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Halide perovskite derivatives present unprecedented physical phenomena among those materials suitable for photovoltaics, such as a fast ion diffusion coefficient. Here we report how to take benefit from this property during the growth of halide perovskite in order to control the morphological and optoelectronic properties of the final thin film. Using a large enough halide reservoir, the nature of the halides present in the final perovskite layer can be exchanged respect the initial salt used in the two step deposition method. In particular, we report the preparation of methylammonium lead bromide (MAPbBr 3 ) thin film using a two-step method based on the transformation of PbI 2 , PbBr 2 and PbCl 2 salts into MAPbBr 3 perovskite after dipping in a MABr solution. The films prepared from different salts present different properties in terms of morphology and optoelectronic properties, thus providing significantly different performance when they are used for the preparation of photovoltaic devices. Interestingly, the use of PbI 2 and PbCl 2 salts reduce the charge recombination and increases the obtained open circuit potential, especially in the former case. However, the highest photocurrent is obtained when PbBr 2 is used. While for PbI 2 and PbCl 2 salts no traces of the former salt are observed in the obtained MAPbBr 3 layer after 10 minutes of dipping time, the presence of PbBr 2 still been detected when this salt is employed as it has been determined by Xray diffraction.2

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Two different electrochemical reduction processes for the removal of dimetridazole, a nitroimidazole-based antibiotic, were examined in this work. A direct electrochemical reduction was first carried out in a home-made flow cell in acidic medium at potentials chosen to minimize the formation of amino derivatives and then the formation of azo dimer. Analysis of the electrolyzed solution showed a total degradation of dimetridazole and the BOD/COD ratio increased from 0.13 to 0.24. An indirect electrochemical reduction in the presence of titanocene dichloride ((CH)TiCl), which is used to reduce selectively nitro compounds, was then investigated to favour the formation of amino compounds over hydroxylamines and then to prevent the formation of azo and azoxy dimers. UPLC-MS/MS analyses showed a higher selectivity towards the formation of the amino compound for indirect electrolyses performed at pH 2. To confirm the effectiveness of the electrochemical reduction, a biological treatment involving activated sludge was then carried out after direct and indirect electrolyses at different pH. The enhancement of the biodegradability was clearly shown since mineralization yields of all electrolyzed solutions increased significantly.

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It is well-known that direct discharges of dye-contaminated wastewaters generated from various industries (i.e., textile, cosmetics and food industries,…) cause severe effects on both aquatic environment and human health. Decontamination of dye-containing wastewaters using nanomaterials-based adsorbents such as carbon nanotubes is regarded as an interesting field of investigation to control these types of pollutants. In this context, a newly prepared ferrocene-modified carbon nanotubes (amFc-MWCNTs) was applied as an adsorbent for the removal of rhodamine B (RhB) dye from aqueous solutions. The structural properties of the hybrid adsorbent were fully characterized using Raman, XPS, EDX, SEM and TEM microscopy. Adsorption isotherms and kinetics of RhB were investigated and multiple models (i.e. Langmuir, Freundlich, Hill,…) were used to fit experimental data. It was found that > 98% of RhB with initial concentration of 10 mg L −1 can be captured within 2 h when using 0.4 g L −1 of amFc-MWCNTs. The adsorption behavior of this nanomaterial fitted well with the Hill isotherm and the pseudo-second-order kinetic model. Moreover, the intra-particle diffusion was identified as the rate-limiting step of the adsorption process. After washing with acetone, regenerated amFc-MWCNTs adsorbent showed good recovery, indicating its reusability and its potential in practical applications.

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