title: Effective Removal of Tetracycline from Aqueous Solution by Organic Acid-Coated Magnetic Nanoparticles.
abstract: Self-assembled iron oxide nanocomposites are good magnetic nano-adsorbents that can be prepared using simple methods. Four types of organic acid-functionalised (oleic acid, undecenoic acid, caprylic acid or hexanoic acid) magnetic nanoparticles (MNPs) were synthesised through a one-pot chemisorption method for the removal of tetracycline (TC) from aqueous solution. The undecenoic acid-coated MNPs (UA-MNPs) exhibited the highest adsorption efficiency and can be easily retrieved with a low-gradient magnetic separator (0.4 Tesla) at pH 5.0 aqueous solution. The TC adsorption process on the UA-MNPs followed the Langmuir isotherm and the maximum adsorption capacities increased from 86.96 mg g(-1) to 222.2 mg g(-1) with the increase in temperature from 288 K to 318 K. The kinetics of adsorption fits pseudo-second-order model perfectly with a rate constant, 5.946 g mg(-1) min(-1) at 298 K. The positive values of the enthalpy (AH) and the negative value of the free energy (AG) indicated an endothermic and spontaneous adsorption process of TC on the UA-MNPs. Moreover, the UA-MNPs possessed excellent ability to adsorb the other three major types of TC antibiotics, including chlortetracycline, oxytetracycline and doxycycline.
authors.forename: Liang
authors.initials: L
authors.lastname: Guo
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Liang
authors.forename: Xuelan
authors.initials: X
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.forename: Kesheng
authors.initials: K
authors.lastname: Wu
authors.forename: Hua
authors.initials: H
authors.lastname: Wei
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Xiong
mesh_terms: D000327:Adsorption; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008280:Magnetics; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles; D017550:Spectroscopy, Fourier Transform Infrared; D013752:Tetracycline / Q000737:chemistry / Q000302:isolation & purification*; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D014874:Water Pollutants, Chemical; D013752:Tetracycline