A biomass-assembled macro/meso-porous nano-scavenger for Hg ion trapping

Abstract

It is desirable to develop a sustainable Hg ion scavenger, which features a high adsorption capacity, fast adsorption kinetics, as well as robust stability and excellent recyclability, but it remains a challenge. Herein, we constructed a bio-based Hg²⁺ nano-scavenger via the electrostatic interaction and hydrogen bonding driven supramolecular self-assembly of natural lignosulfonate (LS), chitosan (CTS) and tannin (TA). The intermolecular interaction enabled the formation of a supramolecular nano-network with a high surface area and abundant macro/meso-porosities, which greatly promoted the exposure of adsorption sites and the fast transport of Hg²⁺ from the solution environment to these adsorption sites. Consequently, LS–CTS–TA achieved a maximum adsorption capacity of 95.24 mg g⁻¹ and followed the Langmuir isotherm model with a characteristic pseudo-second-order kinetics during removal of high concentration Hg. Furthermore, such a robust and heterogeneous nano-network structure of LS–CTS–TA exhibited a high removal efficiency for low concentration mercury and good regeneration ability.