Date of Award

January 2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Mahmut Ersan

Abstract

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants with significant health risks. Among the different technologies for PFAS removal, adsorption is preferable due to low-cost, operational simplicity, and use of regenerable adsorbents. While pilot-scale fixed-bed columns are ideal for evaluating adsorption media, they are time- and resource-intensive. Rapid Small-Scale Column Tests (RSSCTs) offer a practical alternative, yet most studies have focused on granular activated carbon, with limited insight into ion exchange (IX) resins. Due to limited literature on the effect resin preparation on the performance of RSSCTs and their prediction accuracies are unexplored. This study investigates the effect of five grinding techniques: freeze drying & blender grinding (FD&BG), blender grinding (BG), mortar and pestle (MP), ball milling (BM), and jet milling (JM) on the adsorption performance of IX resins for PFAS removal using RSSCTs in single solute (deionized (DI)water background) and multi-solute systems (simulated ground water background).Three PFAS compounds, perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), and perfluorooctanoic acid (PFOA) were tested in DI water, while PFBA and PFOA were also evaluated under simulated groundwater, containing natural organic matter (NOM) and inorganic anions. Different grinding techniques influenced the breakthrough profiles of the PFAS. Characterization revealed that grinding altered key physico-chemical properties: water retention capacity dropped from 46.2% (ungrinded resin) to 6.8% (BM), while total anion exchange capacity increased. XPS analysis showed enhanced accessibility to Cl⁻ and quaternary ammonium groups, and zeta potential became more negative post-grinding. Adsorption breakthough trends varied by PFAS type and grinding method, reflecting differences in removal mechanisms and compared based on half breakthrough BVs (BV₅₀). FD&BG yielded the highest BVs values (3,200 BV₅₀) for PFBA in both DI and simulated groundwater, attributed to enhanced electrostatic interactions and improved exchange site accessibility. For PFHxA, JM IX resin had the highest BVs (5,200 BV₅₀) under single solute system, benefiting from both hydrophilic and hydrophobic interactions. For PFOA, BM achieved the highest BV₅₀ (9,300 BVs) in the DI water background, likely because hydrogen bonding between the resin’s hydroxyl groups and carboxylic head of PFOA enhances its removal alongside the dominant hydrophobic interactions. Whereas MP performed highest BVs (5,600 BV₅₀) in the presence of competing solutes. PFBA was more sensitive to background interference, with BV₅₀ reductions of 37.5–57.5%, compared to 9.7–46.2% for PFOA. The grinding technique also influenced RSSCT predictability. For PFBA, FD&BG correlated best with pilot-scale data under single-solute conditions, while JM was most accurate in multi-solute systems. For PFOA, BG and JM provided the best prediction accuracy up to 70% breakthrough in DI water, whereas MP was most accurate under multi-solute conditions. These results demonstrate that the resin grinding technique is PFAS-specific and significantly affects both adsorption behavior and the prediction accuracy of RSSCTs when scaling up pilot applications.

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