Preparação de copolímeros à base de 2-vinilpiridina com propriedades bactericidas

We report the development of two copolymers based on 2-vinylpyridine, styrene and divinylbenzene (2Vpy-Sty-DVB) with different porosity degrees. The copolymers were subsequently quaternized with methyl iodide. To prepare charge transfer complexes, the unmodified copolymers and their derivatives quaternized with methyl iodine were impregnated with iodine. The antibacterial properties of the polymers were evaluated in dilutions ranging from 10² to 10(7) cells/mL of the auxotrophic OHd5-K12 Escherichia coli strain. It was possible to obtain materials with complete antibacterial activity even in the highest cell concentrations tested.

Un método de bajo costo para la determinación de cobre a nivel de vestigios en matrices de interés ambiental por espectrofotometría en fase sólida (EFS)

A method for determining copper by solid phase spectrophotometry (SPS) was optimized using the Doehlert design. Copper(II) was sorbed on a styrene-divinylbenzene anion-exchange resin as a Cu(II)-1-(2-pyridylazo)-2-naphthol (PAN) complex, at pH 7.0. Resin phase absorbances at 560 and 800 nm were measured directly. The detection limit was found to be 2.5 µg L-1. The relative standard deviation on ten replicate determinations of 10 µg Cu(II) in 1000 mL samples was 1.1%. The linear range of the determination was 5.0-100 µg L-1. The method was applied successfully to the determination of Cu(II) in natural water and vegetable samples.

Síntese do butirato de n-butila empregando lipase microbiana imobilizada em copolímero de estireno-divinilbenzeno

This work investigates the reaction parameters of an immobilized lipase in the esterification reaction of n-butanol and butyric acid. Microbial lipase from Candida rugosa was immobilized onto styrene-divinylbenzene copolymer (STY-DVB) and subsequently introduced in an organic medium containing substrates in appropriate concentrations. Heptane was selected as solvent on the basis of its compatibility with the resin and the enzyme. The influence of molar ratio of acid to alcohol, amount of immobilized lipase and temperature on the butyl butyrate formation was determined. The results were compared with those achieved with free lipase and Lipozyme (commercially immobilized lipase) under the same operational conditions.

Principais métodos de caracterização da porosidade de resinas à base de divinilbenzeno

This paper reviews the most important methods used to characterize the porosity of styrene-divinylbenzene resins. Methods such as adsorption of nitrogen for determination of surface area and mercury intrusion porosimetry for characterization of pore size distribution are related.