Episode 4: Toxic bromate removed from drinking water

Sophia Chen of MRS Bulletin interviews Tina Škorjanc, a PhD student at New York University in Abu Dhabi in the United Arab Emirates, and her professor Dinesh Shetty at Khalifa University, Abu Dhabi, about porphyrin–based covalent organic frameworks they developed that remove the toxic substance bromate from drinking water. Read the article in Chemical Science.
Transcript
SOPHIA CHEN: Drinking water: Whether it’s out of the tap, the refrigerator, or a bottle, we expect it to be clean. Water treatment plants oblige, with a complicated sequence of filtration and purification processes. During a last purification step, the treatment plants add ozone to disinfect the water. The ozone removes odor, color, and taste, and it does this all quickly. But a potential dangerous side effect of the ozone turns harmless, naturally occurring bromine ions in the water into the toxic substance bromate. Tina Škorjanc, a PhD student at New York University in Abu Dhabi in the United Arab Emirates, is working on methods to remove bromate from drinking water.

TINA ŠKORJANC: It has been linked to a whole series of health conditions in humans and has been linked to cancer, which is why we think it is important to remove it.

SC: Škorjanc’s team has developed a new material that can remove bromate much faster than any other existing method.  

TS: We really outperformed other materials which were of different classes. This list included inorganic materials, activated carbons, metal organic frameworks, a couple of other polymers, our rates really surpassed the ones reported for these other materials. 

SC: Dinesh Shetty, Škorjanc’s colleague and a professor at Khalifa University, also in Abu Dhabi, says that their group is the first to create a covalent organic framework specifically for bromate removal. 

DINESH SHETTY: Compared to normal polymers, covalent organic frameworks are ordered structures. It has defined structure, you can study exactly what is happening within this framework, you know exactly where bromate is going, how it is interacting with this material. 

SC: Bromate likes to stick to this material, because the material is positively charged and electrostatically attracts the negatively charged bromate.  

DS: If you think about other covalent organic frameworks, you have to synthesize COF first and then introduce positive charges. We are reducing one step, synthetically, if you think about it. 

TS: We can do our bromate adsorption experiment, take that material which has bromate on its surface and in its pores, remove those molecules by simple treatment with sodium hydroxide followed by neutralization, and we can reuse that same batch for bromate adsorption again. What’s important in the second step is the efficiency doesn’t drop. We’re still able to remove the same amount of bromate that was removed in the first cycle. 

SC: It’s still unclear whether this material will be economically viable for adoption by existing water treatment plants. But their work opens the door to further development of covalent organic frameworks that remove bromate. And in the meantime, their team is working to figure out how to scale up their experiment and eventually test it in a water research center in Abu Dhabi. 

DS: We are dealing with something which can directly impact society. If our plan works, if it becomes water purification material for bromate removal, we are helping millions all around the world. That’s real motivation for us. 

SC: My name is Sophia Chen from the Materials Research Society. Follow us on twitter, @MRSBulletin. Don’t miss the next episode of MRS Bulletin Materials News – subscribe now. Thank you for listening.