Potencial de Salvinia sp. na remoção do corante azul de metileno em ambiente aquoso

Abstract

The growth of cities and, consequently, of the population and consumption and production patterns consequently leads us to problems of environmental contamination, whether by metals, herbicides, dyes, pharmaceuticals, among others. The removal of dyes from water, in particular, is something that requires the use of technologies, thus making the process often costly and expensive. Thus, in the last decade, interest in phytoremediation has arisen, a technology that consists in the use of plants for environmental recovery, reducing the contamination rates of the dye. Among the botanical families traditionally recognized as exemplary for their phytoremediation capacity is the Salviniaceae, a family with species widely used for phytoremediation. Salvinia sp. is a species known mainly for its presence in lakes and rivers and for its reproductive and phytoremediation abilities. In this work, the potential of Salvinia sp. for the removal of methylene blue (MB) dye in aqueous environment was examined. The specimens of Salvinia sp. were collected in the city of Cerro Largo, the hydroponic cultivation was performed on a bench in an acclimatized cultivation room at 23 ºC, where 8 LED lamps were installed to provide luminosity to the plants (12 hours daily). The plants were sanitized and acclimated for a period of 5 days. Twenty growing trays were filled with 2 L of Dutt and Bergmann's nutrient solution contaminated with (MB) at four concentrations (14, 37, 60, 130 mg.L), with an approximate amount of 10 plants per tray for a period of 10 days. (MB) concentrations were measured daily in all treatments. At the end of the experiment it was found that the 14 mg.L treatment showed a decrease of about 67.70% of the initial concentration of the dye, the 37 mg.L treatment showed a decrease of 55.03%, the 60 mg.L treatment showed a decrease of 23.80%, while the 130 mg.L treatment showed a decrease of 10.14% of the initial concentration of the dye. This shows that Salvinia sp. can be successfully used for phytoremediation purposes for environmentally friendly dye removal, since it showed considerable decrease rates of dye concentration for the treatments 14 and 37 mg.L, without the plants showing significant signs of contamination. However, in the treatments of 60 and 130 mg.L the concentration decrease rates were not so high, and the plants showed strong signs of contamination such as necrosis points and large volume loss of hair filaments in the roots. In the four treatments it is possible to observe that in the period from the first to the fourth day the highest percentages of decrease in concentration of the dye were concentrated, showing that exposure in shorter periods can also be effective. Thus, observing the phytoremediation potential of Salvinia sp., we conclude that it presents effectiveness in the removal of dyes from water by the mechanism of phytofiltration.