β-Cyclodextrin Polymers on Microcrystalline Cellulose as a Granular Media for Organic Micropollutant Removal from Water

Abstract

Organic contaminants at low concentrations, known as micropollutants, are a growing threat to water resources. Implementing novel adsorbents capable of removing micropollutants during packed-bed adsorption is desirable for rapid water purification and other efficient separations. We previously developed porous polymers based on cyclodextrins that demonstrated rapid uptake and high affinity for dozens of micropollutants (MPs) in batch experiments. However, these polymers are typically produced as powders with irregular particle size distributions in the range of tens of micrometers. In this powdered form, cyclodextrin polymers cannot be implemented in packed-bed adsorption processes because the variable particle sizes yield insufficient porosity packing and consequently generate high back-pressure. Here we demonstrate a facile approach to remove micropollutants from water in a continuous manner by polymerizing cyclodextrin polymer networks onto cellulose microcrystals to provide a core/shell structure. Batch adsorption experiments demonstrate rapid pollutant uptake and high accessibility of the cyclodextrins on the adsorbent. Similarly, column experiments demonstrate rapid uptake of a model pollutant with minimal back-pressure, demonstrating potential for use in packed-bed adsorption processes. Furthermore, the pollutant-saturated columns were regenerated using methanol and reused three times with almost no change in performance. Column experiments conducted with a mixture of 15 micropollutants at environmentally relevant concentrations demonstrated that removal was determined by the affinity of each micropollutant for cyclodextrin polymers. The cyclodextrin polymer grafted onto cellulose microcrystals is more resistant to both anaerobic and aerobic biodegradation as compared to cyclodextrins and unmodified cellulose crystals, presumably due to the aromatic cross-linkers, demonstrating persistence. Collectively, the findings from this study demonstrate a general strategy to incorporate novel cyclodextrin adsorbents onto cellulose substrates to enable rapid and efficient removal of micropollutants during packed-bed adsorption as well as their promising long-term stability and regeneration capabilities.

Remarkably efficient removal of toxic bromate from drinking water with a porphyrin–viologen covalent organic framework

“…S25 †). Because remediation of ground and drinking water typically involves packed-bed columns, 36 we also conducted adsorption and regeneration experiments in the continuous ow setup (details in the ESI, Fig. S26 †).…”

Emerging Functional Porous Polymeric and Carbonaceous Materials for Environmental Treatment and Energy Storage

“…Implanting these functional components into porous polymers have promoted a new trend of porous material design. [61,[177][178][179][180][181] Dichtel and co-workers reported a rigid aromatic group crosslinked β-CD (P-CDPs) by nucleophilic aromatic substitution of hydroxyl groups of β-CD and tetrafluoroterephthalonitrile (Figure 4a). [56] Both the high surface area (263 m 2 g −1 ) and special contaminants affinity of β-CD enable the rapid removal of organic contaminants from water.…”

“…β‐Cyclodextrin (β‐CD) and other kinds of macrocycles (e.g., pillararenes, calixarenes) possess unique host–guest interaction and well‐defined intrinsic porosities. Implanting these functional components into porous polymers have promoted a new trend of porous material design . Dichtel and co‐workers reported a rigid aromatic group crosslinked β‐CD (P‐CDPs) by nucleophilic aromatic substitution of hydroxyl groups of β‐CD and tetrafluoroterephthalonitrile ( Figure a) .…”

Cellulose-Cyclodextrin Co-Polymer for the Removal of Cyanotoxins on Water Sources

“…The main operational differences between these two approaches are temperature and grafting medium. In particular, epichlorohydrin modification occurs in water at a mild temperature of 65 °C, while the esterification Grafting of cellulose with cyclodextrin has been demonstrated by different chemical methodologies, most of them based on the generation of a covalent bond between the hydroxyl groups of both components using linkers such as epichlorohydrin to form ether bonds [19][20][21][22][23][24]; or with poly(carboxylic) acids to form ester bonds [25][26][27]; however other possibilities with organic solvents, such as dimethyl sulfoxide, have also been achieved successfully [28]. The main operational differences between these Polymers 2019, 11, 2075 3 of 19 two approaches are temperature and grafting medium.…”