(248as) Synthesis of Layered Double Hydroxides Intercalated with Chelating Agents for RARE Earth Element Capture from Aqueous Streams

Authors: 
Roth, E. - Presenter, National Energy Technology Laboratory
Lekse, J. W. - Presenter, National Energy Technology Laboratory
Granite, E. J. - Presenter, U.S. Department of Energy, National Energy Technology Laboratory

Solid layer double hydroxides (LDHs) are promising adsorbents for heavy metal and rare earth element

removal from aqueous streams. LDHs are layered materials that are built of positively charged brucite-like

layers weakly bound with each other by exchangeable anions. LDHs are typically synthetically made and have

positively charged layers that contain different bivalent cations (Mg, Mn, Zn, Cu, Ni, etc.) and trivalent cations

(Al, Fe, Cr, etc.), but can also be formed in clay mineral silicates like kaolinite. These materials have been used

in waste water treatment and in soil remediation to capture heavy metal ions. Additionally, these materials can

be intercalated with different organic molecules to form organic-inorganic hybrid materials that can be used as

sorbents. Specifically, LDHs can be intercalated with chelating anions in the interlayer space to enhance

sorption properties of the materials. Studies on decontamination of aqueous media from U(VI), and sorption of

Cu2+, Cd2+, and Pb2+ reported the use of inorganic hydrotalcite sorbents and LDHs.

In this study a hydrotalcite material was synthesized and compared to a layered double hydroxide

intercalated with ethylenediaminetetracetic acid (EDTA). The materials were fully characterized using various

characterization techniques including SEM, XRD, and BET. The material was then tested for extraction of rare

earth elements from a synthetic ideal aqueous solution. Parameters such as the pH, and the LDH to water ratio

were varied to see the effects on extraction efficiency for the materials. The rare earth element concentration

was measured using ICP-MS.