Heather Hartmann

Development of a Passive Sampler for Detecting PFAS Using Polymer-Organosilica Hybrid Adsorbents

April 5, 2021   /  

Name: Heather Hartmann
Majors: Chemistry, Spanish
Advisors: Dr. Paul Edmiston, Dr. Karl Feierabend

Per-and polyfluoroalkyl substances (PFASs) are environmental contaminants of emerging concern due to their persistence and evidence of adverse health impacts. Environmental monitoring to measure PFAS is of high need to assess water quality and to understand the fate and transport of PFAS. Passive samplers offer advantages in efficiency and cost compared to traditional grab sampling. Swellable organically modified silica modified with crosslinked polyethyleneimine (PEI-SOMS), a weak ion exchange polymer was used in the passive sampling devices. Copper (II) ions were bound to the resin and increase the valency to enhance adsorption of short chain PFAS. Experiments measuring adsorption capture versus time showed the responseto be an equilibrium uptake for all PFAS with short chain carboxylic acids coming to equilibrium after 6 days. Other compounds such as longer chain carboxylates and the sulfonic acids require longer to come to equilibrium (greater than 12 days). The sampling rate was linear for concentrations from 10-50,000 ng/L (3 days sampling time) with an open mesh design using copper PEI-SOMS. The samples showed a high uptake rate, about 5-10 times faster, compared to other passive samplers attributed to the open meshhousing and expanded pores of the adsorbent. I really enjoyed getting to learn more about passive sampling and more about chemistry techniques that I can use beyond Wooster. Future work can also be done to develop a device that homeowners can potentially use to detect PFAS in their own water.

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Heather will be online to field comments on April 16:
10am-noon EDT (Asia: late evening, PST: 6-8am, Africa/Europe: late afternoon)

33 thoughts on “Development of a Passive Sampler for Detecting PFAS Using Polymer-Organosilica Hybrid Adsorbents”

  1. Great work Heather!
    Who do you think will use the passive samplers? Where could the samplers be best used for environmental monitoring?

    1. Hi Doctor Edmiston,
      I think that as the EPA increase its limits on PFAS compounds that can be found in our waterways, that more companies and state or local governments will turn to using these devices to detect PFAS in their waterways. It additionally can be used at air force bases or water treatment plants to detect what is being leached into our groundwater or what is already present in our groundwater. Subsequent iterations of these samplers could also be used by homeowners to detect PFAS in their own home at a low cost compared to traditional grab sampling. These samplers would be best used for environmental monitoring in groundwater wells or narrow bore wells as these devices do not require membranes for sampling and unlike other passive samplers currently in use like POCIS, do not require a large amount of space for environmental monitoring.

  2. This is really great work and so important. I can see that having a way to test water would be so important. I’m wondering if you had discussions about development of a filter (kind of like a brita filter) to get rid of PFAS in water for consumption or if you think this is a logical future step?

    1. Hi Vicki,
      Interesting question! So the goal of this project was to develop a passive sampling device that can be used for environmental monitoring since PFAS has so many adverse health effects. The next logical steps for this project is to then develop passive samplers that could be commercially available for homeowners to use to detect PFAS in their own drinking water or for water treatment plants to use to monitor the levels of PFAS at these plants. However, in regards to removal of PFAS, previous projects have explored removal of PFAS using similar material, Swellable Organically Modified Silica (SOMS). Polymer modified SOMS did show success in being able to remove PFAS from drinking water. However, most water treatment plants currently use Granular Activated Carbon (GAC) (also what is commonly found in most water filters) as a removal method for PFAS, which has adequate adsorption for PFOA and PFOS.

  3. Thanks for sharing your research. Well done! When you’re making PEI-SOMS, am I correct in thinking that PEI is an adjunct that gets trapped inside the polysiloxane matrix (as opposed to the formation of covalent bonds between BTEB and PEI)?

    1. Hi Bonvallet,
      Yes it is my understanding that the polymer is encapsulated in the pores, but PEI was cross-linked within the pores of SOMS which unlike other polymer SOMS does not allow for leaching.

  4. Hi Heather! Thanks for the video, it helped break it down for me as someone who isn’t necessarily science-minded. I’m going to be a homeowner at some point so understanding more about water, water quality, and how that impacts health is really helpful!

