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.

A label-free thymine-rich sequence and a molecular beacon were synthesized to construct a highly sensitive and selective fluorescence probe for the determination of mercury(II). The aptamer of the thymine-rich sequence selectively bonded with mercury(II) with an accompanying change in the fluorescence intensity of the molecular beacon due to the higher affinity of the aptamer with mercury(II). The limit of detection was 12.7 nanomolar, and a linear relationship was obtained between the fluorescence and mercury(II) concentrations up to 1 micromolar. The assay was highly selective for the mercury(II) and not significantly affected by other metal ions.