Controllable Preparation of Superparamagnetic Fe(3)O(4)@La(OH)(3) Inorganic Polymer for Rapid Adsorption and Separation of Phosphate

Superparamagnetic Fe(3)O(4) 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 Fe(3)O(4) surface. The prepared Fe(3)O(4)@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 Fe(3)O(4)@La(OH)(3). It was observed that Fe(3)O(4)@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 Fe(3)O(4)@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 Fe(3)O(4)@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 Fe(3)O(4) microspheres have been synthesized for the first time by a controlled in-situ growth method. Experiments have proved that Fe(3)O(4)@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.