TOWARDS A MECHANISTIC UNDERSTANDING OF DEVELOPMENT AND DESIGN OF CYCLODEXTRIN POLYMERS AS EMERGING ADSORBENTS TO REMOVE PER- AND POLYFLUOROALKYL SUBSTANCES FROM WATER

Ching, Casey

TOWARDS A MECHANISTIC UNDERSTANDING OF DEVELOPMENT AND DESIGN OF CYCLODEXTRIN POLYMERS AS EMERGING ADSORBENTS TO REMOVE PER- AND POLYFLUOROALKYL SUBSTANCES FROM WATER

Abstract

Per- and polyfluoroalkyl substances (PFASs), also known as ‘forever chemicals,’ are a class of persistent fluorinated chemicals that are toxic to humans and negatively impact environmental health. PFASs are thermally stable and can have amphiphilic properties and are thus used in numerous commercial and industrial applications. The widespread detection of PFASs in water bodies motivates environmental engineers to develop practical water treatment approaches to remediate PFAS-contaminated water. Adsorbents such as granular activated carbon (GAC) and ion exchange (IE) resins are inexpensive and widely used, but have some notable deficiencies that motivate the need for alternative adsorbents. Recently, we have found that β-cyclodextrin polymers (CDPs) have potential as alternative adsorbents that can selectively remove PFASs from water. As groundwater and drinking water standards for PFASs become increasingly stringent, we must comprehensively evaluate CDPs so that we can better understand the strengths and shortcomings of CDPs and how to implement CDPs in engineered systems.In my dissertation, I address several research gaps related to the use of CDPs for remediation of PFAS-contaminated water. First, current evaluation of adsorption technologies for PFAS remediation focuses on a small subset of PFAAs which are not necessarily representative of the whole class. In my first project, I expand on our current knowledge by studying the adsorption of a broader set of anionic, zwitterionic, and non-ionic PFASs on CDPs and IE resins. Second, although we have increasing evidence demonstrating that CDPs are an effective adsorbent for PFASs, structurally diverse CDPs exhibit variable performance. In my second project, I performed experiments with 34 structurally diverse CDPs and performed multivariate analyses to discover links between the physicochemical properties of the CDPs and their performance. Third, CDPs are synthesized as powders but implementation into engineered processes will require granular adsorbents of a defined morphology. In my third project, I studied a novel set of CDP granules of varying particle size and characterized their adsorption performance in batch and column experiments. Overall, my dissertation provides greater insight into how we can implement CDPs in engineered processes to remove PFASs from contaminated water.

Description

170 pages

Date Issued

2022-08

Keywords

adsorbent; cyclodextrin polymer; PFAS; polymer; water treatment

Committee Chair

Helbling, Damian E

Committee Member

Steinschneider, Scott
Martinez, Carmen Enid

Degree Discipline

Civil and Environmental Engineering

Degree Name

Ph. D., Civil and Environmental Engineering

Degree Level

Doctor of Philosophy

Types

dissertation or thesis