44 documents found, page 1 of 5
Synthesis and application of a new carboxylated cellulose derivative. Part I: R...
Ferreira, Gabriel Max Dias; Silva, Luis Henrique Mendes da; Teodoro, Filipe Simões; Ramos, Stela Nhandeyara do Carmo; Elias, Megg Madonyk CotaA new carboxylated cellulose derivative (CTA) was prepared from the esterification of cellulose with 1,2,4-Benzenetricarboxylic anhydride. CTA was characterized by percent weight gain (pwg), amount of carboxylic acid groups (nCOOH), elemental analysis, FTIR, TGA, solid-state 13C NMR, X-ray diffraction (DRX), specific surface area, pore size distribution, SEM and EDX. The best CTA synthesis condition yielded a p...
Chromium speciation using aqueous biphasic systems: Development and mechanistic...
Patrício, Pamela R.; Cunha, Roselaine C.; Vargas, Silvia J. Rodriguez; Coelho, Yara Luiza; Silva, Luis Henrique Mendes da; Silva, Maria C. Hespanhol daThe two principal oxidation states of chromium diverge significantly in their biological and toxicological properties, and it is very important to distinguish between them. Develop procedures that are efficient, fast, easier and cheaper for chromium speciation is an analytical challenge. Chromium speciation was investigated using aqueous biphasic systems (ABS) formed by polyethylene oxide (PEO1500) or a tribloc...
Synthesis and application of sugarcane bagasse cellulose mixed esters. Part I: ...
Silva, Luis Henrique Mendes da; Elias, Megg Madonyk Cota; Ferreira, Gabriel Max Dias; Almeida, Francine Tatiane Rezende deSugarcane bagasse cellulose mixed ester succinate phthalate (SBSPh) was synthesized by a novel one-pot reaction method. The effects of temperature, time and mole fraction of succinic anhydride (χSA) on the responses weight gain (wg), number of carboxylic acid groups (nT,COOH), and adsorption capacity (q) of Co2+ and Ni2+ were evaluated by a 23 experimental design. The chemical structure of the material was eluc...
Thermal and spectroscopic analyses on the molecular interaction between eucalyp...
Oliveira, Rubens Chaves de; Silva, Luis Henrique Mendes da; Colodette, Jorge Luiz; Alves, Ericka FigueiredoO conhecimento técnico-científico das interações que ocorrem no processo de impressão offset é escasso, embora várias observações mostrem sua importância. O objetivo deste trabalho foi estudar por análises térmicas e espectroscópicas, na região 1do infravermelho, o tipo de interação dos componentes anatômicos da polpa branqueada kraft de eucalipto com tintas de impressão offset. Foi utilizado um classificador d...
Determination of driving forces for bovine serum albumin-Ponceau4R binding usin...
Lelis, Carini Aparecida; Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max Dias; Hespanhol, Maria do Carmo; Pinto, Maximiliano SoaresPonceau 4R (P4R) and bovine serum albumin (BSA) may interact changing food properties. We compared fluorescence spectroscopy and surface plasmon resonance (SPR) for studying, in vitro, the interactions between BSA and P4R at pH 7.4 and 3.5 in different temperatures. Fluorescence data pointed to the formation of a complex where P4R was bound on site I or II of BSA, with a stoichiometry around one and a binding c...
A green and sensitive method to determine phenols in water and wastewater sampl...
Rodrigues, Guilherme Dias; Lemos, Leandro Rodrigues de; Silva, Luis Henrique Mendes da; Silva, Maria do Carmo Hespanhol da; Minim, Luis AntonioA greener and more sensitive spectrophotometric procedure has been developed for the determination of phenol and o-cresol that exploits an aqueous two-phase system (ATPS) using a liquid–liquid extraction technique. An ATPS is formed mostly by water and does not require organic solvent. Other ATPS components used in this study were the polymer, polyethylene oxide, and some salts (i.e., Li2SO4, Na2SO4 or K2HPO4 +...
Effect of 1‐Butyl-3-methylimidazolium halide on the relative stability between ...
Ferreira, Gabriel M. Dias; Ferreira, Guilherme M. Dias; Agudelo, Álvaro J. Patinõ; Silva, Maria C. Hespanhol da; Rezende, Jaqueline de PaulaIt is well-known that ionic liquids (ILs) alter the properties of aqueous systems containing only surfactants. However, the effect of ILs on polymer–surfactant systems is still unknown. Here, the effect of 1-butyl-3-methylimidazolium bromide (bmimBr) and chloride (bmimCl) on the micellization of sodium dodecyl sulfate (SDS) and its interaction with poly(ethylene oxide) (PEO) was evaluated using conductimetry, f...
Copper recovery from ore by liquid–liquid extraction using aqueous two-phase sy...
Lemos, Leandro Rodrigues de; Santos, Igor José Boggione; Rodrigues, Guilherme Dias; Silva, Luis Henrique Mendes da; Silva, Maria C. Hespanhol daWe investigated the extraction behavior of Cu(II) in the aqueous two-phase system (ATPS) formed by (L35 + MgSO4 + H2O) or (L35 + (NH4)2SO4 + H2O) in the presence of the extracting agent 1-(2-pyridylazo)-2-naphthol (PAN). At pH = 3 and a PAN concentration of 0.285 mmol kg−1, both ATPS lead to the effective separation of Cu(II) from other metallic ions (Zn(II), Co(II), Ni(II) and Fe(III)). High separation factors...
Aqueous two-phase systems of copolymer L64 + organic salt + water: Enthalpic L6...
Andrade, Vivianne Molica de; Rodrigues, Guilherme Dias; Carvalho, Raquel Moreira Maduro de; Silva, Luis Henrique Mendes da; Silva, Maria C. Hespanhol daPhase diagrams of two-phase systems (ATPS) composed by the triblock copolymer L64 + organic salt (sodium tartrate, sodium succinate, sodium citrate, or ammonium citrate) + water, at different temperatures (278, 288, and 298 K) are presented in this work. Contrary to behavior of ATPS formed by inorganic salts, the study of the temperature influence in the liquid–liquid equilibrium behavior of L64–organic salts A...
Liquid–liquid equilibrium of aqueous two-phase systems composed of poly(ethylen...
Lemos, Leandro Rodrigues de; Patrício, Pamela da Rocha; Rodrigues, Guilherme Dias; Carvalho, Raquel Moreira Maduro de; Silva, Maria C. Hespanhol daPhase diagrams of aqueous two-phase systems composed of PEO1500 + salt (di-potassium phosphate + potassium hydroxide or ammonium sulfate or zinc sulfate) + water were determined at (283.15, 298.15, and 313.15) K. All systems produce a large two-phase region; however the influence of temperature on the binodal position seems to be very small. By analyzing the effects of ammonium sulfate or zinc sulfate, it was o...