N-GQDs were characterized by TEM, XRD, UV-Vis and fluorescence, the results indicated that the N-GQDs had good dispersibility, photostability and excitation independent emission fluorescence. After addition of Ag+ solution, Ag+ combined to the surface functional groups of N-GQDs, resulting in an obvious quenching of the fluorescence intensity of N-GQDs. Nevertheless, the fluorescence intensity recovered significantly with the addition of Cl- to the N-GQDs/Ag+ system, this was because of AgCl was formed due to the “soft hard acid base principle”. The change of fluorescence intensity had a linear response to the chloride ion concentration in the range of 8.5-300 μmol L-1, with a detection limit (LOD) of 0.1 μmol L-1. To authenticate the application, the proposed method has been successfully used for quantitative analysis of chloride ion in real samples, including artificial sweat and environmental water.

Resumo em Português:

RECENT ADVANCES IN THE SYNTHESIS OF REMDESIVIR, MOLNUPIRAVIR (EIDD-2801) AND TENOFOVIR: PROMISING MOLECULES IN THE TREATMENT OF COVID-19. The search for new treatments to contain the Covid-19 pandemic has highlighted the importance of nucleoside antivirals, such as Remdesivir, Tenofovir and Molnupiravir. Over the last two years, these molecules have been intensely investigated as promising alternatives against SARS-CoV-2 virus. Considering the increasingly demand for those substances, several research groups are intensely investigating synthetic developments in order to obtain these nucleoside derivatives and their intermediates in a fast, efficient and accessible manner. In this context, this review aims to in-depth present the recent advances concerning the preparation of Remdesivir, Tenofovir and Molnupiravir. Aspects involving differences in the starting materials and reagents, as well as the advantages and limitations of each protocol would be carefully disclosed. Moreover, the use of synthetic tools, such as flow chemistry, organocatalysis and biocatalysis, would also be detailed. Finally, this review also presents aspects involving the scale-up of these transformations, including discussions about stereo- and diastereoselectivity, as well as product isolation details. In summary, an overview of the existing synthetic strategies for these active pharmaceutical ingredients (APIs) are presented.

Resumo em Inglês:

The efforts in dealing with COVID-19 in various aspects are continuously being carried out, such as the photocatalytic process. Interestingly, TiO2 plays an important role as an environmentally friendly photocatalyst with a visible and UV absorption range. The increase in the antiviral performance of this compound is further maximized by formulating TiO2-based composites and doping it to reduce the bandgap. This review aims to determine the challenges of TiO2-based composite as a visible active photocatalyst material for SARS-CoV-2 antiviral. It presents a discussion of the photocatalytic function of TiO2, by comparing the secondary data obtained from viruses that have been successfully degraded by the SARS-CoV-2. The literature search led to the analysis of the photocatalyst quality, structure, composition, and the degraded viruses. This comparison was based on the photocatalyst’s general constituents, such as protein and RNA. The virus morphology as observed in the secondary data was successfully destroyed by hydroxyl radicals resulting from the photocatalytic processes. It was observed that TiO2 photocatalyst generated ROS, capable of inactivating various viruses, therefore, it has the potential in fighting against the SARS-CoV-2. Moreover, further research is needed in photocatalyst design, its role, and the overall mechanism of virus inactivation.

Resumo em Inglês:

This paper is a brief review of silver complexes that have been identified as antibacterial drugs with promising use for the treatment of tuberculosis (TB). This treatment aims to cure and discontinue the transmission of the disease. The excessive and inappropriate use of drugs has jeopardized the effectiveness of antibiotics for the TB treatment, bringing bacterial resistance to them. To achieve these objectives, the drugs used must be able to eliminate rapidly the bacterial population, avoiding the selection of drug-resistant strains and preventing its recurrence. The number of new cases of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) continues to rise. So, it is important to develop more research to introduce new drugs or improve existing ones, which can reduce the treatment time, increasing drug adherence and reducing MDR-TB and XDR-TB. The Ag(I) complexes were described with different types of ligands, and bonds to Ag(I) occur by N, O, P, and S atoms. Metal complexes are presented as options for anti-TB treatments. There are no cases of TB treatments using metal complexes but research in this area show that they could be used in the future to eradicate the bacteria that contaminate environments, surgical materials and other objects.

Resumo em Inglês:

Metabolic profiling of complex biological matrices based on liquid chromatography-mass spectrometry (LC-MS) allows detecting a wide range of metabolites with distinct concentrations and physicochemical properties. Given the complexity of samples and the necessity of a comprehensive approach in untargeted metabolomics, quality control strategies are mandatory to obtain high-quality data. The LC-MS performance must be monitored and evaluated to guarantee data reliability. In this study, a test mixture (TM) was developed, systematically evaluated, and applied to untargeted metabolomics of urine samples from individuals suspected of inborn errors of metabolism. The TM was composed of fifteen analytes that eluted across the entire gradient in reversed-phase columns and ionized in positive/negative electrospray modes. It helped set the LC-MS conditions for urine analysis, from sample reconstitution solvent to selecting the MS ion source parameters. The TM quickly indicated column stationary phase degradation during the batch analysis when employed to monitor and evaluate the LC-MS system in an untargeted metabolomic analysis. Thus, in addition to pooled QC samples, a TM can be employed in untargeted metabolomics to rapidly assess the system performance avoiding unnecessary efforts for further data treatment and multivariate analysis of poor-quality data.

