Navegando por Assunto "Argila pilarizada"

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Acesso aberto (Open Access)
Aplicação de Al-PILC na adsorção de Cu2+, Ni2+e Co2+ utilizando modelos físico-químicos de adsorção
(2007) GUERRA, Denis de Jesus Lima; AIROLDI, Claudio; LEMOS, Vanda Porpino; ANGÉLICA, Rômulo Simões; VIANA, Rúbia Ribeiro
Smectite sample from the Serra de Maicuru area (Pará state, northern Brazil, Amazon region) were used for the pillaring process with Al13. Aluminum pillared clay (Al-PILC) was characterized by XRD, SEM and EDS. the textural analysis using nitrogen adsorption-desorption isotherms. The aim of this paper is to study in how Al-PILC adsorb heavy metals. The adsorption of Cu2+, Ni2+, Co2+ ions from aqueous solution in room temperature by Al-PILC have been carried out. The Langmuir, Freundlich and Temkin adsorption isotherm models have been applied to fit the experimental data, with the first model well adjusted with r = 0.999. The one-surface Langmuir equation provided the best fit to the data. The Freundlich equation presented limitations in rises concentrations, but acceptable values of parameters were obtained (Kf and n) with the use of the three models. The parameters were used to calculate the amount adsorbed Nf, a function constant Cs.
Acesso aberto (Open Access)
Influência da razão Al/argila no processo de pilarização de esmectita
(2006-09) GUERRA, Denis de Jesus Lima; LEMOS, Vanda Porpino; ANGÉLICA, Rômulo Simões; AIROLDI, Claudio
Smectite-type clays from the state of Pará, Brazil, were characterized by XRD, 27Al MAS NMR, FTIR and textural analysis by nitrogen adsorpition-desorption isotherms. In the production of pillared clays, the Al13 ion (keggin's ion) was used. This ion was obtained by the reaction of AlCl36H2O/NaOH solutions with OH/Al=2 molar ratio and with Al/clay ratios of 5, 10, 15, 20, 25 meq/g of clay, intercalated at 25 ºC during 3 h and calcined at 450 ºC (adequate temperature for calcination). The results showed that the pillarization process increased the basal spaces of the natural clay from 14.02 to 18.84 Å and the surface area from 44.30 to 198.03 m2/g (Al/g of clay = 25 meq/g of clay, pH=4). Materials prepared with different Al/g clay ratio showed the maximum Al incorporation for Al/g of clay = 25 meq/g of clay. The thermal stability of the natural clay was improved by the pillaring procedure.
Acesso aberto (Open Access)
Influência da temperatura de formação do íon de Keggin no processo de pilarização de esmectitas
(2005) GUERRA, Denis de Jesus Lima; LEMOS, Vanda Porpino; FERNANDES, Erlyson Farias; ANGÉLICA, Rômulo Simões; COSTA, Marcondes Lima da
Clays pillared with Keggin ions (AL-PILC) have been synthesized at OH/Al=2 molar ratio and various pretreatment temperatures (ambient temperature to 105ºC) in order to determine the optimum preparation conditions of the pillaring agent (Al13). The evolution of basal spacing, FTIR spectra, TG-curves, surface area and pillars number in function of temperatures of Al13 formation were studied. It was observed an increase number pillars and surface area at low temperatures.
Acesso aberto (Open Access)
Influência de argilas pilarizadas na decomposição catalítica do óleo de andiroba
(2007) GUERRA, Denis de Jesus Lima; LEMOS, Vanda Porpino; ANGÉLICA, Rômulo Simões; AIROLDI, Claudio
Smectite-bearing clay samples from Pará state, Amazon region, Brazil, were used for pillaring process in the present study. The natural and pillarized matrices were characterized using XRD and textural analysis using nitrogen adsorption-desorption isotherms. The ions of intercalation (Al13, Ti, Zr) were obtained through chemical reactions of AlCl36H2O/ NaOH, titanium ethoxide /HCl, zirconium acetate /HCl solutions. The Results showed that the pillarization process increases the basal spacing of the natural clay from 15.6 to 20.64 Å and the superficial area from 44 to 358 m2/g (Zr-PILC). The thermal stability of the natural clay was improved by the pillaring procedure. The resulting materials were submitted to catalytic process of decomposition of andiroba oil in a fix bed reactor at 673 ± 1 K. The catalytic activity was determined by the product composition resulting from the chemical reactions. The physicochemical parameters of the catalysts were obtained using XRD, FTIR and textural analysis. The pillared clays showed higher Brønsted acidity, with higher concentration in aromatic hydrocarbons and small concentration of aliphatic hydrocarbons.