Use of Raman spectroscopy to assess the efficiency of MgAl mixed oxides in removing cyanide from aqueous solutions

Calcining magnesium/aluminium layered double hydroxides (Mg/Al LDHs) at 450 degrees C provides excellent sorbents for removing cyanide from aqueous solutions. The process is based on the memory effect of LDHs; thus, rehydrating a calcined LDH in an aqueous solution restores its initial structure. The process, which conforms to a first-order kinetics, was examined by Raman spectroscopy. The metal ratio of the LDH was found to have a crucial influence on the adsorption capacity of the resulting mixed oxide. In this work, Raman spectroscopy was for the first time use to monitor the adsorption process. Based on the results, this technique is an effective, expeditious choice for the intended purpose and affords in situ monitoring of the adsorption process. The target solids were characterized by using various instrumental techniques including X-ray diffraction spectroscopy, which confirmed the layered structure of the LDHs and the periclase-like structure of the mixed oxides obtained by calcination. (C) 2015 Elsevier B.V. All rights reserved.