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 131I 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%.

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