Adonay R. Loiola

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.

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.

Starch and Starch/Zeolite Films Used in Coating and Conservation of Guava Fruit (Psidium guajava)

Starch is used here together with zeolite for production of films to coat guava fruit. Starch and starch/zeolite films were prepared by using gelatin and sorbitol. Guava fruit were coated by means of starch solution and starch solution containing zeolite NaA which had been synthesized from kaolin. Physical-chemical analyses have shown that the used films helped to maintain the natural characteristics of the fruit such as high levels of ascorbic acid for longer periods.

Multivariate Analysis of Perfumes by Ultraviolet Spectrophotometry

An efficient, fast and cost-effective method for detecting adulteration in perfumes by UV spectroscopy and multivariate analysis is proposed. Classification of perfumes, either as original or fake, was accomplished with the spectroscopic data using chemometric techniques such as principal component analysis (PCA), soft independent modeling of class analogy (SIMCA) and linear discriminant analysis (LDA).

Al-MCM-41 Synthesized from Kaolin via Hydrothermal Route: Structural Characterization and Use as an Efficient Adsorbent of Methylene Blue

The mesoporous material Al-Mobil Composition of Matter No. 41 (Al-MCM-41) was successfully obtained from kaolin, a low cost raw material, by means of hydrothermal route. The process of synthesis of Al-MCM-41 was based on calcination of kaolin, dealumination by acid treatment, hydrothermal synthesis in alkaline medium and surfactant extraction. The characterization of the obtained mesoporous material was carried out by techniques such as: X-ray diffraction, infrared vibrational spectroscopy, Si and Al solid state nuclear magnetic resonance, scanning electron microscopy, transmission electron microscopy and N2 adsorption-desorption. The X-ray diffraction at low angles allowed the determination of the cell parameter, which was 4.02 nm. The analyses of scanning and transmission electron microscopy revealed important morphological properties of the synthesized material. N2 adsorption/desorption showed a Brunauer-Emmett-Teller (BET) specific surface area of 1,303 m g, pore volume of 1.23 cm g and average diameter of 2.45 nm. The mesoporous material presented a maximum adsorption capacity of 316 mg g for the cationic dye methylene blue (MB) in a concentration typical of industrial effluents, which makes it a potential adsorbent for MB removal from wastewaters.

Organophosphorus Pesticide in Sapodilla (Manilkara zapota) Fruit

A method based on QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction and gas chromatography-mass spectrometry (GC-MS) detection was described for the pesticides dichlorvos, disulfoton, ethoprophos, parathion methyl, fenchlorphos, chlorpyrifos, azinphos methyl and prothiofos in sapodilla. For all compounds studies, it was observed a strong matrix effect showing the need to use matrix matched calibration strategy. Method was validated, and good linearity (R > 0.99) was obtained for all pesticides studied with limits of detection (LODs) and quantification (LOQs) ranging from 0.01 to 0.06 mg kg and 0.03 to 0.2 mg kg, respectively. Recovery studies were performed at different levels (0.08, 0.10, 0.14, 0.20, 0.35 and 1.17 mg kg) and showed good results (between 70 and 120% with relative standard deviation (RSD) < 20%). A statistical test was applied to the coefficients of the analytical curves obtained in the sapodilla matrix. Analyses of commercial samples showed chlorpyrifos were detected in about 70 and 33% for fruit and pulps samples, respectively. It should be noted that chlorpyrifos is not permitted in sapodilla crops by ANVISA and EC guidelines.

Caracterização geoquímica, mineralógica, termogravimétrica, e por espectrometria de infravermelho de argilominerais representativos da porção central da Província Borborema

Todas as rochas expostas na superficie sofrem intemperismo. Esse processo leva a formacao de minerais secundarios, entre eles os argilominerais, que sao de larga aplicacao em diversos setores produtivos. Os argilominerais sao silicatos de aluminio hidratados, placoides, do grupo da caulinita, montmorillonita, illita, entre outros, constituidos por particulas de diâmetro inferior a 0,002 mm, depositados como sedimentos fluviais, marinhos, lacustres ou eolicos. Nesse trabalho, foram estudadas caulinita branca e cinza, montmorilonita e nontronita oriundas de depositos localizados na Paraiba e no Rio Grande do Norte, provincia Borborema, nordeste do Brasil. Estes materiais apresentam elevado potencial tecnologico, servindo de base de estudo para a producao de adsorventes de contaminantes oriundos de derivados de petroleo, por exemplo. As amostras foram caracterizadas por difratometria de raios X (DRX), analise termogravimetrica (ATG), capacidade de troca cationica (CTC), espectrometria de infravermelho (IR), e microscopia eletronica de varredura (MEV). As analises quimicas das argilas estudadas revelaram elevados teores de SiO 2 e Al 2 O 3 e teores < 10% para TiO 2 , CaO, MgO, Na 2 O e BaO; montmorilonita apresenta altos teores de Fe 2 O 3 (~13%). A caulinita analisada possui, como impurezas, oxidos e hidroxidos de ferro. A montmorilonita e o principal mineral contido nas argilas bentoniticas da regiao. As amostras de montmorilonita sao argilas naturais e possuem elevada capacidade de adsorcao cationica e, portanto, provavelmente eficiente em posteriores ensaios com essa finalidade. Palavras-chave : Argilominerais, Provincia Borborema; Caracterizacao de minerais.

Avaliação da liberação de NH 4 NO 3 ocluido em zeólita 4A a partir de soluções salinas

The zeolite 4A was used to evaluate the thermo kinetics parameters of NH4+ and NO3- ions occluded in its structure. The Osawa method for activation energy calculation was used to evaluate its thermal stability, and the results shown that the ion species interact differently depending on the zeolite pores, which determines the controlled release by its structure.