As argilas são os materiais mais importantes do ponto de vista tecnológico para fabricação de materiais cerâmicos. A sua composição química e mineralógica influencia fortemente as propriedades físicas e químicas que se deseja obter no produto acabado de cerâmica. O objetivo desse trabalho foi avaliar a potencialidade de argilas da formação geológica Calumbi e Riachuelo do estado de Sergipe para aplicação em revestimento cerâmico. Foram coletadas amostras de 3 depósitos argilosos (A, B e C) e caracterizadas por ensaios de granulometria, plasticidade, difração de raios X, análises termogravimétrica e diferencial, infravermelho e fluorescência de raios X. As principais fases identificadas foram quartzo, caulinita, ilita, calcita e feldspatos, sendo que os depósitos B e C apresentaram elevados teores de calcita. Constatou-se que para as condições do processamento cerâmico adotadas as argilas dos depósitos A e B devidamente misturadas são adequadas para serem utilizadas na indústria de processamento de pisos cerâmicos, em especial para a obtenção da classificação do grupo cerâmico BIII.

Clays are the most important materials from the technological point of view, for the production of ceramic materials. Its chemical and mineralogical composition strongly influences the physical and chemical properties to be obtained in the finished product of ceramic. The aim of this paper was to evaluate the potential of clays of the Calumbi and Riachuelo geological formation in Sergipe, Brazil, for the application in ceramic tiles. Samples were collected from 03 clay deposits ("A", "B" and "C") and characterized by granulometryassays, plasticity, X-ray diffraction, and differential thermogravimetric analysis, infrared and X-ray fluorescence. The main identified phases were: quartz, kaolinite, illite, calcite and feldspar, and deposits "B" and "C" showed high levels of calcite. It was found that for ceramic processing conditions adopted in this paper, the properly mixed clay deposits of "A" and "B" are suitable for use in the processing industry ceramic tiles, particularly for obtaining of the classification of the absorption group "BIII".

Palygorskite is fibrous clay in which the structural tetrahedral and octahedral layers are organized in a way that structural channels are formed, leading to high surface area. However, impurities inside the channels and aggregated ones considerably reduce the available area. In order to increase the surface area, an activation treatment can be considered useful. The goal of this work is the activation of palygorskite from Guadalupe, Piauí, via sulfuric acid treatment using a two-level factorial design. The influence of three parameters (solution molarity, temperature and time) on BET surface area was determined. Moreover, samples were characterized via X-ray diffraction (XRD) and fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The largest surface area (282 m²/g) without considerable changes in clay structure and morphology was found in a sample treated with 5M H2SO4 at 70°C for 1h. The main parameters that favored the improvement of the surface area were the solution's molarity, temperature and their interaction.