Robust Sustainable Biomass Fluorescent Wood for Heavy Metal Removal and Solar Water Purification.

Abstract

Heavy metal contamination in aquatic environments represents a severe threat to global ecological security. While conventional method such as fluorescent probes, have been investigated for detection purposes, their real-world deployment remains hampered by inherent drawbacks such as limited sensitivity and poor reusability. Herein, we introduce a "living" composite material, fabricated by incorporating ratiometric fluorescent metal-organic frameworks (MOFs) into the natural microchannels of wood, setting a new benchmark for environmental remediation. Specifically, ZIF-8-hybridized fluorescent carbon dots (DRZ-CDs) were firmly immobilized onto a delignified wood (DW) matrix through electrostatic interactions and chelation, resulting in a bifunctional material (DRZ-CDs-DW). The composite exhibits good performance, with an exceptional Cu²⁺ adsorption capacity of 298.72 mg/g and a low detection limit of 2.3 nM. Going beyond high removal efficiency, we further demonstrate a transformative "waste-to-resource" strategy, in which the exhausted adsorbent (DRZ-CDs-DW+Cu²⁺) is transformed via in situ sulfidation into a photothermal evaporator (DRZ-CDs-DW-CuS). The resulting system achieves an evaporation rate of 3.54 kg·m^-2·h^-1, generating purified water, and is suitable for practical uses such as plant irrigation. In summary, by effectively merging fluorescent carbon dot (CDs) functionalization, wood structural engineering, and solar-driven interfacial evaporation, this work realizes a synergistic combination of environmental cleanup and resource upcycling.