Record high cationic dye separation performance for water sanitation using a neutral coordination framework

Abstract

It is of significant importance to capture and separate organic pollutants from water sources to combat the growing environmental problems. Advanced sorbent materials with rapid, high-capacity and selective sorption performances are desirable. Herein, a coordination framework (LIFM-WZ-4) containing micro-channels with a large percentage (70%) of “naked” nitrogens is reported, affording donor–acceptor (D–A) interaction abilities with specific selectivity for electron-deficient CO₂ gases or cationic dyes. Especially, although with a neutral network, exclusively selective, fast and large adsorption capacities for cationic dyes from aqueous solutions were achieved, with a record high value of 1492.0 mg g⁻¹ for MB⁺ among the materials reported to date. The underlying adsorption mechanism was probed from both kinetic and thermodynamic considerations, revealing a pseudo-second-order kinetic model and a D–A inducing chemisorption process accounting for the unique selectivity. The saturated sorbent can then be readily recovered by dye release in CH₃CN. This easy recyclability provides potential for practical applications in water sanitation and dye separation.