Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Bachelor of Science in Chemical Engineering

Degree Level

Undergraduate

Department

Chemical Engineering

Advisor/Mentor

Wickramasinghe, Ranil

Abstract

Access to clean and safe water is an escalating global concern due to the persistent presence of toxic contaminants in aquatic environments. Among these, synthetic dyes and per- and polyfluoroalkyl substances (PFAS) represent two distinct yet significant classes of pollutants, both posing serious environmental and public health risks. Dyes in water contribute to intense coloration, elevated chemical and biological oxygen demand (COD and BOD), reduced light penetration, and disruption of aquatic ecosystems, with potential health risks to humans upon exposure. PFAS, often termed "forever chemicals," are synthetic organofluorine compounds associated with a range of adverse health effects, including endocrine disruption, reproductive and developmental toxicity, metabolic disorders, and carcinogenicity. Various strategies have been explored to mitigate these pollutants, with adsorption emerging as a promising method. Fly ash, a carbon-rich byproduct of coal combustion, is particularly attractive as an adsorbent due to its low cost, high availability, and large surface area. Its use also supports sustainable waste valorization, enhancing its economic feasibility for large-scale water treatment applications. In this study, fly ash achieved up to 95% removal of dye contaminants, with a maximum adsorption capacity of 120 ± 5 mg/g. For perfluorooctanesulfonic acid (PFOS), up to 53% of removal was observed within 2 hours of treatment. Notably, fly ash sample #2 exhibited superior performance compared to sample #1, likely due to its finer pore structure, rougher surface texture, and higher surface area, which enhance adsorption efficiency. The findings also suggest that acidic conditions favor dye adsorption, while alkaline conditions improve PFOS removal. Electrostatic interactions are proposed as a key mechanism governing the adsorption process.

This work was further developed and submitted to Separation Science and Technology.

Keywords

PFAS; Adsorption; Fly Ash; Water treatment; textile dyes

Download

Share

COinS