Polyol intercalation in copper substituted zinc hydroxide acetate and evaluation of its adsorptive role towards Congo red dye

Abstract

The extent of incorporation of Cu2+for Zn2+ in layered zinc hydroxide acetate to convert it to a hydroxy double salt carried out following titrimetric experiments with KOH solution. The reflections present in the powder X-ray diffraction pattern became broad suggestive of incorporation of copper for zinc. Well defined weight-loss steps, in the thermogravimetric trace of zinc hydroxide acetate, became diffused with the inclusion of copper. The intercalation of various polyols (ethylene glycol, diethylene glycol, and propylene glycol)was performed successfully, exploiting the organophilic character of ZnCu hydroxide acetate. The interlayer spacing expanded for polyol intercalated samples, as indicated by their powder X-ray diffraction patterns.The FT-IR and Raman spectra of polyol intercalated samples confirmed their presence in the interlayer, and the samples showed enhancement in thermal stability. These samples showed mesoporosity and reasonably high surface area (128.6 m2/g). The role of ethylene glycol intercalated ZnCu hydroxy double salt as an adsorbent to remove harmful and carcinogenic CR dye molecules from aqueous solutions investigated. The physisorption process was majorly responsible for the effective removal of CR dye, following a pseudo-second-order kinetics.