A biomimetic SiO₂@chitosan composite as highly-efficient adsorbent for removing heavy metal ions in drinking water

Highly efficient adsorbents for drinking water purification are demanded since the contaminants are generally in a low concentration which makes it difficult for conventional adsorbents. Herein, we present a novel biomimetic SiO₂@chitosan composite as adsorbent with a high adsorption capability towards heavy metal ions including As(V) and Hg(II). The hollow leaf-like SiO₂ scaffold within the adsorbent has a stable chemical property; while on the surface SiO₂, the chitosan nanoparticle provide a large amount of active sites such as amino and hydroxyl groups for adsorbing heavy metal ions. The special SiO₂ structure also prevents the agglomeration and loss of chitosan, which enables the efficient contact between the functional groups of chitosan and heavy metal ions. The SiO₂@chitosan composite exhibits maximum adsorption capacities of 204.1 and 198.6 mg g^-1 towards Hg(II) and As(V), respectively. In addition, the removal efficiency reaches over 60% within 2 min. The adsorption performance enables the presented biomimetic adsorbent suitable for adsorbing low-concentration heavy metal ions, especially possessing a promising potential for drinking water purification.