Investigation of Chromium (III) Adsorption on Acid-Treated Bentonite Evaluation of Kinetic/Thermodynamic Data

Sorption studies were carried out in a batch system using Cr(III) solution on non-treated and acid-treated white-colored calcium-bentonite (WCa-B). WCa-B, which has the highest cation exchange capacity (119 meq/100 g), was treated with 2 different acids (H 2 SO 4 and HCl) at various concentrations. The surface area was increased approximately 5 times (493 m 2 /g) without causing deterioration in the crystal structure of bentonite with 1.0 M H 2 SO 4 activation. To determine the chemical and mineralogical composition of the adsorbent, which was characterized with XRD, XRF, Surface Area and Porosity, TG/DTA, FT-IR, SEM, and EDX. For Cr(III) uptake experiments, a batch method was applied. The highest Cr(III) monolayer adsorption capacity was specified as 219.8 mg/g. To Cr(III) adsorption, Δ H °, Δ S °, and Δ G ° were designated onto adsorbent and it was found that adsorption is coherent with Langmuir monolayer isotherm, adsorption has an endothermic character, and has spontaneously occurred. By using pseudo-second-order and Lagergren kinetic models, Cr(III) adsorptions kinetic experiments were determined, it was designated that the adsorption was exhibited to be proper for the pseudo-second-order kinetic model.