Uptake of As(V) from aqueous solution by anionic clays type FeLDHs

The nature of the metal (Mg and/or Fe) salts, used as precursors during the synthesis process of layered double hydroxides, is used as a controlled variable synthesis parameter to obtain iron-containing anionic clay matrices with specific properties. The XRD and N2 adsorption at 77 K analyses indicate that the structural and the textural features of the synthesized clays are influenced by the use of chloride, sulphate or nitrate, as different salts precursors, during the clay synthesis. The As(V) removal capacity of the tested clays is also a function of the nature of the used salt precursors, the maximum value, equal to nearly 72%, being reached when iron sulphate is used as precursor in the clay synthesis process. After calcination, the arsenate removal capacity is higher than 90% for all the samples.

Iron-containing anionic clays, type LDHs, are synthesized using different metal salts (chloride, nitrate and sulphate) as precursors in the anionic clay synthesis process. The nature of the salt precursors gives rise to the specific structural and textural characteristics of the obtained anionic clay matrices. The As(V) removal capacity from the aqueous solutions of the obtained iron-containing clays reached nearly 72% when iron sulphate is used as salt precursor in the clay synthesis process, while the value decreases to nearly 45% when chlorate salts are used as precursors. After the clay calcination process, the arsenate removal capacity of the clay is higher than 90% for all the tested samples. The composition, the structural features and the textural properties of the tested anionic clays and the derived mixed oxides are all important to establishing these materials’ performances in the process of As(V) removal from the aqueous solutions.