One-step preparation of polyimide-inlaid amine-rich porous organic block copolymer for efficient removal of chlorophenols from aqueous solution

A novel polyimide-inlaid amine-rich porous organic block copolymer(PI-b-ARPOP) was prepared via one-step polymerization by using different molar ratios of melamine(MA)/terephthalaldehyde(TA)/pyromellitic dianhydride(PMDA), at molar ratios of 4/3/1, 4/2/2 and 4/1/3. The copolymer contained both aminal groups belonging to ARPOP and imide groups belonging to PI, and the bonding styles of the monomers and growth orientations of the polymeric chains were diversiform, forming an excellent porous structure. Notably, MA/TA/PMDA(4/2/2) had a surface area and pore volume of 487.27 m~2/g and 1.169 cm~3/g,respectively. The adsorption performance of the materials towards 2,4-dichlorophenol(2,4-DCP) in ultra-pure water was systematically studied. The pH value of 7 was optimal in aqueous solution. Na~+ and Cl~-ions did not negatively affect the adsorption process, while humic acid(HA) slightly decreased the capacity. The equilibrium time was 40 sec, and the maximum adsorption capacity reached 282.49 mg/g at 298 K. The removal process was endothermic and spontaneous, and the copolymer could maintain its porous structure and consistent performance after regeneration by treatment with alkali. Moreover, to further assess the practical applicability of the material, the adsorption performance towards 2,4-DCP in river water was also investigated. This paper demonstrated that the PI-b-ARPOP can be an efficient and practical adsorbent to remove chlorophenols from aqueous solution.