Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/watres Rapid and complete destruction of perchlorate in water and ion-exchange brine using stabilized zero-valent iron nanoparticles Zhong Xiong a , Dongye Zhao a,Ã , Gang Pan b a Environmental Engineering Program, Department of Civil Engineering, 238 Harbert Engineering Center, Auburn University, Auburn, AL 36849, USA b Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085, China article info Article history: Received 24 March 2007 Received in revised form 21 May 2007 Accepted 29 May 2007 Available online 3 June 2007 Keywords: Degradation Ion-exchange brine Nanoparticle Perchlorate Reduction Zero-valent iron Water treatment abstract 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 1C), 90% of perchlorate in both fresh water and a simulated ion-exchange brine (NaCl ¼ 6% (w/w)) was destroyed within 7 h. An activation energy (E a ) of 52.5978.41 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 k SA , 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. & 2007 Elsevier Ltd. All rights reserved. 1. Introduction Perchlorate (ClO 4  ) has been primarily used in solid rocket fuels. It is also used in firework powder, roadside flares, airbag inflators, and fertilizers from Chile (Urbansky, 1998). Past massive applications of perchlorate have left a contamination legacy that perchlorate has been detected at about 400 sites in groundwater, surface water, soil, or public drinking water in more than 35 states across the United States, with concen- trations ranging from 4 mgL 1 to more than 3.7 million mgL 1 (US Government Accountability Office (USGAO), 2005). Re- cently, perchlorate was also detected in milk (Kirk et al., 2005) and bottled water (Snyder et al., 2005). When ingested, perchlorate can impede the endocrine function by blocking iodide from entering the thyroid gland, thereby reducing the production of thyroid hormones. The adverse health effects were reportedly more profound for newborns, children, and pregnant women (Wolff, 1998). A study from the US Centers for Disease Control (CDC) found that almost any amount of perchlorate exposure was linked to a significant change in levels of thyroid hormones (Blount et al., 2006). To reduce human exposure, the USEPA adopted a drinking water equivalent level (DWEL) of 24.5 mgL 1 . Mean- while, California adopted a public health goal of 6 mgL 1 and Massachusetts set the nation’s first drinking water standard of 2 mgL 1 for perchlorate. ARTICLE IN PRESS 0043-1354/$ - see front matter & 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.watres.2007.05.049 Ã Corresponding author. Tel.: +1 334 844 6277; fax: +1 334 844 6290. E-mail address: dzhao@eng.auburn.edu (D. Zhao). WATER RESEARCH 41 (2007) 3497– 3505