ABSTRACT
In this paper, amido-functionalized MOFs with core/shell magnetic particles (Fe3O4@MIL-53(Al)-NH2) was prepared by the solvothermal method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), Vibrating Sample Magnetometer (VSM) and UV/VIS spectrophotometer. The influence of different factors on the adsorption effect of the pollutant, including adsorbent amounts, adsorption time, ionic strength and pH, were explored. It was found that the amine-decorated Fe3O4@MIL-53(Al)-NH2 were efficient for removal of contaminant, with the adsorption capacity for bisphenol A (234.1 mg/g) and tetracycline (84.8 mg/g) under the optimized conditions. The adsorption kinetics and the equilibrium adsorption data indicated that the adsorption process of BPA and TC was more compatible with the pseudo-second-order kinetic model and the Langmuir model, respectively. The thermodynamic values show the adsorption of the mentioned contaminant was spontaneous and endothermic. Moreover, the Fe3O4@MIL-53(Al)-NH2 adsorbent had good regeneration and reusability capacity after five cyclic utilization. All these results show Fe3O4@MIL-53(Al)-NH2 adsorbent could be a potential candidate for future water purification.
ABSTRACT
A magnetic metal-organic frameworks adsorbent (Fe3O4@MIL-53(Al)) was prepared by a typical solvothermal method for the removal of bisphenol A (BPA), tetracycline (TC), congo red (CR), and methylene blue (MB). The prepared Fe3O4@MIL-53(Al) composite adsorbent was well characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and fourier transform infrared spectrometer (FTIR). The influence of adsorbent quantity, adsorption time, pH and ionic strength on the adsorption of the mentioned pollutants were also studied by a UV/Vis spectrophotometer. The adsorption capacities were found to be 160.9 mg/g for BPA, 47.8 mg/g for TC, 234.4 mg/g for CR, 70.8 mg/g for MB, respectively, which is superior to the other reported adsorbents. The adsorption of BPA, TC, and CR were well-fitted by the Langmuir adsorption isotherm model, while MB followed the Freundlich model, while the adsorption kinetics data of all pollutants followed the pseudo-second-order kinetic models. The thermodynamic values, including the enthalpy change (ΔH°), the Gibbs free energy change (ΔG°), and entropy change (ΔS°), showed that the adsorption processes were spontaneous and exothermic entropy-reduction process for BPA, but spontaneous and endothermic entropy-increasing processes for the others. The Fe3O4@MIL-53(Al) was also found to be easily separated after external magnetic field, can be a potential candidate for future water treatment.
ABSTRACT
Trihalomethanes (THMs) are the primary toxic and carcinogenic byproducts during disinfection of drinking water. THMs have been frequently detected in water body and posed a huge threat to human health. Thus, analyzing the trace levels of THMs in an accurate and rapid method for water quality monitoring is important. In this paper, silver-based organic coordination networks (Ag-OCN) were fabricated with different diameters under mild pH condition. After modification with magnet, Fe3O4 @ Ag-OCN as extractant was applied to the magnetic solid-phase extraction of THMs from water samples. Gas chromatography-tandem mass spectrometry was used for sample quantification and detection. The magnetic extractant displayed good linearity in the range of 0.03-10 ug/L, low limits of detection (1.41-10.13â¯ng/L), and good reproducibility (relative standard deviations < 6.31%). Moreover, density-functional theory (DFT) calculation was also applied to investigate the possible interaction mechanism. Combining the experimental data with theoretical calculation, results showed that Fe3O4 @ Ag-OCN was a potential magnetic material for the enrichment and extraction of formed THMs at trace levels from water samples.
ABSTRACT
A composite material that comprised metal-organic nanotubes (MONTs) and a sponge, Cu-MONTs-sponge, was synthesized by using a rapid and convenient surfactant-assisted dip-coating method and used as a high-performance adsorbent for the solid-phase extraction of pharmaceuticals and personal care products (PPCP) from environmental water samples. By adjusting the surfactant concentration, a composite material that contained metal-organic nanotubes and a macroporous 3D porous sponge was constructed. This modified sponge achieved outstanding reproducibility as an adsorbent, with the adsorption of trace or ultratrace amounts of contaminants. Moreover, this composite material was conveniently recycled and its extraction efficiency only decreased by 6.3-12.1 % after 30â adsorption/desorption cycles. The resulting composite exhibited excellent adsorption capacity for PPCPs, which was attributed to its unique porous structure, natural hydrophobicity, and electrostatic interactions between the metal-organic nanotubes and analyte molecules. This Cu-MONTs-sponge material is an ideal adsorbent for the extraction of trace amounts of PPCPs from environmental water samples.