Impact of Activated Carbon Functional Groups on Water-Phase Mercury Capture

Estenia Ortiz, Regina Rodriguez, and Dr. David Mazyck

University of Florida, Gainesville, FL (for all 3)

Mercury (Hg) is a toxic, natural occurring element that can enter and contaminate aquatic and atmospheric systems by natural means or by anthropogenic sources. Powdered activated carbon (PAC) adsorption has been an effective and attractive approach in removing contaminants, such as organic matter and heavy metals, from atmospheric and aquatic systems due to its high porosity and rich surface chemistry. Previous research has found that PAC adsorption can depend heavily on its surface functionality and in essence, functional groups can be added to its surface to further enhance its adsorptive capability.

PACs with nearly identical physical properties, such as surface area, but differing quantities and types of oxygen functional groups were tested for mercury capture. Waters each containing an initial dosage of 100 ppb of Hg were mixed with variously treated PACs at a PAC dosage of 50 ppm. Over a 24-hour period, these samples were analysed for total mercury, filterable mercury, soluble mercury, and Hg adsorbed onto the various treated PACs. Because some of these PACs have been chemically treated with acid to increase oxygen functional groups, this may alter the water contact pH. The goal of this research is to further study the removal kinetics of Hg adsorption in the water matrix. Through this, the performance of post-treated activated carbons with carboxylic, lactonic, carbonyl, and phenolic oxygen functional groups will be better understood.  Furthermore, Hg binding mechanisms will be characterized through sorbent and matrix characteristics.