Nitrate Removal from Aqueous Solutions using Green and Biodegradable Zerovalent Iron Nanoparticles

Zerovalent iron nanoparticles (ZVIN) had high potential for nitrate removal from aqueous solutions due to high surface area and reactivity of them. The aim of this study was nitrate removal from aqueous solutions using environmentally friendly stabilized ZVIN. ZVIN were synthesized via chemical reduction by sodium borohydride. In order to preventing of ZVIN from being agglomerated these particles were stabilized by natural and green biopolymers of Guar gum and Xantan gum. Xantan gum+ Guar gum stabilized ZVIN had the most efficiency for nitrate reduction from aqueous solutions. Results also revealed optimum contact times for nitrate removal were 100, 50 and 40 minutes for Bare, Guar gum and Xantan gum+ Guar gum stabilized ZVIN respectively. The optimum pH values for nitrate reduction were 2, 5 and 6 for Bare, Guar gum and Xantan gum+ Guar gum stabilized ZVIN respectively. Nitrate removal efficiency increased by increasing of ZVIN dosages (2 to 10 g/L) from 66.01 to 76.06, 83.43 to 91.36 and 89.47 to 96.16 percent for Bare, Guar gum and  Xantan gum+ Guar gum stabilized ZVIN respectively. The results showed when nitrate dosages enhanced (from 100 to 400 mg/L) the efficiency of nitrate removal from aqueous solutions decreased from 66.17 to 47.97, 84.26 to 69.06 and 88.65 to 75.49 percent for Bare, Guar gum and  Xantan gum+ Guar gum stabilized ZVIN respectively. Results of this study revealed that application of polymeric stabilizers caused increasing zero-valent iron nanoparticle efficiency in nitrate removal from aqueous solution.