Nitrate removal by synthetic nanoscale zero-valent iron in aqueous recirculated reactor

 

Sustain. Environ. Res., 21(6), 353-359 (2011)

 

AUTHOR(S)

Jia-Chin Hsu, Chih-Hsiang Liao and Yu-Lun Wei

KEY WORDS

Nitrate removal, nanoscale zero-valent iron (nZVI), CO2

ABSTRACT

The object of this study was to investigate the capability of nitrate removal by nanoscale zerovalent iron (nZVI) particles in a re-circulated flow reactor of 4.3 L liquid volume. Nitrate removal of 70% was observed with the initial pH of 6.4 with the solution being pre-purged by N2 gas (anoxic condition) at a rate of 50 mL min-1. However, when the solution was bubbled with CO2 (anoxic condition), the nitrate removal efficiency was less than 5% with the initial pH of 4.0. As the pH was adjusted by H2SO4 and NaOH to the range of 6-8, nitrate removal efficiency of 80-84% could be obtaine d. Such results demonstrate that carbonic acid generate d from CO2 bubbling may play strongly an inhibiting role in nitrate removed by the nZVI. In addition, based on nitrate mass balance, the end product was mostly dominated by ammonium at the initial pH 10. For the initial pH such as 6 and 8, some other nitrogen-containing species have been formed in the reaction, in addition to nitrite and ammonium.

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