The Usefulness of X-ray Diffraction and Thermal Analysis to Study Dietary Supplements Containing Iron

X-ray powder diffraction (XRPD) and thermal analysis (differential scanning calorimetry/derivative of thermogravimetry (DSC/DTG)) are solid-state techniques that can be successfully used to identify and quantify various chemical compounds in polycrystalline mixtures, such as dietary supplements or drugs. In this work, 31 dietary supplements available on the Polish market that contain iron compounds, namely iron gluconate, fumarate, bisglycinate, citrate and pyrophosphate, were evaluated. The aim of the work was to identify iron compounds declared by the manufacturer as food supplements and to try to verify compliance with the manufacturer’s claims. Studies performed by X-ray and thermal analysis confirmed that crystalline iron compounds (iron (II) gluconate, iron (II) fumarate), declared by the manufacturers, were present in the investigated dietary supplements. Iron (II) bisglycinate proved to be semi-crystalline. However, depending on the composition of the formulation, it was possible to identify this compound in the tested supplements. For amorphous iron compounds (iron (III) citrate and iron (III) pyrophosphate), the diffraction pattern does not have characteristic diffraction lines. Food supplements containing crystalline iron compounds have a melting point close to the melting point of pure iron compounds. The presence of excipients was found to affect the shapes and positions of the endothermic peaks significantly. Widening of endothermic peaks and changes in their position were observed, as well as exothermic peaks indicating crystallization of amorphous compounds. Weight loss was determined for all dietary supplements tested. Analysis of the DTG curves showed that the thermal decomposition of most food supplements takes place in several steps. The results obtained by a combination of both simple, relatively fast and reliable XRPD and DSC/DTG methods are helpful in determining phase composition, pharmaceutical abnormalities or by detecting the presence of the correct polymorphic form.

Historical and SEM-EDS Analysis of a 14th-16th Century Triangular Crucible from Sandomierz, Poland

The collection of the District Museum in Sandomierz holds a previously unidentified and unpublished triangular ceramic crucible. After at least fifty years since its acquisition, it was possible to obtain detailed information about its chemical composition and presumed use in the past. Based on analogies from Central Europe, it is possible to date it typologically to the 14th-16th centuries. The stamp mark on the bottom of the crucible points to Tulln in Austria as the place of its origin. The SEM-EDS analysis revealed the presence of graphite in the ceramic mass of the vessel as well as carbon and iron compounds on its inner wall, which indicates its possible use in the production of steel by carburising of iron.

Arsenate and Arsenite Sorption Using Biogenic Iron Compounds: Treatment of Real Polluted Waters in Batch and Continuous Systems

Arsenic pollution in waters is due to natural and anthropogenic sources. Human exposure to arsenic is associated with acute health problems in areas with high concentrations of this element. Nanometric iron compounds with large specific surface areas and higher binding energy produced by some anaerobic microorganisms are thus expected to be more efficient adsorbents for the removal of harmful metals and metalloids than chemically produced iron oxides. In this study, a natural consortium from an abandoned mine site containing mainly Clostridium species was used to biosynthesize solid Fe(II) compounds, siderite (FeCO3) and iron oxides. Biogenic precipitates were used as adsorbents in contact with solutions containing arsenate and arsenite. The adsorption of As(V) fitted to the Langmuir model (qmax = 0.64 mmol/g, KL = 0.019 mmol/L) at the optimal pH value (pH 2), while the As(III) adsorption mechanism was better represented by the Freundlich model (KF = 0.476 L/g, n = 2.13) at pH 10. Water samples from the Caracarani River (Chile) with high contents of arsenic and zinc were treated with a biogenic precipitate encapsulated in alginate beads in continuous systems. The optimal operation conditions were low feed flow rate and the up-flow system, which significantly improved the contaminant uptake. This study demonstrates the feasibility of the application of biogenic iron compounds in the treatment of polluted waters.

