Scalable and selective deuteration of (hetero)arenes

Isotope labelling, particularly deuteration, is an important tool for the development of new drugs, specifically for identification and quantification of metabolites. For this purpose, many efficient methodologies have been developed that allow for the small-scale synthesis of selectively deuterated compounds. Due to the development of deuterated compounds as active drug ingredients, there is a growing interest in scalable methods for deuteration. The development of methodologies for large-scale deuterium labelling in industrial settings requires technologies that are reliable, robust and scalable. Here we show that a nanostructured iron catalyst, prepared by combining cellulose with abundant iron salts, permits the selective deuteration of (hetero)arenes including anilines, phenols, indoles and other heterocycles, using inexpensive D2O under hydrogen pressure. This methodology represents an easily scalable deuteration (demonstrated by the synthesis of deuterium-containing products on the kilogram scale) and the air- and water-stable catalyst enables efficient labelling in a straightforward manner with high quality control.

Synthesis and Characterisation of Metal Chalcogenide Nanocrystals

<p>Nanomaterials are defined as materials which possess features with dimensions of less than 100 nm. Nanocrystals are a subclass of nanomaterials, where the absolute dimensions of individual particles are within this range. Various effects become evident at such small scales, including notably: alterations in electronic structure and magnetic behaviour; and the predominance of surface chemistry. Consequently, the synthesis of nanocrystals with tailored properties via chemical methodology has become an area of some interest. Metal chalcogenides form an important class of inorganic materials, which includes many technologically important semiconductors. Metal chalcogenides feature prominently among semiconductor nanocrystals synthesised to date, but the development of magnetic nanocrystals has focused primarily on metal, and metal oxide phases. Thus the aim of this project was the investigation and development of synthetic methodology for producing nanocrystals, focusing on the metal chalcogenides, with specific emphasis on magnetic metal chalcogenides (iron sulfides). Properties of nanocrystals and metal chalcogenides are discussed in Chapter 1. As described in Chapter 2, metal chalcogenide nanocrystals were synthesised by high temperatures solution-phase reactions, and all samples were characterised by Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS) and Electron Diffraction (ED). Powder X-ray Diffraction (XRD), Scanning Quantum Interference Device magnetometry (SQUID), Thermogravimetric analysis (TGA), Ultraviolet-visible (UV-vis) absorption and fluorescent emission spectroscopy were also used extensively. CdSe nanocrystals with diameters <10 nm are noted for their size-dependent absorption and emission in the visible region. As described in Chapter 3, an established synthesis was used to produce CdSe nanocrystals in order to explore the size-dependence of the optical properties of the nanocrystals, and to explore the possibility of transferring the nanocrystals to aqueous media. As described in Chapter 4, high temperature reaction of iron salts and elemental sulfur in non-aqueous coordinating solvents was used to produce Fe1-xS and Fe3S4 nanocrystals. The factors affecting phase-selectivity, particle size and morphology were ascertained; and the magnetic properties of pure Fe1-xS, pure Fe3S4 and mixtures of Fe1-xS and Fe3S4 were investigated. As described in Chapter 5, thermal decomposition of iron salts in a coordinating solvent was used to synthesis iron metal or iron oxide intermediates, which could either be oxidised to iron oxide spinel; or sulfidised in situ to iron thiospinel (Fe3S4) nanocrystals. This approach proved to be a good source of small, monodisperse iron oxide spinel and iron thiospinel nanocrystals with the same average dimensions. The magnetic properties of the highly-researched iron oxide spinel nanocrystals were determined, and contrasted to those of the their far less investigated thioanalogues. As described in Chapter 6, metal polysulfido complexes of the type [M(N-MeIm)x]Sy/MSy(N-MeIm)x (M = Fe, Zn, Mg; N-MeIm = N-methylimidazole) were synthesised from metal powders, elemental sulfur and N-MeIm; then thermolysed in coordinating solvents to afford metal sulfide nanocrystals. Thus establishing a new general route for synthesis of metal sulfide nanocrystals from low-cost starting materials.</p>

Research on the effects of ferric salt added into aeration tank for phosphorus removal on biochemical system

In this paper, two iron salts, ferrous chloride (FeCl2) and ferric chloride (FeCl3), are directly added into an aeration tank for phosphorus removal, and their effects on the biochemical system are studied; the water quality parameters such as pH and alkalinity are also investigated. The extent of influence of the added iron salts on the pH and alkalinity of aerated solutions is demonstrated to be FeCl3 > FeCl2. When the dosage of iron ions is 20 mg/L, the decrease in pH and alkalinity caused by FeCl3 is 0.5 and 65 mg/L, which is higher than FeCl2 by 2% and 26%. The initial phosphorus removal effect of FeCl2 is worse than that of FeCl3, but after continued aeration and oxidation, the phosphorus removal effect of FeCl2 can be improved; however, the final phosphorus removal effect is basically the same as that of FeCl3 added directly. The results show that FeCl2 is preferred when iron salt is added directly into the aeration tank to remove phosphorus. The proposed scheme can reduce the effect of iron salts on the alkalinity of the biochemical system on the premise of ensuring the phosphorus removal effect of the system, and is conducive to ensuring the stable operation of the biochemical system.

