Recent Advances in Sustainable Biopolymer-Based Nanocomposites for Heavy Metal Removal from Water

The search for new technologies for the removal of heavy metals has intensified due to the increasing contamination of aquatic environments. In this context, biopolymer-based nanocomposites have stood out in the synthesis of new adsorbent materials. These nanocomposites are considered promising due to their abundance, low toxicity, versatility, and high affinity for metal ions. Therefore, this work presents a comprehensive discussion on the development, properties, and performance of biopolymer-based nanocomposites applied to the removal of heavy metals from aqueous systems. Biopolymers such as chitosan, cellulose, alginate, lignin, and pectin are highlighted due to their functional groups and the possibility of chemical modification and/or incorporation of nanoparticles to improve adsorption capacity. In addition, the main mechanisms involved in the metal adsorption process, such as ion exchange, electrostatic attraction, complexation, and chelation, are discussed together with the most commonly used isotherm and kinetic models to describe adsorption behavior. Furthermore, the potential for reuse of these materials is also described in order to evaluate their stability. Finally, possible processes related to nanoparticle leaching, bioaccumulation, and potential ecological risks are also discussed.