The presence of metal ions in water is concerning as they present several harmful effects on human health. In addition, they are non-biodegradable, and their toxicity, observed even at low concentrations, can be exacerbated by bioaccumulation and biomagnification, which increase exposure along the food chain. New alternative decontamination processes are needed, with adsorption gaining attention due to the presence of binding sites and the surface area of adsorbent materials. Porous materials, such as hydrogels that exhibit three-dimensional polymeric structures produced by crosslinking, have been highlighted for water decontamination. Chitosan has attracted attention for its biodegradability, biocompatibility, non-toxicity, and low cost, as well as for its amine and hydroxyl groups, which enable it to interact with metal ions. Furthermore, incorporating modified nanocellulose may enhance adsorption capacity. Therefore, the present work investigates the development of chitosan hydrogel and the incorporation of modified nanocellulose in the removal of metal ions. Eucalyptus residue was treated using oxidative and alkaline treatments to remove lignocellulosic components, then ground in a ball mill and homogenized in an Ultra-Turrax to obtain cellulose nanostructures (CN). The CN was then modified using di-EDTA in pyridine, centrifuged with different solvents, dried, and the sample was named CN-EDTA. To prepare the chitosan hydrogels (CH), chitosan was dissolved in a 2% (v/v) acetic acid solution to obtain a 1% (w/v) concentration, and glutaraldehyde was subsequently added as a cross-linking agent. The hydrogel composites were produced by incorporating CN-EDTA at 1%, 3%, 5%, and 10%. The infrared and nuclear magnetic resonance analyses identified the effective modification in CN-EDTA, evidenced by the appearance of signals attributed to carboxylate groups. The modified CN exhibited a lower zero-charge potential and an improved metal-ion sorption capacity. Kinetics and isotherm studies indicated that the material has a heterogeneous surface in which chemisorption interactions are prominent, but that physisorption interactions are also present. The modified CNs showed greater removal capacity than the unmodified CN, with CN-EDTA achieving qmax values of 1.50, 1.29, 0.99, and 1.60 mmol g-1 for copper, nickel, cadmium, and chromium ions, respectively. The incorporation of CN-EDTA into the chitosan hydrogel matrix improved the intrinsic sorption potential, with the CH-10%CN-EDTA formulation standing out. The hydrogels exhibited a high-water absorption capacity, exceeding 300%. Kinetic and isotherm studies demonstrated that internal diffusion had a greater influence on the process, which was associated with hydrogel swelling. The sorption may be associated with chemisorption, in which the composite hydrogel CH-10%CN-EDTA exhibited qmax values of 0.87, 1.60, 1.32, and 1.99 mmol g-¹ for copper, nickel, cadmium, and chromium ions, respectively. The results suggest that the developed materials hold promise as environmentally friendly alternatives for water decontamination.
Comissão Organizadora
Pedro Alves da Silva Autreto
Comissão Científica
Ferramenta completa de submissão, avaliação e publicação de anais para eventos científicos.
