Floating MIL-88A(Fe)@expanded perlites catalyst for continuous photo-Fenton degradation toward tetracyclines under artificial light and real solar light.

In this work, MIL-88A(Fe) was immobilized onto the expanded perlites to fabricate the floating MIL-88A(Fe)@expanded perlites (M@EP) catalyst via high throughput batch synthesis method under room temperature. The as-prepared M@EP could efficiently activate H2O2 to achieve 100% tetracycline antibiotics (TCs) removal under both artificial low power UV light (UVL) and real sunlight (SL) irradiation. The toxicological evaluation, growth experiment of mung beans and antimicrobial estimation revealed the decreasing aquatic toxicity of the TCs intermediates compared to those of the pristine TCs. A self-designed continuous bed reactor was employed to investigate the long-term operation of the M@EP. The findings demonstrated that the antibiotics mixture can be continuously degraded up to 7 days under UVL and 5 daytimes under SL irradiation, respectively. More importantly, ca. 76.9% and 81.6% of total organic carbon (TOC) removal efficiencies were accomplished in continuous bed reactor under UVL and SL irradiation, respectively. This work advances the immobilized MOFs on floating supports for their practical application in large-scale wastewater purification through advanced oxidation processes. ENVIRONMENTAL IMPLICATION: This work presented the high throughput production and photo-Fenton degradation application of floating MIL-88A(Fe)@expanded perlites (M@EP). Three tetracycline antibiotics (TCs) were selected as model pollutants to test the degradation ability of M@EP in batch experiment and continuous operation under artificial light and solar light. The complete TCs degradation could be accomplished in self-designed device up to 7 d under UV light and 5 d under real solar light. This work tapped a new door to push MOFs-based functional materials in the real water purification.

Heterogeneous photo-Fenton degradation toward sulfonamide matrix over magnetic Fe3S4 derived from MIL-100(Fe).

Magnetic Fe3S4 was facilely derived from MIL-100(Fe) as the precursor and thioacetamide (TAA) as the sulfur source under hydrothermal condition. The as-prepared Fe3S4 was adopted as catalyst to promote the photo-Fenton process, in which sulfamethoxazole (SMX) was used as representative pollutant sample to test the oxidative degradation performance of Fe3S4. The results showed that Fe3S4 exhibited excellent photo-Fenton-like oxidation decomposition performances toward sulfamethoxazole (SMX) under both UV and visible light. A possible degradation mechanism over Fe3S4 in the photo-Fenton reaction is put forward based on quenching experiments and electron spin resonance (ESR). About 41% total organic carbon (TOC) removal efficiency of sulfamethoxazole (SMX) over the as-prepared Fe3S4 can be accomplished within 40 min. As well, different sulfonamide antibiotics (SAs) like sulfamethoxazole (SMX), sulfisoxazole (SIM) and sulfadiazine (SDZ) were selected to further investigate the oxidative degradation activity of Fe3S4 in this photo-Fenton-like reaction system, in which the possible degradation pathways of SMX, SIM and SDZ were put forward based on UHPLC-MS analysis. This work provided a new strategy to prepare magnetic Fe3S4 as catalyst for advanced oxidation process, which can be easily separated from the treated water samples to accomplish facile recovery and recyclability.

Robust Cr(VI) reduction over hydroxyl modified UiO-66 photocatalyst constructed from mixed ligands: Performances and mechanism insight with or without tartaric acid.

Hydroxyl modified UiO-66 ((OH)2-UiO-66-X%, X represents the mass content ratio of introduced 2,5-dihydroxyterephthalic acid) was prepared via a solvothermal reaction between zirconium tetrachloride, benzene-1,4-dicarboxylic acid (H2BDC), as well as 2,5-dihydroxyterephthalic acid (H2BDC-(OH)2). It was found that hydroxyl groups can act as the intramolecular hole scavenger to boost the photo-induced charge carrier separation to enhance Cr(VI) reduction. The photocatalytic Cr(VI) reduction activities of (OH)2-UiO-66-X% were investigated upon the irradiation of low-power ultraviolet LED light. The findings demonstrated that (OH)2-UiO-66-20% with good cyclicity and stability exhibited superior photocatalytic performances to both UiO-66 and (OH)2-UiO-66. The introduction of hydroxyl groups can also extend the light absorption region to longer wavelength in visible range, which provides possibility for displaying photocatalytic activities under sunlight. The effect of small molecule organic acid (SOAs), pH value, and co-existing inorganic ions on photocatalytic performances of (OH)2-UiO-66-20% were investigated. Tartaric acid (TA) as typical SOAs was introduced to the reaction system to further boost the photocatalytic Cr(VI) reduction via acting as hole scavenger, constructing charge-transfer-complex for quick electron transportation, and producing COO·- radicals. This work opened a new opportunity for modified MOFs for boosted elimination activities for environmental pollutants.

