Herein, the adsorption performance of sodium-doped graphitic carbon nitride in relation to the removal of methyl blue is investigated. The adsorbent was synthesized via the direct thermal polycondensation of cyanamide in the presence of sodium chloride. The inclusion of sodium in graphitic carbon nitride resulted in a substantial improvement of its adsorption capacity and adsorption kinetics. The maximum capacity for methyl blue was at least 8 times higher in comparison to commercial activated carbon and even 36 times higher than in the case of undoped material. The obtained adsorbents had very low porosity, and the resultant high adsorption capacities, as determined from the experiments, pointed to the extraordinary adsorption. Moreover, the equilibrium of the adsorption process was reached at the contact time less than 5 min. The obtained adsorbent was thoroughly investigated by means of various physical and chemical analyses. Additionally, the regeneration studies of the spent adsorbents were carried out.

The synthesis of graphitic carbon nitride (g-CN) doped with s-block metals is described. The materials were synthesized via thermal polycondensation of cyanamide and the appropriate metal chloride. The inclusion of the metal precursor strongly influenced the surface chemistry features as well as the textural, morphological, and structural properties of the g-CN. The doping of g-CNwith s-block metals markedly enhanced its adsorption performance, which was studied during the removal of two model solutes (methyl blue and copper ions) from aqueous solutions. The maximum adsorption capacity for the organic dye was increased by 680 times after the doping process. The uptake of copper(II) increased ca. 30 times for the doped g-CN. The improvement of the adsorption performance is discussed in terms of the surface chemistry and textural features.