Industrial wastewater treatment wastes used as oxygen carriers in energy generation processes

The paper contains the results of a study on a promising combustion technology known as chemical looping combustion (CLC). The main advantage of CLC is the production of a highly concentrated CO2 stream without any energy penalty for its separation, together with NOx emissions reduction. The objective of this work was to examine novel oxygen carrier (OC) materials for their practical applications with gaseous fuel/air. We report a simple, economical and environmentally friendly method for the large-scale synthesis of OCs from wastes. The reactivity tests for OCs made from wastewater from a coking plant were performed in a thermogravimetric analyser. For selected temperatures, reduction–oxidation cycles were performed. The effect of temperature on the reaction rates, the effect of waste treatment and the oxygen transport capacity were determined. The waste material demonstrated good thermal stability and maintained its redox behaviour over cycling. ICP-OES and XRD data revealed these materials that contained beneficial amounts of Fe species and silicon oxide, which improved stability. The study showed that these waste materials are excellent examples of raw materials that can enable a decrease in OC production costs with the additional benefit of the practical management of post-wastewater sediments from coke oven wastewater plants

Phase structure and magnetic properties of Fe-Nb-B-Pt type of bulk nanocrystalline alloys

The paper refers to magnetic and structure properties of the (Fe80Nb6B14)1xPtx (x = 0:15, 0.3, 0.4 and 0.6) bulk nanocrystalline alloys prepared using the vacuum suction casting technique. The samples were in the form of rods with diameters ranging from 0.5 mm to 1.5 mm. It was shown that the optimal Pt content is x = 0:4 with the coercive eld equal to 0.2 T and maximum energy product jBHjmax = 11:2 kJ/m3. The magnetic properties can be associated with Fe-Pt, Fe and Fe-B phases, depending on the alloy composition

Influence of cooling rate on structural and magnetic properties of (Fe78Nb8B14)1-xTbx alloys

In the presented work we are focused on the influence of cooling rate on structural and magnetic properties of (Fe78Nb8B14)1-xTbx (x = 0.08, 0.1, 0.12) nanocrystalline bulk alloys. The samples were fabricated using the vacuum suction technique with different cooling rates controlled by different sample diameters (from 0.5 to 1.5 mm). The increased Nb content leads to the formation of specific microstructure and allows obtaining ultra-high coercive alloys just after casting without any additional treatment. The coercivity exceeds 8.6 T at the room temperature in case of optimal chemical and preparation conditions (x = 0.12, d = 0.5 mm) and 5.6 T for x = 0.1. The impact of Tb content as well as the cooling rate on magnetic and structural (XRD, SEM, MFM) properties is widely discussed in the context of reduction of rare earths in the RE-based permanent magnets

Size effect of hard magnetic properties of Fe-Nb-B-Tb milled alloys

The paper refers to magnetic and structural properties of powders made of Fe-Nb-B-Tb ultra-high coercive alloy. The initial alloy was milled in a low energy mill for 1 h and 14 h. With increasing milling time we observed gradual deterioration of hard magnetic properties i.e. the coercive field decreases from 5.51 T to 0.14 T for the bulk alloy and 14 h milled powder, respectively. However, for the 1 h milling time the micrometric powder reveals quite high coercivity of 2.77 T which is promising for possible applications in magnetic composites[…

Influence of transition and rare earth elements on magnetic properties of Fe-Nb-B-M (M = Ni, Ag, Gd, Tb) bulk nanocrystalline alloys

In this work we present magnetic properties of the (Fe80Nb6B14)1xMx (where M = Ni, Ag, Gd, Tb and x = 0:08, 0.16, 0.32) bulk nanocrystalline alloys prepared by making use of mould casting technique. The applied preparation technique is favorable to nanocrystallization of the alloys with mean diameters of crystallites ranged from about 10 nm to 30 nm. Phase identi cation reveals a formation of ternary RE2Fe14B and binary REFe2 phases dependently on the alloy composition. It was found that for the alloys with Ag addition magnetic moment of Fe atom increases from 2.26 B to 3.36 B for x = 0:08 and x = 0:32, respectively. For Ni addition this quantity decreases with increasing x due to appearing of Fe Ni (fcc) phases. For Gd, Tb additions the alloys are ferrimagnetic with compensation composition ranged between x = 0:08 and x = 0:16. The both rare earth alloying additions cause a signi cant magnetic hardening especially in the case of Tb

Ultra-fast current aided sintering of high coercive magnetic powders and composites

