Highly efficient and chemoselective singlet oxygen oxidation of unprotected methionine was performed in water using a continuous mesofluidic reactor. Sustainable process engineering and conditions were combined to maximize process efficiency and atom economy, with virtually no waste generation and safe operating conditions. Three water-soluble metal-free photosensitizers [Rose Bengal, Methylene Blue, and tetrakis­(4-carboxy­phenyl)­porphyrin] were assessed. The best results were obtained with Rose Bengal (0.1 mol %) at room temperature under white light irradiation and a slight excess of oxygen. Process and reaction parameters were monitored in real-time with in-line NMR. Other classical organic substrates (α-terpinene and citronellol) were oxidized under similar conditions with excellent performances.

a b s t r a c tAn increasingly known application of nanomaterials in the construction industry is related to the photoactivity ability of semiconductors, where nano-anatase TiO 2 is perhaps the most well-known photocatalytic semiconductor and one which possesses a strong oxidizing capability. To analyze the photo-efficiency of four TiO 2 coatings and the effect of SiO 2 interlayer on the mechanic and photocatalytic activity in Rhodamine B (RhB) and NO x photodegradation, two photocatalytic cement series have been prepared. First, cement mortar was coated with three commercial TiO 2 suspensions (GG1, GC7 and CG13) and a home-made titania sol-gel (TEA), and secondly an insertion of a SiO 2 layer was applied on cement surface before spraying the TiO 2 layer.All studied TiO 2 -cements exhibited a significant RhB and NO x photodegradation, arising almost total RhB molar conversions, and upper 53% for NO x photo-oxidation respectively. Nevertheless, although SiO 2 layer deposited in between mortar and TiO 2 -cement did not stabilize the commercial TiO 2 coatings, a good adhesion was observed when silica was applied joint to the home-made titania gel (TEA), probably as a consequence of the interactions encountered between SiO 2 and TiO 2 gels. CG7-Si-Cem exhibited high rate at shorter irradiation times, but TEA-Cem and TEA-Si-Cem can be considered as very interesting and potential photocatalytic mortars due to useful mechanical properties, with a very good coatings adhesion that provides promising outdoor use, and good photo-efficiencies in RhB and NO x photo-oxidation.

Continuous flow photochemistry relying on photosensitizers faces two main challenges: 1) Photodegradation (bleaching) and 2) the downstream removal of the photosensitizer. Rose bengal (RB) is a common photosensitizer utilized for photooxygenation reactions with singlet oxygen (1O2), but is notoriously sensitive to photobleaching and difficult to remove from reactor effluents. The heterogenization of photosensitizers on mesoporous silica nanoparticles (MSNs) is arguably a viable option for such applications. Herein, we report on the use of RB covalently incorporated into MSNs (RB@MSNs) for photooxygenation reactions under continuous flow conditions. RB@MSNs enable the 1O2 photooxygenation of various organic substrates upon irradiation with 540 nm LEDs. A series of organic substrates were evaluated including methionine, α‐terpinene, 2‐furoic acid, triphenylphosphine, citronellol and cyclopentadiene. These results emphasize an improved resistance to photobleaching, and the possibility to use RB@MSNs as an easily recoverable catalyst, which could be removed from the reactor effluent either a) by centrifugation or b) by in‐line membrane filtration.

Abstract:In this work, the process parameters involved in the electrophoretic deposition (EPD) to obtain thin TiN films was studied and optimised. The stability of commercial TiN nanopowder in isopropyl alcohol adding a cationic polymer (polyethylenimine) as dispersant, with different molecular weights, was investigated to determine the kinetics of the deposition and to reach the most efficient EPD process. Cathodic EPD was performed over electro-polished stainless steel substrates. It was found that the provided dispersion when the PEI with the highest molecular weight was added to the suspension, leads to the best deposition behaviour for short times. New flocculation phenomena were described which affect to the sticking factor, and thus to the evolution of the EPD kinetics. As a result of the designed stabilization system, a reliable and versatile EPD method to produce well consolidated nano-TiN coatings at 1200• C in vacuum atmosphere was described.

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