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

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.