Triazine- and Heptazine-Based Porous Organic Polymer Networks for the Efficient Removal of Perfluorooctanoic Acid

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 S BET 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.

Modulating Narrow Bandgap in a Diacetylene Functionalized Woven Covalent Organic Framework as a Visible Light Responsive Photocatalyst

“…The disappearance of the aldehyde group of Cu(PDB) 2 BF 4 at 190 ppm indicates the high polymerization degree of this COF. [ 16,40 ] The acetylenic carbons appear at 70 and 80 ppm, confirming that the functionality of the linkers has not changed during synthesis. (Detailed NMR assignments are provided in Figure S1, Supporting Information.…”

“…Considering the pH dependency of SMX, we also studied the degradation efficiency of SMX at different pH levels (Figure S11, Supporting Information). [ 40 ] In the dark, the adsorption of SMX on the surface of Cu‐PhenBDA‐COF in acidic pH was higher than in neutral or basic pH. This adsorption trend correlates to the different surface charges of the COF, which has a zero‐point charge at pH 5.8.…”

Substitution and Orientation Effects on the Crystallinity and PFAS Adsorption of Olefin-Linked 2D COFs

“…Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are the two most common PFAS forms used and spread in the environment for decades . These types of PFASs have been widely detected in different parts of the environment and even in human blood. − Using solid adsorbents for PFAS removal, especially from water, is one of the most efficient, environmentally friendly, and economically feasible techniques that have been reported. ,− Carbonaceous materials, anion-exchange resins, porous organic and molecular imprinted polymers, minerals, and metal–organic frameworks (MOFs) are the reported adsorbents used for the removal of PFASs from water. ,,− Most of these materials exhibit large specific surface areas with suitable pore sizes and particular functional groups for the enhanced adsorption capacity of PFASs. However, these adsorbents suffer drawbacks such as slow adsorption rate, poor regeneration ability, and structural change at different pH levels.…”

Unusual 3,4-Oxidative Coupling Polymerization on 1,2,5-Trisubstituted Pyrroles for Novel Porous Organic Polymers

“…Porous organic polymers (POPs) have emerged as highly promising materials in the fields of energy and environment over the past decades. − Their exceptional performance on adsorption and separation, − catalysis, − energy storage, and conversion − has made them valuable for applications such as water treatment, − adsorption and conversion of greenhouse gases, − adsorption of metal ions, − and membrane separation. − These capabilities highlight the significant potential of POPs in addressing various challenges in the realms of energy and environmental sustainability. The characters and functions of POPs are tunable through the strategic design of functional monomers as well as polymerization techniques. − …”