Bioinspired, Carbohydrate-Containing Polymers Efficiently and Reversibly Sequester Heavy Metals.

Abstract

Water scarcity and heavy metal pollution are significant challenges in today's industrialized world. Conventional heavy metal remediation methods are often inefficient and energy-intensive, and produce chemical sludge. To address these issues, we developed a bioinspired, carbohydrate-containing polymer system for efficient and selective heavy metal removal. Using ring opening metathesis polymerization, we synthesized polymers bearing amphiphilic glucuronate side chains capable of selectively binding heavy metal cations in mixed media. In samples containing high concentrations of heavy metals (>550 ppb), these polymers rapidly form a filterable precipitate upon metal capture, reducing the concentration of cation to <1.5 ppb within 3 min, as measured by inductively coupled plasma mass spectrometry. This system effectively removes cadmium ions from highly contaminated solutions to levels below the Agency for Toxic Substances and Disease Registry limit for Cd2+ in drinking water and selectively removes both Cd2+ and Pb2+ from lake water spiked with trace amounts of metal. Acidification triggers protonation of the glucuronate groups, releasing the heavy metals and resolubilizing the polymer. This capture-and-release process can be repeated over multiple cycles without loss of binding capacity. As such, this study introduces a novel class of recyclable materials with pH-responsive properties, offering potential for applications in water remediation and beyond.