L. R. D. da Silva

Structural analysis of zeolite NaA synthesized by a cost-effective hydrothermal method using kaolin and its use as water softener

Zeolite 4A (LTA) has been successfully synthesized by a hydrothermal method, where kaolin was used as silica and alumina source. The synthesized zeolite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), laser granulometry, and FTIR spectroscopy. XRD data from the Rietveld refinement method confirmed only one crystallographic phase. Zeolite A morphology was observed by SEM analysis, and it showed well-defined crystals with slightly different sizes but with the same cubic shape. Particle size distribution of the crystals was confirmed by laser granulometry, whereas FTIR spectroscopy revealed significant structural differences between the starting material and the final zeolite product used as water softener.

Synthesis and Characterization of Cr2O3 Nanoparticles Obtained by Gelatin

Nanoparticles of Cr2O3 were synthesized by means of gelatin and (KCr(SO4)2 12H2O). The particle size measured with X-ray diffraction (XRD) technique and confirmed by Transmission Electron Microscopy (TEM) is in the range of 15-60nm. We demonstrated that particle size increase with the sintering temperature in the interval of 500-800C and the surface area decrease. Also, other complementary techniques such as SEM and TGA were used to confirm our results. Introduction The interest in the physical of nanoparticles has increased in the last decades because of the different properties encountered in these materials when compared to their corresponding bulk. Chromium oxide nanoparticles have several applications such as catalysis of CO [1] and H2S [2], green pigments [3], thermal protection [4], wear resistance [5,6] as in advanced digital recording systems [7] that depend on the crystalline size and morphology. Reduced particle size is also needed for improved sintering abilities, that means decreased sintering temperatures and increased density of sintered powders [8]. Several methods have been implemented in order to obtain the nanocrystalline chromium oxide, including microwave plasma [9], sol-gel [10,11] and mechanochemical processing [12]. From an idea similar to that of using coconut water [13] as a precursor to obtain metal oxide, in this work we used commercial gelatin assuming that both precursors are constituted of the protein in the gelatin composition. Recently, Fe2O3 was obtained by gelatin with particle size of 100 nm [14]. Also, gelatin was used as a new application in medicine to obtain drugs with dimension of nanometer [15].

Caracterização termogravimétrica e espectroscópica das propriedades ácidas da zeólita ZSM-22

A acidez da estrutura da zeolita ZSM-22 foi determinada por analise termica. A energia de ativacao, calculada pelo metodo de Ozawa, envolveu uma energia de termodecomposicao de 18,44 kJ.mol-1. O valor do fator pre-exponencial A foi de 2,2746. Suas propriedades texturais foram determinadas por analise de dessorcao/adsorcao de nitrogenio, cujos resultados indicaram a existencia de microporosidade, com area de superficie de 257 m2.g-1, volume de microporos de 0,041 cm3.g-1 e diâmetro de poros de 32,6 A. Analises de luminescencia, utilizando europio como sonda, sugerem que a acidez e distribuida uniformemente dentro da estrutura da zeolita.

Síntese e caracterização de vermiculita mesoporosa obtida por modificação com sais complexos de alumínio e lantânio

The studies of increased basal interplanar spacing, pore distribution and surface area, mesoporous of a clay obtained from vermiculite precursor were obtained by intercalation of cationic polyhydroxy oligomer Al13 and a mixture (LaxAl13-x) obtained by doping with lanthanum, followed by calcination to form the pillars. The characterizations of the samples were performed by X-ray diffraction, Mossbauer spectroscopy, nuclear magnetic resonance solid state (27Al MAS-NMR) and N2 isotherms (BET). The presence of lanthanum in the structure of vermiculite resulted in the increase of its area and porosity.

N-octane catalytic isomerization with aluminium and aluminiumlanthanum pillared nontronite

Nontronite samples pillared with aluminium (Pt/Al-PilM) and aluminium-lanthanum (Pt/AlLa-PilM) were prepared from natural nontronite, characterized and tested as catalyst in n-octane hydroisomerization reaction. The results were compared with those obtained from the same reaction using commercial Y-zeolite impregnated with platinum (Pt-Y). Experiments with commercial zeolite show that platinum is essential to maintain the reactional selectivity of the products. The conversion capacities of (Pt/Al- PilM) and (Pt/AlLa-PilM) were 70% and 40%, respectively, surpassing the Pt-Y performance of 30%, but with the same selectivity. X-ray diffraction data show that organic matter oxidation followed by cationic homogenization is of paramount importance for pillared clay preparation.

Estudo da intercalação de compostos orgânicos em caulins na forma ácida

The feasibility of using major clays such as kaolin in the adsorption processes, can occur through chemical modification by intercalation in their structures phyllite. Samples of kaolin in the region of northeast Brazil, one white and one gray of a portion of the region Borborema-served in the state of Paraiba, were interspersed with dimethylsulfoxide, oxalic acid and citric acid. The characterization natural and modified techniques were used X-ray diffraction, thermal analysis and absorption spectroscopy in the infrared.

Efeito do glutaraldeído na adsorção de extrato proteico da Ipomoea Batatas (L) Lam na superficie de uma zeólita analcima

The analcime zeolite (Na16Al16Si32O96.nH2O) was treated with hydrochloric acid 0.25 mol.L-1, followed by the funcionalization with glutaraldehyde and immersed in the proteic extract obtained from gross extract of sweet potato pulp (Ipomoea Batatas (L) Lam), which presents in its composition the polyphenol oxidase enzyme (PPO). Other samples were submitted to the same procedure with characterizations by scanning electron microscopy, Fourier Transform Infrared spectroscopy and thermogravimetry.

Avaliação da capacidade dessecante de duas zeolitas obtidas da modificação hidrotérmica de um caulim vermelho do Ceará, Brasil

As zeolitas P e phillipsita obtidas previamente, a partir de reacoes hidrotermicas em meio alcalino de um caulim vermelho do Ceara, foram submetidas a avaliacoes quanto a capacidade dessecante aplicadas ao solvente acetato de etila contendo quantidades de agua que variam de 0,1 a 1%v/v. Os resultados mostram que ambas zeolitas apresentam boa capacidade dessecante, tendo a phillipsita alcancado um desempenho notadamente superior ao da zeolita P.