EFFECT OF Ti4+/CLAY RATIO ON THE PROPERTIES OF TITANIUM PILLARED BENTONITE AND ITS APPLICATION FOR Cr (VI) REMOVAL

Natural abundant bentonite collected from Jambi Province, Indonesia has been successfully pillared with titanium by using titanium propoxide as the titanium source.The titanium pillared bentonite (Ti-PilB) was prepared with different Ti 4+ /clay ratios ranging from 1 to 15 mmol/g in order to evaluate the maximum amount of the titanium pillar in the interlayer space of bentonite.The natural bentonite (NB) and Ti-PilB were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Fluorescence (XRF).The Ti-PilB sample was used as an adsorbent for Cr (VI) removal from aqueous solution in a batch system.Cr (VI) adsorption on Ti-PilB was highly affected by pH, where the optimum adsorption efficiency was recorded at pH 4. The adsorption kinetic investigation revealed that the adsorption process was reached the equilibrium state at 120 min.The adsorption kinetic model was predicted using the pseudo-first-order model and pseudo-second-order model.However, the adsorption data were best fitted with the pseudo-second-order model with the maximum adsorption capacity of 6.527 mg/g.The thermodynamic adsorption study of the adsorption data showed that the change of the Gibbs free energy (∆ ) value was negative, which mean that the adsorption process was spontaneous.Furthermore, the change of enthalpy value obtained to be positive indicated that the adsorption process was an endothermic nature.