Metal-induced decomposition of perchlorate in pressurized hot water

Decomposition of perchlorate (ClO4-) in pressurized hot water (PHW) was investigated. Although ClO4- demonstrated little reactivity in pure PHW up to 300 °C, addition of zerovalent metals to the reaction system enhanced the decomposition of ClO4- to Cl− with an increasing order of activity of (no metal) ≈ Al < Cu < Zn < Ni << Fe: the addition of iron powder led to the most efficient decomposition of ClO4-. When the iron powder was added to an aqueous ClO4- solution (104 μM) and the mixture was heated at 150 °C, ClO4- concentration fell below 0.58 μM (58 μg L−1, detection limit of ion chromatography) in 1 h, and Cl− was formed with the yield of 85% after 6 h. The decomposition was accompanied by transformation of the zerovalent iron to Fe3O4. This method was successfully used in the decomposition of ClO4- in a water sample contaminated with this compound, following fireworks display at Albany, New York, USA.

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► ClO4- showed little reactivity in pure pressurized hot water (PHW) up to 300 °C.
► Metal additive dramatically enhanced the decomposition of ClO4- to Cl− in PHW.
► Iron led to the most efficient reaction, producing Cl− with yields of 85–86%.
► ClO4- in water after fireworks display was successfully decomposed by this method.