Enhanced arsenic removal from water by mechanochemical synthesis of Ca–Al–Fe ternary composites

Abstract To date, there have been many studies on arsenic removal by the multi-metal Fe/Al oxide compound adsorbents. The various precious metal oxides were usually incorporated to enhance the removal efficiency while increasing the cost of the complex adsorbents remarkably. In this work, the traditional method of adding rare or precious metal oxides was abandoned, high efficiency and low-cost Ca–Al–Fe ternary composite was synthesized through mechanochemical processing and low temperature calcination for the efficient removal of As(III). The SEM-EDS, BET, XPS and TG-DSC were employed to characterize the Ca–Al–Fe ternary composite before and after As(III) adsorption. Moreover, the As(III) removal mechanism and the composition and physical properties of the Ca–Al–Fe ternary composite were also studied. The kinetics study fitted the pseudo-second-order model, and the adsorption isotherm followed the Freundlich model, of which the maximum adsorption capacity up to 56.86 mg/g. The Ca–Al–Fe ternary composite is of high activity and amorphous type, which can be attributed to the Al(III) and freshly generated Fe(III) to generate Fe–Al hydroxide enhancing the high adsorption capacity. The excellent As(III) removal efficiency and reusability of the Ca–Al–Fe ternary composite suggested its vast application prospects as a competitive candidate for As(III) pollution remediation in water.