Effective adsorption of Cr (VI) from aqueous solution using natural Akadama clay

In this study, natural Akadama clay was used for Cr (VI) removal from aqueous solution. Batch experiments were carried out to investigate the effect of contact time, initial pH, and adsorbent dose on Cr (VI) adsorption. Results showed that Cr (VI) adsorption on natural Akadama clay reached equilibrium in 180 min. The Cr (VI) removal efficiency of 46.8% without pH adjustment increased to 73.8% at the optimum initial pH of 2. The maximum adsorption capacity was 4.29 mg g−1 at an initial concentration of 50.0 mg L−1 and adsorbent dosage of 5 g L−1. The equilibrium data fitted Freundlich isotherm better than Langmuir isotherm, and they were well explained by pseudo-second-order kinetic model. Adsorption mechanism analysis proved that electrostatic adsorption dominated during the removal process. Results from this study demonstrate that natural Akadama clay has the potential to be an efficient adsorbent for Cr (VI) adsorption compared to other natural mineral adsorbents.

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► Akadama clay was first used to remove Cr (VI) from aqueous solution.
► The maximum Cr (VI) adsorption capacity achieved 4.29 mg g−1.
► Electrostatic adsorption dominated the Cr (VI) adsorption process.
► Natural Akadama clay can provide an alternative method for Cr (VI) removal.