Activated Carbon is extremely effective and feasible at removing unwanted contaminants that may pose health threats such as mercury and it has been widely accepted for the removal of mercury (Hg) from coal-fired power plant flue gas. Activated carbon’s surface chemistry can play a key role when removing Hg from this gaseous stream and therefore the characterization of activated carbon’s surface is essential to understand help simplify and better recognize the chemical reactions occurring on the surface of the activated carbon. This work examines the relationship between Hg removal and the types of oxygen functional groups on the surface of activated carbon. It will primarily study the enhancement of the carboxylic, lactonic and phenolic oxygen functional groups through post activation treatments on activated carbons manufactured from various raw materials. Traditionally Boehm titrations have been used to determine these three acidic functional groups on the activated carbon surface based on the concept of acid-base neutralization analysis. This qualitative and quantitative technique has been extensively used on activated carbons of different origins to investigate and detect surface oxygen functional groups. In this work activated carbons were acid treated at varying concentrations which were then characterized for physical and chemical properties. The physical characterizations included surface area, pore volume, average pore size, and density. The chemical characterization techniques implemented to study the amphoteric nature of activated carbon were Boehm titrations and Fourier Transform Infrared (FTIR) Spectroscopy. Activated carbons with different concentrations of functional groups were compared for Hg adsorption and treated activated carbons showed greater removal than the virgin activated carbon. Carboxylic functional group concentration was associated with Hg uptake in the air phase contradictory to other theories that suggest that an active site where electron sharing occurs is responsible for the oxidation and adsorption mechanisms of Hg.

Activated carbon surface chemistry: Significance of oxygen functional groups for mercury adsorption

251st National Meeting (2016)

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