Keywords

Water treatment, PFAS, Activated biochar, Nanomembrane filtration

Abstract

Per- and polyfluoroalkyl substances (PFAS) persist in water systems and resist conventional treatment, particularly short-chain species. This dissertation evaluates three biochars, [unwashed (UWB), acid-washed (AWB), and super-activated (SAB)], for removing PFBA, PFBS, PFOA, and PFOS. Batch tests quantified removals and supported kinetic and isotherm analyses; BET, FTIR, and SEM characterized texture and surface chemistry. SAB showed the highest capacity and was deployed as a pretreatment to nanofiltration (NF) in a hybrid process that enhanced the removal of short-chain PFAS while sustaining near-complete rejection of their long-chain counterparts.

Water matrix effects were probed by varying dissolved organic carbon (DOC), divalent-ion levels (Ca2+ and Mg2+), and pH for the individual biochars, and DOC and ions for the SAB-NF system. Long-chain PFAS (PFOA, PFOS) consistently outperformed short-chain analogues (PFBA, PFBS). SAB adsorption was governed by chemisorption with intra-particle diffusion control, and isotherms indicated favorable multilayer uptake. DOC suppressed PFAS removal via site competition. Divalent cations enhanced short-chain PFAS adsorption by electrostatic charge-shielding and cation-bridging, whereas pH modulated surface charge and headgroup speciation, favoring adsorption under acidic conditions and attenuating it at high pH.

The molecular dynamics simulations of PFAS-SAB-water determined interfacial distributions and verified the mechanisms observed in the experiments, including chain-length-dependent hydrophobic partitioning and pore confinement for long chains, and ion- and pH-mediated electrostatic control for short chains. Thus, SAB and water matrix properties govern PFAS uptake, demonstrating that SAB pretreatment coupled with NF offers a scalable pathway to improve removal, especially of short-chain PFAS.

Completion Date

2025

Semester

Fall

Committee Chair

Sadmani, A H M Anwar

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Department of Civil, Environmental, and Construction Engineering

Format

PDF

Language

English

Release Date

12-15-2026

Document Type

Dissertation

Campus Location

Orlando (Main) Campus

Subjects

Water--Purification--Organic compounds removal; Water--Purification--Adsorption; Water--Purification--Membrane filtration; Perfluorinated chemicals; Water--Purification--Research

Download

Available for download on Tuesday, December 15, 2026

Share

COinS
 

Accessibility Statement

This item was created or digitized prior to April 24, 2027, or is a reproduction of legacy media created before that date. It is preserved in its original, unmodified state specifically for research, reference, or historical recordkeeping. In accordance with the ADA Title II Final Rule, the University Libraries provides accessible versions of archival materials upon request. To request an accommodation for this item, please submit an accessibility request form.