Evaluación del potencial del hidrogel a base de fibras de celulosa para la remoción de cadmio en medios acuosos.

Abstract

Cadmium (Cd+2) is a heavy metal considered highly toxic, its characteristics have made it the major pollutant of water sources due to industrial activities, especially at the end of a process in mining activities, this pollutant bioaccumulates in aquatic organisms, affecting not only their biodiversity, but also alters the trophic chain. The main objective of this experimental work is to evaluate the efficiency of a composite hydrogel modified with cellulose fibers, chitosan and polyethylenimine for the removal of cadmium in aqueous solutions, to elaborate three adsorbent materials FC, CS/PEI and FC/CS/PEI, to perform the characterization of the materials by XR, SEM, FTIR, swelling and retention, and to verify the adsorption capacity from a stock solution with a concentration of 2500 ppm at different pH (3,4,5,6). Through the present experimental work, it could be demonstrated that the FC/CS/PEI composite hydrogel exhibited a significantly higher cadmium adsorption capacity than its individual precursors, reaching a maximum of 31.22 mg/g at pH 5. This efficiency is attributed to the synergy between nanocellulose, chitosan and polyethylenimine, whose functional groups facilitated the electrostatic interaction and the formation of coordination bonds with the metal ions. The material exhibited a high zero charge potential (9.2196), promoting the adsorption of cations in alkaline media. FTIR analysis confirmed the preservation of the active functional groups, which favor adsorption, while X-ray diffraction revealed a low degree of crystallinity (53.72 %), reinforcing this effect. The FC/CS/PEI hydrogel displayed a dense structure with low porosity (10.52 μm), which enhanced its stability and resistance. Furthermore, it reached the highest swelling percentage (2313.88 % at 90 min) and exhibited high stability in water retention, with a release of less than 1 % after 60 hours. These results highlight the composite hydrogel as an efficient and viable material for the remediation of waters contaminated with heavy metals, with potential for optimization and scale-up.