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International audience; Scaling process is the main problem encountered in industrial plants using water. Several factors, (pH, temperature, hydrodynamic conditions, metal surface, and especially, water composition),can affect the scaling kinetics of calcium carbonate (CaCO3), one of the main component of scaling. In addition, some foreign ions added can considerably modified the scaling rates. In thiswork, the inhibiting effects of Zn2+ and Cu2+ cations on CaCO3 precipitation were studied in a 50°F synthetic carbonic solution by using fast controlled precipitation (FCP) and scaling quartz crystal microbalance (SQCM) methods, for homogeneous and heterogeneous scaling deposition, respectively. Results showed that Zn2+ and Cu2+ ions are efficient, at high concentrations (≥ 1mg/L), to delay or even to prevent nucleation/growth of CaCO3. FCP measurements showed a complete inhibition of the homogeneous CaCO3 precipitation after 120 min in synthetic solutioncontaining 5 mg/L and 4 mg/L of Cu2+ and Zn2+, respectively. SQCM measurements showed that the surface coverage of the metallic substrate by a layer of CaCO3 is reduced when the amount of these cations increased. Zn2+ cations inhibited the heterogeneous CaCO3 precipitation moree fficiently than Cu2+. SEM and XRD results indicated that both cations affect calcium carbonatenucleation by changing the morphology of CaCO3 crystals

International audience; Scale deposition is a common issue in industrial plants, which creates technical problems, i.e. reduction of heat transfer, decrease of flow rate due to an obstruction of pipes. Therefore, the development of some appropriate methods based on well suitable in situ sensors to evaluate and predict the scaling propensity of water is a major concern in current research. This would be a good strategy for the optimization of anti-scaling treatments.In this study, scaling tests were carried out using a sensitive sensor, which has been developed using a quartz crystal microbalance with a pre-calcified electrode surface (SQCM). This technique allowed studying the influence of the supersaturation on the scaling rate. The set-up was tested with different water samples which were brought to a given supersaturation coefficient by degassing the dissolved CO2. The prediction of the scaling propensity of water was then possible through the relationship between the scaling rate on a pre-calcified surface and the supersaturation coefficient. In addition, the kinetics of CaCO3 deposit on the pre-calcified SQCM surface was found to be slower for natural water than for synthetic water (same calcium concentration). Furthermore, the activation energy for scale deposit, in synthetic water, was found to be 22 kJ.mol−1, which may be related to the diffusion of ions and/or CaCO3 nuclei in solution.

International audience; The formation of calcium carbonate in water has important implications in industry. Chemical antiscalant is usually used to control scale depositions. Plant extracts have been recently used as new green antiscalant agents, as they can be easily prepared and are environmentally friendly. In this study, stock aqueous solutions of Spergularia rubra and Parietaria officinalis, two plants used in traditional medicine to treat or prevent urolithiasis, were obtained by infusion. The antiscaling properties of these extracts towards CaCO3 formation were tested by using chronoamperometry and Fast Controlled Precipitation methods. The aqueous solution of S. rubra was further fractionated to isolate compounds of lower polarity. Their efficiency towards CaCO3 precipitation was characterized by Fast Controlled Precipitation method. The inhibiting efficiency of this fractionated solution was greater than that of the stock aqueous solution.

International audience; The formation of calcium carbonate in water has some important implications in geoscience researches, oceanchemistry studies, CO2 emission issues and biology. In industry, the scaling phenomenon may cause technicalproblems such as reduction of heat transfer efficiency in cooling systems and obstruction of pipes.The use of chemicalswhich act as antiscalant is a common approach in the control of scale deposition. However,inorganic nitrogen and phosphorous compounds are involved in eutrophication process. Therefore, it is of primeimportance to find alternative solutions, i.e. green inhibitors of scale formation. This last decade, several newscaleinhibitors, that are more ecological compared with conventional inhibitors, have been reported in the literature.Plant extracts have been also recently used as newgreen antiscalants. Indeed, as they can be easily extracted andare environmentally friendly, they represent an interesting alternative source of "natural" organic molecules.In this review, a focus of some green antiscalants derived frompetrochemicals has been reported. Then the effortsdone those last years to obtain green inhibitors, either by using “natural” organic molecules or extracted fromplants were summarized. Such green inhibitors might be used in various technical areas, i.e. energy, water,food and beverages industries.

An organophosphorous ligand terminated by an amine group has been used here for the first time to functionalize γ-Fe 2 O 3 nanoparticles and to immobilize an enzyme onto their surface in a covalent way. The immobilization of β-glucosidase onto the maghemite nanoparticles was carried in this work out via a reductive amination reaction pathway which involves the terminal amine group on the ligand. The enzymatic activity of the bound enzyme was evaluated in terms of the classical Michaelis–Menten kinetics. Indeed, the affinity of the bound enzyme for the substrate is preserved and is not affected by the high amount of enzymes onto the surface of the nanoparticles. Moreover, the related enzymatic activity slightly decreases compared to that of the free enzyme. Such functionalized nanoparticles could help to improve the delivery and the recovery of biomolecules in biomedical applications by using a magnetic field. They could also provide a magnetic support which could be involved as a contrast agent, a biological label and a mediator for magnetic hyperthermia.

International audience; The tetrapodal pentaamine 2,6-C5H3N[CMe(CH2NH2)2]2 (pyN4, 1), which possesses four equivalent primary amino groups, has been used to prepare the diiron(III) oxo complex [(1)2Fe2(μ2-O)](ClO4)4(2), by aerobic oxidation of the mononuclear iron(II) aqua complex in methanol. This synthesis is unusual because iron(II) complexes of primary amines are normally unstable with respect to metal-induced ligand oxidation. X-ray as well as Mössbauer data indicate a high-spin electronic configuration for the metal centres in the dinuclear complex.

International audience; The Proteus mirabilis catalase is one of the most efficient heme-containing catalase and forms a relatively stable compound II. Samples of compound II were prepared from PMC enriched in 57Fe. For the first time, two different forms of compound II, namely low pH compound II (LpH II) (43%) and high pH compound II (HpH II) (25%), have been characterized by Mössbauer spectroscopy at pH 8.3. The ratio LpH II/HpH II increases irreversibly with decreasing pH. The large quadrupole splitting value of LpH II (ΔEQ = 2.29 (2) mm/s, with δ/Fe = 0.03 (2) mm/s), compared to that of HpH II (ΔEQ = 1.47 (2) mm/s, with δ/Fe = 0.07 (2) mm/s), reflects the protonation of the ferryl group. Quadrupole splitting values of 1.46 and 2.15 mm/s have been computed by DFT for optimized models of the ferryl compound II (model 1) and the protonated ferryl compound II (model 2), respectively, starting from the FeIVO model initially published by Rovira and Fita [C. Rovira, I. Fita, J. Phys. Chem. B 107 (2003) 5300–5305]. Therefore, we attribute the LpH II compound to a protonated ferryl FeIV–OH complex, whereas the HpH II compound corresponds to the classical ferryl FeIVO complex.