Fine Tuning of the Dimensionality of Zinc Silicate Nanostructures and Their Application as Highly Efficient Absorbents for Toxic Metal Ions

The controllable synthesis of materials with the desired crystal structure and dimensionality is of great significance in material science. In this work we report the successful synthesis of amorphous and crystalline zinc silicates with different dimensionalities and well-defined shapes, including hollow spheres, nanowires and membranes. The structure-related absorption properties have been studied. A detailed study of their ability to remove Pb(II), Cd(II), Cr(III), and Fe(III) ions has been performed. The amorphous zero-dimensional (0-D) hollow spheres show the best removal ability for all the metal ions investigated. In particular, their absorption capacity for Pb(II) ions is 129 mg/g, which is double the value reported for magnesium silicate hollow spheres. However, the removal abilities of crystalline one-dimensional (1-D) nanowires and two-dimensional (2-D) membranes are found to be dependent on the charge of the target metal ion. In general, nanowires show better removal capacity for trivalent ions, especially Fe(III), while 2-D membranes exhibit better removal capacity for divalent ions.