Pillar[5]arene-based Polymer Network for Efficiently Removing Perfluorooctanoic Acid through Synergistic Binding Interactions.

Perfluorooctanoic acid (PFOA) is currently one of the most important chemicals posing environmental risks, and there is an urgent need to find methods to efficiently remove PFOA from environmental media. Here, two decaamino-pillar[5]arene-based fluorine-rich polymer networks, called FA2P-P and FA6P-P, were constructed using a convenient method. FA6P-P had an excellent ability to take up PFOA, and had a capacity of 1423 (mg PFOA) (g FA6P-P), which is the second highest adsorption capacity reported for any PFOA sorbent. FA6P-P removed >99 % of the PFOA from a solution and decreased the PFOA concentration from 1000 μg L in 5 min at an exceedingly low adsorbent loading of 0.7 mg L, giving a final PFOA concentration <4 ng L, which is lower than the most recent enforceable maximum concentration set by the United States Environmental Protection Agency. A high rate constant (k) of 55.8 g mg h was observed. Pillar[5]arene gives the material hydrophobic properties and also amino sites and hydrophobic chains, which are synergistic PFOA binding sites. The polymer was very stable and readily regenerated. The results indicated that pillar[5]arene-based porous organic polymer sorbents are excellent candidates for capturing PFOA.