Synthesis of Layered Double Hydroxides Containing a Biodegradable Amino Acid Derivative and Their Application for Effective Removal of Cyanide from Industrial Wastes

In this work, we report ultrasonic-assisted synthesis of layered double hydroxides (LDHs) containing biodegradable amino acid derivative, N,N'-(pyromellitoyl)-bis-l-isoleucine diacid, and their application for removal of cyanide ions from industrial wastes. The structure of the modified MgAl LDHs was studied using transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), FT-IR spectroscopy, and X-ray diffraction (XRD) techniques. The ability of the prepared LDHs for adsorption of cyanide ions from aqueous solutions was examined, and the effects of the different parameters were investigated. It was found that, under optimum conditions, the proposed LDHs adsorbent can remove 98.7% of cyanide content of the aqueous solution in less than 35 min. Compared to the recently reported methods for removal of cyanide; the proposed method has several advantages. First, the adsorbent particles (LDHs) are synthesized via an environmentally acceptable route; because water is used as solvent under ultrasonic irradiation. Second, cyanide ions are exchanged with biodegradable anions, thus the proposed method does not produce toxic waste. Third, the prepared adsorbent has high adsorption capacity and the fast adsorption kinetics, thus it can be used for lowering the concentration of cyanide in the wastes to below regulatory limits in practically acceptable times.