Study on Simultaneous Removal of Dye and Heavy Metal Ions by NiAl-Layered Double Hydroxide Films.

Herein, nickel-aluminum-layered double hydroxide (NiAl-LDH) films were prepared by the hydrothermal method. Based on the photoinduced reduction ability and degradation of LDHs on heavy metal ions and organic compounds, NiAl-LDH films displayed favorable simultaneous removal performance. Benefiting from the electron traps of heavy metals reduced from solution, the coexisting metal ions improved the photocatalytic activity of NiAl-LDH films on methyl orange. The higher the Fermi level of coexisting metal ion was, the higher the photocatalytic degradation rate of methyl orange obtained. Meanwhile, the removal rates of heavy metal ions (Ag, Pb, and Cu) from wastewater were both enhanced and could reach 95%. NiAl-LDH films showed affinity toward Ag. Furthermore, NiAl-LDH films are tightly coupled with the substrate, providing active sites and a simple method for the catalyst recovery. This study provides new insights into the simultaneous removal of heavy metal ions and organic pollutants using LDH films.