Removal of Hexacyanoferrate(II) Using Zn-Al-OAc Hydrotalcite as an Anion Exchanger


Cyanide is a highly toxic anion and ingestion exposure can be fatal. Cyanide can be removed from water systems using Zn-Al-OAc hydrotalcite (OAc-=acetate) as an ion exchanger. A synthesis of Zn-Al-OAc hydrotalcite has been performed and it was used as an anion exchanger to reduce the concentration of cyanide in the form of [Fe(CN)6]4-. Zn-Al-OAc hydrotalcite was prepared using a stoichiometric method followed by hydrothermal treatment. The chemical composition of Zn-Al-OAc hydrotalcite was found to be Zn0.73Al0.27(OH)2(OAc) The anion exchange reaction of OAc- by [Fe(CN)6]4- was fit to yield a second order reaction rate constant of k = 0.215 M-1s-1 with R2=0.996. The anion exchange capacity (AEC) was found to be 219 meq [Fe(CN)6]4-/100g hydrotalcite. It was found that Zn-Al-Fe(CN)6 hydrotalcite could not be regenerated by OAc-.


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