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As an indispensable medicine, antibiotics are widely used in daily life, but following the substantial discharge of various wastewater, which result in antibiotic resistance of microbial pathogens and jeopardizes the health of ecosystems. There is an urgent need to tackle drug residues. After decades of intensive research, photocatalysis technology has been developed into an efficient technology for wastewater treatment due to its economic and environmental-friendly properties. Here, the photocatalyst NH2-MIL-101(Fe)/TiO2 composite was fabricated to degrade the antibiotics: tetracycline hydrochloride (TC), doxycycline hydrochloride (DC), and levofloxacin hydrochloride (LEV). The NH2-MIL-101(Fe)/TiO2 photocatalysts exhibited excellent visible light harvesting performance with a narrow band gap (2.19 eV), low recombination ratio of photoinduced carriers, good photoelectric response, low resistance and long charging life. NH2-MIL-101(Fe)/TiO2 (MT0.50 molar ratio Fe:Ti = 1:1) showed the highest degradation effect, with the degradation rates of 91.52%, 80.11%, and 88.13% for TC, DC, and LEV in 6 h, with kinetic constants of 0.00510 min−1, 0.00344 min−1 and 0.00503 min−1, respectively. The catalysts exhibited significantly increased photocatalytic activity and excellent stability compared to NH2-MIL-101 (Fe) and TiO2. In addition, MT0.50 still showed good photodegradation effect under simulated different pH and ionic strength, indicating that MT0.50 has good adaptability and practical application. The study of photocatalytic mechanism showed that ·OH was the main active substance in the degradation process, which played an important role in degrading antibiotics. In addition, three possible degradation pathways for antibiotics were proposed based on the intermediates detected by LC–MS, and the photocatalysts also showed great stability and excellent antimicrobial effects. Therefore, the present study provides a new strategy and enriches the mechanisms involved in the wastewater treatment of NH2-MIL-101(Fe)/TiO2 photodegradation of various antibiotics. [ABSTRACT FROM AUTHOR]

Coordination complexes were widely used in advanced oxidation processes. The ligands with various substituents could lead to differences in the catalytic properties and mechanisms. In this work, the iron(III)–N,N′‐dipicolinamide (FeL) complexes (the iron(III) complexes with substituents –CH3, –H, –Cl and –NO2 named as FeL1, FeL2, FeL3 and FeL4, respectively) were used to activate hydrogen peroxide (H2O2) for degrading dyes wastewater. Mechanism studies indicated that the FeL4/H2O2 system contains the FeV=O in addition to the same •OH and O2•− as the other systems, which made it exhibit more excellent performance than others. The results of the performance tests showed that the FeL4/H2O2 system could remove 97%, 89%, 100%, 83%, 100%, and 99% of RR195, RY145, RB194, RB19, MB, and RhB, respectively, which proved the good application performance of the FeL4/H2O2 system. In addition, the performance of the FeL4/H2O2 system was not influenced by anions and natural organics. This study verified the feasibility of modulating the catalytic performance of the complexes by changing the substituents and provided an efficient catalytic system for dyeing wastewater treatment. [ABSTRACT FROM AUTHOR]

Polyphosphazene derivatives are gaining popularity due to their eco-friendly character and high content of flame-retardant components. Herein, a polyphosphazene derivative (PZAF) microsphere was successfully synthesized utilizing an in-situ template approach, which was then employed as an additive flame retardant in polyethylene terephthalate (PET) to improve the fire safety. Thermogravimetric analysis revealed that PZAF promoted the pyrolysis of PET in advance to generate a stable char layer that protects the matrix from heat, consequently increasing char residues. With addition of 10 wt% PZAF, the PET nanocomposites obtained a V-0 grade in vertical combustion test and its LOI value increased from 24.2 vol% to 32.1 vol%. Moreover, the peak heat release and carbon monoxide production decreased by 46.6% and 50.6%, respectively. This was because the phosphonic acid fragments and pyridine ring compounds produced by the PZAF pyrolysis encouraged the development of a robust char layer. Meanwhile, the •PO radicals generated by the pyrolysis of PZAF could capture free radicals in the gas phase, ultimately ending the chain reaction of combustion. Also, mechanical properties of the PET nanocomposites were noticeably enhanced by the addition of 3 or 5 wt% PZAF. [ABSTRACT FROM AUTHOR]

A poly (cyclotriphosphazene‐resveratrol) (PRS) microsphere was synthesized via a feasible in‐situ template approach and applied to poly (ethylene terephthalate) (PET) for ameliorating its flammable and melt‐dropping issues. The prepared PRS microspheres displayed superior thermal stability and flame retardancy. By incorporating only 2 wt% of PRS microspheres into PET matrix, the limiting oxygen index value was increased from 23.3% to 28.3% and reached the UL‐94 V‐0 level without any after‐flame time. Cone calorimeter test demonstrated that the HRR and THR of PET/FR2.0 composite decreased significantly by 31.1% and 13.5%, respectively, which remarkably increased the fire safety of PET. On the other hand, the tensile strength and elongation at break of PET/FR2.0 composite decreased slightly, whereas the tensile modulus was increased by 10.5% than that of the pure PET. Moreover, the fire‐retardant mechanism of PRS microspheres was fully investigated, revealing that PET/FR system would generate compact and continuous char layers rapidly during combustion, the underlay materials would not be further cracked due to the isolation of external heat and oxygen. Nonflammable gases such as ammonia were also released to dilute the concentration of combustible gases around the PET matrix, achieving an efficient flame retardant effect. [ABSTRACT FROM AUTHOR]

Triclinic iron vanadate (n-type FeVO4) thin films were fabricated for the first time by spray pyrolysis and elucidated as a potential photoanode material for solar water oxidation. FeVO4 has an ideal band gap for a photoanode of ∼2.0 eV, which corresponds to a potential solar-to-hydrogen (STH) efficiency of 16%. However, our findings show that the photoelectrochemical performance of FeVO4 is limited by very poor charge carrier separation efficiency in the bulk. Time-resolved microwave conductivity (TRMC) measurements revealed that the low mobility (∼5 × 10−5 cm2 V−1 s−1) and short diffusion length (∼2 nm) of undoped FeVO4 are the main reason for its fast bulk recombination. To overcome the poor charge separation efficiency in the bulk, molybdenum doping was used to enhance its mobility, lifetime, and carrier concentration. Doping with 2% Mo increased the photocurrent density by more than 45% at 1.6 V vs. RHE. Finally, we show that the near-ideal band gap of FeVO4 can be combined with the favorable carrier mobility of BiVO4 in a mixed phase compound, Fe1−xBixVO4, a new photoanode candidate for solar water splitting. [ABSTRACT FROM AUTHOR]