Preparation of a novel magnetic microporous adsorbent and its adsorption behavior of p-nitrophenol and chlorotetracycline

Abstract A novel method for fabricating hypercrosslinked magnetic polymer beads with improved acid resistance was developed. Magnetite nanoparticles were covered with tetraethoxysilane and vinyltriethoxysilane, followed by co-polymerization and post-crosslinking. The resulting M150 beads were highly stable at pH ≥ 2 and were superparamagnetic, with a saturation magnetization of 3.1 emu/g. M150 exhibited a specific surface area of 1022.4 m 2 /g and an average pore width of 2.6 nm. The adsorption of p -nitrophenol and chlorotetracycline (CTC) onto M150 and the commercial non-magnetic resins NDA 150 and XAD-4 followed both pseudo-first-order and pseudo-second-order equations. M150 displayed much faster kinetics than the other resins because of its small particle size and abundant macropores. The adsorption isotherm of p -nitrophenol onto the three resins fitted the Freundlich equation ( R 2  > 0.98), whereas CTC adsorption was better described by the Langmuir isotherm. p -Nitrophenol adsorption was optimal at pH ≤ 4, whereas CTC adsorption was optimal at pH 5–6. All three sorbents showed high reusability for p -nitrophenol adsorption. XAD-4 demonstrated the highest reusability for CTC. The CTC adsorption capacities of M150 and NDA150 decreased by 12.42% and 20% after 10 adsorption–desorption cycles, respectively.