title: Synergistic integration of ion-exchange and catalytic reduction for complete decomposition of perchlorate in waste water.
abstract: Ion-exchange has been frequently used for the treatment of perchlorate (ClO4(-)), but disposal or regeneration of the spent resins has been the major hurdle for field application. Here we demonstrate a synergistic integration of ion-exchange and catalytic decomposition by using Pd-supported ion-exchange resin as an adsorption/catalysis bifunctional material. The ion-exchange capability of the resin did not change after generation of the Pd clusters via mild ethanol reduction, and thus showed very high ion-exchange selectivity and capacity toward ClO4(-). After the resin was saturated with ClO4(-) in an adsorption mode, it was possible to fully decompose the adsorbed ClO4(-) into nontoxic Cl(-) by the catalytic function of the Pd catalysts under H2 atmosphere. It was demonstrated that prewetting the ion-exchange resin with ethanol significantly accelerate the decomposition of ClO4(-) due to the weaker association of ClO4(-) with the ion-exchange sites of the resin, which allows more facile access of ClO4(-) to the catalytically active Pd-resin interface. In the presence of ethanol, >90% of the adsorbed ClO4(-) could be decomposed within 24 h at 10 bar H2 and 373 K. The ClO4(-) adsorption-catalytic decomposition cycle could be repeated up to five times without loss of ClO4(-) adsorption capacity and selectivity.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology , Daejeon, 305-701, Korea.
authors.forename: You-Na
authors.initials: YN
authors.lastname: Kim
authors.forename: Minkee
authors.initials: M
authors.lastname: Choi
mesh_terms: D000327:Adsorption; D002384:Catalysis; D004777:Environment; D007474:Ion Exchange; D007475:Ion Exchange Resins; D007700:Kinetics; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry; D010316:Particle Size; D010472:Perchlorates / Q000737:chemistry*; D012996:Solutions; D013696:Temperature; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D007475:Ion Exchange Resins; D010165:Palladium; D010472:Perchlorates; D012996:Solutions; D062065:Wastewater; D014874:Water Pollutants, Chemical; C494474:perchlorate