Leaching of iodide (I-) and iodate (IO3-) anions from synthetic layered double hydroxide materials

Several studies have previously demonstrated that layered double hydroxides (LDHs) show considerable potential for the adsorption of radioiodine from aqueous solution; however, few studies have demonstrated that these materials are able to store radioactive I-131 for an acceptable period. The leaching of iodide (I-) and iodate (IO3-) form Mg/Al LDHs has been carried out. Contact time appeared to be a more significant variable for the leaching of iodate (IO3-) compared to that of iodide (I-). Experimental results are fitted to the pseudo second order model, suggesting that diffusion is likely to be the rate-limiting step. The presence of carbonate in the leaching solution appeared to significantly increase the leaching of iodide (I-) as did the presence of chloride to a lesser extent. The maximum amount of iodate (IO3-) leached using ultrapure water as the leaching solution was 21% of the iodate (IO3-) originally present. The corresponding result for iodide (I-) was even lower at 3%. (C) 2016 Elsevier Inc. All rights reserved.