Perchlorate reduction by nanoscale iron particles

We report herein the near complete reduction of perchlorate (ClO4-) to chloride by nanoscale iron particles. The iron nanoparticles also reduce chlorate (ClO3-), chlorite (ClO2-) and hypochlorite (ClO-) to chloride. No reaction was observed with microscale iron powder under identical conditions. The temperature sensitivity of the perchlorate-nanoparticle reaction is evidenced by progressively increasing rate constant values of 0.013, 0.10, 0.64 and 1.52 mg perchlorate per g nanoparticles per hour (mg-g(-1)-hr(-1)), respectively, at temperatures of 25, 40, 60 and 75 degrees C. The activation energy of perchlorate-iron reaction was calculated to be 79.02 +/- 7.75 kJ/mole. Despite favorable thermodynamics, the relatively large activation energy for this reaction suggests that perchlorate reduction is limited by the slow kinetics. The nanoscale iron particles may represent a potential treatment method for perchlorate-contaminated water.