Formação de hidrogéis à base de celulose para adsorção de íons CU2+ e ZN2+ em soluções aquosas

Abstract

Potentially toxic elements, also known as heavy metals, are used in many industrial processes. The release of wastewater containing these elements in hydrous bodies leads to the degradation of aquatic ecosystems, due to their toxicity and the possibility of bioaccumulation in living beings along the food chain. In the literature, there are several methods of treating wastewater containing metal ions. Among them, adsorption stands out. However, the use of biopolymers as adsorbents is rarely reported. In this respect, the objective was to prepare and evaluate the potential of cellulosebased hydrogels in the adsorption of Cu2+ and Zn2+ ions in aqueous solutions. The formulated hydrogels are presented as an ecologically correct alternative, since cellulose comes from renewable sources and crosslinking agents are nontoxic. There were three methodological steps: cellulose solubilization, hydrogel crosslinking and analysis of the hydrogel adsorption potential in aqueous solutions. In the first stage, the Lithium Chloride/Dimethylcetamide (LiCl/DMAc) system proved to be efficient for dissolving cellulose. The second part consisted of the introduction of chelating functions (carboxylic acid) through the crosslinking of the hydrogel with citric and succinic acids. The adsorption test was performed in a simulated fluid and the determination of the concentration of Cu2+ and Zn2+ ions was determined, respectively, by visible ultraviolet spectroscopy and complexation titration. A relative comparison was made between the noncrosslinked and crosslinked hydrogels. For copper adsorption, the retention of this metal by hydrogels was observed qualitatively. Regarding the removal of zinc, there was an indication of increased adsorption for the modified hydrogels. In the future, new analyzes will be carried out to evaluate the capacity of metal retention by hydrogels.