Cationic Surfactant‐Modified Covalent Organic Frameworks for Nitrate Removal from Aqueous Solution: Synthesis by Free‐Radical Polymerization

Abstract Development of efficient adsorbents for nitrate removal is vital for tackling increasing nitrate contamination. We report a free‐radical polymerization strategy to prepare a cationic surfactant‐modified covalent organic framework (DhaTab‐S) for removing nitrate ions from aqueous solution. DhaTab‐S was prepared by grafting a cationic surfactant diallyldimethylammonium chloride solution on vinyl‐containing COF (DhaTab‐V). The adsorption capacity for nitrate was pH‐dependent with the maximum at pH 6, and the adsorption process was largely influenced by ionic strength. The adsorption equilibrium for nitrate on DhaTab‐S was reached within 40 minutes and followed pseudo‐second‐order kinetics. DhaTab‐S showed a nitrate adsorption capacity of 108.8 mg g −1 , which is about 15 times that of COF before surfactant modification. The large adsorption capacity makes DhaTab‐S a promising candidate for nitrate removal from aqueous media.