Pillarization of Bentonite using Fe3+/Ti4+ and Its Application for Congo Red and Direct Violet Removal

Abstract

: Bentonite was pillarized by using Fe 3+ /Ti 4+ metal oxide ratio 2:1 and 1:2. The pillarization product was characterized by using XRD analysis and FT-IR spectrophotometer. XRD diffractogram showed that the optimal product was obtained at Fe 3+ /Ti 4+ ratio 2:1. At this ratio, basal spacing of bentonite layer is 15 Å while bentonite with ratio 1:2 has basal spacing 12.86 Å. Bentonite 2:1 ratio was applied on Congo red adsorption. The isotherm adsorption was calculated and followed Freundlich model having adsorption rate (k) 0.0008 (min -1 ) for Congo red and 0.00045 (min -1 ) for direct violet. The adsorption capacity (qe) of Congo red at 70 °C is 68 mol/g that larger than 51 mol/g for direct violet. The adsorption energy (E) of Congo red at 70°C is 4.90 kJ/mol also higher then direct violet with 1.01 kJ/mol. The enthalpy (ΔH) and entropy (ΔS) is decreased with increase of Congo red and direct violet concentration. The optimum pH was obtained at 3 whereas the maximum amount of Congo red adsorbed is 90.60 mg/L. Direct violet shows maximum amount of adsorption at pH 4 with 79.61 mg/L.