Removal of single dye and dye mixture from aqueous solution with alginate-coated calcined layered double hydroxide and illite clay composite beads

Abstract

Alginate-coated calcined layered double hydroxide and illite clay (Alg@CLDH@ Illite) composite beads were fabricated and tested for single and mixture dye adsorption from aqueous solution. Adsorption characteristics of the as-fabricated beads were assessed by using Methylene Blue (MB) and Congo Red (CR) as adsorbates. As-prepared samples were characterised by using X-ray diffraction (XRD), Thermogravimetry/Differential Scanning Calorimetry (TG–DSC), Fourier transform infrared spectroscopy (FTIR), and point of zero charge (pHpzc). The characterisations demonstrated that the incorporation of CLDH powder/clay mixture can not only enhance thermal stability but also can improve the adsorption performance. The adsorption kinetics of dyes onto composite beads followed the linear form of pseudo-second-order model and their equilibrium data were fitted well to the Freundlich model. The results showed that the Alg@CLDH@Illite composite is able to adsorb anionic and cationic dyes from a binary dye mixture with high sorption capacities in short time 50 min.