Exchanged zeolite adsorbent for removing Cr(VI): Kinetics, thermodynamics and adsorption mechanism

ABSTRACT

In this work, copper-exchange-zeolite was prepared as appropriate material for the elimination of Cr(VI). The materials were characterised by SEM/EDX, N₂ adsorption-desorption, and FTIR. pH effects, initial Cr(VI) concentration, contact time, and temperature on adsorption efficiency were evaluated. The materials have uniform and regular crystal shapes indicating an unmodified morphology according to SEM findings. The amount adsorbed is optimal at pH = 10 for all zeolites. The Pseudo-second-order model describes best kinetic adsorption. The adsorbed quantity decreases with temperature whatever the material. The maximum adsorption capacity was 9.30 mg g⁻¹. The effect of competing anions on adsorption was examined, it was discovered that the CO₃^2- had a significant impact on adsorption efficiency. The activation energy value of Cr(VI) adsorption on exchanged zeolite was 0.120 kJ mol⁻¹. The electrostatic interaction between CrO₄^2- and Cu²⁺ inserted in the zeolite explains the adsorption mechanism The result was confirmed by the diffusion Boyd and D-R model. The present study indicates that this material is efficient adsorbent to eliminate Cr(VI) in Industrial rejects.

KEYWORDS:

• NaX
• Cu-exchange
• adsorption
• electrostatic
• Cr(Vi)
• mechanism

Acknowledgments

The authors acknowledge the significant financial support offered by the General Direction of Scientific Research and Technology Development (DGRSDT, MESRS, Algeria).

Disclosure statement

No potential conflict of interest was reported by the author(s).