One-step synthesis of magnetic N-doped carbon nanotubes derived from waste plastics for effective Cr(Ⅵ) removal

The magnetic nitrogen-doped carbon nanotube is prepared by one-pot using waste plastics as feedstock in the existence of the urea and Fe(NO3)3 for Cr(Ⅵ) removal form wastewater. The characterization analysis indicates that the nitrogen is successfully doped on the magnetic nitrogen-doped carbon nanotube with specific surface area of the 158.71 m2/g and saturation magnetization of the 36.47 emu g−1. The existence of the nitrogen group and Fe3C contributes to Cr(Ⅵ) removal by complexation and reduction with adsorption capacity of the 27.47 mg g−1. The adsorption data is fitting well with the Pseudo-second order model, demonstrating chemisorption of Cr(Ⅵ). The Cr(Ⅵ) removal mechanism analysis indicates that Fe0, Fe2+, H*, oxygen-containing group and nitrogen-containing group are crucial to Cr(Ⅵ) removal. The key mechanism of the enhanced Cr (VI) removal is the reductive capacity by dissolved Fe2+, which accounts for 23.6 % of the overall Cr(VI) removal. The magnetic nitrogen-doped carbon nanotube is prepared from waste plastic for Cr (VI) removal from wastewater.