Highly efficient removal of Pb(II) and Cd(II) ions using magnesium hydroxide nanostructure prepared from seawater bittern by electrochemical method

Abstract

In this work, we successfully synthesized magnesium hydroxide (Mg(OH)2) nanostructure from seawater bittern by electrochemical method. The synthesis was performed at room temperature employing graphite and nickel as anode and cathode, respectively, without any pH adjustment. The Mg(OH)2 nanomaterial was obtained in platelet form with length and thickness dimensions of 100–200 and 30–50 nm, respectively. From the surface analysis, the as-synthesized Mg(OH)2 nanomaterial has a large surface area (193.7 m2 g–1) and high pore volume (0.563 cm3 g–1), thus promising to be used as the adsorbent for the removal of Pb(II) and Cd(II) ions. Kinetics analyses show that these heavy metal ions followed the pseudo-second-order model with a rate constant (k2p) of 2.27 × 10–5 and 2.52 × 10–5 g mg–1 min–1 for Pb(II) and Cd(II) ions, respectively. Meanwhile, the maximum adsorption capacity (qmax) according to the Langmuir isotherm model for Pb(II) and Cd(II) ions was estimated to be 4.03 × 103 and 2.98 × 103 mg g–1, respectively. These remarkable qmax values were mainly driven by a large surface area and high pore volume of the as-synthesized material. Furthermore, the material can be remarkably reused for at least six consecutive cycles without significant loss in the adsorption capacity. This work is capable of providing highly efficient removal of heavy metal ions route by utilizing a low cost and highly reusable nanostructured Mg(OH)2, shows promising prospects for further large-scale applications.