Synthesis of Poly(cyclotriphosphazene-co-4,4′-diaminodiphenysulfone) Microspheres and Their Adsorption Properties for Cationic Dyes (Methylene Blue)

Poly (cyclotriphosphazene-co-4,4′-diaminodiphenyl sulfone) (PZD) microspheres were prepared by precipitation polymerization with simple scheme and convenient operation, and used as a special effect adsorbent for adsorbing cationic dye, which is methylene blue (MB) in water. The synthesized PZD microspheres were characterized by SEM, TEM and XPS techniques. The influences of temperature, adsorption time, pH initial MB solution concentration and adsorbent dosage on MB adsorption were studied. The experimental results show that the adsorption of MB dye by PZD microspheres is more in line with the pseudo-second-order kinetics model than the pseudo-first-order kinetic model. In addition, the adsorption process was further resolved using Weber’s intraparticle diffusion model. Thermodynamic experiments show that the adsorption process is spontaneously carried out by endotherm. The mechanism of adsorption of MB dye by PZD microspheres may be related to the existence of a lot of electron-rich atoms N, P, S in the adsorbent, the electrostatic attraction and π–π stacking effect between PZD microspheres and MB dye.