An organic-inorganic hybrid adsorbent was prepared and its application for the uptake of CuII ions from aqueous solutions was studied. The polymer network was composed of poly(dimethylsiloxane) (PDMS), vinyltrimethoxysilane (VTMS), and 2-(dimethylamino)ethyl methacrylate (DMAEMA), described as PDMS-net-P(VTMS-co-DMAEMA). The chemical groups, thermal stability and morphology of this hybrid adsorbent were characterized using techniques of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). In adsorption studies, saturation of the active sites of the material was observed at pH 5, after 3 days, with each gram of material capable of adsorbing 0.48 mmol of copper(II). The fractionary-order and Sips models provided the best fits to the experimental data in kinetic and equilibrium studies of the adsorption process, respectively. Moreover, an acceptable reusability was found for this cross-linked organic-inorganic hybrid adsorbent after usage-regeneration cycles without significantly losing its original activity.

Functionalized elastomeric networks were obtained via a polycondensation reaction between poly(dimethylsiloxane) (PDMS) containing Si(CH3)2OH as end groups and an imidazole- or benzimidazole-modified alkoxysilane. The structure of the polymeric materials was characterized via attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and solid-state 13C and 29Si NMR spectroscopy, which indicated the presence of silsesquioxane units that acted as nodes on the PDMS chains and linked the functional groups. Thermogravimetric analysis (TGA) of the product indicated high thermal stability with an initial weight-loss temperature around 450 K. The capacity for the removal of copper(II) from aqueous solution was estimated from adsorption isotherms, yielding values of 35.74 and 66.09 mg g-1, respectively, for benzimidazole-and imidazole-functionalized materials. The major adsorption models were evaluated to fit the removal data of copper(II) and the model elaborated by Sips was determined to provide the best fit for both prepared materials.

O objetivo deste estudo é caracterizar plantas apícolas nativas, quanto a sua capacidade de extrair e acumular elementos-traço do solo e suas conseqüências na sanidade do pólen produzido. Os elementos-traço Cu, Mn, Pb e Zn foram analisados em solo, planta e pólen apícolas em Teresina (PI), Brasil, por espectrofotometria de absorção atômica com atomização em chama. Considerando as espécies de plantas estudadas, os metais Cu e Pb apresentaram nas raízes maiores teores de B. platypetala com 47,35 e 32,71 µg.mL-1 e H. suaveolens com 39,69 e 17,06 µg.mL-1, respectivamente, enquanto na parte aérea os metais Mn e Zn apresentaram os maiores teores, em S. verticillata com 199,18 e 85, 73 µg.mL-1. No pólen os teores de Cu, Mn, Pb e Zn varia de 5,44 a 11,75 µg.mL-1; 34,31 a 85,75 µg.mL-1; 13,98 a 18,19 µg.mL-1 e 50,19 a 90,35 µg.mL-1, respectivamente. Esses resultados indicam que, no pasto apícola, a translocação (do solo ao pólen apícola) de Mn e Zn foi mais eficiente do que Cu e Pb, portanto, o pólen apícola poderá ser utilizado como complemento alimentar sem causar riscos à saúde humana.

The purpose of this study is to characterize native bee plants regarding their capacity to extract and accumulate trace elements from the soil and its consequences to the sanity of the produced pollen. The trace elements Cu, Mn, Pb and Zn were analyzed in soil, plants and bee pollen from Teresina region (PI), Brazil, by flame atomic absorption spectrophotometer. Considering the studied plant species, Cu and Pb metals presented in the highest levels in the roots of B. platypetala with 47.35 and 32.71 μg.mL-1 and H. suaveolens with 39.69 and 17.06 μg.mL-1, respectively, while in the aerial parts Mn and Zn metals presented the highest levels in S. verticillata with 199.18 and 85.73 μg.mL-1. In the pollen, the levels of Cu, Mn, Pb and Zn vary from 5.44 to 11.75 μg.mL-1; 34.31 to 85.75 μg.mL-1; 13.98 to 18.19 μg.mL-1 and 50.19 to 90.35 μg.mL-1, respectively. These results indicate that in the apicultural pasture the translocation (from soil to pollen) of Mn and Zn was more effective than in case of Cu and Pb, therefore, the bee pollen can be used as food supplement without causing risks to human health.

The aim of the present work was to develop and optimize a method for determination of bioavailable phosphorus in samples of feces and fish feed using ultrasound extraction and subsequent quantification by visible spectrophotometry. Using as extractor solution HNO3 0.50 mol L-1, the great conditions of extraction established were: sample mass - 100 mg, samples granulometry - < 60 µm, sonification time - five cycles of 40 s and ultrasound potency - 136 W. The proposed method was applied in studies of digestibility of this nutrient in different feeds used in diets of juvenile of Nile tilapia.