The global occurrence in water resources of organic micropollutants, such as pesticides and pharmaceuticals, has raised concerns about potential negative effects on aquatic ecosystems and human health. Activated carbons are the most widespread adsorbent materials used to remove organic pollutants from water but they have several deficiencies, including slow pollutant uptake (of the order of hours) and poor removal of many relatively hydrophilic micropollutants. Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500-900 degrees Celsius) and does not fully restore performance. Insoluble polymers of β-cyclodextrin, an inexpensive, sustainably produced macrocycle of glucose, are likewise of interest for removing micropollutants from water by means of adsorption. β-cyclodextrin is known to encapsulate pollutants to form well-defined host-guest complexes, but until now cross-linked β-cyclodextrin polymers have had low surface areas and poor removal performance compared to conventional activated carbons. Here we crosslink β-cyclodextrin with rigid aromatic groups, providing a high-surface-area, mesoporous polymer of β-cyclodextrin. It rapidly sequesters a variety of organic micropollutants with adsorption rate constants 15 to 200 times greater than those of activated carbons and non-porous β-cyclodextrin adsorbent materials. In addition, the polymer can be regenerated several times using a mild washing procedure with no loss in performance. Finally, the polymer outperformed a leading activated carbon for the rapid removal of a complex mixture of organic micropollutants at environmentally relevant concentrations. These findings demonstrate the promise of porous cyclodextrin-based polymers for rapid, flow-through water treatment.

Per- and poly fluorinated alkyl substances (PFASs), notably perfluorooctanoic acid (PFOA), contaminate many ground and surface waters and are environmentally persistent. The performance limitations of existing remediation methods motivate efforts to develop effective adsorbents. Here we report a β-cyclodextrin (β-CD)-based polymer network with higher affinity for PFOA compared to powdered activated carbon, along with comparable capacity and kinetics. The β-CD polymer reduces PFOA concentrations from 1 μg L to <10 ng L, at least 7 times lower than the 2016 U.S. EPA advisory level (70 ng L), and was regenerated and reused multiple times by washing with MeOH. The performance of the polymer is unaffected by humic acid, a component of natural organic matter that fouls activated carbons. These results are promising for treating PFOA-contaminated water and demonstrate the versatility of β-CD-based adsorbents.

Per-and polyfluorinated alkyl substances (PFAS), such as perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS), and ammonium perfluoro-2-propoxypropionate (GenX), contaminate ground and surface waters throughout the world. The cost and performance limitations of current PFAS removal technologies motivate efforts to develop selective and high-affinity adsorbents. Covalent organic frameworks (COFs) are unexplored yet promising adsorbents because of their high surface area and tunable pore sizes. Here we show that imine-linked two-dimensional (2D) COFs bearing primary amines adsorb GenX rapidly at environmentally relevant concentrations. COFs with partial amine incorporation showed the highest capacity and fastest removal, suggesting that the synergistic combination of the polar group and hydrophobic surfaces are responsible for GenX binding. A COF with 28% amine loading also removed more than 90% of 12 out of 13 PFAS. These results demonstrate the promise of COFs for PFAS removal and suggest design criteria for maximizing adsorbent performance.

The cost-effective and energy-efficient removal of organic micropollutants (MPs) from water and wastewater is challenging. The objective of this research was to evaluate the performance of porous β-cyclodextrin polymers (P-CDP) as adsorbents of MPs in aquatic matrixes. Adsorption kinetics and MP removal were measured in batch and flow-through experiments for a mixture of 83 MPs at environmentally relevant concentrations (1 μg L) and across gradients of pH, ionic strength, and natural organic matter (NOM) concentrations. Performance was benchmarked against a coconut-shell activated carbon (CCAC). Data reveal pseudo-second-order rate constants for most MPs ranging between 1.5 and 40 g mg min for CCAC and 30 and 40000 g mg min for P-CDP. The extent of MP removal demonstrates slower but more uniform uptake on CCAC and faster but more selective uptake on P-CDP. Increasing ionic strength and the presence of NOM had a negative effect on the adsorption of MPs to CCAC but had almost no effect on adsorption of MPs to P-CDP. P-CDP performed particularly well for positively charged MPs and neutral or negatively charged MPs with McGowan volumes greater than 1.7 (cm mol)/100. These data highlight advantages of P-CDP adsorbents relevant to MP removal during water and wastewater treatment.

Organic micropollutants (MPs) are anthropogenic substances that contaminate water resources at trace concentrations.M any MPs,i ncluding per-a nd polyfluorinated alkyl substances (PFASs), have come under increased scrutiny because of their environmental persistence and association with various health problems.Ab-cyclodextrin polymer linked with tetrafluoroterephthalonitrile (TFN-CDP) has high affinity for cationic and many neutral MPs from contaminated water because of anionic groups incorporated during the polymerization. But TFN-CDP does not bind many anionic MPs strongly,i ncluding anionic PFASs.T oa ddress this shortcoming,w er educed the nitrile groups in TFN-CDP to primary amines,w hich reverses its affinity towards charged MPs.T FN-CDP exhibits adsorption distribution coefficients (log K D values) of 2-3 for cationic MPs and À0.5-1.5 for anionic MPs,w hereas the reduced TFN-CDP exhibits log K D values of À0.5-1.5 for cationic MPs and 2-4 for anionic MPs, with especially high affinity towards anionic PFASs.K inetic studies of the removal of 10 anionic PFASs at environmentally relevant concentrations showed 80-98 %r emoval of all contaminants after 30 min and was superior to commercial granular activated carbon. These findings demonstrate the scope and tunability of CD-based adsorbents derived from as ingle polymerization and the promise of novel adsorbents constructed from molecular receptors.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.