Synthesis and Characterisation of Metal Chalcogenide Nanocrystals

<p>Nanomaterials are defined as materials which possess features with dimensions of less than 100 nm. Nanocrystals are a subclass of nanomaterials, where the absolute dimensions of individual particles are within this range. Various effects become evident at such small scales, including notably: alterations in electronic structure and magnetic behaviour; and the predominance of surface chemistry. Consequently, the synthesis of nanocrystals with tailored properties via chemical methodology has become an area of some interest. Metal chalcogenides form an important class of inorganic materials, which includes many technologically important semiconductors. Metal chalcogenides feature prominently among semiconductor nanocrystals synthesised to date, but the development of magnetic nanocrystals has focused primarily on metal, and metal oxide phases. Thus the aim of this project was the investigation and development of synthetic methodology for producing nanocrystals, focusing on the metal chalcogenides, with specific emphasis on magnetic metal chalcogenides (iron sulfides). Properties of nanocrystals and metal chalcogenides are discussed in Chapter 1. As described in Chapter 2, metal chalcogenide nanocrystals were synthesised by high temperatures solution-phase reactions, and all samples were characterised by Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS) and Electron Diffraction (ED). Powder X-ray Diffraction (XRD), Scanning Quantum Interference Device magnetometry (SQUID), Thermogravimetric analysis (TGA), Ultraviolet-visible (UV-vis) absorption and fluorescent emission spectroscopy were also used extensively. CdSe nanocrystals with diameters <10 nm are noted for their size-dependent absorption and emission in the visible region. As described in Chapter 3, an established synthesis was used to produce CdSe nanocrystals in order to explore the size-dependence of the optical properties of the nanocrystals, and to explore the possibility of transferring the nanocrystals to aqueous media. As described in Chapter 4, high temperature reaction of iron salts and elemental sulfur in non-aqueous coordinating solvents was used to produce Fe1-xS and Fe3S4 nanocrystals. The factors affecting phase-selectivity, particle size and morphology were ascertained; and the magnetic properties of pure Fe1-xS, pure Fe3S4 and mixtures of Fe1-xS and Fe3S4 were investigated. As described in Chapter 5, thermal decomposition of iron salts in a coordinating solvent was used to synthesis iron metal or iron oxide intermediates, which could either be oxidised to iron oxide spinel; or sulfidised in situ to iron thiospinel (Fe3S4) nanocrystals. This approach proved to be a good source of small, monodisperse iron oxide spinel and iron thiospinel nanocrystals with the same average dimensions. The magnetic properties of the highly-researched iron oxide spinel nanocrystals were determined, and contrasted to those of the their far less investigated thioanalogues. As described in Chapter 6, metal polysulfido complexes of the type [M(N-MeIm)x]Sy/MSy(N-MeIm)x (M = Fe, Zn, Mg; N-MeIm = N-methylimidazole) were synthesised from metal powders, elemental sulfur and N-MeIm; then thermolysed in coordinating solvents to afford metal sulfide nanocrystals. Thus establishing a new general route for synthesis of metal sulfide nanocrystals from low-cost starting materials.</p>

Removal of Flotation Collector O-Isopropyl-N-ethylthionocarbamate from Wastewater

Flotation collector O-isopropyl N-ethylthionocarbamate (IPETC) is widely used for separation of sulfide ores. Its removal from water by several oxidation processes was studied. Photocatalytic oxidation with air in the presence of iron salts, utilizing solar irradiation or artificial UV-A light is very efficient. Oxidation leads through the formation of O-isopropyl N-ethylcarbamate and several other reaction intermediates to total decomposition of organic compound in the final stage in 1 day. Similar results were obtained with a Fenton type oxidation with hydrogen peroxide and iron salts. Treatment with sodium hypochlorite yields mainly O-isopropyl N-ethylcarbamate. The formation of this compound in wastewaters can be of concern, since simple alkyl carbamates are cancer suspect agents.

