Rapid degradation of tetracycline hydrochloride by heterogeneous photocatalysis coupling persulfate oxidation with MIL-53(Fe) under visible light irradiation.

This work demonstrates a facile route to assemble MIL-53(Fe) by solvothermal method. Sulfate radical-based advanced oxidation processes (SR-AOPs) coupling with photocatalysis based on MIL-53(Fe) were investigated under visible light. The catalytic effect of MIL-53(Fe) for the degradation of tetracycline hydrochloride (TC-HCl) was systematically studied, as well as the reusability of the catalyst and the effect of operating parameters. The results indicated that 99.7 % of TC (300 mg/L) could be degraded within 80 min in the SR-AOPs coupling with photocatalysis processes, as compared to 71.4 % for the SR-AOPs and only 17.1 % for the photocatalysis. The trapping experiments and electron spin-resonance spectroscopy (ESR) showed the photogenerated electrons of MIL-53(Fe) under visible light irritation were trapped by persulfate to generated sulfate radicals which effectively suppressed the recombination of photogenerated carriers. And also, the SO4- could be formed by the conversion between Fe (Ⅲ) and Fe (Ⅱ) in MIL-53(Fe). Moreover, OH and O2- generated by the reaction increased significantly due to the increase of SO4- which generated more OH and reduced photogenerated carrier recombination respectively. Thus, the degradation efficiency of TC-HCl was improved. Furthermore, the degradation pathway for TC-HCl was proposed using the theoretical calculations and liquid chromatography coupled with mass spectrometry.

Zhang Y ，Zhou J ，Chen J ，Feng X ，Cai W ... -  《-》

High Efficiency Removal Performance of Tetracycline by Magnetic CoFe(2)O(4)/NaBiO(3) Photocatalytic Synergistic Persulfate Technology.

Zhang J ，Zhang S ，Bian X ，Yin Y ，Huang W ，Liu C ，Liang X ，Li F ... -  《MOLECULES》

Visible light enhanced persulfate activation for degradation of tetracycline via boosting adsorption of persulfate by ligand-deficient MIL-101(Fe) icosahedron.

In this work, Fe-based metal-organic frameworks (Fe-MOFs) are prepared by a simple solvothermal method, in which acetic acid/N, N-dimethylformamide (HAc/DMF) mixture solvents are employed to regulate the particle morphology, exposed facets and ligand defects. At HAc/DMF = 0/50, 5/45 and 8/42 (volume ratio), the irregular particles (MIL-53(Fe)), elongated icosahedrons (5H-MIL-101(Fe)) and icosahedrons (8H-MIL-101(Fe)) are obtained, respectively. Under visible light irradiation (λ > 420 nm) and the addition of sodium persulfate (PS), 5H-MIL-101(Fe) shows the highest degradation activity for tetracycline (TC). Specifically, 80% of TC has been removed by 5H-MIL-101(Fe) within 25 min, and the degradation kinetics rate is 3.03 times higher than that over MIL-53(Fe). The improvement of catalytic activity is mainly attributed to the active facets exposed and ligand defects of 5H-MIL-101(Fe). Density functional theory (DFT) calculation further confirms that the active facets exposed and ligand defects of 5H-MIL-101(Fe) favor the adsorption and activation of PS, benefiting the generation of •SO4-. Besides, a probable degradation pathway of TC is proposed based on trapping experiments and liquid chromatography-mass spectrometry (LC-MS) test. Furthermore, the toxicities of intermediates are predicted by the quantitative structure-activity relationship (QSAR) mathematical model. This work demonstrates that visible light enhanced PS activation (Vis-PSA) can more effectively degrade organic pollutants, and this work also provides a simple strategy to precisely regulate ligand defects and actively exposed facets of Fe-MOFs to enhance the adsorption and activation of PS.

Cheng G ，Yuan C ，Ruan W ，Ma B ，Zhang X ，Yuan X ，Li Z ，Wang D ，Teng F ... -  《-》

Modified MIL-100(Fe) for enhanced photocatalytic degradation of tetracycline under visible-light irradiation.

Iron-based metal-organic frameworks (MOFs) with low cost and excellent photocatalytic potential are extremely attractive in the field of energy utilization and environmental remediation. In this study, a novel In2S3/MIL-100(Fe) photocatalyst was successfully synthesized by a facile solvothermal method for the first time. Several technologies (such as X-ray diffraction, scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy) were used to characterize the as-obtained samples and demonstrate the successful combination of MIL-100(Fe) and In2S3. Experimental results showed that 18% of tetracycline (TC) was adsorbed under dark condition and another 70% of TC was degraded under visible-light irradiation when treating 100 mL of TC solution (10 mg/L) with 30 mg of In2S3/MIL-100(Fe) composites. The corresponding TC removal efficiency was almost 1.9 and 1.6 times higher than that of pure MIL-100(Fe) and In2S3, respectively. The mechanism investigations revealed that the heterojunction composite exhibited superior charge transfer than either MIL-100(Fe) or In2S3, and this caused more efficient separation of electron-hole pairs. As a result, more radicals and holes were generated in the composite, leading to better photocatalytic performance. This work highlights the powerful combination of MOFs and semiconductor, which is a promising approach to fabricate heterojunction photocatalyst for wastewater purification.

He Y ，Dong W ，Li X ，Wang D ，Yang Q ，Deng P ，Huang J ... -  《-》

In situ photoreduction of structural Fe(III) in a metal-organic framework for peroxydisulfate activation and efficient removal of antibiotics in real wastewater.

Structural Fe(III) is widely found in various coordination complexes and inorganic compounds. In this work, a typical Fe-based metal organic framework (MOF) (viz. MIL-100(Fe)) was chosen as an example in the activation of peroxydisulfate (PDS) for the removal of antibiotic pollutants. Interestingly, an auto-acceleration effect was observed in the process of MIL-100(Fe) activating PDS aided by visible light irradiation. Compared to the processes with MIL-100(Fe)-activated PDS alone and the photo-activated PDS alone, the degradation efficiency of sulfamethoxazole (SMX) obtained in the visible light assisted PDS activation by MIL-100(Fe) process was enhanced by 2.1 and 5.6 times, respectively. Therein, the photogenerated electrons from MIL-100(Fe) carried out an in situ reduction of the surface structural Fe(III) to form Fe(II), which in turn significantly improved the PDS activation efficiency in the generation of ·OH and O2-· radicals for the removal of SMX. The degradation pathways of SMX were deduced based on the experimental results and theoretical calculations. Acute toxicity estimation indicated the formation of less toxic products after the treatment of SMX. Additionally, degradation of five antibiotics in the real wastewater were investigated to further confirm the advantages of such in situ photoreduced structural Fe(III) in MOFs to activate the PDS process.

Yin R ，Chen Y ，He S ，Li W ，Zeng L ，Guo W ，Zhu M ... -  《-》