College of Natural Resources and Environment, Joint Institute for Environmental Research & Education, South China Agricultural University, Guangzhou 510642, China.
College of Natural Resources and Environment, Joint Institute for Environmental Research & Education, South China Agricultural University, Guangzhou 510642, China; Agro-Environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China.
Sci Total Environ. 2018 Oct 1;637-638:69-78. doi: 10.1016/j.scitotenv.2018.04.300. Epub 2018 May 6.
In present study, the feasibility of applying a natural adsorbent with Fe modification (Fe-modified argillaceous limestone, FAL) on the competitive adsorption of heavy metals (i.e., Cd, Pb and Ni) was evaluated. The current results revealed an efficient adsorption on Cd, Pb and Ni in mono-metal system. Further experiments demonstrated a high selectivity of Pb during the competitive adsorption of Cd, Pb and Ni. The adsorption selectivity of the metal ions followed the order of Pb ≫ Cd > Ni. In addition, both pH and ionic strength are important factors affecting the metal adsorptions. It is interestingly that various NOMs (i.e., humic acid (HA) and glycine (Gly)) exerted different effects on the adsorption behaviors, probably due to the different affinities for Pb, Cd and Ni and the redistribution of newly-formed metal-DOM complexes. X-ray photoelectron spectroscopy (XPS) analysis together with X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) analysis revealed that the metal adsorptions were mainly regulated via the synergistic mechanisms of ion exchange by Na, Ca, and Al, precipitation to form CdCO and Pb(OH)(CO), as well as complexes of FAL-OPb and FAL-ONi by hydroxyl groups on the surface of FAL. The application of FAL would be a promising option in leading to an efficient heavy metal removal.
在本研究中，评估了用 Fe 修饰的天然吸附剂（Fe 改性泥灰岩，FAL）应用于重金属（即 Cd、Pb 和 Ni）竞争吸附的可行性。目前的结果表明，在单金属体系中，FAL 对 Cd、Pb 和 Ni 具有高效的吸附能力。进一步的实验表明，在 Cd、Pb 和 Ni 的竞争吸附中，FAL 对 Pb 具有高选择性。金属离子的吸附选择性顺序为 Pb>Cd>Ni。此外，pH 值和离子强度都是影响金属吸附的重要因素。有趣的是，各种 NOM（即腐殖酸（HA）和甘氨酸（Gly））对吸附行为表现出不同的影响，这可能是由于它们对 Pb、Cd 和 Ni 的亲和力不同，以及新形成的金属-DOM 配合物的再分配不同。X 射线光电子能谱（XPS）分析以及 X 射线衍射（XRD）和能量色散光谱仪（EDS）分析表明，金属的吸附主要是通过 Na、Ca 和 Al 的离子交换、形成 CdCO 和 Pb(OH)(CO)的沉淀以及 FAL-OPb 和 FAL-ONi 等协同机制来调节的，这些机制是由 FAL 表面的羟基形成的。FAL 的应用将是一种很有前途的选择，可以有效地去除重金属。
