Preparation of Zn-Al layered double hydroxide intercalated with triethylenetetramine-hexaacetic acid by coprecipitation: uptake of rare-earth metal ions from aqueous solutions

作者：Kameda Tomohito^*; Shimmyo Tetsu; Yoshioka Toshiaki

来源：RSC Advances, 2014, 4(86): 45995-46001.

DOI：10.1039/c4ra06795a

A Zn-Al layered double hydroxide intercalated with triethylenetetramine-hexaacetic acid (TTHA.Zn-Al LDH) was prepared by the dropwise addition of a Zn-Al nitrate solution to a TTHA solution at a constant pH value of 10.0. The TTHA.Zn-Al LDH could uptake rare-earth metal ions such as Nd3+ ions from aqueous solutions. This can be attributed to the chelating ability of the TTHA ions in the interlayer, i.e., Nd-TTHA complexes could be formed in the interlayer. However, the TTHA.Zn-Al LDH could hardly uptake Sr2+ ions from aqueous solutions, indicating that the TTHA ions in the interlayer did not function as effective chelating agents for Sr2+ ions. Therefore, TTHA.Zn-Al LDH could uptake Nd3+ ions selectively from an aqueous mixture of Nd3+ and Sr2+ ions. This was confirmed by the fact that the uptake amount after 120 min was 0.078 and 0.007 mmol g(-1) for Nd3+ and Sr2+, respectively, when TTHA.Zn-Al LDH was added to a 1 : 1 mixed nitrate solution of Nd3+ and Sr2+ ions. In this case, the degree of selectivity, i.e., the Nd/Sr molar ratio, was 10.7. Furthermore, TTHA.Zn-Al LDH was superior to ethylenediaminetetraacetate (EDTA).Zn-Al LDH for the uptake of Nd3+ ions, which can be attributed to the order of the stability of the metal-chelate complexes: Nd-TTHA complex > Nd-EDTA complex.

• 出版日期2014