Covalent Triazine Polymer-Fe₃O₄ Nanocomposite for Strontium Ion Removal from Seawater

A microporous covalent triazine polymer (CTP) is synthesized via a Friedel-Crafts reaction and used as a solid support to immobilize magnetite Fe₃O₄ nanoparticles. 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 °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.