Triazine- and Heptazine-Based Porous Organic Polymer Networks for the Efficient Removal of Perfluorooctanoic Acid
Dana Abdullatif, Ahmadreza Khosropour, Anahita Khojastegi, Imann Mosleh, Leila Khazdooz, Amin Zarei, Alireza Abbaspourrad
Abstract
The presence of perfluorooctanoic acid, a perfluoralkyl substance, in water sources has raised health concerns due to its toxicity. Finding effective adsorbents is essential to ensure healthy sources of water for consumption. In this study, a heptazine-based polymer network (Py-HPOP) was synthesized using a one-pot nucleophilic substitution of 2,5,8-trichloro-s-heptazine (TCH) with 4,4′,4″,4‴-(pyrene-1,3,6,8-tetrayl) tetraaniline (Py-TA). For comparison, a triazine-based polymeric network (Py-TPOP) was also prepared using 2,4,6-trichloro-1,3,5-triazine under similar conditions. Both polymers were used to treat aqueous solutions containing 1 mg/L PFOA. Py-TPOP exhibited superior adsorption capacity (98.4% PFOA removal) relative to Py-HPOP (80.8% PFOA removal) despite Py-HPOP’s higher Brunauer–Emmett–Teller (BET) surface area SBET at 205 m2 g–1. The effect of electrostatic interactions was also observed as a critical factor for PFOA adsorption as demonstrated by the change in PFOA adsorption by both polymers under basic, neutral, and acidic conditions. This investigation illustrates a facile synthesis of amorphous covalent frameworks as strong, competitive adsorbents for PFOA removal from water.