Laboratory of Process and Chemical Engineering, Department of Applied Chemistry, National School of Agro-industrial Sciences, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon; J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 182 23, Prague 8, Czech Republic.
J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 182 23, Prague 8, Czech Republic.
Chemosphere. 2018 Oct;209:617-622. doi: 10.1016/j.chemosphere.2018.06.080. Epub 2018 Jun 11.
The duration of in-situ generation of iron corrosion products (FeCPs) prior the remediation process (so called "aging" of metallic iron (Fe)), was found as the key parameter affecting the efficiency of Fe for water remediation. Batch experiments were performed in buffered solutions (pH 4.0, 4.7 and 5.5) and under oxic conditions (presence of dissolved oxygen) using Zn as probe contaminant. The time-dependent (0-16 d) concentration changes of aqueous Fe and Zn were monitored using differential pulse polarography (DPP). During the time of pre-corrosion varying from 0 to 6 d, an "induction period" of the corrosion occurs in the first one - 2 h when no Fe ion is released in the solution. After this period, Fe was identified in solution and its concentration progressively increases up to 6 h, then starts to decrease and after 6 d nearly disappears. Experiments with Zn reveal that the most efficient Fe remediation occurs after 6 h of pre-corrosion. This coherence thus proves that the presence, the amount and the age of FeCPs ("degree" of corrosion) significantly impact the removal efficiency of Zn in Fe/HO systems. The present study severely refute the wording 'reactivity loss' and states that progress in designing sustainable Fe/HO systems will not be achieved before the role of "active" FeCPs is clarified.
在修复过程之前（即所谓的金属铁（Fe）“老化”）原位生成铁腐蚀产物（FeCPs）的持续时间被发现是影响 Fe 用于水修复效率的关键参数。在缓冲溶液（pH 值 4.0、4.7 和 5.5）和有氧条件（存在溶解氧）下进行了批次实验，使用 Zn 作为探针污染物。使用差分脉冲极谱法（DPP）监测水相 Fe 和 Zn 的时间依赖性（0-16 d）浓度变化。在从 0 到 6 d 的预腐蚀时间内，在最初的 2 h 内发生腐蚀的“诱导期”，在此期间，溶液中没有释放 Fe 离子。在此期间之后，溶液中鉴定出 Fe，其浓度逐渐增加至 6 h，然后开始下降，6 d 后几乎消失。Zn 的实验表明，在 6 h 的预腐蚀后，Fe 的修复效率最高。因此，这种一致性证明了 FeCPs 的存在、数量和年龄（“腐蚀程度”）显著影响 Fe/HO 系统中 Zn 的去除效率。本研究强烈驳斥了“反应性损失”一词，并指出在澄清“活性”FeCPs 的作用之前，设计可持续 Fe/HO 系统的进展不会取得。
