5种天然矿物修复铅污染沉积物的实验研究

以重金属离子Pb2+为研究对象,通过吸附解吸实验,研究了沸石、方解石、钾长石、钙基和钠基膨润土等5种天然矿物材料对水体中Pb2+的吸附固定效果,它们的吸附等温线都符合Langmuir等温吸附模型。结果表明试验所用方解石对Pb2+的饱和吸附量约为185mg/g,是其他几种材料的2～3倍,而且方解石对Pb2+具有明显的不可逆吸附现象,使得吸附后的Pb很难解析下来,说明方解石对水溶液中Pb2+的固定能力非常强。利用模拟自然水体性质的电解液对方解石吸附后Pb的生物有效性进行评价,结果表明被方解石固定后Pb的生物有效性非常低。最后结合方解石作为原位活性覆盖材料的经济可行性和生态风险性分析,说明方解石作为重金属污染沉积物修复的原位活性覆盖材料具有较强的实际可操作性,为后继的重金属污染沉积物的原位活性覆盖技术提供理论支持。

Experimental Study on in situ Remediation of Pb-contaminated Sediments by Active Capping with Five Natural Minerals

In order to explore the feasibility of in situ capping of lead contaminated sediments, a bench scale experiment was carried out, involving fivemineral materials as Pb-adsorbents including calcite, zeolite, K-feldspar, Ca-bentonite and Nabentonite. Isothermal sorption and desorption tests showed well conformity of the isothermals with the Langmuir equation. The result revealed the best sorption capacity, 185mg/g, of the calcite, two to three times more than other minerals. Moreover, calcite showed stronger resistant desorption (desorption hysteresis). The bio-availability test ensued indicated a very low level of Pb-bioavailability after sorption by calcite. Furthermore, mis paper briefly gave an account of the economic feasibility and made the ecological risk analysis associated with using calcite for sub-aqueous capping heavy metal-contaminated sediments.