Utilização de adsorventes à base de sílica para remoção de contaminantes orgânicos em meios aquosos

Abstract

The incidence of organic contaminants in the environment has increased more and more in recent years, mainly due to population growth and technological advances. Several organic pollutants have reached aquatic environments, threatening the water quality, flora and fauna because they are easily disseminated and difficult to remove. In this work, silica-based adsorbent materials were synthesized to promote the removal of organic contaminants in aqueous media. The adsorption efficiency of dyes and pharmaceuticals was investigated, using methylene blue (MA) and dipyrone sodium (DIP) as reference pollutants. MA is a synthetic dye used by the textile production industry and found in large volumes in industrial effluents. Its presence in aqueous media interferes with the transmission of sunlight, impairing the photosynthetic activity of the flora. DIP, the active ingredient of some of the most consumed medicines in the world, is one of the drugs that reach aquatic environments due to human excretion, continuous and incorrect disposal, and inefficient treatment of effluents in water and sewage treatment plants, causing damage mainly to aquatic species. The adsorbent materials were synthesized using a simple and environmentally friendly sol-gel processing route. Silica gel is a material with a high specific surface area (SSA), porous texture and high chemical reactivity. Due to these factors, it is widely used to promote adsorption. The samples were functionalized with amino groups using two different routes, co-condensation and the post-grafting method. It was observed that the produced samples, despite the absence of catalyst, surfactant or heat treatment step during their preparation, are promising materials, presenting mesoporous networks with high ASE values and good performances in adsorption of AM and DIP. Furthermore, easy regeneration of the samples via thermal treatment was observed, allowing reuse in subsequent adsorption cycles.