A biomimetic porous fibre bundle adsorbent for the rapid and complete removal of multiple low-level heavy metal ions

Improving diffusion and mass transfer kinetics to enhance the synchronous removal efficiency of adsorbents for low concentrations of various heavy metal ions is of great significance for reducing heavy metal removal. Here, a biomimetic porous fibre bundle adsorbent with multiple adsorption sites was constructed by embedding and bonding porous coconut shell biochar on amino and sulfhydryl group-functionalized cellulose nanofibre bundles in the process of fibrogenesis, which was inspired by the principle of spider silk. The high porosity, specific surface area (212.17 m2/g) and swelling rate (184 %) of the porous fibre bundle could effectively improve the diffusion and mass transfer kinetics. Multiple adsorption sites of amino, carboxyl, and sulfhydryl groups endow the adsorbent with a synchronous removal rate for various heavy metal ions in water. Therefore, the porous fibre bundle could remove low concentrations of Pb(II), Cu(II), Cd(II) and Cr(VI) to safe drinking water level standard concentrations (US EPA) within 20 min. This study provided a simple method for designing an effective adsorbent for lowering heavy metal removal.