Chitosan, Gelatine, and Cellulose Based Hydrogels for the Removal of Potentially Toxic Elements from Aquaculture Water: A Comparative Study

Since aquaculture is playing an increasingly important role in food supply, ensuring the healthiness of aquatic environments is a fundamental issue. Anthropogenic activities are often a source of contamination for water and, among the pollutants released, potentially toxic elements (PTEs) represent a well-known hazard to human health and ecosystem safety. In this study, carboxymethylcellulose-alginate (HY-ACMC), methacrylated-chitosan (HYMCHI), and methacrylated-gelatine (HY-MGEL) hydrogels are synthesized, characterized, and tested as sorbents for PTEs removal. The removal efficiency is significantly affected by pH and contaminants’ concentration. Furthermore, experiments in real aquaculture samples from Italy and Denmark farms are carried out to evaluate the matrix effect. Finally, hydrogel regeneration is optimized and sorbent efficiency for multiple cycles of water remediation treatment is investigated. All tested materials show promising removal capabilities even in real water. HY-ACMC has proven to be the most effective for single-cycle remediation treatments thanks to its high performance in all the studied conditions, although it is unstable to regeneration. On the other hand, regeneration with Na2EDTA improves HY-MCHI efficiency, granting its prolonged employment over time. Considering both performances in real water samples and reusability results, HY-MGEL seems to be the most reliable material for multiple cycles of water remediation treatments.