The third generation (G-3) poly(propyleneimine)hexadecaamine dendrimer (DAB-Am-16) was grafted onto the chloropropylsilica gel surface (DPPIPS). The modified silica (DPPIPS) was characterized by Electronic (Uv-Vis), vibrational and Electron Paramagnetic Resonance (EPR), spectrocopies, surface area (331.07 m².g-1) and porosity analyses (pore diameter of 41.9 nm) and cyclic voltammetry technique. The copper adsorption studies were performed using a batchwise process and the DPPIPS showed adsorption capacities of 16.3, 47.8 and 659.5 mol.g-1 in aqueous, ethanol and acetone medium, respectively, with recoveries close to 100% after percolation with HCl 1.0 mol.L-1. The results suggest that the sorption of copper ions on DPPIPS occurs mainly by surface complexation and a Langmuir model allowed describing the sorption of the metal ions on DPPIPS. As an application of this chemically modified material, copper was determined in real samples of distilled spirits and fuel alcohol.

Octakis (hydridodimethylsiloxy) octasilsesquioxane was hydrosilated with allyl chloride using Spiers catalyst (H2PtCl6). This reaction was monitored using FT-IR spectroscopy. The synthesized product was characterized by 13C, 29Si NMR (MAS), SEM, FT-IR, Thermogravimetric techniques. The three propyl groups alpha, beta, gamma, (to the terminal silicon atom), associated of an allyl chloride, were clearly seen in the 13C NMR (alpha-CH2 at 31.8; beta-CH2 at 37.7; gamma-CH2 at 50.1 ppm). In addition, the 29Si NMR spectrum of the final product, exhibits three Q signals for Q type silicon attributed to Q² (-90.1) Q³ (-100.2) and Q4 (-111.3ppm). The presence of allyl chloride substitutes in octameric cube confers a relative porosity and thermal stability to the material.

Nitroprussiato de ferro (FeNP) foi sintetisado e caracterizado por Infravermelho e absorção atômica. FeNP foi incorporado em eletrodo de pasta de grafite empregando-se como técnica de estudo a voltametria cíclica. O comportamento eletroquímico do eletrodo de pasta de grafite contendo FeNP apresenta dois processos eletródicos com potencial médio (Em) de (Em)1 = 0,24 V e (Em)2 = 0,85 V ( KCl =1,0M; v = 20 mV.s-1 vs ECS) atribuídos aos pares redox ( FeII/FeIII ) e FeII(CN)5NO/ FeIII(CN)5NO, respectivamente. A intensidade de corrente dos pares redox aumenta, linearmente com a velocidade de varredura indicando um controle de adsorção. O eletrodo de pasta de grafite modificada com FeNP apresenta estabilidade por vários dias. O estudo eletroquímico do eletrodo de pasta de grafite modificada com FeNP foi examinado em várias soluções de eletrólitos suporte sendo que a natureza do cátion afetam a intensidade de corrente e os potenciais dos pares redox ,deslocando (Em)1 para potenciais mais positivos na sequência: K+ >Na+>Li+ enquanto que a natureza do anion (Cl-, NO3-,SO4=) não afeta os pares redox. Os voltamogramas obtidos em diferentes concentrações de KCl (0,05 - 2,5 M)exibem deslocamentos do (Em)1 para potencial de valores mais positivos. Este deslocamento é linear com a variação da concentração do eletrólito suporte. A inclinação da reta é de 66 mV por década de concentração indicando a ocorrência de um processo quase nernstiano. O potencial médio permanece praticamente constante em pH entre os valores de 3,0 e 8,0. Um outro processo eletródico com (Em)3 = 0,47 V ocorre em pH < 3, sendo este atribuído a formação de novas espécies intermediárias.

Iron nitroprusside (FeNP) was syntetised and characterized by IR and atomic absorption. The FeNP was incorporated into a carbon paste electrode and the electrochemical studies were perfomated with cyclic voltammetry. The cyclic voltammogram of FeNP into carbon paste exhibit two redox couple with following midpoint potentials (Em); (Em)1 = 0.24 V and (Em)2 = 0.85 V vs SCE ( KCl =1.0M; v = 20 mV.s-1) assigned to the Fe(II)/Fe(III) and Fe(II)(CN)5NO / Fe(III)(CN)5NO respectively. At sweep rates between 10 and 100 mV.s-1 the peaks currents intensity increase linearly with sweep rate. The FeNP incorporated into a graphite paste electrode is very stable for several days. The electrochemical behavior of the FeNP was examined in solution of various supporting electrolytes. For two processes the nature of the cation affect the Em as current intensity, shifting the Em for more positive potentials, in following order : Li+>K+>Na+. The nature of the anion (Cl-,NO3-, SO4(2-) did not affect both redox couples. The voltammograms obtained with different KCl concentrations (0.05 -2.5M) exhibit a shift in the (Em)1 to more positive potentials, this change is linear with the supporting electrolyte concentrations change. The slop of the strainght line is 66 mV for decade of the potassium concentration, which indicate a sub - nernstian process. It was verified that the mid-point potential (Em) remained practically constant at pH between 8 and 3. However, a new process with (Em)3 (0,47 V) appears at pH < 3 and was ascribed to formation of intermediary species.