Adsorption characteristics of anionic azo dye Ponceau 4 R in water environment using SiO2-CeO2 nanocomposites: experimental consideration and modeling

Abstract

Ionic organic dyes are the emerging pollutants that strongly influence to water environment. Adsorption of an anionic dye, Ponceau 4 R on SiO₂-CeO₂ nanocomposites was investigated in the present study. The SiO₂-CeO₂ nanocomposites with nanosilica rice husk were synthesized and examined by XRD, EDX, SEM, FT-IR, and ζ potential. The best conditions for Ponceau 4 R adsorption on SiO₂-CeO₂ were obtained at pH 4, adsorption time 90 min and 10 mg/mL SiO₂-CeO₂ dose. The removal efficiencies and the maximum adsorption capacity of Ponceau 4 R using SiO₂-CeO₂ achieved greater than 99% and 15.63 mg/g, respectively. Adsorption isotherms of Ponceau 4 R and on SiO₂-CeO₂ increased with increasing ionic strengths that were represented by Langmuir, Freundlich, and Temkin models. A pseudo-second-order model was applicable to represent the kinetic of Ponceau 4 R adsorption on SiO₂-CeO₂. Based on the changes in SiO₂-CeO₂ charge by zeta potential and vibrational groups by FT-IR, we demonstrate that electrostatic interactions mainly contributed to the Ponceau 4 R adsorption on SiO₂-CeO₂ surfaces.