Hexavalent chromium removal from a simulated wastewater using Fe(II) modified bentonite

Hexavalent chromium is reported to be highly toxic, mutagenic and carcinogenic; hence treatment of water and wastewater contaminated with this element by low-cost and environmentally friendly methods is of great importance. Therefore the aim of present study was to evaluate the efficiency of Fe(II) modified bentonite for hexavalent chromium removal from a simulated wastewater.

In this study, Fe(II) modified bentonite was synthesized. Structure and morphology of bentonite were investigated by XRD and SEM techniques. Experiments were carried out as central composite design with three input parameters namely initial hexavalent chromium, pH and adsorbent dosage at 5 levels. Finally, the results were assessed by adsorption isotherm models.

The findings revealed that complete removal efficiency of Cr (VI) achieved at pH of 2, initial hexavalent chromium concentration of 20 mg/L and adsorbent dose of 5 g/L. The adsorption isotherm model found to fit well with Langmuir isotherm model and revealed that the monolayer adsorption of hexavalent chromium at adsorbent surface was happened. The equilibrium data better fitted the Langmuir isotherm model suggested a monolayer adsorption nature of the modified bentonite.

  The findings in this study showed the promise of use of Fe(II) modified bentonite for Cr (VI) removal. Moreover, response surface methodology can be used as an effective method to optimize hexavalent chromium removal from wastewaters.