BACKGROUND A magnetic conjugated microporous polymer (MCMP) composite was designed with bromo groups of CMP and amino groups on the surface of Fe3O4 nanoparticles that acted as promising adsorbents for wastewater treatment. Fe3O4 nanoparticles were successfully bonded on the predesigned CMP material to form the MCMP by means of a new and simple nucleophilic substitution reaction in organic media. RESULTS The MCMP could be separated by applying an external magnetic field because of the Fe3O4 nanoparticles. It exhibited sufficient dye adsorption for methylene blue (MB) with a high sorption capability of 869.43 mg g(-1) in aqueous solutions. The recovery and reusability of MCMP were >70% after six cycles of desorption and regeneration, indicating that the MCMP had excellent cycle stability. The magnetization saturation strength of MCMP was 13.5 emu g(-1) which was sufficient to be magnetically separated from wastewater using artificial magnetic fields. CONCLUSION The MCMP possessed excellent adsorption capacity and dispersibility, and good recyclability after banded with functionalized Fe3O4 nanoparticles. The excellent properties of MCMP indicated that it could be used as an adsorbent with great application potential for quick separation of water pollutants such as dyes in wastewater treatment. (c) 2019 Society of Chemical Industry