Core–shell magnetic nano-powders with an excellent decolorization effect on dye wastewater

In recent years, zero-valent nano-iron (nZVI) has received extensive attention due to its excellent decolorization effect on dye wastewater. In this paper, zero-valent nano-iron-nickel (nZVIN) powders were prepared by a simple, efficient and non-polluting method. The powder has a unique core–shell structure and excellent oxidation resistance. Hence the problem that nZVI powders are easily oxidized and difficult to store is solved. Due to the addition of Ni, the magnetic properties of the nZVIN powders are enhanced, which facilitates the recycling of the powders using a magnetic field after sewage treatment. In the decolorization treatment of dye wastewater simulated with Congo red (CR) dye, nZVIN powders can maintain a removal rate of more than 90% for CR solutions with different pH values (7.0–11.5) and an initial dye concentration (50–200 mg L(−1)). The research results show that nZVIN powders have broad application prospects in the treatment of azo dye wastewater.