A microporous covalent triazine polymer (CTP) is synthesized via a Friedel-Crafts reaction and used as a solid support to immobilize magnetite Fe3O4 nano-particles. Thermogravimetric analysis shows that approximately 60 wt % Fe3O4 is loaded onto the composite, and transmission electron microscopy analysis illustrates that the Fe3O4 nanoparticles are uniformly impregnated into the CTP surface. The CTP-Fe3O4 nanocomposite is an efficient adsorbent for the removal of strontium ion (Sr2+) from seawater. Response surface methodology, employed to optimize the removal of Sr2+, confirms that the optimal conditions for this removal are 0.55 mg, pH 7, 40 degrees C, and 250 min. The experimental results illustrate that the adsorption process fits well with the Freundlich isotherm, with a correlation coefficient of 0.976 and a maximum adsorption capacity of 128 mg g(-1). The kinetic study demonstrates that the adsorption behavior follows pseudo-second-order kinetics. The adsorbent is easily recovered from seawater using an external magnetic field, thereby offering facile and economic separation of the adsorbent.