Pillarization of layer double hydroxides (Mg/Al) with keggin type K4[α-SiW12O40]•nH2O and its application as adsorbent of procion red dye

Abstract

Pillarization of layered double hydroxides with polyoxometalate K₄[α-SiW₁₂O₄₀]•nH₂O at various times i.e. 3, 6, 9, 12, 24, 36 and 48 hours has been done. The pillared product was characterized by FT-IR spectrophotometer and XRD. The optimum pillared layered double hydroxides of polyoxometalate K₄[α-SiW₁₂O₄₀]•nH₂O was used as an adsorbent of procion red dye. The results of characterization using FT-IR spectrophotometer is not yet show the optimum pillarization process. The characterisation using XRD the successfully of pillared layered double hydroxides of polyoxometalate K₄[α-SiW₁₂O₄₀]•nH₂O showing the existence of diffraction angle 8.5^o with intensity 355. Furthermore, the pillared layered double hydroxides of polyoxometalate K₄[α-SiW₁₂O₄₀]•nH₂O with time variation of 12 hours was applied as an adsorbent of procion red dye. The results show the adsorption rate was 0.523 min^-1, the highest of absorption capacity at 70^oC was 10.8 mol/g, the highest energy of absorption 70 ^oC was 125 kJ/mol. The enthalpy (∆H) and entropy (∆S), decrease as the increasing concentration of procion red dye.

Keywords: layered double hydroxides, polyoxometalate, pillaration, procion red, adsorption