Enhanced adsorption of acid brown 14 dye on calcined Mg/Fe layered double hydroxide with memory effect

The Mg/Fe layered double hydroxide (LDH) with carbonate interaction and its calcined product (CLDH) were synthesized and used as adsorbents for the removal of acid brown 14 (AB 14) from aqueous solutions. Effect of various physic-chemical factors such as contact time, temperature, adsorbent dosage, initial AB 14 concentration and solution pH were investigated. The results showed that the synthesized CLDH was efficient and had a much higher adsorption capability of 370.0 mg/g for AB 14 compared with that of the LDH, 41.7 mg/g. The X-ray diffraction patterns of the CLDH before and after the adsorption demonstrated that the adsorption was significantly enhanced by reconstruction of its original layered structure in the presence of AB 14 with the memory effect. It was found that the adsorption isotherms were well described by Langmuir model for both the LDH and the CLDH with correlation coefficient (R2) > 0.99, the adsorption kinetics of AB 14 on these two adsorbents followed the pseudo-second-order kinetic model. The results indicated that the calcined Mg/Fe layered double hydroxide is an efficient adsorbent for the treatment of waste water with high concentration of anionic dyes.

► Calcined Mg/Fe layered double hydroxide (CLDH) with memory effect was synthesized.
► CLDH showed much higher adsorption capacity for AB 14 (370 mg/g) than that of LDH.
► Reconstruction of LDH structure for CLDH in the presence of AB 14 was confirmed.
► This CLDH might be used as an efficient adsorbent for waste water treatment of anionic dyes.