The paper refers to pulverization and sintering of the (Fe80Nb6B14)0.88Tb0.12 high coercive alloy. The powder was sintered using the ultra-fast current aided method. It turned out that too long discharge time leads to appearing of a soft magnetic phase and simultaneously, decrease in coercivity of the compacted powder. Nevertheless, it was possible to establish preference technology parameters, preserving magnetic hardness of the alloy. As a final test, an impact of Co-powder addition on magnetic properties was studied. The introduced soft magnetic phase (about 20 wt. %) caused about 30% increase of magnetic remanence, which is a result of direct exchange interactions between the two phases

Influence of Dissolving Fe–Nb–B–Dy Alloys in Zirconium on Phase Structure, Microstructure and Magnetic Properties

This paper refers to the structural and magnetic properties of [(Fe80Nb6B14)0.88Dy0.12]1−xZrx (x = 0; 0.01; 0.02; 0.05; 0.1; 0.2; 0.3; 0.5) alloys obtained by the vacuum mold suction casting method. The analysis of the phase contribution indicated a change in the compositions of the alloys. For x < 0.05, occurrence of the dominant Dy2Fe14B phase was observed, while a further increase in the Zr content led to the increasing contribution of the Fe–Zr compounds and, simultaneously, separation of crystalline Dy. The dilution of (Fe80Nb6B14)0.88Dy0.12 in Zr strongly influenced the magnetization processes of the examined alloys. Generally, with the increasing x parameter, we observed a decrease in coercivity; however, the unexpected increase in magnetic saturation and remanence for x = 0.2 and x = 0.3 was shown and discussed

X-ray and thermal analysis of selected drugs containing acetaminophen

Studies carried out by X-ray and thermal analysis confirmed that acetaminophen (paracetamol), declared by the manufacturers as an Active Pharmaceutical Ingredient (API), was present in all studied medicinal drugs. Positions of diffraction lines (2θ angles) of the studied drugs were consistent with standards for acetaminophen, available in the ICDD PDF database Release 2008.ID2θI values were lower than 0.2°, confirming the authenticity of the studied drugs. Also, the values of interplanar distances dhkl for the examined samples were consistent with those present in the ICDD. Presence of acetaminophen crystalising in the monoclinic system (form I) was confirmed. Various line intensities for API were observed in the obtained diffraction patterns, indicating presence of the preferred orientation of the crystallites in the examined samples. Thermal analysis of the studied substances confirmed the results obtained by X-ray analysis. Drugs containing only acetaminophen as an API have melting point close to that of pure acetaminophen. It was found that presence of other active and auxiliary substances affected the shapes and positions of endothermal peaks significantly. A broadening of endothermal peaks and their shift towards lower temperatures were observed accompanying an increase in the contents of additional substances being “impurities” in relation to the API. The results obtained by a combination of the two methods, X-ray powder diffraction (XRPD) and differential scanning calorimetry/thermogravimetry (DSC/TGA), may be useful in determination of abnormalities which can occur in pharmaceutical preparations, e.g., for distinguishing original drugs and forged products, detection of the presence of a proper polymorphic form or too low content of the active substance in the investigated drug

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

A Study of Catalytic Oxidation of a Library of C2 to C4 Alcohols in the Presence of Nanogold

The classical stoichiometric oxidation of alcohols is an important tool in contemporary organic chemistry. However, it still requires huge modifications in order to comply with the principles of green chemistry. The use of toxic chemicals, hazardous organic solvents, and the large amounts of toxic wastes that result from the reactions are a few examples of the problems that must be solved. Nanogold alone or conjugated with palladium were supported on different carriers (SiO2, C) and investigated in order to evaluate their catalytic potential for environmentally friendly alcohol oxidation under solvent-free and base-free conditions in the presence H2O2 as a clean oxidant. We tested different levels of Au loading (0.1–1.2% wt.) and different active catalytic site forms (monometallic Au or bimetallic Au–Pd sites). This provided new insights on how the structure of the Au-dispersions affected their catalytic performance. Importantly, the examination of the catalytic performance of the resulting catalysts was oriented toward a broad scope of alcohols, including those that are the most resistant to oxidation—the primary aliphatic alcohols. Surprisingly, the studies proved that Au/SiO2 at a level of Au loading as low as 0.1% wt. appeared to be efficient and prospective catalytic system for the green oxidation of alcohol. Most importantly, the results revealed that 0.1% Au/SiO2 might be the catalyst of choice with a wide scope of utility in the green oxidation of various structurally different alcohols as well as the non-activated aliphatic ones