    What made you decide to do your IS on this topic?

    1. Hi Lauren,
      It definitely can get complicated! I decided to do this for my Chemistry IS because I had been working with PFAS for the past two years and I really enjoyed learning about this carcinogen and I wanted to work on a project that will help more people be able to detect and environmentally monitor PFAS in our waterways. I had in the past done traditional grab sampling in Ghana and knew how time consuming it is to do grab sampling, which is part of the reason why I wanted to work on developing an easier way to do environmental monitoring.

      1. That’s really important work and I’m so glad you are furthering research on it!

        Congratulations on finishing two very different research topics!!!

  5. Nice job, Heather! Is there a reason current samplers are not as good at detecting short chains?

    1. Hi Doctor Morris,
      It has to do with the adsorbent that is being used and the competition that has been observed in multiple PFAS solutions. The shorter chain PFAS like PFBA rely on ionic interactions between the head group and the adsorbent while the longer chain PFAS rely on ionic interactions of the head group and the hydrophobic interactions between the carbon fluorine chain. At longer adsorption times, it has been noted that the longer chains are better able to be detected which potentially has to do to the competition between the longer chain and shorter chain compounds competing for binding on the adsorbent. Additionally, at longer adsorption times the binding sites may already be full of PFAS compounds then favoring binding through hydrophobic interactions instead of ionic interactions leading to less accurate adsorption of shorter chain compounds than what is present in the water.

  6. Nice work Heather! What aspects of the lab work have you most enjoyed and has work on this project shaped the types of research you hope to pursue in graduate school?

    1. Hi Doctor Sobeck,
      Thank you! I have enjoyed working the most with the LC-MS/MS which is why I decided to go to graduate school for more mass spec work. I also have enjoyed working in lab and being able to get my own work system down where I can run experiments by myself. However, after working with PFAS and doing environmental chemistry work for the past 3 years, I have decided to adventure outside of this field and do more biomedical research for graduate school.

  7. Hi Heather! Congrats on finishing both of your ISes! For this project, what would you consider cost-effective? Does it just mean that the average household could afford to purchase a test periodically to test their water quality?

    1. Hi Riley,
      Cost-effective would be considered a device that would be cheaper to use than traditional grab sampling and other passive samplers on the market. However, there are other factors that go into cost-effective like time and accessibility of use for environmental monitoring. For the average household, cost-effective would be a passive sampler device that could be periodically used to test water, but for environmental monitoring in the environment or water treatment plants it would mean cheaper and easier to use than current samplers in use and grab sampling.

  8. Hello Heather,

    Very impressive work. Is there a high profile advocate raising the level of awareness of PFAS, similar to what Bill Gates is attempting to do with his climate change book?

    1. Hi Kenyon,
      As far as I know, there is not and under the Trump administration there had been rollbacks in the guidelines for PFAS. However, under the Biden administration environmental monitoring for carcinogens like PFAS might become more relevant as more and as more people are becoming aware of the dangers of PFAS in their drinking water.

  9. Congratulations Heather! What type of research will you be doing at Vanderbilt and what was your favorite part of IS?

    1. Hi Holly,
      I don’t exactly know yet because I’m in an umbrella program meaning I can do research ranging from pharmacology to neuroscience, but I do know that I want to continue to explore mass spec but with more medical applications. My favorite part of IS was being able to work in the lab especially during a COVID school year. I also enjoyed that I had two projects because I was able to explore different aspects of IS in each major.

  10. Congratulation, Heather! Very interesting work! I appreciated hearing a little about what you were doing when we were in class, so it’s great to see the whole thing!

  11. Heather, well done! As your Moot coach who has little to no science knowledge, thank you for the video. So impressed with your Moot participation in addition to these 2 ISes.

    1. Hi Natalie,
      I could not have done as well this year in Moot without you and Mark!

  12. Great work, Heather! The amount of data you were able to collect and analyze is remarkable and you clearly have a good understanding of the importance of your results.

    1. Hi Doctor Feierabend,
      Thank you so much! There was so much data but it really is environmentally relevant!

  13. Heather! This is so awesome, and so important for the future of sustainable water systems. Best of luck with grad school and everything else in your future!

    1. Hi Emily,
      Thank you! I wish you the best of luck as well and hope you had a good year!

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