Highly efficient removal of methyl blue from aqueous solution using a novel nitrogen-doped porous magnetic carbon

Developing magnetic adsorbents with high adsorption capacity and rapid adsorption rate is one of the greatest challenges for the removal of methyl blue (MB) from aqueous media. In this work, a novel nitrogen-doped porous magnetic carbon (denoted as N-PMC) was designed and synthesized by one-step pyrolysis method. The obtained novel porous carbon N-PMC was found highly effective in removing MB from aqueous solution. The MB adsorption rate (k(2) = 1.34 mg g(-1) min(-1)) of N-PMC is rapid, which is 15-20 times greater than those of activated carbon. The maximum adsorption capacity of N-PMC at room temperature calculated from the Langmuir model was 1,053.5 mg g(-1), one of the highest values among the currently reported magenetic adsorbents. Both experimental results and the DFT calculations illustrated that the electrostatic interaction between the N heteroatoms of the N-PMC and MB, which was responsible for efficient adsorption. Furthermore, the N-PMC could be easily isolated by magnetic force and recycled at least five times without significant loss in adsorption capacity. Therefore, the convenient synthetic route, the high adsorption capacity, the rapid adsorption rate and fast separation process make the porous carbon an attractive adsorbent for removing organic dyes from aqueous solution.