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

Ma, Yan, Zhou, Qing, Li, Aimin, Shuang, Chendong, Shi, Qianqian, Zhang, Mancheng
Journal of hazardous materials 2014 v.266 pp. 84-93
acid tolerance, adsorbents, adsorption, chlortetracycline, equations, macropores, magnetite, nanoparticles, p-nitrophenol, pH, particle size, polymers, porous media, resins, sorption isotherms, surface area
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 3.1emu/g. M150 exhibited a specific surface area of 1022.4m2/g and an average pore width of 2.6nm. 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 (R2>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.