Synthesis of Li/Al layered double hydroxide-guest composites under mild acid conditions

Abstract Layered double hydroxides (LDHs) are known as ‘anionic clays’. They comprise a class of material with positively charged octahedral double hydroxyl layers and exchangeable anions. The Li/Al LDH term includes a group of LDHs with Li/Al octahedral double hydroxyl layers. We have demonstrated a modifed method, using Li/Al LDH-OH (OH− as interlayer anions) as the starting material, for preparing Li/Al LDH-X (X represents interlayer anions, including dioctyl sulphosuccinate (DOSS), dodecyl sulphate (DDS), mercaptoacetate (MA), EDTA, Tiron and dichromate) under mild acid conditions (pH in the range 4 to 5). However, in the case of acidsensitive anions, Fe(CN)64−, Li/Al LDH-Fe(CN)64− can be prepared by a two-step procedure using Li/Al LDH-DOSS or similar compounds as intermediates to react with acid-sensitive anions under mild alkaline conditions (pH ≈ 9).