Avaliação do efeito de argilas bentoníticas da Paraíba para descoramento de óleos vegetais pós-consumo.

Abstract

In this study, bentonite clays (Tonsil and Aporofo) from Paraíba region were tested and evaluated in the decoloration process of used vegetable oils which were collected from households in the city of Campina Grande-PB. A sample of fresh oil was used for comparison purposes. Characterizations were carried out for the clay and used and fresh vegetable oils before and after treatment. Prior to the decoloration process, the clays were characterized by: X-ray Diffraction (XRD), X-ray fluorescence (XRF), grain size distribution and measurements of the surface area (BET). XRD results show the presence of the montmorillonite clay mineral and through XRF the characteristic composition of bentonite clays was confirmed. The highest percentage of fine particles was found in Tonsil (measured by granulometry and BET). This means that the Tonsil clay would be more efficient en the decoloration process of oil when compared to Aporofo clay. The results from XRD and Infrared Spectroscopy (FTIR) of the clays after the decoloration process showed that the Tonsil clay retained on the filter had a more amorphous structure and a higher infrared absorbance (identified as organic part from oil) in relation to Aporofo, possibly due to enhanced adsorption of pigments present in the oil. Samples of fresh and used vegetable oils with and without treatment were characterized by viscosity, acidity content, humidity, residue and FTIR. The viscosity of the oil treated with the Tonsil clay was lower compared to the fresh oil and treated with the Aporofo clay. A decrease in the content of acidity of the treated oils was observed in relation to untreated oil. The contents of humidity and residue remained within the standards established by the ANP. The FTIR result of the oil treated with Tonsil clay showed spectra with greater similarity the fresh oil. According to the results, it was conclude that within the clays considered in this study, Tonsil showed better results in the treatment of the studied oils, making them similar to fresh oils.