Sarin P, Snoeyink V L, Bebee J, Jim K K, Beckett M A, Kriven W M, Clement J A
Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, IL 61801, USA.
Water Res. 2004 Mar;38(5):1259-69. doi: 10.1016/j.watres.2003.11.022.
Iron release from corroded iron pipes is the principal cause of "colored water" problems in drinking water distribution systems. The corrosion scales present in corroded iron pipes restrict the flow of water, and can also deteriorate the water quality. This research was focused on understanding the effect of dissolved oxygen (DO), a key water quality parameter, on iron release from the old corroded iron pipes. Corrosion scales from 70-year-old galvanized iron pipe were characterized as porous deposits of Fe(III) phases (goethite (alpha-FeOOH), magnetite (Fe(3)O(4)), and maghemite (alpha-Fe(2)O(3))) with a shell-like, dense layer near the top of the scales. High concentrations of readily soluble Fe(II) content was present inside the scales. Iron release from these corroded pipes was investigated for both flow and stagnant water conditions. Our studies confirmed that iron was released to bulk water primarily in the ferrous form. When DO was present in water, higher amounts of iron release was observed during stagnation in comparison to flowing water conditions. Additionally, it was found that increasing the DO concentration in water during stagnation reduced the amount of iron release. Our studies substantiate that increasing the concentration of oxidants in water and maintaining flowing conditions can reduce the amount of iron release from corroded iron pipes. Based on our studies, it is proposed that iron is released from corroded iron pipes by dissolution of corrosion scales, and that the microstructure and composition of corrosion scales are important parameters that can influence the amount of iron released from such systems.
腐蚀的铁管释放铁是饮用水分配系统中“有色水”问题的主要原因。腐蚀的铁管中存在的腐蚀垢会限制水流，还会使水质恶化。本研究的重点是了解关键水质参数溶解氧（DO）对旧的腐蚀铁管中铁释放的影响。对一根使用了70年的镀锌铁管的腐蚀垢进行了表征，其为Fe(III)相（针铁矿（α-FeOOH）、磁铁矿（Fe₃O₄）和磁赤铁矿（α-Fe₂O₃））的多孔沉积物，在垢层顶部附近有一层壳状致密层。垢层内部存在高浓度的易溶性Fe(II)。研究了在流动水和静止水条件下这些腐蚀管的铁释放情况。我们的研究证实，铁主要以亚铁形式释放到主体水中。当水中存在溶解氧时，与流动水条件相比，静止时观察到的铁释放量更高。此外，还发现静止时增加水中的溶解氧浓度会减少铁的释放量。我们的研究证实，增加水中氧化剂的浓度并保持流动条件可以减少腐蚀铁管中铁的释放量。基于我们的研究，提出铁是通过腐蚀垢的溶解从腐蚀铁管中释放出来的，并且腐蚀垢的微观结构和组成是影响此类系统中铁释放量的重要参数。
