Preparation of ultrathin perovskite nanosheets by the exfoliation of H2CaTa2O7 for high-performance lead removal from water

Intercalation and delamination of two-dimensional solids are effective steps for exploiting their unique properties. Herein, the chemical exfoliation of the n-alcohol derivative of H2CaTa2O7 results in a colloidal suspension of monolayer nanosheets. Microscopic observation confirms the delamination of the parent perovskite. The thickness of the nanosheet obtained is 1.2 ± 0.1 nm. The dimensionally tailored H2CaTa2O7 nanosheets exhibit exceptional uptake of 300 mg g−1 Pb(II) ions at pH 5.0, and adsorption equilibrium is achieved in a short time span of 30 seconds. Experimental studies demonstrate that the treatment capacity for Pb(II) ions in simulated drinking water is 1.67 × 105 kg water per kg adsorbent. Desorption of Pb(II) ions is efficiently realized using 1 M HCl, which greatly reduces the cost associated with the regeneration. The large surface area of the ultrathin nanosheets and their nonporous structure facilitate the uptake of Pb(II) ions.