A Simplified Method for Synthesis of <scp>l</scp>-Tyrosine Modified Magnetite Nanoparticles and Its Application for the Removal of Organic Dyes

Abstract

In this work, l-tyrosine modified magnetite nanoparticles (TMNPs) are prepared by a facile ultrasound assisted solution route and used for adsorption of both methylene blue (MB) and methyl orange (MO), the typical cationic and anionic dye, respectively. The as-prepared magnetic adsorbents TMNPs are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), Fourier transform infrared (FT-IR), and vibrating sample magnetometer (VSM). The influential factors (solution pH and contact time) to the adsorption of the dyes by the magnetite nanoparticles are investigated. The adsorption kinetics illustrates the suitability of employing the pseudo-second-order kinetic model. Three isothermal adsorption models (Langmuir, Freundlich, and Temkin) are tested to investigate the adsorption properties. The results show that the adsorption behavior fits quite well with the Langmuir model. Thermodynamic parameters (ΔG°, ΔH°, and ΔS°) are estimated and implied that the adsorption process is spontaneous and exothermic in nature. Moreover, TMNPs can be successfully regenerated and reused for at least five cycles without compromising the adsorption capacity, which is greatly reduced the using cost.