Ahn Se Chang, Oh Seok-Young, Cha Daniel K
Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716, USA.
J Hazard Mater. 2008 Aug 15;156(1-3):17-22. doi: 10.1016/j.jhazmat.2007.11.104. Epub 2007 Dec 4.
Kinetics of nitrate reduction by zero-valent iron at elevated temperatures was studied through batch and column experiments. It was hypothesized that under increased solution temperatures, the zero-valent iron may accelerate the reduction of nitrate by overcoming the activation energy barrier to nitrate reduction. The results of the batch experiment showed the synergistic effects of elevated temperature (75 degrees C) and a buffered condition (pH 7.4 with 0.1 M HEPES) to enhance the rate of nitrate reduction by zero-valent iron from 0.072+/-0.006 h(-1) ((0.35+/-0.03) x 10(-4) L m(-2) h(-1)) at room temperature to 1.39+/-0.23 h(-1) ((1.03+/-0.07) x 10(-3) L m(-2) h(-1)). Complete nitrate removal was obtained in a Fe(0) column after 30 min under both buffered and unbuffered conditions at 75 degrees C. These results indicate that a temperature increase could overcome the energy barrier. We suggest that an iron reduction process at moderately elevated temperature (50-75 degrees C) may be a suitable method for removing nitrate from industrial discharges.
通过间歇实验和柱实验研究了高温下零价铁还原硝酸盐的动力学。据推测，在溶液温度升高的情况下，零价铁可能通过克服硝酸盐还原的活化能障碍来加速硝酸盐的还原。间歇实验结果表明，高温（75℃）和缓冲条件（pH 7.4，含0.1 M HEPES）具有协同效应，可将零价铁还原硝酸盐的速率从室温下的0.072±0.006 h⁻¹（（0.35±0.03）×10⁻⁴ L m⁻² h⁻¹）提高到1.39±0.23 h⁻¹（（1.03±0.07）×10⁻³ L m⁻² h⁻¹）。在75℃下，无论是缓冲条件还是非缓冲条件下，Fe(0)柱在30分钟后都实现了硝酸盐的完全去除。这些结果表明温度升高可以克服能量障碍。我们认为，在适度升高的温度（50 - 75℃）下进行铁还原过程可能是一种从工业排放物中去除硝酸盐的合适方法。
