Medium-chain alkylated magnetic ion-exchange resins via low-pressure UV initiation for superior phosphate adsorption

This study proposed a UV-initiated strategy for the synthesis of magnetic ion exchange resins. Two novel magnetic resins were successfully prepared by suspension polymerization method using 1-iodohexane as a long carbon chain alkylating agent under low-pressure ultraviolet (UV) initiation conditions. The polymerization reaction time of resin was significantly reduced to 2 h due to the UV initiation. MGD resin properties exhibited high synthetic stability and good reproducibility. The prepared resin particles possessed rich micropores and mesopores structure with a particle size of 50–250 um. The long carbon chain alkylating agent (1-iodohexane) could improve increasingly the adsorption capacity for phosphate (69.65 %) compared with the short carbon chain alkylating agent (dichloroethane). Site energy analysis found that the concentrated distribution of high-energy sites and surface homogeneity of resins contributed to their high adsorption capacity. DFT calculations, characterizations of resins before and after adsorption, and stoichiometric experiments revealed the electrostatic attraction and ion exchange dominated the removal mechanisms of phosphate adsorbed on prepared resins. DFT results indicated longer chain lengths enhanced both the non-electrostatic and electrostatic components of the adsorption energies. Therefore, compared to thermal initiation, low-pressure UV initiation offered advantages such as high efficiency, rapidity, low-carbon and environmental friendliness for the preparation strategy of a new generation of high-performance magnetic resin.