A degradação de soluções aquosas de índigo carmim (IC), azul de metileno (MB) e laranja de metilo (MO) assistida pela luz visível foi conseguida sobre a superfície de nanotubos (NTs) de TiO 2 impregnados com riboflavina (RF). Soluções aquosas diluídas de RF na presença de RF-NTs TiO 2 irradiados com luz UV produziram O 2 , CO e CO 2 como principais produtos gasosos. As mesmas soluções quando irradiadas com luz visível mostraram que o O 2 foi o produto principal obtido. Esta geração de O 2 in situ com luz visível permite a degradação dos corantes, sem a necessidade de borbulhar ar ou oxigênio no sistema de reação. A degradação fotocatalítica de MO, MB e IC pode ser descrita por um modelo de cinética de pseudo-primeira ordem obtendo ca. 100% de degradação de MB, MO e IC em menos de 3 h de iluminação de luz visível. Os resultados aqui apresentados são altamente promissores em vista da potencial aplicação dos catalisadores RF-TiO 2 NTs preparados com dois compostos ambientalmente corretos na degradação de poluentes utilizando radiação solar.Visible light-assisted degradation of indigo carmine (IC), methylene blue (MB) and methyl orange (MO) aqueous solutions has been achieved on the surface of TiO 2 nanotube (NT) arrays impregnated with riboflavin (RF). Diluted RF water solutions in the presence of RF-TiO 2 NTs irradiated with UV light produced O 2 , CO and CO 2 as main gas products. On the contrary, the same solutions irradiated with visible light evolved O 2 as a main product. This in situ O 2 generation under visible light absorption allows the degradation of the dyes without the necessity to bubble air or oxygen in the reaction system The photocatalytic degradation of MO, MB and IC can be described by a pseudo-first-order kinetic model obtaining ca. 100% degradation of MB, MO and IC in less than 3 h of visible light illumination. The results provided here are highly promising in view of various photocatalytic applications of the prepared RF-TiO 2 NTs catalysts by two environmentally friendly compounds in the degradation of pollutants using solar radiation.

No abstract

The excellent performance of hybrid metal-halide perovskite nanocrystals (NCs) contrasts with their unsatisfactory stability in a high-humidity environment or water. Herein, polymer composite lead-halide perovskites (LHPs) NCs were prepared by casting or spin-coating to produce a high fluorescence yield and a fully water-resistant material. Poly(L-lactide) (PLla), polypropylene glycol (PPGly), and polysulfone (PSU) commercial polymers were used to prepare suspensions of MAPbBr 3 −HDA NCs (MA: CH 3 NH 3 ; HDA: hexadecylamine). The MAPbBr 3 −HDA@PLla suspension exhibited a maximum fluorescence quantum yield of 93% compared to 43% for the pristine MAPbBr 3 −HDA NCs. Strong emissions around 528 nm were also observed, with the same full width at half maximum value of 20 nm, demonstrating the successful fabrication of brightly luminescent LHP NCs@polymer combinations. Time-resolved photoluminescence measurements directly observed the enhanced spontaneous emission of the NCs induced by the polymeric environment. However, the cast films of MAPbBr 3 −HDA NCs mixed with PLla or PPGly did not resist water immersion. On the contrary, MAPbBr 3 −HDA@PPGly/PSU films containing well-dispersed ∼10 nm LHP NCs retained a bright green fluorescence emission even after 18 months under air conditions or water immersion up to 45 °C. From water contact angle measurements, profilometry, and X-ray photoelectron spectroscopy data, it could be assumed that the slightly hydrophobic PSU polymer is responsible for the high water stability of the fluorescent films, which avoids MAPbBr 3 −HDA NC degradation. This work shows that the LHP NC dispersion in dissolved commodity polymers holds great promise toward the long-term stability of LHP NC composites for the future development of wearable electronic devices and other waterproof applications.

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adem.202201592.

The high glycerol miscibility in water needs more efficient processes to decrease the cost of dehydration. Water stable poly(vinyl alcohol) based membranes cross‐linked with 15% w/w of maleic acid were used for dehydrating glycerol‐water mixtures using pervaporation (PV). The membranes were characterized using water contact angle, profilometry, Fourier transformed infrared spectroscopy‐attenuated total reflectance, x‐ray photoelectron spectroscopy, water stability, swelling tests, and PV. Membranes were treated using dry methods with vacuum ultraviolet (VUV; 162 nm) or ultraviolet (UV)‐C (254 nm) radiation and exposed to O2 or acrylic acid vapors, respectively. The VUV and UV‐C treatments improve PV performances, increasing the water separation selectivity more than 4 and 8.5 times, respectively. UV‐C treatments exhibit a water flux (kg m−2 h−1), selectivity and PSI (kg m−2 h−1) of 0.3, 250, and 87.4 respectively. Highly hydrophilic functional groups grafted onto the surface of the membranes after irradiation favor the selective transfer of water through the membrane. Overall, the VUV or UV‐C membrane treatments show great PV prospect in glycerol dehydration.