Nanocomposites of GO/γ-Fe2O3 were used for magnetic dispersive solid-phase microextraction (m-d-μ-SPE) of six pesticides from river water samples, followed by the determination using high performance liquid chromatography-diode array detection. The synthesis of the nanocomposites is described and characterized using Fourier transform-infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. A central composite design was used to optimize the extraction time, sample solution pH, and adsorbent amount. The solvent type and volume for desorption and the effect of the ionic strength for adsorption were also investigated. The optimum adsorption conditions were achieved at 84 min of extraction time, pH 5.4, 115 mg of absorbent, and 1% (m/v) of NaCl, while the desorption solvent selected was 1.0 mL of methanol-acetic acid (9:1, v/v). The limits of detection ranged from 0.1 to 0.9 μg L-1, and a good precision was achieved with relative standard deviation (RSD) lower than 7.6% (n = 10). The accuracy of the method was accessed by recovery tests ranging from 82 to 117% (n = 3, RSD < 8%). GO/γFe2O3 GOγFe2O3 GOγFeO GO/γ Fe2O3 GO γ Fe O GO/γ-Fe2O solidphase solid phase mdμSPE m d μ SPE (m-d-μ-SPE samples chromatographydiode chromatography diode transforminfrared transform infrared spectroscopy Xray X ray diffraction microscopy time amount investigated 8 54 5 4 5.4 11 absorbent 1 m/v mv v (m/v NaCl 10 0 1. methanolacetic methanol acetic 91, 91 9 1, (9:1 v/v. vv v/v . v/v) 01 0. 09 L1, L1 L L-1 (RSD 76 7 6 7.6 n 10. 10) 117 3 8%. 8% 8%) γFe2O3 γFe GO/γFe2O GOγFe GOγFe2O GOγ FeO Fe2O 5. (9: L- 7. γFeO γFe2O (9 (

The generation of clean, zero-carbon, and renewable energy is a challenge for the development of a sustainable and egalitarian society. Hydrogen gas can be produced by water electrolysis and has been claimed as the most promising option to replace fossil fuels. The oxygen evolution reaction (OER) is the most energetically demanding step of the water splitting and requires the use of electrocatalysts to overcome the kinetic barrier. Iron oxide nanomaterials have been emerging as a low-cost and Earth-abundant OER electrocatalysts. The synthesis of iron oxide assisted by plant extract is an eco-friendly approach to obtain nanomaterials with unique properties. Herein, we investigated iron oxide synthesized with the assistance of Camellia sinensis extract, under different experimental conditions towards oxygen evolution reaction electrocatalysis. Pure phases of iron oxide were obtained, ferrihydrite and maghemite showed overpotentials of 460 and 480 mV at a current density of 10 mA cm–2, respectively. After calcination, hematite was formed and the overpotential was raised to 610 and 810 m V, respectively. The lower overpotential of the amorphous materials could be related to the lower electron transfer resistance and faster reaction rate. On the other hand, the calcinated materials presented higher specific activity, stability and higher Faradaic efficiency. clean zerocarbon, zerocarbon zero carbon, carbon zero-carbon society fuels (OER barrier lowcost low cost Earthabundant Earth abundant ecofriendly eco friendly properties Herein electrocatalysis obtained 46 48 1 cm2 cm 2 cm–2 respectively calcination 61 81 V rate hand activity efficiency 4 cm– 6 8

This work proposes the reuse of spent ground coffee waste (SCG) extracts as eco-friendly corrosion inhibitors for carbon steel in acid medium, and the correlation between their anticorrosive efficiency and chemical composition. The extraction method was optimized using a central composite design, and the chemical composition of the extracts was accessed using UV-Vis spectrometry, HPLC, and ICP-OES. EIS and Potentiodynamic Polarization (PP) tests evaluated the anticorrosive properties of the extracts. Total phenol content ranged from 93 mg L-1 to 219 mg L-1 Gallic Acid Equivalent. The highest concentration of phenolic compounds was observed for syringic acid (78.67 mg L-1), while the lowest concentration was verified for (-)-epigallocatechin-3-O-gallate (0.01 mg L-1). The Pearson correlation coefficient showed no correlation between the Rct and the total phenol content, although, positive correlations with the Rct was observed for caffeic acid, (+)-catechin, ferulic acid, and protocatechuic acid. EIS analysis revealed that all of the extracts could act as corrosion inhibitors. The best performance was verified for C3 extract (IE % = 94.83%). PP tests showed that this extract acted as a mixed inhibitor, with a predominant cathodic effect. Therefore, the valorization of the extracts as corrosion inhibitors was successfully achieved.

Uma nova abordagem para introdução de amostras utilizando uma câmara de nebulização de baixa pressão foi empregada para a determinação de Hg e outros elementos por espectrometria de massa com plasma indutivamente acoplado. O sistema consiste de uma camara de nebulização ciclônica conectada a um nebulizador e a um tubo de sucção. A taxa de sucção, otimizada em 0,3 L min- 1, foi utilizada para induzir a baixa pressão no interior da câmara de nebulização. Não houve diferenças nos parâmetros do plasma, avaliados antes e após a aplicação da sucção; no entanto, a vazão de gás de nebulização foi ligeiramente afetada. O efeito de memória para Hg foi reduzido utilizando a câmara de nebulização de baixa pressão e limites de detecção na ordem de µg L - 1 foram obtidos para todos os elementos. Amostras de referência certificadas foram analisadas obtendo-se boa concordância com os valores certificados.

A new sample introduction setup employing a low pressure spray chamber was applied for Hg determination simultaneously to other trace elements by inductively coupled plasma mass spectrometry. The system consists of a cyclonic spray chamber connected to a nebulizer and to a suction tube. A suction rate, optimized at 0.3 L min-1, was employed to induce reduced pressure inside the spray chamber. The plasma parameters were evaluated without and upon application of the low pressure spray chamber, and the only affected parameter was the nebulizer gas flow-rate. Memory effect for Hg was dramatically reduced using the low pressure spray chamber. Detection limits were obtained in the µg L-1 range for all elements. Digested certified reference samples were analyzed using the proposed system, and good agreement between certified and obtained values was achieved for all elements.