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 (H2SO4 and HCl) at various concentrations. The surface area was increased approximately 5 times (493 m2/g) without causing deterioration in the crystal structure of bentonite with 1.0 M H2SO4 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, Delta H degrees, Delta S degrees, and Delta G degrees 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.

Automated summary

In this study, white-colored calcium-bentonite was treated with different acids to increase its surface area without deteriorating its crystal structure. Adsorption experiments revealed that the adsorption of Cr(III) onto the bentonite followed the Langmuir monolayer isotherm, and the process was both endothermic and spontaneous.