Formation of Pb(IV) oxides in chlorinated water
Formation of Pb(IV) oxides in chlorinated water
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DOI：
10.1002/j.1551-8833.2005.tb07523.x
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发表时间：
2005-11
期刊：
影响因子：
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通讯作者：
D. Lytle;M. Schock
中科院分区：
文献类型：
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作者：
D. Lytle;M. Schock
最近的研究表明，Pb(IV) 氧化物在饮用水分配系统中发挥着重要的地球化学作用。然而，大多数饮用水中铅控制指南都是基于 Pb(II) 固体控制铅溶解度的假设。因此，需要更好地了解水中 Pb(IV) 的化学性质。长期铅沉淀实验在 pH 6.5、8 和 10、含或不含硫酸盐的氯化水 (1–3 mg/L Cl2) 中进行。结果表明，只要用游离氯维持高悬浮氧化还原电位，就会随着时间的推移形成两种二氧化铅（IV）多晶型物 - plattnerite（β-PbO2）和 scrutinyite（α-PbO2）。这两种矿物质都不是自发形成的，并且形成速率随着 pH 值的增加而增加。水白铅矿和/或白铅矿最初沉淀出来，随着时间的推移消失或与 PbO2 共存。水的 pH 值决定了矿物的存在。高pH值有利于水白铅矿和透晶石；低pH值有利于白铅矿和铂矿。随着 Pb(II) 向 Pb(IV) 的转变，颗粒颜色从白色变为深红色，再变为深灰色（随 pH 值而变化），并且铅溶解度降低。如果允许游离氯消散，老化过程（即矿物学、颜色和溶解度）是可逆的。
Recent research has shown that Pb(IV) oxides play a significant geochemical role in drinking water distribution systems. However, most of the guidance for lead control in drinking water is based on the presumption that Pb(II) solids control lead solubility. Therefore, a better understanding of the chemistry of Pb(IV) in water is needed. Long‐term lead precipitation experiments were conducted in chlorinated water (1–3 mg/L Cl2) at pH 6.5, 8, and 10, with and without sulfate. Results showed that two Pb(IV) dioxide polymorphs—plattnerite (β‐PbO2) and scrutinyite (α‐PbO2)—formed over time, as long as a high suspension redox potential was maintained with free chlorine. Neither mineral formed spontaneously, and the rate of formation increased with increasing pH. Hydrocerrusite and/or cerrusite initially precipitated out and over time either disappeared or coexisted with PbO2. Water pH dictated mineralogical presence. High pH favored hydrocerrusite and scrutinyite; low pH favored cerrusite and plattnerite. Along with a transformation of Pb(II) to Pb(IV) came a change in particle color from white to a dark shade of red to dark grey (differing with pH) and a decrease in lead solubility. If free chlorine was permitted to dissipate, the aging processes (i.e., mineralogy, color, and solubility) were reversible.