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An alternative material to activated carbon for water remediation is reported: a porous material based on crosslinked cyclodextrins that is better than activated carbons at adsorbing a range of pharmaceuticals, pesticides and other anthropogenic pollutants. Near-instant removal of organic micropollutants from water Water purification and remediation is often carried out using various forms of activated carbon; it is inexpensive, but only partially removes many organic pollutants. However, regenerating activated carbon for reuse is energy intensive, requiring high temperatures, and performance decreases upon recycling. Now William Dichtel, Damian Helbling and colleagues have developed an alternative to activated carbon for water remediation: a high-surface-area, mesoporous polymer of [beta]-cyclodextrin. Not only does the material outperform activated carbons at adsorbing a range of pharmaceuticals, pesticides and other pollutants, but it is easily regenerated by washing at room temperature. 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.sup.1,2,3,4,5. 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).sup.6,7 and poor removal of many relatively hydrophilic micropollutants.sup.8. Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500-900 degrees Celsius) and does not fully restore performance.sup.9,10. Insoluble polymers of [beta]-cyclodextrin, an inexpensive, sustainably produced macrocycle of glucose, are likewise of interest for removing micropollutants from water by means of adsorption.sup.11. [beta]-cyclodextrin is known to encapsulate pollutants to form well-defined host-guest complexes, but until now cross-linked [beta]-cyclodextrin polymers have had low surface areas and poor removal performance compared to conventional activated carbons.sup.11,12,13. Here we crosslink [beta]-cyclodextrin with rigid aromatic groups, providing a high-surface-area, mesoporous polymer of [beta]-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 [beta]-cyclodextrin adsorbent materials.sup.7,8,11,12,13. 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., Author(s): Alaaeddin Alsbaiee [sup.1] , Brian J. Smith [sup.1] , Leilei Xiao [sup.1] , Yuhan Ling [sup.2] , Damian E. Helbling [sup.2] , William R. Dichtel [sup.1] Author Affiliations: (1) [...]

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 (1-5). 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) (6, 7) and poor removal of many relatively hydrophilic micropollutants (8). Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500-900 degrees Celsius) and does not fully restore performance (9, 10). 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 (11). 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 (11-13). 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 P-cyclodextrin adsorbent materials (7, 8, 11-13). 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., Porous β-CD-containing polymers (P-CDPs) were derived from nucleophilic aromatic substitution of hydroxyl groups of (β-CD by tetrafluoroterephthalonitrile (1). Although 1 has been copolymerized with bifunctional catechols previously (14), its reaction [...]

Highlights: [•] A novel core–shell magnetic nanocomposite γ-Fe2O3@Cu/Al-MCM-41 was synthesized. [•] Cu in higher amounts results in less order structure of mesoporous silica. [•] Al incorporation helps to retain a high surface area and ordered mesopores. [•] The catalyst displayed efficient Fenton-like catalytic activity for phenol removal. [Copyright &y& Elsevier]

Organic micropollutants (MPs) are anthropogenic substances that contaminate water resources at trace concentrations. Many MPs, including per- and polyfluorinated alkyl substances (PFASs), have come under increased scrutiny because of their environmental persistence and association with various health problems. A β-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, including anionic PFASs. To address this shortcoming, we reduced the nitrile groups in TFN-CDP to primary amines, which reverses its affinity towards charged MPs. TFN-CDP exhibits adsorption distribution coefficients (log K D values) of 2-3 for cationic MPs and -0.5-1.5 for anionic MPs, whereas the reduced TFN-CDP exhibits log K D values of -0.5-1.5 for cationic MPs and 2-4 for anionic MPs, with especially high affinity towards anionic PFASs. Kinetic studies of the removal of 10 anionic PFASs at environmentally relevant concentrations showed 80-98 % removal 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 a single polymerization and the promise of novel adsorbents constructed from molecular receptors., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)