No abstract

In this approach, a nonchromatographic method was developed for selective extraction and determination of Cr(III) concentration in isotonic and energy drinks by FAAS. This new method uses Luffa cylindrica fibers as the solid phase extraction and an off-line flow injection system. Cr(III) and Cr(VI) adsorption behavior onto Luffa fibers allowed the selective separation of Cr(III) in the pH range of 4 to 5. The system variables were optimized through full factorial and Doehlert designs. Under optimal conditions, the detection and quantification limit for Cr(III) was 19.2 µg·L−1 and 63.9 µg·L−1, respectively, with precision below 0.19%. A high tolerance toward interfering ions was observed for the proposed method. Recovery test results obtained for different isotonic and energy drinks samples were higher than 87.6%. The method’s accuracy was confirmed through analysis of certified reference materials, water and sediment river samples (APS-1071 and APS-1066).

O rápido desenvolvimento industrial e agrícola tem favorecido o aumento desenfreadono número de poluentes liberados no meio ambiente, principalmente, de metais tóxicosem água. Como consequência, faz-se necessário o desenvolvimento de novas tecnologiasde baixo custo, reprodutíveis e efiazes para a remoção desses contaminantes. Dentreessas tecnologias, a utilização de nanoadsorventes de óxidos metálicos vem recebendodestaque. Assim, o presente trabalho visa sintetizar o CaMoO4 utilizando radiação pormicro-ondas, caracterizar estruturalmente, morfologicamente e estudar o potencial deadsorção para íons Cd (II) e Mn (II). Observa-se que em pH 9, o material sintetizadoapresenta excelente potencial adsortivo para os íons cádmio (95%) e manganês (85%).

This chapter provides an overview and discusses analytical strategies for metallic ions determination using solid phase extraction. Solid phase extraction (SPE) is a much-used technique for extraction and/or concentration of complex samples, so that the analytes present in low concentration were detected mainly using chromatographic methods. However, in recent years, this technique has been widely used in the development of methodologies for metallic ions determination in the deferential samples. This technique shows simplicity and rapidity comparing with other conventional techniques, liquidliquid extraction, cloud point extraction and others. Solid phase extraction procedures become even more interesting when commercial adsorbents are exchanged for others with higher adsorptive capacity, selectivity, flexibility, economy and low environmental impacts. For this purpose, some inorganic, organic and several natural adsorbents are used. New approaches to obtain adsorbent materials from natural sources such as fungi, bacteria, industrial residues and composting materials have received attention. These materials have been used in the development of analytical methods with varied proposals, such as preconcentration or speciation of metal ions.

The present work aims to use organic residues of coffee capsules as adsorbent material for adsorption of Cu(ІІ), Co(ІІ), Ni(ІІ) and Cd(ІІ) ions in aqueous systems. In order to know the properties of the adsorbent, it was subjected to characterization by dispersive energy X-ray fluorescence (EDXRF), Absorption Spectroscopy in the Infrared Region (IR) and determination of pH at the Zero Charge Point (pHPCZ). The analysis by EDXRF after the adsorption procedure revealed an increase in the intensity of the peaks related to the cooper and the appearance of peaks related to the cobalt and nickel. The IR spectra showed bands referring to the main functional groups present in the organic residue of coffee capsules. pHPCZ revealed a neutral surface in a range of 6 to 8. The factors that influence the adsorption process, such as pH, adsorbent mass and adsorption time, were evaluated in a univariate manner, with the optimal values of 9, 80 mg and 60 minutes being obtained, respectively. The kinetic evaluation of the adsorption process was performed, indicating that the Ni(II) and Co(II) ions were better adjusted to the Avrami model, the Cd(II) ion to the pseudo-second order model and the Cu(II) ion fit the Avrami and pseudo-second order models, which can be explained by both. O presente trabalho visa utilizar resíduos orgânicos de cápsulas de café como material adsorvente para adsorção dos íons Cu(ІІ), Co(ІІ), Ni(ІІ) e Cd(ІІ) em sistemas aquosos. A fim de conhecer as propriedades do adsorvente, o mesmo foi submetido à caracterização por Fluorescência de Raios X por energia dispersiva (EDXRF), Espectroscopia de Absorção na Região do Infravermelho (IV) e determinação do pH no Ponto de Carga Zero (pHPCZ). A análise por EDXRX após o procedimento de adsorção revelou um aumento na intensidade dos picos referentes ao cobre e o surgimento de picos referentes cobalto e níquel. Os espectros de IV mostraram bandas referentes aos principais grupos funcionais presentes no resíduo orgânico de cápsulas de café. O pHPCZ revelou uma superfície neutra em uma faixa de 6 a 8. Os fatores que influenciam o processo de adsorção, como pH, massa de adsorvente e tempo de adsorção, foram avaliados de forma univariada, sendo obtido os valores ótimos de 9, 80 mg e 60 minutos, respectivamente. A avaliação cinética do processo de adsorção foi realizada, indicando que os íons Ni(II) e Co(II) se ajustaram melhor ao modelo de Avrami, o íon Cd(II) ao modelo de pseudo-segunda ordem e o íon Cu(II) se ajustou aos modelos de Avrami e pseudo-segunda ordem, podendo ser explicado por ambos.