Facile synthesis of highly water-dispersible and monodispersed Fe3O4 hollow microspheres and their application in water treatment

Abstract

Highly water-dispersible and monodispersed Fe 3 O 4 hollow microspheres have been synthesized by a simple one-pot hydrothermal method, in which sodium polyacrylate (PAAS) was used as a dispersant and size-controlling reagent. The results showed that the obtained Fe 3 O 4 hollow microspheres were composed of nanoparticles less than 15 nm in diameter and exhibited superparamagnetic properties with relatively high saturation magnetization at room temperature. Meanwhile, the negatively-charged carboxyl groups from PAAS were closely attached to the surface of the Fe 3 O 4 hollow microspheres, which made them highly water-dispersible. The reaction process was systematically investigated and we found that the Fe 3 O 4 hollow microspheres in our experiment were formed through a self-template process, where the solid a-Fe 2 O 3 microspheres generated at the initial stage transformed into Fe 3 O 4 hollow microspheres through the synergetic effect of Ostwald ripening and reduction. Additionally, the PAAS, by regulating the viscosity of the reaction solution through varying the concentration, could indirectly adjust the size of the Fe 3 O 4 hollow microspheres ranging from 200 nm to 340 nm. Finally, the obtained Fe 3 O 4 hollow microspheres were demonstrated to be an excellent adsorbent of heavy metal ions like Pb 2+ due to their abundant carboxyl groups and magnetic separability.

Growth mechanism of bioglass nanoparticles in polyacrylonitrile-based carbon nanofibers

“…In Ostwald ripening mechanism, a characteristic stated is the formation of spherical-type particles, for the material diffusion in the atomistic level was isotropic as mentioned in our previous study 27 and literature. 26,49,50 In coalescence mechanism, whereas, the feature is the formation of irregular-shaped particles as a result of anisotropic and random diffusion-collision of sub-particles. 25,51,52 Therefore, the growth of BG nanoparticles with well-distributed spherical shape along CNFs was dominated by Ostwald ripening mechanism at the sintering temperature of 800 C and the initial stage of the sintering temperature of 1000 C. As the sintering going on, the spherical BG nanoparticles in CNF/BG-1000 began to merge into irregular-shaped particles, which meant coalescence had taken part in the morphology evolution.…”

<p>Hollow Prussian Blue Nanospheres for Photothermal/Chemo-Synergistic Therapy</p>

“…The monodisperse Fe 2 O 3 nanospheres were prepared through the hydrothermal reaction reported previously. 40 The as-obtained Fe 2 O 3 nanospheres (15 mg) were dispersed in a water-ethanol mixture (40 mL) including PVP (0.2 g) under an ultrasound instrument for 2 h at room temperature (25°C) and mechanical stirring (300 r/min) at the same time. After 0.1 mL K 4 [Fe(CN) 6 ]•3H 2 O (0.1 M) solution were added, 5 mL HCl solution (7.2 M) were introduced by a peristaltic pump.…”

Enantioselective absorption of enantiomers with maleic anhydride-β-cyclodextrin modified magnetic microspheres

“…[16][17][18][19] Furthermore, magnetic microspheres can be used for further functionalization to be widely applied to a range of disciplines, including environmental remediation, drug delivery, cancer diagnosis and magnetic resonance imaging. [20][21][22][23][24] In recent years, several groups have used chiral selector-modied MNPs for separation of chiral compounds. Wei et al employed MNPs coated with an immobilized cellulose derivative for the research of racemates.…”