Conventional activated carbon sorbents are produced from relatively expensive materials, and often have high cost, which limit their large-scale application in the treatment of flue gas from power plants. Hence, recent efforts have been directed towards the use of various biomass raw materials to prepare and evaluate new activated carbon for Hg0 removal. However, the availability vast biomass resources in the world’s oceans provide sustainable alternatives to limited land resources, which could be explored and utilized for the preparation of biochars for energy and environmental applications. In this study, novel activated carbons and pyrolysis chars were prepared from two representative marine seaweed species (sargassum and enteromorpha), and their efficiencies and mechanisms for mercury removal evaluated in a fixed bed reactor. Brunauer-Emmett-Teller (BET), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) spectrum were used to characterize and determine the physical and chemical properties of these samples. The effects of modification methods, modification temperatures, reaction temperatures, and flue gas components on Hg removal were also studied. The experimental data were also tested with different adsorption kinetic models for the best fits, and standard thermodynamic parameters evaluated in order to elucidate mercury adsorption mechanisms. The results appear to reveal that the performances of seaweed biomass-based activated carbons for elemental mercury removal, are by far more superior to those of seaweed biomass-based pyrolysis chars. The presence of O2 or NO favored the Hg0 removal, while SO2 or H2O(g) exhibited antagonistic effects. It was determined that the Hg0 process was a combination of physisorption and chemisorption; with the excellent physical properties (specific surface area and pore structure), and the surface active sites (C-Cl groups (resulting from treatment with FeCl3, ZnCl2 and CeCl3 solutions) and oxygen species) responsible for the physisorption and chemisorption, respectively.

Preparation of novel seaweed biomass-based activated carbon and use for gaseous elemental mercury (Hg0) removal

2019 Fall National Meeting

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