Simple synthesis of Ni-containing ordered mesoporous carbons and their adsorption/desorption of methylene orange

► A simple route has been developed to synthesize Ni/OMCs without using a solvent for dissolving carbon precursor or magnetic source. ► The materials exhibited soft ferromagnetic characteristics desirable for the application in dye adsorption and separation under an external magnetic field. ► A simple desorption equation was obtained and the physical meanings of the parameters were well defined.