Department of Civil and Environmental Engineering, KAIST, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Republic of Korea.
J Hazard Mater. 2011 Jan 30;185(2-3):1513-21. doi: 10.1016/j.jhazmat.2010.10.078. Epub 2010 Oct 27.
This study investigates the fate of nitrogen species during nitrate reduction by nano-scale zero valent iron (NZVI) and related reaction mechanisms. The NZVI used for the experiments was prepared by chemical reduction without a stabilizing agent. NZVI has great ability to reduce nitrate. However, the question of what end-product results from nitrate reduction by NZVI has sparked controversy. Establishing nitrogen mass balance by quantitative analysis of aqueous phase and gas-phase nitrogen species, this study clearly determines that nitrate was converted to ammonium ion followed by ammonia stripping under a strong alkaline condition, which leads to a decrease in the total aqueous nitrogen amount. Moreover, some of the major reactions, which consisted of nitrate reduction, ammonia production, and ammonia stripping were modelled by pseudo first-order kinetics. According to the model estimation results, additional reaction mechanisms would exist in an early stage of reaction. This might be due to the adsorption and desorption reaction which could be explained by the core-shell structure model.
本研究考察了纳米零价铁（NZVI）还原硝酸盐过程中氮物种的归宿及相关反应机理。实验中所用的 NZVI 是通过无稳定剂的化学还原法制备的。NZVI 具有很强的还原硝酸盐的能力。然而，NZVI 还原硝酸盐的最终产物是什么的问题一直存在争议。通过对水相和气相氮物种的定量分析建立氮质量平衡，本研究明确确定，在强碱性条件下，硝酸盐先转化为铵离子，然后通过氨吹脱，导致总氮量减少。此外，一些主要反应，包括硝酸盐还原、氨生成和氨吹脱，通过拟一级动力学进行了模拟。根据模型估计结果，在反应的早期阶段可能存在其他反应机制。这可能是由于吸附和解吸反应，这可以用核壳结构模型来解释。
