High-Affinity Detection and Capture of Heavy Metal Contaminants using Block Polymer Composite Membranes Yizhou Zhang Joseph R. Vallin Jugal Kishore Sahoo Feng Gao Bryan W. Boudouris Matthew J. Webber William A. Phillip 10.1021/acscentsci.8b00690.s001 https://acs.figshare.com/articles/journal_contribution/High-Affinity_Detection_and_Capture_of_Heavy_Metal_Contaminants_using_Block_Polymer_Composite_Membranes/7429856 Adsorptive membranes offer one possible solution to the challenge of removing and recovering heavy metal ion contaminants and resources from water supplies. However, current membrane-based sorbents suffer from low binding affinities, leading to issues when contaminants are present at trace concentrations or when the source waters have a high concentration of background electrolytes that compete for open binding sites. Here, these challenges are addressed in the design of a highly permeable (i.e., permeability of ∼2.8 × 10<sup>4</sup> L m<sup>–2</sup> h<sup>–1</sup> bar<sup>–1</sup>) sorbent platform based on polysulfone and polystyrene-<i>b</i>-poly­(acrylic acid) composite membranes. The membranes possess a fully interconnected network of poly­(acrylic acid)-lined pores, which enables the surface chemistry to be tailored through sequential attachment of polyethylenimine brushes and metal-binding terpyridine ligands. The polyethylenimine brushes increase the saturation capacity, while the addition of terpyridine enables high-affinity binding to a diversity of transition metal ions (i.e., Pd<sup>2+</sup>, Cd<sup>2+</sup>, Hg<sup>2+</sup>, Pb<sup>2+</sup>, Zn<sup>2+</sup>, Co<sup>2+</sup>, Ni<sup>2+</sup>, Fe<sup>2+</sup>, Nd<sup>3+</sup>, and Sm<sup>3+</sup>). This platform removes these metal contaminants from solution with a sorbent capacity of 1.2 mmol g<sup>–1</sup> [based on Cu<sup>2+</sup> uptake]. The metal capture performance of the functionalized membranes persists in spite of high concentrations of competitive ions, with >99% removal of Pb<sup>2+</sup> and Cd<sup>2+</sup> ions from artificial groundwater and seawater solutions. Breakthrough experiments demonstrate the efficient purification of feed solutions containing multiple heavy metal ions under dynamic flow conditions. Finally, fluorescence quenching of the terpyridine moiety upon metal ion complexation offers an in situ probe to monitor the extent of sorbent saturation with a Stern–Volmer association constant of 2.9 × 10<sup>4</sup> L mol<sup>–1</sup>. The permeability, capacity, and affinity of these membranes, with high-density display of a metal-binding ligand, offer a chemically tailored platform to address the challenges that arise in ensuring clean water. 2018-12-06 14:50:50 binding affinities feed solutions metal ions  under membrane-based sorbents High-Affinity Detection saturation capacity metal ion complexation surface chemistry sorbent saturation sorbent capacity fluorescence quenching binding sites metal-binding terpyridine ligands polyethylenimine brushes breakthrough experiments high-affinity binding trace concentrations metal-binding ligand flow conditions sequential attachment transition metal ions water supplies Block Polymer Composite Membranes Adsorptive membranes offer metal ion contaminants challenge terpyridine moiety functionalized membranes background electrolytes seawater solutions source waters polyethylenimine brushes increase sorbent platform Heavy Metal Contaminants metal contaminants