What is the story of beta-cyclodextrin polymer?
Polar organic molecules, such as bisphenol A, are major sources of water pollution and hence filter materials are designed intentionally to filter out such organic molecules. It is of greater research interest to figure out how to remove polar organic molecules as compared to non-polar organic molecules from water because polar organic molecules dissolve to a certain extent in water. Hence, a simple filtration system to remove solid from liquid does not work. More science has to be involved in designing a filtration system to remove polar organic molecules from water. A recent study has found that beta-cyclodextrin polymer can actually filter out polar organic molecules much more effectively and faster as compared to current water filters, e.g. activated charcoal. Not only does beta-cyclodextrin polymer work better, it is arguably cheaper to manufacture as compared to current technologies. As of now, the cost of making beta-cyclodextrin polymers is half of what is required for making activated charcoal. This means greater accessibility to good water filtration systems.
How does beta-cyclodextrin polymer work?
beta-cyclodextrin is made up of 7 of the sugar rings in a cyclic arrangement. The sugar ring itself consists of 6 carbon atoms. Even though the structure might seem complicated, the synthesis is quite straightforward. By treating starch with certain enzymes, beta-cyclodextrin can be produced with relative ease.
What the researchers did in the water filter study was to link each of the 7 sugar rings in beta-cyclodextrin by an aromatic compound, tetrafluoroterephthalonitrile (structure shown in red in the 1st diagram). By doing so, the scientists ensure that the cyclic structure is both rigid and porous. It is important that the structure is porous so as to maximize absorbent performance. After all, what is the point of a water filtration system if the water can’t pass through?
Where are we going with beta-cyclodextrin polymer?
Will beta-cyclodextrin polymer work or will it just remain as a novel idea? Besides effectiveness and cost of production, another really important factor here is safety. It is important that we are sure that the water that passes through the beta-cyclodextrin polymer is safe for drinking – not just for the moment but over time as well. What makes beta-cyclodextrin very promising is the fact that it is made up of sugar subunits and sugar is definitely safe for consumption. However, the same cannot be said about tetrafluoroterephthalonitrile. The chemical tetrafluoroterephthalonitrile itself is poisonous and should not be ingested. Will the beta-cylodextrin polymer degrade over time after prolonged usage? Will tetrafluoroterephthalonitrile find its way to the filtered water? Further research will tell us.