Recebido em 20/2/13; aceito em 18/7/13; publicado na web em 21/8/13 MODIFICATION AND CHARACTERIZATION OF RESIDUE ELECTRIC ARC FURNACE DUST (EAFD) FOR APPLICATION IN CHROMIUM (VI) REDUCTION REACTIONS. In this study, electric arc furnace dust (EAFD) was thermally modified at different temperatures under H 2 flow or charcoal in order to obtain reduced iron phases (Fe 3 O 4 , FeO and Fe 0 ). The formation of these phases was confirmed by powder X-ray diffraction. The tests performed for reducing Cr (VI) using resultant materials obtained after thermal treatment of the EAFD showed excellent results, with PAE600H (EAFD reduced at 600 ºC under H 2 flow) decreasing around 100% of the Cr (VI) in only 10 minutes of reaction. These results indicate the possibility of adding value to the residue, obtaining materials that offer great potential for environmental applications.

Lead and cadmium were determined in non-mineralized raw milk samples employing dispersive solid phase extraction with magnetic restricted access carbon nanotubes (M-RACNTs), followed by flame atomic absorption spectrometry analysis. M-RACNTs were obtained by modifying carbon nanotubes (CNTs) with magnetite nanoparticles and then covering with a chemically crosslinked bovine serum albumin (BSA) external layer. The M-RACNTs particles were very efficient to capture the metals and exclude proteins from the milk, being easily separated from the sample using a neodymium magnet. The extraction parameters were appraised by multivariate optimization (factorial design and Doehlert matrix). The method was validated and proved to be robust for small variations, simple, fast, sensitive and selective. The determination coefficient and limit of quantification were 0.998 and 10 µg L-1, respectively, for both Pb2+ and Cd2+ ions. The developed method was able to determine both metals in concentrations below the maximum residue limits (20 and 50 µg L-1 for Pb2+ and Cd+, respectively, in Brazil), demonstrating that M-RACNTs are promising materials for metal extraction in protein-rich samples, without the need for mineralization procedures.

Lead and cadmium were determined in non-mineralized raw milk samples employing dispersive solid phase extraction with magnetic restricted access carbon nanotubes (M-RACNTs), followed by ame atomic absorption spectrometry analysis. M-RACNTs were obtained by modifying carbon nanotubes (CNTs) with magnetite nanoparticles and then covering with a chemically crosslinked bovine serum albumin (BSA) external layer. The M-RACNTs particles were very e cient to capture the metals and exclude proteins from the milk, being easily separated from the sample using a neodymium magnet. The extraction parameters were appraised by multivariate optimization (factorial design and Doehlert matrix). The method was validated and proved to be robust for small variations, simple, fast, sensitive and selective. The determination coe cient and limit of quanti cation were 0.998 and 10 µg L -1 , respectively, for both Pb 2+ and Cd 2+ ions. The developed method was able to determine both metals in concentrations below the maximum residue limits (20 and 50 µg L -1 for Pb 2+ and Cd + , respectively, in Brazil), demonstrating that M-RACNTs are promising materials for metal extraction in protein-rich samples, without the need for mineralization procedures.Recently, the use of smart sorbents to extract metals from complex samples has increased, mainly due to the simplicity and security of this procedure. Carbon nanotubes (CNTs) can be an important sorbent in this case, due to their high adsorptive capacity (Herbst et al. 2004;Barbosa et al. 2015). However, the use of commercial CNTs is limited in the preparation of biological samples, given that proteins can bind to the