Highly efficient removal of arsenic(III) from aqueous solution by zeolitic imidazolate frameworks with different morphology

In this study, zeolitic imidazolate frameworks (ZIFs) sorbents with three different morphology (cubic ZIFs, leaf-shaped ZIFs and dodecahedral ZIFs) were successfully synthesized in aqueous solution via green methods at room temperature and tested for removal of As(III). The ZIFs are all high crystalline, and with a BET surface area of 958.4, 12.7 and 1151.2m2/g for cubic ZIFs, leaf-shaped ZIFs and dodecahedral ZIFs, respectively The experiment revealed that all three adsorbents exhibited excellent adsorption capacities of As(III) despite distinct specific surface area and morphology. The adsorption isotherms of cubic ZIFs, leaf-shaped ZIFs and dodecahedral ZIFs were generally fitted by Langmuir model and the maximum adsorption capacities were 122.6, 108.1, 117.5mg/g, respectively at pH 8.5. At initial concentration of 200?g/L, As(III) was rapidly decreased to below 10?g/L by the three ZIFs in 2h at a adsorbent dosage of 0.2g/L. It was found that zinc hydroxyl substitution was the main surface complexation method for As(III) adsorption onto the three ZIFs evidenced by the FTIR and XPS results.