UTILIZAÇÃO DE DIFERENTES TIPOS DE ADSORVENTES NA REMOÇÃO DE ÍONS METÁLICOS EM EFLUENTES: UMA REVISÃO

Abstract

Anthropogenic activities have increased the amount of pollutants and consequently their concentration in the environment through the discharge of industrial and municipal effluents, mining, urban and agricultural runoff, fine sediments from the erosion of springs, among others. Generally, these contaminating sources discharge their effluents into water bodies. To reduce the contamination of water resources it is necessary to treat these effluents, and industrial waste is one of the most polluting sources. Among the decontamination processes, adsorption is the most viable alternative, in which adsorbents are used to remove metallic ions or molecules. The adsorbents can originate from organic or inorganic compounds or can be synthesized. Through mathematical equations, such as isotherms, it is possible to determine the efficiency of the process carried out. This work consisted of a survey of scientific studies on adsorbent materials used in the adsorption process. It was selected 50 works, where 31 correspond to articles (15 foreign language and 16 national), 14 dissertations and 5 theses, taken from databases such as Portal Capes, Scielo Portal, and Repositories of dissertations and theses. It was found that biosorbents from agroindustrial waste, as well as from living or dead microorganisms have shown highly absorptive properties. The metal ions commonly exploited were Cu(II), corresponding to 56%, Cd(II) and Pb(II), both 42% and Zn(II) 36%. It is observed that the most used isotherms in the analyzed studies are Langmuir and Freundlich, which mostly follow the Langmuir model, fitting well to the analysis of all metallic ions described in these studies. In relation to the kinetic models applied, it was found that the adsorption equilibrium follows the pseudo-second order kinetic model. The studies in highlight are those that use algae as a biosorbent, besides being a promising option for the high capacity of adsorption, greater than 90%, it is also economically viable, because they are usually collected in coastal areas of the world's oceans because they proliferate ubiquitously and abundantly, and in other cases are given by biodiesel industries, in which the waste generated is reused.