Nitrate reduction by nano-Fe/Cu particles in packed column S. Mossa Hosseini a , B. Ataie-Ashtiani b, ⁎, M. Kholghi a a Irrigation and Reclamation Dept., University of Tehran, Karaj, Iran b Department of Civil Eng., Sharif University of Technology, Tehran, Iran abstract article info Article history: Received 15 September 2010 Received in revised form 1 March 2011 Accepted 18 March 2011 Available online 13 April 2011 Keywords: NZVI Nitrate reduction Nano Fe/Cu particles Packed sand column Batch experiment In this work the application of a modified surface nano zero valent iron (NZVI) as bimetallic Fe/Cu particles to remove high concentration of NO 3 - -N through packed sand column has been studied. Dispersed nano-Fe/Cu particles has been synthesized in water mixed ethanol solvent system (1:4 v/v) and described by XRD pattern, TEM and SEM images and BET analyze. Batch experiments have been conducted to investigate the effect of percentage coating of Fe 0 by Cu on the nitrate removal. Research on packed sand column (120 cm length, 6.5 cm inner diameter) has been done under conditions of Nano-Fe/Cu concentration (2, 5, and 8 g l -1 of solution), high initial NO 3 - -N concentration (100, 200, and 300 mg l -1 ) and pore water velocity through sand (0.125, 0.250, and 0.375 mm s -1 ) in seven sets. Results of batch experiments indicated the efficient coating percentage of Fe 0 by Cu in NO 3 - -N reduction was 2.5% (w/w). In addition, increase of pore velocity of water through packed sand has negative effect on the nitrate reduction rate. In contrast, increasing the injected mass of nano particles and the influent NO 3 - -N concentration would increase the rate of NO 3 - -N reduction. The best condition to reduce NO 3 - -N has been observed at end of sand column as 75% of influent concentration when nano-Fe/Cu concentration = 8 g l -1 , high initial NO 3 - -N concentration = 100 mg l -1 and pore water velocity through sand = 0.125 mm s -1 . © 2011 Elsevier B.V. All rights reserved. 1. Introduction NO 3 - -N concentration higher than Maximum Concentration Level (MCL) in drinking water causes significant risk to human health such as blue baby syndrome in infants and the development of cancer when it is reduced in the form of nitrite ([1]; Haugen et al., 2003). In this regards many countries have set standard limit for in drinking water as 10 ppm [2]. Sources of NO 3 - -N include agricultural runoff, landfill leachate, leaking septic tanks, municipal storm water runoff, animal feeding oper- ations and industrial waste [3,4]. Among the existing technologies for removing NO 3 - -N (e.g. ion exchange, reverse osmosis, electrodialysis, and biological denitrification), using of Zero Valent Iron (ZVI) has been attracted thinks of many researchers (e.g., [5,6]). Although in early 1990s, granular ZVI has been first employed in Permeable Reactive Barrier (PRBs) as an electron donor to reduce NO 3 - -N but it did not gain its popularity until the last decade when appeared in the size of nanometer. Advantages of nano-zero valent iron (NZVI) particles in remedi- ation of NO 3 - -N are due to small size of particles which is resulted in larger specific surface area and higher surface reactivity. In addition, these particles are non-toxic, ubiquitous, and inexpensive and can be effectively injected to contaminated zones by groundwater ([7], Saleh et al., 2007, [8]). In spite of NZVI efficiency in reduction of nitrate from water, but it faced critical issues for in-situ applications when injected in porous media. Some of these challenges include strong tendency of aggre- gation, agglomeration, rapid settlement on the solid phase surface which resulted consolidation, pore plugging and significant loss of porosity and permeability of porous media [9]. In addition, ground- water commonly has relatively high values of ionic strength, which is suitable for the reduction of electrostatic repulsion between nano particles and increase of aggregation [10]. Aggregation can cause reduction of NZVI transport through porous media. Research show that iron nano-particles may travel only a few centimeters in porous media from the injection position under typical groundwater con- ditions [11]. Johnson et al. [12] discussed that transport of significant mass loading of bare NZVI in porous media without varying large pore velocity through packed medium, mechanical increasing of NZVI, and/ or use of amendments to the NZVI, is confronted by serious difficulty. Many efforts have been carried out to prepare a stable suspension of NZVI by modifying particle surface to enhance the mobility of NZVI in porous media. In this regards promising new synthetic methods are being developed to produce more mobile ZVI nano-particles and re- duced sticking coefficients without giving up significant reactivity. Many surface modifier and anionic surface chargers such as polyacrylic acid [13], Non-ionic surfactants such as polyoxyethylene sorbitan monolaurate [14], PV3A [15], starch [16], noble metals [17] and oil [18]. Desalination 276 (2011) 214–221 Abbreviations: NZVI, Nano zero valent iron; XRD, X-ray Diffraction; TEM, Transmission Electron Microscopy; BET, Brunauer, Emmett and Teller Method; MCL, Maximum Concentration Level; ZVI, Zero Valent Iron; PRB, Permeable Reactive Barrier; PV3A, Polyvinyl Alcohol-Co-Vinyl Acetate-Co-Itaconic Acid; TCA, Tetra-Chloro-Ethane; DI water, De-ionized water; PV, pore volume; UV–Vis, Ultra Violet–Visible; R N , Reynolds's number. ⁎ Corresponding author. E-mail address: ataie@sina.sharif.ir (B. Ataie-Ashtiani). 0011-9164/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2011.03.051 Contents lists available at ScienceDirect Desalination journal homepage: www.elsevier.com/locate/desal