Desenvolvimento de método para degradação do corante rodamina B

Abstract

The textile industry, which includes purging, mercerizing, desizing, bleaching and dyeing operations, uses large volumes of fresh water and chemicals. During the dyeing stages, various synthetic dyes are used that contribute to the generation of liquid effluents with a contaminant load that can cause serious damage, not only to the aquatic environment but also to human health. Due to the profile of the textile sector's effluents, the treatment process involves different stages to meet the standards determined by current legislation. In this regard and in line with the principles of green engineering, there is a growing number of studies in the area of nanotechnology to contribute to the treatment stages for the degradation or adsorption of dyes in the effluent in an efficient, safe, low-cost manner, using the minimum amount of energy and reagents. In this sense, this study proposes to synthesize “magnetic nanoparticles” (MPPs) of Iron Oxide III (Fe3O4) and evaluate their efficiency in the photocatalytic degradation of the dye rhodamine B. The synthesis of the Fe3O4 MNPs consisted of the reaction of Fe2SO4. 7H2O as precursor and vegetable extract of potato and cassava as reducing and stabilizing agent. The materials obtained were characterized by the techniques of X-ray Diffraction (XRD) and Energy Dispersive X-ray Spectrometry (EDX). Although the synthesis from cassava extract presented a higher yield, the predominant phase was goethite, while for the potato extract the majority phase was magnetite Fe3O4, the object of the present study. The optimization of photocatalysis, using synthetic magnetite, consists of a 22 factorial design with a central point to evaluate the influence of the amount of nanoparticles and the time required for the degradation of the rhodamine B dye. For this purpose, 3.0 mL of rhodamine B dye solution at 10 mg L-1 (pH = 5) were used and the results showed that the time of 30 min and the lowest masses were the best conditions for degradation of rhodamine B dye under ultraviolet (UV) exposure. This same material degrades the dye under solar radiation. The optimized conditions were applied to Fe3O4 MNPs, synthesized from potato extract, in duplicate under UV radiation. The results visually showed the degradation of the rhodamine B dye, with subsequent evaluation of absorbance by UV-VIS spectrophotometry in the range of 400 to 700 nm. Therefore, the Fe3O4 NPMs from potato extract were efficient, low-cost, easy to synthesize, sustainable and promising for the treatment of textile industry effluents.