Evaluation of nanocellulose films enriched with humic substances for remediation of environments contaminated by Cd and Pb

Strategies to minimize the impacts generated on the environment, with the use of ecologically interesting and low-cost adsorbent materials are of environmental relevance. In this sense, this work sought to associate the characteristics of nanocellulose and humic substances (HS) in the development of films for removing potentially toxic metals in aquatic environments, aiming at environmental remediation. The interaction of metallic species both in the film with only nanolelulose (NF) and in films containing different levels of humic substances occurs mainly through carboxyl groups. The removal of Cd and Pb metals by nanocellulose films with and without humic substances increased directly proportionally to the mass of humic substances incorporated into the nanocellulose films, making it possible to infer the importance of HS in the interaction with metallic species. Furthermore, the films can be applied to a wide temperature range, mainly with environmental applications in mind, since the degradation temperature starts at 280 °C and can reach up to 450 °C depending on the content of humic substances added. For films with different concentrations of humic substances (NFHS0.5; NFHS1; NFHS2; and NFHS5), they had a 100% removal degree for cadmium and lead metals (Ci = 2.0 mg L−1), with a contact time of 30 min. The predominant adsorption mechanism is second order suggesting that the process is predominantly controlled by chemical interactions. From the results obtained, it was evident that nanocellulose films with HS have a high removal capacity with Cd and Pb ions and their reusability capacity demonstrates the efficiency of this material in remediating contaminated environments.