Synthesis of a Novel Porous Self-Settling Magnetic Anion Exchange Resin and its Removal Mechanism for Tannic Acid

A new porous self-precipitating magnetic anion exchange resin (CMIET) doped with gamma-Fe2O3 was prepared by suspension polymerisation and characterized by FT-IR, TGA, SEM, BET, and VSM. An adsorbent with a rough surface porous structure, enriched with a mesoporous strong magnetic self-absorbent was obtained. A specific surface area of 19.10 m2/g, a pore volume of 0.2045 cm3/g, a pore size of 36.71 nm exchange capacity of 7.81 mmol/g, and an equilibrium adsorption capacity of up to 46.28 mg/g were measured. The effects of contact time, initial concentration, and solution pH were investigated by batch adsorption experiments. In the removal process, the removal rate of TA was up to 95 % at pH=4-7, saturation adsorption was achieved in 30 min, and regeneration time of 120 min could restore the resin activity. The adsorption isotherm of TA on the resin was by the Langmuir model, the adsorption kinetics was by the Pseudo Secondary Kinetic model, and the adsorption process was spontaneous heat absorption. The regeneration experiments showed good reusability of CMIET, a highly efficient and fast magnetic ion exchange resin with a wide range of applications in the aqueous environment. Firstly, the TA diffuses to the resin surface and is electrostatically attracted to the -N+(CH3)3 group. Secondly, the -OH group in TA is hydrogen bonded to the resin. Finally, there are many mesopores and micropores on the surface of the resin, and the TA molecules are adsorbed into the internal pores of the resin and undergo pi-pi interactions.image