Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, Campus Box 1180, 1 Brookings Drive, St. Louis, MO 63130, USA.
Water Res. 2011 Dec 1;45(19):6525-34. doi: 10.1016/j.watres.2011.09.050. Epub 2011 Oct 5.
Lead release from pipe scales was investigated under different water compositions, stagnation times, and flow regimes. Pipe scales containing PbO(2) and hydrocerussite (Pb(3)(OH)(2)(CO(3))(2)) were developed on lead pipes by conditioning the pipes with water containing free chlorine for eight months. Water chemistry and the composition of the pipe scales are two key factors affecting lead release from pipe scales. The water rarely reached equilibrium with pipe scales within one day, which makes solid-water contact time and corrosion product dissolution rates the controlling factors of lead concentrations for the conditions tested. Among five water compositions studied, a solution with orthophosphate had the lowest dissolved lead release rate and highest particulate lead release rate. Free chlorine also decreased the dissolved lead release rate at stagnant conditions. Water flow increased rates of release of both dissolved and particulate lead by accelerating the mass transfer of lead out of the porous pipe scales and by physically destabilizing pipe scales. Dissolved lead comprised the majority of the lead released at both stagnant and laminar flow conditions.
研究了在不同水成分、停滞时间和流动状态下,从管垢中释放的铅。通过用含有游离氯的水对铅管进行为期八个月的调理,在铅管上形成了含有 PbO(2)和羟硅铅矿(Pb(3)(OH)(2)(CO(3))(2))的管垢。水化学和管垢的组成是影响管垢中铅释放的两个关键因素。水在一天内很少与管垢达到平衡,这使得固-水接触时间和腐蚀产物溶解速率成为测试条件下铅浓度的控制因素。在所研究的五种水成分中,含正磷酸盐的溶液具有最低的溶解铅释放率和最高的颗粒状铅释放率。静止条件下,游离氯也降低了溶解铅的释放率。水流通过加速多孔管垢中铅的传质,并通过物理方式使管垢不稳定,增加了溶解态和颗粒态铅的释放速率。在静止和层流条件下,释放的铅主要以溶解态形式存在。