Removal of nitrate from radioactive wastewater using magnetic multi-walled carbon nanotubes

In the solidification process using asphalt as a medium, nitrate oxidizes the medium and makes it unstable. Therefore, in order to efficiently remove nitrate from wastewater, a magnetic adsorbent was synthesized (m-MWCNTs), and physicochemical properties of m-MWCNTs were confirmed by SEM, TEM, XRD, FT-IR, BET, and VSM analyses. In the process of synthesizing m-MWCNTs, the amount of magnetite introduced on the surface of MWCNTs could be controlled by increasing the concentration of the chemical agent that becomes the Fe precursor. In addition, the amount of nitrate adsorption increased with higher magnetite content on the surface of MWCNTs. The adsorption process followed the Langmuir model and pseudo-second-order kinetics. In nitrate adsorption using m-MWCNTs, pH was the main condition to determine the adsorption amount, and as the pH increased, the amount of nitrate adsorption decreased. Thermodynamic experiments revealed that the adsorption of nitrate by m-MWCNTs is an endothermic and spontaneous process. [Display omitted] •Magnetic MWCNTs (m-MWCNTs) was synthesized successfully for removal of nitrate.•Increasing Fe3O4 loading on MWCNTs surface leads to an increase in nitrate adsorption capacity.•Adsorption of nitrate by m-MWCNTs was favorable in acidic conditions.