Efficient Capture of Heavy Metal Ions and Arsenic with a CaY-Carbonate Layered Double-Hydroxide Nanosheet.

Nanosheets consisting of two-dimensional (2-D) nanomaterials made up of Ca(2+) (Ca), and Y(3+) (Y) cations and carbonate [CO(3) (2-)] anions in the interlayer with a uniform thickness and lengths of around 10 μm have been successfully synthesized in a hydrotalcite layer structure, otherwise known as a layered double hydroxide, using a facile hydrothermal method. The resulting CaY-CO(3) (2-) layered double-hydroxide (LDH) materials demonstrate outstanding affinity and selectivity for toxic transition metal ions such as Cr(3+), Ni(2+), Cu(2+), Zn(2+), Pb(2+), Cd(2+), and Hg(2+) as well as metalloid As(3+). The adsorption of all of the highly toxic metal ions from the aqueous solution was found to be exceptionally rapid and highly selective, with more than 95% removal achieved within 30 min. For AsO(3), a strong adsorption potential of 452 mg/g was observed at pH 7.0, which is better than most values previously reported. The distribution coefficient K (d) values can exceed ∼10(6) mL/g for Cr(3+), Pb(2+), and As(3+), which are highly toxic. The fabricated materials have excellent chemical stability: they retain their well-defined lamellar shapes even under mildly acidic conditions.