Rapid removal of organic micropollutants from water by a porous β-cyclodextrin polymer

Abstract

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.

Dynamic Macromolecular Material Design—The Versatility of Cyclodextrin‐Based Host–Guest Chemistry

“…Recently,p orous b-CD polymers were utilized by Dichtel and co-workers for the removal of micropollutants from water. [170] Thes tudied porous b-CD polymers were obtained by nucleophilic aromatic substitution of tetrafluoroterephthalonitrile and b-CD.Abroad range of organic micropollutants could be absorbed, for example,p esticides, plastic components,a nd pharmaceuticals.T he same group utilized b-CD-grafted cotton fabric for the removal of pollutants. [171] Dai and co-workers reported the formation of porous hyper-cross-linked b-CD polymers,w hich could be utilized for the absorption of small molecules as well as act as catalyst supports.…”

Absorbance based water quality indicators as parameters for treatment process control with respect to organic substance removal

“…The individual equations may be replaced by one general equation (5), which describes the relationship between UV 272 absorbance and UV 254 absorbance in the entire range studied of these indicators, for all types of water y=0.8173x (5) with also very good fit to the linear model (R 2 =0.9976).…”

“…The presence of organic substances in water for human consumption and the possibility of removing organic matter in unit water treatment processes has been the object of studies worldwide for many years [1][2][3][4][5]. Due to possibility of generation of organic substances harmful to human health in unit processes [6][7], especially during the disinfection process, it is necessary to ensure a most effective elimination of organic substances during water treatment.…”

TiO2 immobilised on biopolymer nanofibers for the removal of bisphenol A and diclofenac from water

“…Polymers like chitosan [19], cyclodextrin [20], cellulosic biopolymer [21], alginic acid [22], and guar gum [23] have been extensively studied for this purpose. Biopolymers have also been studied for stabilization of nanoparticles [24] e.g.…”