Liu Ruiqiang, Zhao Dongye
Department of Civil Engineering, 238 Harbert Engineering Center, Auburn University, Auburn, AL 36849, USA.
Water Res. 2007 Jun;41(12):2491-502. doi: 10.1016/j.watres.2007.03.026. Epub 2007 May 7.
This study prepared and tested a new class of iron phosphate (vivianite) nanoparticles synthesized with sodium carboxymethyl cellulose (CMC) as a stabilizer for in situ immobilization of lead (Pb(2+)) in soils. Batch test results showed that the CMC-stabilized nanoparticles can effectively reduce the TCLP (toxicity characteristic leaching procedure) leachability and PBET (physiologically-based extraction test) bioaccessibility of Pb(2+) in three representative soils (calcareous, neutral, and acidic). When the soils were treated for 56 days at a dosage ranging from 0.61 to 3.0 mg/g-soil as PO(4)(3-), the TCLP leachability of Pb(2+) was reduced by 85-95%, whereas the bioaccessibility was lowered by 31-47%. Results from a sequential extraction procedure showed a 33-93% decrease of exchangeable Pb(2+) and carbonate-bound fractions, and an increase in residual-Pb(2+) fraction when Pb(2+)-spiked soils were amended with the nanoparticles. Addition of chloride in the treatment further decreased the TCLP-leachable Pb(2+) in soils, suggesting the formation of chloro-pyromorphite minerals. Compared to soluble phosphate used for in situ metal immobilization, application of the iron phosphate nanoparticles results in approximately 50% reduction in phosphate leaching into the environment.
本研究制备并测试了一类新型的磷酸铁（蓝铁矿）纳米颗粒，该颗粒以羧甲基纤维素钠（CMC）作为稳定剂，用于土壤中铅（Pb(2+)）的原位固定。批次试验结果表明，CMC稳定的纳米颗粒能够有效降低三种代表性土壤（石灰性、中性和酸性）中Pb(2+)的TCLP（毒性特征浸出程序）浸出率和PBET（基于生理学的提取试验）生物可利用性。当土壤以0.61至3.0 mg/g-土壤的PO(4)(3-)剂量处理56天时，Pb(2+)的TCLP浸出率降低了85-95%，而生物可利用性降低了31-47%。连续提取程序的结果表明，当用纳米颗粒对加Pb(2+)的土壤进行改良时，可交换态Pb(2+)和碳酸盐结合态部分减少了33-93%，而残留态Pb(2+)部分增加。处理中添加氯化物进一步降低了土壤中TCLP可浸出的Pb(2+)，这表明形成了氯磷灰石矿物。与用于原位金属固定的可溶性磷酸盐相比，应用磷酸铁纳米颗粒可使磷酸盐向环境中的浸出减少约50%。
