Pyrolysis of deinked paper sludge to synthesize adsorbents for elemental Hg vapors

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Deinked paper sludge (DPS) was pyrolyzed at 600°C, 750°C, and 900°C in dry nitrogen to synthesize adsorbents. The performance of the pyrolyzed DPS for the gas-phase adsorption of elemental mercury (Hg0) was investigated, and the performance was compared with that of BPL activated carbon as received (Calgon Carbon Corporation). In addition, the adsorption capacities of pyrolyzed DPS for Hg0 were compared with those published for other activated carbon adsorbents. The physical and chemical properties of pyrolyzed DPS and BPL were characterized to assess their differences, and those differences were used to hypothesize reasons for differences in their adsorption performance for Hg0. Characterization of the adsorbents was conducted using BET surface area, X-ray diffraction, thermal gravimetric analyses, scanning electron microscopy, electron dispersion spectroscopy, and Fourier transform spectroscopy. Pyrolyzed DPS performed better than BPL for Hg0 adsorption, despite the significant difference in surface area (pyrolyzed DPS ∼50 m2/g; BPL 1100 m2/g). Reasons for differences in adsorption performance are likely due to the pore size distribution, presence of and access to surface active sites, and morphology of the pyrolyzed deinked paper sludge compared with BPL. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 524–534, 2013