Caracterização e avaliação das propriedades adsortivas da casca de laranja na remoção do corante Direct Blue 86

Abstract

Dyes are organic compounds used to provide color and / or brightness to various types of materials such as papers and textile. However, the aromatic complex generally present in the chemical structure of the colorants turns the molecules highly stable and, moreover, some types of dyes are toxic and even carcinogenic, which requires wastewater treatment containing these compounds to comply with current legislation. Some textile effluents processes cannot meet legislation, which encourages the study of adsorption processes to remove dyes, as this technique presents moderate cost, shorter processing time and few variables to be controlled. In this context, the use of environmental liabilities as adsorbent materials has emerged, replacing the activated carbon, of higher cost. The orange peel, an example of agro-industrial waste, has the adsorption potential that can be exploited for the removal of dyes. The objective of this work was to evaluate the adsorption capacity of the Direct Blue 86 dye, routinely used in the textile industry, using powdered orange peel as an adsorbent. The orange peel was characterized by its humidity content, ash content, particle size analysis, infrared spectroscopy and scanning electron microscopy. The study of the adsorptive properties of orange peel understands iodine index, methylene blue index, zero point of charge and contact time to find adequate conditions of dye adsorption with orange peel powder. The orange peel powder (OPP) showed to be effective as an adsorbent material for textile dye, due to the physicochemical properties indicate porous structure compatible with the adsorption of molecules with dimensions of up to 15 micrometers. The OPP answered the ABNT NBR 2133 norm showing lower humidity content of 8%. The ash content indicated few impurities in the material, with a value of (2.79 ± 0.06) %. The methodology used in adsorption experiments did not allow quantification of the dye in the solutions, leading to an investigation of the possible causes. The results showed the Dlimonene, orange peel component, as responsible for the non-viability of the methodology employed, so it was not possible to quantify the study through the contact time of variation (adsorption kinetics), pH, temperature and adsorption isotherm by this method. Even so, laboratory-prepared OPP showed adsorption properties similar to those of materials found in literature, which suggests the development of future work with other methods of quantification.