Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
J Colloid Interface Sci. 2011 Aug 15;360(2):398-407. doi: 10.1016/j.jcis.2011.04.064. Epub 2011 May 7.
The surfaces of nano-hydroxyapatite (nHAP) used for contaminated soil and groundwater remediation may be modified to render nHAP highly mobile in the subsurface. Humic acid (HA) is widely used to modify and stabilize colloid suspensions. In this work, column experiments were conducted to determine the effects of contaminant (e.g., Cu) concentration, ionic strength (IS), and ion composition (IC) on the transport behavior of HA-modified nHAP in saturated packed columns. IS and nature of the cation had strong effects on the deposition of nHAP, and the effect was greater for divalent than for monovalent cations. Divalent cations have a greater capacity to screen the surface charge of nHAP, and Ca(2+) bridges the HA-modified nHAP colloidal particles, which causes greater deposition. Moreover, Cu(2+) had a greater effect on the transport behavior than Ca(2+) due to their strong exchange with Ca(2+) of nHAP and its surface complexation with nHAP. The relative travel distance L(T), of the injected HA-modified nHAP colloids, ranges from less than one to several meters at varying Cu concentrations, ISs, and ICs in saturated packed columns. The results are crucial to evaluate the efficacy of nHAP on the remediation of contaminated soil and groundwater environments.
用于污染土壤和地下水修复的纳米羟基磷灰石 (nHAP) 的表面可能经过修饰，以使 nHAP 在地下具有很高的迁移性。腐殖酸 (HA) 广泛用于修饰和稳定胶体悬浮液。在这项工作中，进行了柱实验以确定污染物（例如 Cu）浓度、离子强度 (IS) 和离子组成 (IC) 对饱和填充柱中 HA 修饰的 nHAP 迁移行为的影响。IS 和阳离子的性质对 nHAP 的沉积有很强的影响，对于二价阳离子的影响大于对于一价阳离子的影响。二价阳离子具有更大的能力屏蔽 nHAP 的表面电荷，并且 Ca(2+) 桥接 HA 修饰的 nHAP 胶体颗粒，这导致更大的沉积。此外，由于 Cu(2+) 与 nHAP 的 Ca(2+) 发生强烈交换及其与 nHAP 的表面络合，因此 Cu(2+) 对迁移行为的影响大于 Ca(2+)。在不同 Cu 浓度、IS 和 IC 的饱和填充柱中，注入的 HA 修饰的 nHAP 胶体的相对迁移距离 L(T) 的范围从小于 1 米到几米。这些结果对于评估 nHAP 在污染土壤和地下水环境修复中的功效至关重要。