New Inverse Emulsion-Polymerized Iron/Polyaniline Composites for Permanent, Highly Magnetic Iron Compounds via Calcination

The hydrophilic initiator potassium persulfate (KPS) was converted into a hydrophobic molecule by complexing with cetyltrimethylammonium bromide (CTAB) at both ends of the molecule (CTAPSu). Inverse emulsion polymerization thus proceeded inside micelles dispersed in the affluent toluene with CTAPSu as the initiator. Polyaniline (PANI) formed inside the micelles and entangled with Fe3O4 nanoparticles already esterified with oleic acid (OA). Iron composites consisted of OA-esterified Fe3O4 nanoparticles covered with PANI after de-emulsification. After calcination at 950 °C in an argon atmosphere, the resultant iron compound was a mixture of α-Fe (ferrite) and Fe3C (cementite), as determined by X-ray diffraction. Eventually, the calcined iron compounds (mixtures) demonstrated superparamagnetic properties with a high saturation magnetization (Ms) of 197 emu/g, which decayed to 160 emu/g after exposure to the atmosphere for four months.

Dissolution of iron in sodium chloride solution during alternating current polarization

Iron compounds are widely used in many industries and engineering, and even in medicine. The existing methods of obtaining iron compounds are multi-stage and complex. The purpose of this work is to obtain iron (II) hydroxide and oxide from metal waste under alternating current action using one and two half-cycles. For the first time, the electrochemical behavior of iron electrode was studied by electrolysis method during alternating current polarization of industrial frequency in sodium chloride solutions. The iron polarization was carried out in pair with titanium, while the current density on the iron electrode varied in the range of 200-1200 A/m2, and on the titanium is in the range of 20-100 kA/m2. It is established that in the anode half-cycle of alternating current, iron is oxidized to form divalent ions. At this moment, the titanium electrode is in the cathode half-cycle, hydrogen is released on it, hydroxyl ions are formed in the cathode space. In the solution, ions interact with iron (II) ions to produce iron hydroxide. At temperatures above 600C, iron (II) hydroxide is dehydrated with the production of iron (II) oxide. The electrolysis was carried out in two electrolyzers connected to each other in parallel with the immersion of pair of “titanium-iron” electrodes into each electrolyzer. The iron dissolution occurs simultaneously in two half-cycles of alternating current and this approach is proposed for the first time. The process productivity increases by more than 1.5 times.

OXIDATION-REDUCTION PROCESSES IN THE SOILS OF RICE AGROCENOSES OF THE KUBAN REGION (RUSSIA)

Background: The studies were carried out on the Maryano-Cheburgolsky irrigation array in the Krasnoarmeisky district of the Krasnodar Territory. Aim: This work aims to study the oxidation-reduction processes and activity of iron compounds in meadow-chernozem and meadow-boggy soils of rice agrocenoses of the Kuban region. Methods: Soil samples were taken from paddy fields occupied by rice and perennial grasses, in which the pH value, redox potential (Eh, mV), magnetic susceptibility (χ×10-3 S.I. units), and the content of active iron compounds (FeO and Fe2O3, mg/100 g) were determined. Results and Discussion: The reductive processes created in the soils of rice fields after flooding led to the transformation of poorly soluble Fe2O3 compounds into more active reaction forms of FeO. The maximum content of FeO and the minimum amount of Fe2O3 were recorded during the period of negative Eh values. The maximum reduction of iron in meadow-boggy and meadow-chernozem soils was achieved by the phase of flowering of rice plants at Eh = -127, pH = 7.36 units, rH2 = 10 and Eh = -152...-167 mV, pH = 6.89-7.10 units, rH2 = 9, respectively. Conclusions: In the soil of permanent rice cultivation, the dynamics of Eh and iron compounds are similar to the fields of rice crop rotation. In non-flooded soils of rice fields under perennial grasses, the oxidative regime prevails, and the transformation of iron compounds is not expressed. The minimum values of χ coincide with the maximum content of ferrous iron in soils at negative Eh values, which corresponds to the rice flowering phase. Correlation coefficients of χ with Eh, FeO, and Fe2O3 equal from +0.66 to +0.75, from -0.69 to -0.84, and from +0.74 to +0.77, respectively. The χ value increases in the soil under crops of perennial grasses with a predominance of oxidative processes. The correlation coefficient between χ and Fe2O3 equals from +0.83 to +0.90.