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 acid-sensitive anions, Fe(CN)(6)(4-), Li/Al LDH-Fe(CN)(6)(4-) 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 approximate to 9)

The removal and recovery of Cr(VI) by Li/Al layered double hydroxide (LDH)

“…Thus, the increase in basal spacing of Cr(VI) containing Li/Al LDH at pH 4 is due to the adsorption of larger dichromate anions. This result is consistent with results reported previously [25,35].…”

Removal of 2-Chlorophenol from Aqueous Solution by Mg/Al Layered Double Hydroxide (LDH) and Modified LDH

“…[13][14][15] LDHs have biological, pharmaceutical, and environmental applications. [16][17][18] The general known…”

Well‐Crystallized CO32–‐Type LiAl–LDH from Urea Hydrolysis of an Aqueous Chloride Solution

“…The strong band at 1359 cm –1 is from the symmetric vibrations of the CO 3 2– anion in the interlayer space. The bands at 1004 and 745 cm –1 are assigned to the deformation of –OH, whereas Al–O stretches are indicated by the bands at 538 and 461 cm –1 14b…”

“…The situation in LiAl–CO 3 –LDH seems intermediate14b,16,31 and a univocal relationship between the structure and synthesis method seems impossible. We modeled the diffraction pattern of HT120‐48 starting from the models of Thiel et al,21 Ramesh et al,32 and Britto et al16 and employing the DIFFaX+33 software for a proper refinement of the model parameters.…”