Rapid and complete destruction of perchlorate in water and ion-exchange brine using stabilized zero-valent iron nanoparticles

Perchlorate has emerged as a widespread contaminant in groundwater and surface water. Because of the unique chemistry of perchlorate, it has been challenging to destroy perchlorate. This study tested the feasibility of using a new class of stabilized zero-valent iron (ZVI) nanoparticles for complete transformation of perchlorate in water or ion-exchange brine. Batch kinetic tests showed that at an iron dosage of 1.8 g L−1 and at moderately elevated temperatures (90–95 °C), 90% of perchlorate in both fresh water and a simulated ion-exchange brine (NaCl=6% (w/w)) was destroyed within 7 h. An activation energy (Ea) of 52.59±8.41 kJ mol−1 was determined for the reaction. Kinetic tests suggested that Cl(VII) in perchlorate was rapidly reduced to chloride without accumulation of any intermediate products. Based on the surface-area-normalized rate constant kSA, starch- and CMC-stabilized ZVI nanoparticles degraded perchlorate 1.8 and 3.3 times, respectively, faster than non-stabilized ZVI particles. Addition of a metal catalyst (Al, Cu, Co, Ni, Pd, or Re) did not show any reaction improvement. This technology provides an effective method for complete destruction of perchlorate in both contaminated water and brine.