Simultaneous removal of arsenate and antimonate in simulated and practical water samples by adsorption onto Zn/Fe layered double hydroxide

• A ferric-based layered double hydroxide (Zn–Fe-LDH) has been synthesized.
• Zn–Fe-LDH shows excellent adsorption performance toward both arsenate and antimonate.
• As(V) and Sb(V) in practical polluted water samples were removed simultaneously and efficiently.
• Column tests demonstrated the high handling capacity of Zn–Fe-LDH for As(V) and Sb(V).

This study proposes the use of a Zn/Fe layered double hydroxide (Zn–Fe-LDH) material to achieve the simultaneous and efficient removal of As(V) and Sb(V) in aqueous solutions. The Zn–Fe-LDH material has been synthesized by a co-precipitation method and used to remove arsenate and antimonate in both simulated and practical polluted water samples. The adsorption performances were studied by batch experiments and column tests. The experimental result of simulated water samples showed that the adsorption of As(V) or Sb(V) onto Zn–Fe-LDH material can be well described by the Sips isotherm model. It was found that the maximum adsorption capacity for As(V) and Sb(V) in single pollutant system was 151.37 mg g−1 and 122.03 mg g−1, respectively. When the adsorbent dosage was 0.2 g L−1, the batch experiments showed that the residual concentration of arsenic or antimonate can be decreased from 2 mg L−1 to lower than 0.005 mg L−1. For the practical polluted water samples from Xikuangshan area, the result showed that the dosage of 0.2 g L−1 Zn–Fe-LDH can make both the arsenic and antimony residual concentrations meet the limit value of drinking water standard recommended by WHO. It is deduced from the column tests that 1 kg Zn–Fe-LDH material might treat 12,500 L polluted water from1 mg L−1 arsenate and 1 mg L−1 antimonate to the level below 10 μg L−1 and 5 μg L−1 simultaneously. It is demonstrated that the synthesized Zn–Fe-LDH material is a potential attractive adsorbent for the simultaneous removal of As(V) and Sb(V) in water.

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