Preparation and adsorption property of a unique sodium titanate with large size hierarchical structure

Sodium titanate material has been employed for the adsorption of heavy metal ions in water due to its open crystal structure and large layer spacing. However, its preparation conditions are harsh and recovery is difficult, which limits its practical application. In this paper, the sea urchin-like sodium titanate (SST) with hierarchical structure was synthesized under simple conditions. The chemical formula of obtained SST is Na 1.32 H 0.68 Ti 3 O 7 ·1.26H 2 O, the overall shape is spherical, and the average size is 1.7 μm. SST has a large specific surface area (351.64 m 2 /g) and demonstrates outstanding adsorption capacity for heavy metal ions (Ag + Cu 2+ and Cr 3+ ) in water. At room temperature and pH = 5, the adsorption of Ag + , Cu 2+ and Cr 3+ can reach equilibrium within 30 min, and the maximum adsorption capacity can respectively reach to 386.10 mg/g, 137.08 mg/g and 54.81 mg/g, which main mechanism is ion exchange and inner layer complexation. The sample also exhibits good recovery performance. After adsorption of heavy metal ions, SST can completely settle in a short time, which is conducive to its recovery. The advantages of simple preparation method, excellent adsorption behavior and outstanding recycling performance make SST promising to be further applied in practice.