Browsing by Author "Orlando, Ricardo Mathias"

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    Application of aqueous two-phase system for selective extraction and clean-up of emerging contaminants from aqueous matrices.
    (2021) Assis, Roberta Condé de; Mageste, Aparecida Barbosa; Lemos, Leandro Rodrigues de; Orlando, Ricardo Mathias; Rodrigues, Guilherme Dias
    This review approaches how aqueous two-phase systems (ATPS), in their various compositions (e.g., polymer + salt, copolymer + salt, ionic liquid + salt, acetonitrile + salt), can be efficiently used for extraction, pre concentration, and clean-up of analytes in aqueous samples to determine the compounds classified as emerging contaminants (ECs). In the literature, there are some studies using ATPS applied to ECs, like pesticides, pharmaceuticals, illicit drugs, personal care products, alkaloids, and hormones, even when in trace concentrations. The ATPS is an alternative to the conventional liquid-liquid extraction technique. However, it is predominantly composed of water and do not generally use organic solvents and, therefore, is based on the principles of green chemistry. An ATPS approach has a unique advantage because it can extract neutral, anionic, cationic, polar, and nonpolar compounds, even when present simultaneously in the same sample. This review covers how this simple and low environmental impact technique has been employed for the analysis of different classes of emerging contaminants.
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    Application of aqueous two-phase systems for the extraction of pharmaceutical compounds from water samples.
    (2020) Assis, Roberta Condé de; Mageste, Aparecida Barbosa; Lemos, Leandro Rodrigues de; Orlando, Ricardo Mathias; Rodrigues, Guilherme Dias
    In this study, the proposal was to use aqueous two-phase systems (ATPS) as a sample preparation technique for the determination of five pharmaceuticals, classified as emerging contaminants (EC): ibuprofen, paracetamol, ciprofloxacin, norfloxacin and amoxicillin. The evaluation of this study was performed through the partition co efficient (K) of each pharmaceutical by varying some parameters of the system, such as the pH value of the me dium, the nature of the ATPS-forming electrolyte and polymer, the tie-line length (TLL), the system temperature and the mass ratio between the top and bottom phases of the ATPS. Values of K between 9.30 and 1150 were ob tained for the five pharmaceuticals during the system optimization. The ATPS also proved to be efficient as a sam ple preparation technique in the partition of the studied pharmaceuticals when applied to water samples, including drinking water, surface water and filtered water from a water treatment plant. The values of the parti tion coefficients found in these complex samples ranged from 2.49 to 74.2.
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    Bixin as a new class of biosorbent for Hg2+ removal from aqueous solutions.
    (2021) Vieira, Júlia Condé; Diniz, Mariana Cristine Coelho; Mendes, Louise Aparecida; Sinisterra Millán, Ruben Dario; Rodrigues, Guilherme Dias; Orlando, Ricardo Mathias; Windmoller, Cláudia Carvalhinho
    In this study, the apocarotenoid bixin was investigated as a potential biosorbent for Hg2+ in aqueous solutions. Bixin was used to form a thin film on an inert support using the drop-coating technique. This film was char- acterised using ATR-FTIR, SEM, and TGA-DTG techniques. Parameters that influence adsorption, such as pH, temperature, NaCl concentration, salt type, bixin mass, and supports for the bixin film, were evaluated. Using 0.112 mg of a bixin covering on a cellulose filter, the sorbent material was able to remove 75 % of Hg2+ from a 2.0 mL, 0.3 mg g− 1 , pH 6.00, 25 ◦C solution after 180 min of contact. Kinetics studies were carried out between 5 and 1440 min, and the pseudo-first-order adsorption model was applied. Equilibrium isotherm data were ana- lysed, and the best fit was for the non-linear Freundlich model, with an R2 of 0.9868, RMSE of 0.37, and maximum sorption capacity of 85.38 mg g− 1 obtained by the Langmuir model. The bixin film was applied in spiked environmental samples (lake and mining effluent), and it achieved 86 % Hg2+ removal. The results show that the bixin film is a suitable alternative for efficiently removing mercury from various aqueous systems. This introduces a new class of biosorbent based on apocarotenoids, which are sustainable, low cost, nontoxic, and easily obtainable.
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    Extraction of estrogen hormones from water samples using an aqueous two-phase system : a new approach for sample preparation in the analysis of emerging contaminants.
    (2021) Domingues, Junielly Tomaz; Orlando, Ricardo Mathias; Almeida, Mariana Ramos; Lemos, Leandro Rodrigues de; Mageste, Aparecida Barbosa; Rodrigues, Guilherme Dias
    In this study, an environmentally friendly method of extracting steroid hormones, 17α-ethinylestradiol, levo norgestrel, gestodene, cyproterone acetate and estradiol valerate, using an aqueous two-phase system was developed. The aqueous two-phase system was applied as an organic solvent-free liquid–liquid extraction technique for the determination of these compounds by UV–Vis spectrophotometry in environmental samples. The experimental conditions were evaluated through the pH value of the medium (3.00–11.0), the nature of the electrolyte and polymer forming the system, the tie-line length (26.76–62.53% w/w), the temperature (278.15–313.15 K), and the mass ratio between the bottom and top phases of the system (1–5). The recovery efficiency was evaluated using the partition coefficient and the analytical signal of each hormone in the top phase. The study was carried out through univariate and multivariate optimization and, for the first time, in teractions of tie-line length, polymer forming the system and temperature were observed, and these directly influenced the partition of hormones in aqueous two-phase system. An overall experimental condition for the recovery of all hormones simultaneously (L35 + Na2SO4 + H2O, at pH = 3.00, tie-line length = 64.06% w/w, temperature = 298.15 K and mass ratio between the bottom and top phases of the system = 5) was determined. Partition coefficients (8.8 ± 0.8) to (4533 ± 48) were obtained for the hormones in samples of drinking water, samples from lake and river water, and filtered water from a water treatment plant. Thereby, the aqueous two phase system proved to be an innovative and good organic solvent free liquid–liquid extraction of hormones in environmental samples.