A 'top modification' strategy for enhancing the ability of a chitosan aerogel to efficiently capture heavy metal ions

Chitosan is a promising substitute for heavy metal ion adsorbents. However, traditional pure chitosan adsorbents have certain disadvantages that limit their application. In this paper, a 'top modification' strategy was used to enhance the capturing ability of chitosan adsorbents. A chitosan aerogel was prepared via physical crosslinking and then enhanced by immersion in ethylenediamine tetraacetic anhydride solution. Finally, an enhanced chitosan aerogel was obtained, and analyses were used to describe its structure, adsorption properties and mechanism. Results showed that both the porous structure and the combined complexations dramatically improved the capturing ability of the chitosan aerogel for heavy metal ions. The theoretical adsorption capacities of the enhanced aerogel for Cu²⁺, Pb²⁺ and Cd²⁺ reached 108.14, 143.73 and 84.62 mg/g, respectively. Due to their environmental friendliness, good adsorption performance, easy separation and reusability, enhanced aerogels have become viable solutions to removing heavy metal pollutants from aquatic systems.