Magnetite nanoparticles with aminomethylenephosphonic groups: synthesis, characterization and uptake of europium(III) ions from aqueous media

Two adsorbents with covalently bound aminomethylenephosphonic acid functions (and referred to as MNPs/AMPA and MNPs/SiO2-AMPA) were synthesized from two types of amino-functionalized magnetic nanoparticles (MNPs) via Moedritzer-Irani reaction. The sorbents with anchored dopamine ligand (MNPs/dopa) or aminopropyl groups (MNPs/SiO2-NH2), and the MNPs/AMPA were characterized by X-ray diffraction, FTIR, transmission electron microscopy and vibrating sample magnetometry. Surface modification does not adversely impact the physical properties of the starting magnetite. Compared to the size of the unmodified Fe3O4 (magnetite) nanoparticles (7–12 nm), the average size of functionalized nanoparticles is increased to 10–16 nm. Similarly, the magnetic saturation decreased from 67.5 emu g-1 to 42.0 emu g−1, and the surface area is increased up to 205 m2 g−1 for MNPs/SiO2-AMPA. The kinetics of the adsorption of Eu(III) on the sorbent is ultra-fast, and equilibria are attained within 5–10 min at room temperature. The adsorption kinetics can be described by a pseudo-second-order model. Adsorption and desorption conditions were tested with respect to the removal of Eu(III) ions from water solution. The adsorption capacities for Eu(III) at pH 7.0 are 77 mg g−1 and 69 mg g−1 for MNPs/AMPA and MNPs/SiO2-AMPA nanoparticles, respectively. Eu(III) was quantified by ICP-MS. The limit of detection (LOD) for Eu(III) is 0.05 ng L−1 (based on the 3σ criterion), with an enrichment factor of 150. The selectivity over ions such as Tb(III), Fe(III), Zn(II), Cu(II), and Ca(II) ions was studied. Under optimal condition the distribution coefficient for Eu(III) relative to these ions is near 105 mL g−1. The sorbents can be easily retrieved from even large volumes of aqueous solutions by magnetic separations. The method was tested for spiked water samples (with recoveries from 96.6–102.5%) and for rock minerals.Financial support was provided by Ministry of Economy and Competitiveness (MINECO, Spain) MAT2016-78155-C2-1-R and EU (FP-7-PEOPLE-2009-IRSES grant No. 247603)

New phosphate-sulfates with NZP structure

NaZr2–xBx(PO4)3–2x(SO4)2x (0 ≤ x ≤ 1.25, B = Mg, Co, Ni, Cu, Zn), and NaZr2– xRx(PO4)3–x(SO4)x (0 ≤ x ≤ 1.25, R = Al, Fe) phosphate-sulfates series have been prepared by a sol–gel process. These compounds belong to the NaZr2(PO4)3 (NZP) structure family and crystallize in hexagonal crystal system, space group R c. Limited solid solution series were found to exist; their formation temperatures and thermal stability limits were determined. Particle sizes as determined by microstructure observation were 50–200 nm, and for Cu- and Zn-containing samples, 200–500 nm. The thermal expansion of phosphate-sulfate NaZr1.25Cu0.75(PO4)1.5(SO4)1.5 was studied in the range 25–700°C. Thermal expansion coefficients and thermal expansion anisotropy were found to be αa = –5.40 × 10–6 °C–1, αс = 18.88 × 10–6 °C–1, αavg = 2.69 × 10–6 °C–1, and Δα = 24.28 × 10–6 °C–1

Crystallographic studies of NaZr2(PO4)(3) phosphates at high temperatures

European Crystallography Meeting (31st. 2018. Oviedo, Spain

Preparation and thermal expansion of calcium iron zirconium phosphates with the NaZr2(PO4)3 structure

Ca0.5(1+x)Zr2–xFex(PO4)3 phosphates have been synthesized by a sol–gel process. The individual compounds and solid solutions obtained crystallize in the NaZr2(PO4)3 structure (trigonal symmetry, sp. gr. R ). Using high-temperature X-ray diffraction, we have determined their thermal expansion parameters in the temperature range from 25 to 800°C. With increasing x, the magnitudes of their linear thermal expansion coefficients and thermal expansion anisotropy decrease. Most of the synthesized phosphates can be rated as low-thermal-expansion compounds and can be regarded as materials capable of withstanding thermal “stress”

Preparation of NZP-type Ca0.75+0.5xZr1.5Fe0.5(PO4)3-x(SiO4)x powders and ceramic, thermal expansion behavior

Ca0.75+0.5xZr1.5Fe0.5(PO4)3–x(SiO4)x (x = 0–0.5) solid solutions have been synthesized by a sol–gel process and characterized by X-ray diffraction, IR spectroscopy, and differential scanning calorimetry. As expected, the synthesized phosphatosilicates crystallize in a NaZr2(PO4)3-type structure (trigonal symmetry, sp. gr. R c). The thermal expansion of the solid solutions has been studied by high-temperature X-ray diffraction in the temperature range from 25 to 800°C. Their thermal expansion parameters have been calculated and analyzed as functions of composition. High-density ceramics based on the Ca0.875Zr1.5Fe0.5(PO4)2.75(SiO4)0.25 phosphatosilicate have been produced by spark plasma sintering and their structure and properties have been studied in detail