Porous organic polymers incorporating BODIPY moieties for efficient removal of organic dyes from aqueous solutions

Abstract

Developing efficient adsorbents for the removal of organic dyes from aqueous solutions is highly desirable due to the severe environmental and human safety concerns associated with dye-contaminated wastewater. Herein, we report two porous organic polymers (BIPOPs) incorporating BODIPY moieties via the Sonogashira reaction between dibrominated BODIPY and alkynyl-containing aromatics. This incorporation of BODIPY moieties into a porous framework bestows the materials with efficient adsorption functionality, resulting in a significantly enhanced capacity for organic dye adsorption compared to a BODIPY-free porous organic polymer. The developed BIPOPs exhibit remarkable efficacy in capturing various dyes, with a maximum adsorption capacity of 2207 mg g⁻¹ (for rhodamine B adsorbed by BIPOP-1), surpassing or matching those of most known dye adsorbents. The adsorption equilibrium data fit better to a Sips isotherm model (R² > 0.99) in comparison with Langmuir and Freundlich isotherm models, while the adsorption kinetics are well described by the pesudo-second-order kinetic model (R² = 0.99999 for rhodamine B); these results suggest that the adsorption process is predominantly governed by chemisorption. Notably, the adsorbent displays sustained high adsorption capacity even after five cycles of recycling. Mechanistic investigation reveals that the high adsorption capacity of rhodamine B is a direct consequence of the synergistic integration of π–π interactions, hydrogen bonding interactions, and electrostatic interactions, predominantly facilitated by BODIPY units with dyes, alongside the porous structures. This underscores the significance of BODIPY units in the capture of rhodamine B. These findings establish BODIPY-incorporating porous networks as promising candidates for the efficient removal of dyes from aqueous media. This simple strategy can be extended to conceive and fabricate more BODIPY-based dye adsorbents.