Resumo em Inglês:

In this work, a self-made dip-coater equipment was developed for the fabrication of thin films. The assembly of the apparatus was carried out using simple mechanical and electronic pieces, recycle parts, and spending an inexpensive budget suitably. The production, software design, and features of the device were focused on the sol-gel dip-coating method, which involves gravitational draining and drying processes, as well as continued condensation reactions. The dip-coater was based on the Arduino microcontroller and a step motor. The immersion speed in the solution, the waiting time, and the withdrawal process were typed by a digital control panel, where the optimal range found for speed was 0.1 - 6.0 mm s-1 without vibration interferences. The total fabrication cost of the fabricated dip coater was less than 100 USD and the assembly process was not complicated. Finally, the performance of the dip-coater was evaluated through the deposit of copper oxide and iron oxide films on fluorine-doped tin oxide glass substrates layer by layer. The field emission scanning electron microscopy cross-section images confirm the formation of thin films with thickness in the nanoscale range, with good stability and sameness achieved through the control thickness during the dip-coating method under ambient conditions.

Resumo em Português:

COOPERATIVE AND COLLABORATIVE LEARNING TO TEACH CHEMICAL EQUILIBRIUM TO FRESHMAN STUDENTS. This paper describes cooperative (jigsaw) and collaborative activities (Peer-Led Team Learning) carried out in the BSc degree in Chemistry at the São Carlos Institute of Chemistry, the University of São Paulo, Brazil. The dynamics of discursive interactions established among students in the cooperative and collaborative groups was investigated based on the Model proposed by Kumpulainen and Mutanen, by analyzing the following: functions of speech, cognitive processing and social processing. In this perspective, the influence of the level of structure of the activities was studied. The results obtained point to the possibility of adapting both types of activities in higher education chemistry courses.

Resumo em Português:

OPTIMIZATION OF THE EXTRACTION OF ANTHOCYANINS PRESENT IN BLACK BEANS AND IMPREGNATION OF THE EXTRACT IN NATURAL POLYMERIC MATRIX FOR USE AS A pH INDICATOR. In this work, a method of extracting natural indicators, anthocyanins, present in black beans was optimized. The best extraction condition was obtained with 50 g of beans and 93 g of water, under agitation at 150 rpm, at a temperature of 40oC for 24 h. The wavelengths of greatest absorption for the indicator in its acidic and basic form were 523 nm and 620 nm respectively and these wavelengths were used to determine the pKa of the indicator. At least three pKa values were observed: 1.9; 7.2 and 10.7. A simplified condition for anthocyanins extraction, the same amount of water, tap water in these case, and beans kept together for 12 h without agitation and temperature control, was also evaluated. Both extracts were impregnated with qualitative filter paper, coffee filter paper and cotton buds and the materials impregnated with the indicator were tested with solutions of HCl, vinegar, NaOH and milk of magnesia. A comparison between the impregnated material and a universal pH indicator paper using buffer solutions pH 4.0, 7.0, 10.0 and 11.2 proved the applicability of the developed material since it presented adequate distinction in its color for the different pH conditions.

Resumo em Português:

OXYGEN IN THE COVID-19 CONTEXT: WHAT WE KNOW ABOUT THE MOLECULE WE BREATHE AND THE CENTRAL ROLE OF CHEMISTRY. In this work, the role of chemistry in the coronavirus disease 2019 (COVID-19) pandemic is highlighted through the medical oxygen supply crises in Brazil, as an example of oxygen utility in health. Starting from oxygen chemical characterization, the oxygen cycle in nature is discussed to show how oxygen is formed through photosynthesis, followed by the description of the industrial oxygen production from atmospheric air, including physical-chemical aspects. The use of medical oxygen concentrator is presented and how this device works from the chemical point of view. Besides, the noninvasive and painless oximetry is described in terms of how oxygen saturation level in blood is measured using LED - light emitting diode.

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ARE AOPs THE FUTURE OF ECOTOXICOLOGY? AOPs (Adverse Outcome Pathways) were introduced in the field of ecotoxicology due to the need of replacement of the classic system for assessing adverse results (considering only the mortality of organisms exposed to certain substances or mixtures) to a predictive system based on the measurement of biological events occurring primarily at a molecular level and having clear biological relationships with potential adverse effects on more complex biological systems. AOPs are useful for organizing and integrating information related to the toxic potential of chemical substances alone or in mixtures, in exposed organisms, supporting the prediction and understanding of the effects induced by stressors and the development of action plans in order to reduce the exposure of organisms to acceptable levels. This tool is already gaining strength and being used worldwide by scientists, and in the future it may be the basis for the regulation of chemical substances and their mixtures. This article presents the basic principles related to the development and use of an AOP, in a simple and objective way, in addition to presenting a practical example of this tool, which can be considered the future of ecotoxicology.