Nitrate reduction by nano-Fe/Cu particles in packed column

In this work the application of a modified surface nano zero valent iron (NZVI) as bimetallic Fe/Cu particles to remove high concentration of NO₃^--N through packed sand column has been studied. Dispersed nano-Fe/Cu particles has been synthesized in water mixed ethanol solvent system (1:4v/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 Fe⁰ by Cu on the nitrate removal. Research on packed sand column (120cm length, 6.5cm inner diameter) has been done under conditions of Nano-Fe/Cu concentration (2, 5, and 8gl^-1 of solution), high initial NO₃^--N concentration (100, 200, and 300mgl^-1) and pore water velocity through sand (0.125, 0.250, and 0.375mms^-1) in seven sets. Results of batch experiments indicated the efficient coating percentage of Fe⁰ by Cu in NO₃^--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 NO₃^--N concentration would increase the rate of NO₃^--N reduction. The best condition to reduce NO₃^--N has been observed at end of sand column as 75% of influent concentration when nano-Fe/Cu concentration=8gl^-1, high initial NO₃^--N concentration=100mgl^-1 and pore water velocity through sand=0.125mms^-1.