Sulfonated Hollow Covalent Organic Polymer: Highly-Selective Adsorption toward Cationic Organic Dyes over Anionic Ones in Aqueous Solution

A sulfonated hollow covalent organic polymer (sh-COP-P) was prepared by post sulfonation of hollow covalent organic polymer (h-COP-P) synthesized through poly-condensation of tetrabiphenylporphyrin (TBPP). In comparison with h-COP-P, sh-COP-P exhibits significantly enhanced adsorption capacity of organic cationic dyes in aqueous solutions accompanied with notably reduced adsorption capacity of anionic dyes. This gives sh-COP-P a satisfactory performance in selectively separating cationic organic dyes from anionic ones, mainly attributed to the electrostatic interaction between polymer backbone and the guest molecules.