Formatted Title
Optimizing Adsorption of Micropollutants through Non-Covalent Interactions with Graphene in Different Water Matrices
Background/Objectives
Water security is a growing concern with physical and economic scarcity occurring due to increased freshwater demand and lack of infrastructure investment. With greater regulatory scrutiny on water resources micropollutants (MPs) or personal care and pharmaceutical products (PCPPs) are emerging contaminants as many of these compounds are not quantitatively removed by tertiary treatment. Therefore, post-treatment media filtration may be required to ensure safe use or environmental discharge. Although activated carbon (AC) is the leading adsorbent in the water treatment industry, graphene nanoplatelets (GnP) offer targeted opportunities to increase performance of micropollutant adsorption. While AC is limited to diffusion, surface area, and hydrophobic interactions, GnPs offer the added benefit of π-π electron donor-acceptor system as an important mechanism to selectively target micropollutants. π-π interactions are a driving force for graphene adsorption of MPs which provides significant improvements in kinetic. The use of GnP as a sorbent for micropollutants show a higher sensitivity compared to commonly used GAC, suggesting its potential to use in environmental conditions with source water chemistry with background organic matter.
Approach/Activities
Removal of MPs was tested with different water matrices to explore competing contaminants with micropollutants in dirty water. Total organic carbon, dissolved organic carbon, non-organic material, and other organics were analyzed in the different matrices determine if GnP is better for absorption with environmental condition. Isotherm and kinetics experiments were performed to determine the absorption capacity and kinetic performance of each adsorbent for MPs.
Results/Lessons Learned
The expected result is to see a decrease in GAC absorption in dirty water compared to GnP absorption due to the selectivity provided by π-π interactions. Kinetics should show a faster rate for GnP than GAC. Notably, non-selective adsorptive media remove a wide range of organic compounds present in the water being treated. Therefore, harnessing π-π interactions of GnP provides an alternative mechanism for MP removal that mitigates fouling, reduces residence time, and can be applied as a polishing step for the wide range of aromatic contaminants in multiple water sources for more efficient filtration of emerging contaminants.