CHARACTERIZATION AND EVALUATION OF CYCLODEXTRIN POLYMERS AS ALTERNATIVE ADSORBENTS TO ACTIVATED CARBON FOR MICROPOLLUTANT REMOVAL DURING WATER AND WASTEWATER TREATMENT
The occurrence of a variety of anthropogenic organic compounds in natural water resources has been well documented over the last decades. To meet the demands of a rapidly growing population, over hundreds of thousands of anthropogenic chemicals are used globally every day for the production of food, energy, and industrial products. Because many of these chemicals are designed to be persistent and stable, intensive production and use leads to their accumulation in the environment. Micropollutants (MPs) are organic chemicals that typically occur at trace concentrations in the environment and include broad groups of chemicals such as personal care products, pharmaceuticals, pesticides, and industrial chemicals. Long-term exposure to MPs in water can result in the collapse of aquatic ecosystems, the spread of antibiotic resistance, and may lead to chronic human health problems. Conventional water and wastewater treatment processes do not adequately remove MPs due to their diverse physicochemical properties and low concentrations. This deficiency has motivated the development of tertiary treatment alternatives including advanced oxidation processes (AOPs) and activated carbon (AC) adsorption. Whereas AOPs and AC adsorption are effective at removing MPs during water and wastewater treatment, there are some well-described drawbacks that have limited their global implementation. There is a clear need for alternative solutions that effectively remove MPs from water and address the deficiencies of AOPs and AC adsorption. Porous β-cyclodextrin polymers (P-CDP) have recently been demonstrated to outperform many conventional adsorbents for the removal of organic chemicals from water. However, the potential for P-CDP to be used as an alternative adsorbent to AC for efficient MP removal during water and wastewater treatment remains unknown. More research is needed to push the development of P-CDP from lab tests to practical implementation in engineering processes. Three adsorption studies were designed to comprehensively characterize and evaluate P CDP as a next-generation adsorbent to replace or complement AC adsorption for the removal of MPs during water and wastewater treatment. The first study benchmarks the performance of a coconut-shell AC (CCAC) and P-CDP to adsorb MPs from water under environmentally relevant scenarios with respect to adsorption kinetics, equilibrium removal, and resistance to fouling by common matrix constituents. The second study establishes Quantitative Structure-Activity Relationships (QSARs) between the physicochemical properties of a diverse set of MPs and their distribution coefficients (KD) measured on CCAC and P-CDP to fully interpret the adsorption mechanisms on both adsorbents. The third study utilizes simulated batch adsorption followed by ultrafiltration (BA-UF) and packed bed filtration (PBF) processes with environmentally derived water samples from diverse sources to characterize the effects of background water matrix constituents on MP removal by CCAC and P-CDP. This research provides a systematic evaluation of P-CDP as an alternative to AC for MP removal during water and wastewater treatment. The findings of this research will push the further development of P-CDP adsorbents towards practical implementation.
micropollutant; Environmental engineering; Activated Carbon; Cyclodextrin Polymer; Adsorption
Helbling, Damian E.
Gu Leip, April Zhongchun; Steinschneider, Scott
Civil and Environmental Engineering
Ph.D., Civil and Environmental Engineering
Doctor of Philosophy
dissertation or thesis