Controllable Preparation of Superparamagnetic Fe3O4@La(OH)3 Inorganic Polymer for Rapid Adsorption and Separation of Phosphate

Superparamagnetic Fe3O4 particles have been synthesized by solvothermal method, and a layer of dense silica sol polymer is coated on the surface prepared by sol-gel technique; then La(OH)(3) covered the surface of silica sol polymer in an irregular shape by controlled in situ growth technology. These magnetic materials are characterized by TEM, FT-IR, XRD, SEM, EDS and VSM; the results show that La(OH)(3) nanoparticles have successfully modified on Fe3O4 surface. The prepared Fe3O4@La(OH)(3) inorganic polymer has been used as adsorbent to remove phosphate efficiently. The effects of solution pH, adsorbent dosage and co-existing ions on phosphate removal are investigated. Moreover, the adsorption kinetic equation and isothermal model are used to describe the adsorption performance of Fe3O4@La(OH)(3). It was observed that Fe3O4@La(OH)(3) exhibits a fast equilibrium time of 20 min, high phosphate removal rate (>95.7%), high sorption capacity of 63.72 mgP/g, excellent selectivity for phosphate in the presence of competing ions, under the conditions of phosphate concentration 30 mgP/L, pH = 7, adsorbent dose 0.6 g/L and room temperature. The phosphate adsorption process by Fe3O4@La(OH)(3) is best described by the pseudo-second-order equation and Langmuir isotherm model. Furthermore, the real samples and reusability experiment indicate that Fe3O4@La(OH)(3) could be regenerated after desorption, and 92.78% phosphate removing remained after five cycles. Therefore, La(OH)(3) nanoparticles deposited on the surface of monodisperse Fe3O4 microspheres have been synthesized for the first time by a controlled in-situ growth method. Experiments have proved that Fe3O4@La(OH)(3) particles with fast separability, large adsorption capacity and easy reusability can be used as a promising material in the treatment of phosphate wastewater or organic pollutants containing phosphoric acid functional group.

Automated summary

Superparamagnetic Fe3O4 particles were synthesized by solvothermal method, and a layer of dense silica sol polymer was coated on the surface prepared by sol-gel technique; then La(OH)(3) deposited on the surface of silica sol polymer by controlled in situ growth technology. These materials showed excellent adsorption capacity for phosphate removal, with a high removal rate, high sorption capacity, and good selectivity in the presence of competing ions. Moreover, the Fe3O4@La(OH)(3) particles demonstrated fast separability, easy reusability, and high stability.