Facile synthesis of novel bi-heteroatom functionalized hyper-crosslinked porous polymers with efficient adsorption of methylene blue and methyl orange

In this work, we designed and synthesized two novel bi-heteroatom functionalized hyper-crosslinked porous polymers (HCP-CT and HCP-CF) through a simple one-step Friedel–Crafts alkylation reaction. The resulted polymers N/S bi-heteroatom functionalized polymer HCP-CT and N/O bi-heteroatom functionalized polymer HCP-CF both have good adsorption property for organic dyes such as methyl orange (MO) and methylene blue (MB) in aqueous solution due to its rich pore structure, high specific surface area and rich-heteroatoms of pore surface. It is worth mentioned that the maximum adsorption capacity (q_max) of cationic dye MB by the porous polymer HCP-CT at room temperature was reached up to 1571.46 mg/g, which is much higher than that of most reported porous materials. Furthermore, the adsorption capacity of HCP-CT for the cationic dye MB was more than seven times that of the anionic dye MO (q_max = 212.77 mg/g). Also, the polymer HCP-CF for the MB adsorption capacity (q_max = 352.11 mg/g) was more than twice higher than that of anionic dye MO (q_max = 131.75 mg/g). The above trends may be because of the stronger electrostatic interaction between the negatively charged N-S/O bi-heteroatom of HCP-CT and HCP-CF with the cationic dye MB than that of MO. In addition, the removal percentage of polymers HCP-CT and HCP-CF still remained above 80% after five adsorption–desorption cycles. Hence, this work may provide a convenient synthetic route to develop a novel hyper-crosslinked polymer with high capacity for the entrapment of dyes from aqueous solution.