Sulfonate-Modified Calixarene-Based Porous Organic Polymers for Electrostatic Enhancement and Efficient Rapid Removal of Cationic Dyes in Water

Abstract

The development of fast and efficient adsorbents for removal of low concentration refractory organics in water is significant. In this work, a novel calix[4]arene-based  porous organic polymer CaPy is constructed through Sonogashira-Hagihara cross-coupling polycondensation. The strong polar sulfonate is further anchored onto the polymer skeleton of CaPy and three sulfonate-modified anionic polymers CaPy-S1, CaPy-S2, and CaPy-S3 were obtained and fully characterized. The electrostatic enhanced polymers demonstrated the instant and high-capacity adsorption performance for cationic dyes Rhodamine B (RhB) and methylene blue (MB). The adsorption performances exhibited that the maximum adsorption capacity of CaPy-S1 toward RhB and MB are 2648 and 1307 mg g -1 respectively, and the maximum adsorption capacity toward RhB was the highest reported case among current synthetic adsorbents. The pseudo-second-order rate constant of CaPy-S2 toward MB was 4.3220 g mg -1 min -1 indicating one of the fastest adsorption speeds. The CaPy-S1 could still remove >99% RhB from aqueous solution after seven adsorption cycles, showing that it may have the potential for application in the deep treatment of wastewater. This work provided an effective approach for improving adsorption performance by post-modification.

Keywords: Porous organic polymers, Post-synthetic modification, Dyes adsorption, Water treatment, Sulfonic acid groups