Bisphenol A cleanup over MIL-100(Fe)/CoS composites: Pivotal role of Fe-S bond in regenerating Fe2+ ions for boosted degradation performance.

Series of MIL-100(Fe)/CoS composites (MxCy) were facilely fabricated using ball-milling method. The optimum M50C50 exhibited extremely higher Fenton-like catalytic degradation activity toward bisphenol A (BPA) than the pristine MIL-100(Fe) and CoS. The significant improvement of BPA degradation was attributed to the synergetic effect between MIL-100(Fe) and CoS with the synergistic factor being 95.7%, in which the Fe-S bonds formed at the interface of the two components facilitate the Fe3+/Fe2+ cycle by improving the electron mobility both from Co to Fe and from S to Fe. Furthermore, the influence factors like co-existing inorganic ions and pH values on the catalysis activity of M50C50 were explored. The possible reaction mechanism was proposed and confirmed by both active species capture tests and electron spin resonance (ESR) determinations. It was found that M50C50 demonstrated good reusability and water stability, in which the morphology and structure were not changed obviously after five runs' operation. To our best knowledge, it is the first work concerning the interfacial interaction of Fe-MOF/MSx to promote Fe3+/Fe2+ cycle in Fe-MOFs for the purpose of organic pollutants degradation in the Fenton-like AOPs system.

Polyaniline modified MIL-100(Fe) for enhanced photocatalytic Cr(VI) reduction and tetracycline degradation under white light.

The Z-scheme MIL-100(Fe)/PANI composite photocatalysts were facilely prepared from MIL-100(Fe) and polyaniline (PANI) by ball-milling, and were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), UV-visible diffuse-reflectance spectrometry (UV-vis DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence emission spectrometry (PL). The photocatalytic activities of MIL-100(Fe)/PANI composites were investigated via tetracycline degradation and hexavalent chromium reduction in aqueous solution under the irradiation of white light. The results revealed that the MIL-100(Fe)/PANI composite photocatalysts exhibited outstanding photocatalytic activities toward Cr(VI) reduction and tetracycline decomposition. The effects of pH and coexisting ions on the photocatalytic Cr(VI) reduction were investigated. As well, the primary active species were identified via electron spin resonance (ESR) determination. A possible Z-scheme photocatalyst mechanism was proposed and verified. Finally, MIL-100(Fe)/PANI composites demonstrated good reusability and stability in water solution, implying potentially practical applications for real wastewater treatment.

Simultaneous Cr(VI) reduction and Cr(III) removal of bifunctional MOF/Titanate nanotube composites.

In this study, a series of BUC-21/titanate nanotube (BT-X) composites were facilely fabricated via ball-milling of 2-dimensional (2D) metal-organic framework (MOF) BUC-21 and titanate nanotubes (TNTs). The BT-X composites were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), UV-visible diffuse-reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectrometer (XPS) and high resolution transmission electron microscopy (HRTEM). Both the photocatalytic reduction from Cr(VI) to Cr(III) and adsorptive removal of formed Cr(III) of BT-X composites were systematically investigated under different conditions including pH values and co-existing inorganic ions. It was found that BUC-21 (100 mg)/TNTs (100 mg) (BT-1) composites demonstrate remarkable ability of photocatalytic Cr(VI) reduction and adsorptive Cr(III) removal, as well as good reusability and stability. It is believed that the introduction of TNTs could capture the formed Cr(III) from the surface of BUC-21, which provided more active sites exposed to enhance the Cr(VI) reduction.