Model-Driven Strategies for Sulfide Control in a Regional Wastewater System Receiving Tannery Effluents in Portugal

Ageing infrastructure are a concern for many wastewater utilities. This is accentuated with the presence of hydrogen sulfide within the sewer headspace, known to induce concrete corrosion, toxicity and odours. Some industrial effluents contain significant sulfide concentrations, however most field studies in the literature refer to domestic networks, or lab/pilot scale sulfide abatement strategies for varied effluents. Hence, the objectives of this work are: (1) To obtain data regarding the evolution of sulfides in a full-scale industrial sewer system in Portugal, receiving wastewater from a number of tanneries; (2) model their fate within the system and (3) experimentally evaluate sulfide precipitation with iron salts. Field work evidenced heavily sulfide loaded effluents, exceeding by far literature values for sewer systems. Modelling was carried out based on the AeroSept+ model, specifically calibrated to this type of effluent. Results showed the model was capable of reproducing the overall levels of sulfide in wastewater and H2S in the sewer headspace, while allowing insights into industrial discharges, originating a set of proposed interventions for sulfide abatement. This may be carried out by iron salts addition, in a ratio of 2.75:1, at existing monitoring stations. This approach was fundamental for an affordable performance assessment, under considerable uncertainty.

Cyanide Removal and Recovery by Electrochemical Crystallization Process

Alkaline chlorination, an efficient but high chemical cost process, is commonly employed for cyanide (CN−) removal from CN-rich wastewater streams. CN− removal and recovery through the precipitation of Prussian Blue (Fe4III[FeII(CN)6]3, PB) or Turnbull’s Blue (Fe3II[FeIII(CN)6]2, TB) were realized using iron salts, leading to a cost-effective and sustainable process producing a valuable recovery product. However, the precipitation of PB and TB is highly affected by pH and dissolved oxygen (DO). CN− removal and recovery from CN-containing water by crystallization of PB and/or TB were investigated using dissolved iron that was electrochemically generated from a sacrificial iron anode under various pH values, initial CN− levels (10 to100 mg/L) and DO levels (aeration, mechanical mixing, and N2 purging). It was shown that the complexation of CN− with Fe ions prevented the vaporization of HCN under acidic pH. At pH of 7 and initial CN− concentration of 10 mg/L, CN− removal efficiency increases linearly with increasing Fe:CN− molar ratios, reaching 80% at the Fe:CN− molar ratio of 5. A clear blue precipitate was observed between the pH range of 5–7. CN− removal increases with increasing initial CN− concentration, resulting in residual CN− concentrations of 8, 7.5 and 12 mg/L in the effluent with the Fe:CN− molar ratio of 0.8 for initial concentrations of 10, 50 and 100 mg CN−/L, respectively. A polishing treatment with H2O2 oxidation was employed to lower the residual CN− concentration to meet the discharge limit of <1 mg CN−/L.

Use of Prophylactic Iron Salts Supplementation During Gestation and Development of Gestational Diabetes Mellitus in Women From 2015 Pelotas (Brazil) Birth Cohort Study

Background This study aims to evaluate the association between the use of iron salts during the first two trimesters in non-anemic women and the development of gestational diabetes mellitus (GDM). Methods The study used maternal data from 2015 Pelotas Birth Cohort. All non-anemic women at 24th week (N = 2463) were eligible for this study. GDM was self-reported by women. Crude and adjusted logistic regression were performed considering level of significance = 0.05. Results Among the women studied, 69.7% were exposed to prophylactic iron supplementation in the two first trimesters of gestation. The prevalence of GDM among those exposed was 8.7% (95%CI 7.4–10.1) and among those who were not exposed was 9.3% (CI95% 7.4–11.6). Iron supplementation was not associated with increased risk of GDM in crude (OR = 0.9; 95%CI 0,7–1,3) and adjusted analysis (OR = 1.1; 95% CI 0,8–1,6). Conclusions The results suggested that routine iron use in non-anemic pregnant women does not increase the risk of developing gestational diabetes. This evidence supports the existing national and international guidelines, whose recommendation is prophylactic iron supplementation for all pregnant women as soon as they initiate antenatal care in order to prevent iron deficiency anemia.

Evaluation of Photosensitive Paper Coatings as Detectors for Instrumentation-Free UV Photometric Analysis Based on Photography-Based Photometry

Photography-based photometry is a technique developed to perform high throughput UV photometric analysis without instrumental detectors in resource-limited settings. Its principle relies on the illumination of a sample with UV irradiation and then capturing the transmitted irradiation on a photosensitive paper surface. Therefore, the photosensitive surface acts as a detector for the determination of the concentration of analytes in the sample. This work aims to investigate the optimum photosensitive paper coatings for capturing the transmitted UV irradiation. To this end, photosensitive coatings based on silver, iron, and dichromate salts were tested using three assays of pharmaceutical and biochemical interest. The results from both calibrations, using standard solutions and the application in real samples, show that photosensitive coatings based on iron salts provide the best results. Importantly, the detection limits and the linear range of the calibration curves were better than those obtained with standard photometry. Based on these findings, cyanotype green papers, are proposed as optimum detectors for photography-based photometry. This finding simplifies the operation of the technique enabling the fabrication of prototype readers for analytical assays performed in resource limited settings, point-of-need applications or in the field.