Kinetics and Effect Factors of Reductive Denitrification with Nanoscale Zero-valent Iron

Nitrate in drinking water is a harmful component to human health. Nanoscale zero-valent iron (NZVI) with 20~40 nm size and Brunauer Emmett Teller (BET) surface area of 49.16 m²/g was synthesized in the laboratory for removal of nitrate from water. Batch experiments were conducted to investigate the denitrification kinetics of NZVI and the factors affecting the denitrification of nitrate such as pH, NZVI dosage as well as the initial nitrate concentration. Experimental results suggest that the low pH value is more favorable for nitrate reduction. Additional, the test results also showed that in certain limits the reduction rate of nitrate increased with increase of NZVI dosage and decreased with increase of initial concentration of nitrate. The dynamics equation for the pseudo first order reaction was obeyed.Surface adsorption and redox reaction were the principal removal mechanism during the denitrification of nitrate by NZVI. Possible reaction ways for nitrate reduction by NZVI were also discussed. The products from nitrate reduction depended upon the reaction condition. Under the condition of this study, the final product from nitrate reduction did not N₂ but NH⁺₄-N. More studies should be conducted to prevent or solve this problem.