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Retention of Chromium (VI) on a Macroporous Char Following ChemChar Gasification and Successive Leaching with Water and Acids
Author(s) -
Marrero Thomas W.,
Manahan Stanley E.
Publication year - 2005
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143005x41717
Subject(s) - char , chromium , nitric acid , chemistry , aqueous solution , hydrochloric acid , leachate , leaching (pedology) , nuclear chemistry , chemical engineering , inorganic chemistry , pyrolysis , environmental chemistry , organic chemistry , environmental science , soil science , engineering , soil water
A granular macroporous char, triple‐reverse‐burn (TRB) char, was loaded with 23.40 mg Cr/g TRB char from an aqueous solution, and the retained metal was leached by water, 0.66 M nitric acid, concentrated nitric acid, and concentrated hydrochloric acid before and after treatment by a reductive thermal gasification process (ChemChar process developed by ChemChar Research, Inc., Columbia, Missouri). The chromium leachate was analyzed by flame atomic adsorption. Reverse‐ and forward‐mode gasifications were performed on the metal‐laden char. With the exception of a 10% mass loss of carbon, the reverse mode gasification process does not change the physical characteristics of the granular char, but does increase the retention of the chromium from 16.7 to 24.2%, depending on the leachant. The forward mode gasification process produces a vitrified (or glasslike) ash residue. There was an 11.6 to 13.1% increase in the retention of the chromium by the slag and ash when compared to the nongasified chromium‐loaded TRB char. Chromium (VI) was effectively removed from solution by TRB char and found to be retained to a higher degree on the char after a reductive thermal treatment.