Synthesis of Highly Selective Magnetic Mesoporous Adsorbent

Abstract

Magnetic MCM-41 of large surface area (ca. 800 m2 g−1) and high magnetization (ca. 8.3 emu g−1) was prepared at a reasonable iron oxide nanoparticles loading of 10 wt % by a two-step synthesis process. The 8 nm iron oxide nanoparticles (i.e., 30 m2 g−1) were embedded in the MCM-41 with no observable effects on the particle morphology and pore symmetry, but a slight change (i.e., <20%) in the textural properties and surface chemistry was detected. Aminopropyls (2.7 mmol g−1) were grafted on the mesopore channels followed by the adsorption of 1.2 mmol g−1 Fe3+ to prepare selective adsorbents for arsenic(V) and chromium(VI) oxyanions. Detailed analyses indicated that the surface modifications of the magnetic and nonmagnetic MCM-41 by aminopropyls and Fe3+ yield similar site chemistry and accessibility. The Fe3+-magMCM-41 and Fe3+-MCM-41 displayed comparable adsorption capacity and selectivity. Both adsorbed only As(V) and Cr(VI) oxyanions (i.e., 1.0 and 2.0 mmol g−1, respectively), and none of the Cu(II). The magnetic adsorbent was easily dispersed in aqueous solution and can be removed by a magnet (1550 G) at a rate of 1 cm min−1 compared to 0.004 cm min−1 by gravity.

Removal of tetracycline antibiotics from aqueous solution by amino-Fe (III) functionalized SBA15

“…N 1s spectra exhibited two peaks: 399.5 eV was assigned to the amino group, and the peak at 401.0 eV was attributed to amino perturbed by Fe (III), which was also reported by Chen et al and Zuo et al [32,33]. After TC adsorption, the binding energy of 401.0 eV decreased to 400.5 eV, and the relative content increased from 44% to 61%, 53%, 52% for TC, OTC and CTC, respectively (Table S1).…”

Preparation of amino-Fe(III) functionalized mesoporous silica for synergistic adsorption of tetracycline and copper

“…Langmuir Freundlich 399.3-399.6 eV can be assigned to ANH 2 or ANH, and the peak at 401.4-401.7 eV is assigned to amino perturbed by a positive cation, NH 2 AFe(III), which was also observed by Chen et al (2009), Zuo et al (2012. After TC uptake, only slight shifts of the two peaks were observed which attributed to the interaction between Fe(III) and amide of TC.…”

Organic Ligands Made Porous: Magnetic and Catalytic Properties of Transition Metals Coordinated to the Surfaces of Mesoporous Organosilica

“…However, in agreement with EPR a large paramagnetic background contribution was discovered in the m(H) measurements, which is present not only at 300 K but also at 6 K. Therefore, the case reported here is different to studies in which magnetic effects in mesoporous materials were caused by larger and clearly identifiable nanoparticles (e.g., iron oxide). [30] 2.1.…”