A comprehensive study on iodine uptake by selected LDH phases via coprecipitation, anionic exchange and reconstruction

Abstract

We explored the use of selected layered double hydroxides (LDHs) of different compositions and obtained by means of different routes (i.e., coprecipitation, anionic exchange and reconstruction) as iodine/iodate adsorbents. The influence of speciation (iodide vs. iodate) on iodine uptake was rather strong, resulting in much lower iodide incorporation. The Fourier transform of iodine K X-ray absorption edge data (EXAFS) of all iodate-LDHs showed a single I-O scattering path of 1.8 Å . Thermal stability and leaching experiments showed that the incorporated iodate and iodide were rather loosely bound in the interlayer space and were easily released under heating to 180°C and leaching with Milli-Q water and brine solution.

[Sn2S6]4– Anion-Intercalated Layered Double Hydroxides for Highly Efficient Capture of Iodine

“…Layered double hydroxides (LDHs) possess positively charged layers and exchangeable interlayer anions. − Due to the particular compositions and structures, LDHs acting as sorbents have displayed a vast perspective in removing environmental contaminants . Ma et al reported [S x ] 2– -intercalated LDH (MgAl-S x -LDH) and found that interlayered [S x ] 2– reduced I 2 to [I 3 ] − ions which were immobilized within the LDH gallery, realizing a maximum iodine capture ( q m ) of 1520 mg/g .…”

Application of hydrotalcite in soil immobilization of iodate (IO3−)

“…In aqueous environments and soil systems, iodine exists mainly as iodide (I À ) and iodate (IO 3 À ). 7,8 In some cases, IO 3 À is the predominant iodine form, which accounts for up to approximately 70% of total iodine, with iodide and organoiodine being minor components. 9,10 The fate and mobility of iodine in soils depend largely on its interactions with soil components.…”

“…[33][34][35][36][37][38][39] The underlying mechanisms of sorption of anions by LDHs includes: 7,33 (1) anion exchange; (2) surface adsorption; and (3) reformation. Although LDH shows a relatively high potential sorption capacity for iodine anions, the presence of competing anions, including carbonate, phosphate and sulphate, has a signicant impact on uptake of the target anions from an aqueous solution.…”

“… 27,28 Several groups have investigated the potential application of LDH and related materials in the removal of iodine from aqueous solutions. 7,9,29–32 Theiss et al briefly reviewed the published scientific literature, and, with further investigation, concluded that LDH is a promising iodine removal material. 33 …”