Complete degradation of perchlorate in ferric chloride and hydrochloric acid under controlled temperature and pressure.
Despite favorable thermodynamics, the reduction of perchlorate (ClO4-) is kinetically limited in aqueous media because of its high activation energy. In this paper, a new methodology has been presented for degrading ClO4- in an FeCl3-HCl solution at an elevated temperature (< 200 degrees C) and/or pressure (approximately 20 atm). Results indicate that the rate constant for the pseudo-first-order reaction between ClO4- and ferrous Fe(II) (in excess) increased nearly 3 orders of magnitude when the temperature was increased from 110 to 195 degrees C, and a complete reduction of ClO4- occurred in < 1 h at 195 degrees C in the FeCl3-HCl solution. The activation energy of the reaction was calculated to be about 120 kJ/mol. Additionally, a flow-through reactor was constructed based on the batch kinetic measurements, and a nearly complete degradation of ClO4- was observed under continuous-flow mode. Because the FeCl3-HCl solution has been successfully used in regenerating selective anion-exchange resins sorbed with ClO4- during water treatment, this new methodology offers a cost-effective means to degrade ClO4- while not altering the chemical properties of the FeCl3-HCl regenerant solution so it can be reused, eliminating the production of secondary wastes.
Gu
Baohua
B
Oak Ridge National Laboratory, P.O. Box 2008, MS-6036, Oak Ridge, Tennessee 37831-6036, USA. b26@ornl.gov
Dong
Weijin
W
Brown
Gilbert M
GM
Cole
David R
DR
D000837:Anion Exchange Resins; D002712:Chlorides; D005290:Ferric Compounds / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry*; D007700:Kinetics; D010472:Perchlorates / Q000737:chemistry*; D011312:Pressure; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods; D014874:Water Pollutants, Chemical
D000837:Anion Exchange Resins; D002712:Chlorides; D005290:Ferric Compounds; D010472:Perchlorates; D014874:Water Pollutants, Chemical; D006851:Hydrochloric Acid; C024555:ferric chloride