Synthesis of polyphenolic mesoporous nanocomposite for removal of acid dye from aqueous media: Adsorption studies

The aim of this study is immobilization of mesoporous silica by tannin (tannin@SBA-15) for removal of acid blue 62 from aqueous media and determines the adsorption isotherm, thermodynamic and kinetic parameters. The characterization of adsorbent was carried out by different techniques such as Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N2 adsorption/desorption, scanning electron microscope (SEM) and transmission electron microscope (TEM). UV-Vis spectrophotometer was also applied to determine the amount of remaining dye in the solution. The Effect of some parameters such as pH, adsorbent dosage and contact time for removal of acid blue 62 was examined and optimized at temperatures ranging from 25 to 45 ⁰C. For determining the type of Isotherm model, Langmuir, Freundlich and Temkin were used and for attaining the Thermodynamic parameters such as changes in Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS), Vant Hoff equation were applied. Optimum values were pH of 2, contact time of 90 min and absorbent dosage of 0.03 g. The Langmuir isotherm model showed very good agreement with the equilibrium data with maximum adsorption capacity of 1000 mg/g. The thermodynamic analysis also revealed that the adsorption process was feasible, spontaneous and exothermic. The results also indicated that the adsorption of acid blue 62 onto Tannin-aminated SBA-15 follows the pseudo-second order kinetic model. Tannin@SBA-15 has a good potential for acid blue 62 dye adsorption from aqueous media.