Synthesis of ferromagnetic ordered mesoporous carbons for bulky dye molecules adsorption

The magnetic mesoporous carbon materials have been synthesized by chemical activation followed by reduction of Fe(NO 3 ) 3 under N 2 condition. All these materials possess dual-pore mesopore texture (2.8–2.9   nm and 3.5–4.1   nm), large surface areas (975–1321   m 2 /g), and high pore volumes (0.85–1.08   cm 3 /g). The adsorption capability and behavior of four dyes, methylthionine chloride (MC), methyl orange (MO), rhodamine B (RB), and gongo red (GR), were carried out on these magnetic bimodal mesoporous carbon materials. All the materials show the well adsorption capacity of the four dyes (highest reach 768   mg/g). After investigating the adsorption isotherms of these dyes, they all fit the typical Langmuir adsorption model. And the adsorption amount is mainly affected by BET surface area and the structure/size matching between adsorbent and adsorbate. With the highest BET surface area and 1D short mesopore structure, the sample shows the larger adsorbing capacity for the smaller molecular dyes (MC, MO). Moreover, the 1D long mesopore is benefit to absorb the dye with 1D long chain structural molecule (GR), while the storage capacity of RB (2D molecular structure) on 1D mesoporous adsorbent is the lowest.