X-ray Micro-Computed Tomography: A Powerful Device to Analyze the 3D Microstructure of Anode-Electrolyte in BaZr0.8Y0.2O3 Protonic Ceramic Electrochemical Cells and the Reduction Behavior

New advanced fuel cell technologies are moving towards high-temperature proton conductors (HTPCs) to meet environmental issues. Their elaboration remains a challenge and micro-computed tomography (µCT) is an innovative way to control their quality. NiO-BZY anodic supports of a protonic ceramic electrochemical cell (PCEC), elaborated by co-tape casting and co-sintered at 1350 °C, were coated with a BZY20 electrolyte layer by DC magnetron sputtering. The µCT allowed to observe defects inside the volume of these PCEC half-cells and to show their evolution after an annealing treatment at 1000 °C and reduction under hydrogen. This technique consists in obtaining a 3D reconstruction of all the cross-sectional images of the whole sample, slice by slice. This allows seeing inside the sample at any desired depth. The resolution of 0.35 µm is perfectly adapted to this type of problem considering the thickness of the different layers of the sample and the size of the defects. Defects were detected, and their interpretation was possible thanks to the 3D view, such as the phenomenon of NiO grain enlargement explaining defects in the electrolyte, the effect of NiO reduction, and finally, some anomalies due to the shaping process. Ways to anticipate these defects were then proposed.

Influence of a Prior Oxidation on the Reduction Behavior of Magnetite Iron Ore Ultra-Fines Using Hydrogen

The reduction behavior of raw and prior-oxidized magnetite iron ore ultra-fines with hydrogen was investigated. Reduction tests were conducted with a thermogravimetric analyzer in a temperature range from 873 K to 1098 K at 1.1 bar absolute, using hydrogen as reducing gas. The experimental results show that a prior oxidation of the magnetite has a positive effect on the reduction behavior because of changing morphology. The apparent activation energies show a turnaround to negative values, depending on the prior oxidation and degree of reduction. A multi-step kinetic analysis based on the model developed by Johnson–Mehl–Avrami was used to reveal the limiting mechanism during reduction. At 873 K and 948 K, the reduction at the initial stage is controlled by nucleation and chemical reaction and in the final stage by nucleation only, for both raw and pre-oxidized magnetites. At higher temperatures, 1023 K and 1098 K, the reduction of raw magnetite is mainly controlled by diffusion. This changes for pre-oxidized magnetite to a mixed controlled mechanism at the initial stage. Processing magnetite iron ore ultra-fines with a hydrogen-based direct reduction technology, lower reduction temperatures and a prior oxidation are recommended, whereby a high degree of oxidation is not necessary.

Peran Moderasi Komitmen Profesional terhadap Perilaku Reduksi Kualitas Audit Periode Pandemi Covid-19

The aims of this study was to examine the effect of time budget pressure and locus of control on the behavior of auditors performing audit quality reduction behavior in the midst of the covid-19 pandemic. In addition, to find out profesional commitment to moderate the effect of time budget pressure and locus of control on audit quality reduction behavior in the midst of the covid-19 pandemic. The population in this study are auditors who work in Public Accounting Firms, the sampling method used purposive sampling and obtained a sample of 64 respondents who collected data using google form. Data analysis used multiple linear regression and moderated regression analysis (MRA). This study found that external locus of control had a positive effect on audit quality reduction behavior and the moderating role of profesional commitment was not supported. This study implies that auditors can adapt to current conditions except for auditors who have an external locus of control and policy makers can pay attention to this.

Electrochemical Formation of Elemental Boron in LiCl–KCl–KBF4 at 723 K

The electrochemical reduction behavior of B(III) ions was investigated in LiCl–KCl–KBF4 at 723 K. The results of cyclic voltammetry using Mo, Ag, and Ni electrodes suggested the reduction of B(III) to B(0) at potentials of 1.5 V or at a more negative potential (vs. Li+/Li). Spherical electrodeposits were observed after potentiostatic electrolysis at 1.1–1.5 V. From the results of X-ray photoelectron spectroscopy, scanning transmission electron microscope/energy-dispersive X-ray spectroscopy (STEM/EDX), and selected area electron diffraction, it was concluded that the spherical electrodeposits obtained at 1.1 V were elemental amorphous boron. The purity of the products was 85 wt% boron, as determined by STEM/EDX analysis. The current efficiency of elemental B electrodeposition was 96.2% in this system. The formation of Ni2B at 1.1–1.9 V was indicated by X-ray diffraction, although it was not the main product. These results indicate that the presence of B(III) ions in a melt causes a fatal adverse effect on the recycling process of Nd–Fe–B magnets due to the reduction of B(III) ions. Further, the possibility of reducing the energy and cost of the elemental boron production process was discussed.

Low-Temperature Hydrothermal Treatment (HTT) Improves the Combustion Properties of Short-Rotation Coppice Willow Wood by Reducing Emission Precursors

The worldwide transformation from fossil fuels to sustainable energy sources will increase the demand for biomass. However, the ash content of many available biomass sources exceeds the limits of national standards. In this study, short-rotation coppice willow biomass was hydrothermally treated at 150, 170 and 185 °C. The higher heating value increased by 2.6% from x¯ = 19,279 J × g−1 to x¯ = 19,793 J × g−1 at 185 °C treatment temperature. The mean ash content was reduced by 53% from x¯ = 1.97% to x¯ = 0.93% at 170 °C treatment temperature, which was below the limit for category TW1b of the European pellet standard for thermally treated biomass. The nitrogen, sulfur and cadmium concentrations were reduced below the limits for category TW1b of the European biomass pellet standard (N: from 0.52% to 0.34%, limit at 0.5%; S: from 0.051% to 0.024%, limit at 0.04%; Cd: from 0.83 mg × kg−1 to 0.37 mg × kg−1, limit at 0.5 mg × kg−1). The highest reduction rates were sampled for phosphor (80–84%), potassium (78–90%), chlorine (96–98%) and lithium (96–98%). The reduction behavior of the elements is discussed according to the chemical processes at the onset of hydrothermal carbonization. The results of this study show that HTT has the potential to expand the availability of biomass for the increasing worldwide demand in the future.

Catalytic Reduction Performance of Carboxylated Alginic Acid Derivatives

In this study, the catalytic reduction behavior of carboxylated alginic acid derivatives has been investigated against the harmful organic dyes including Methyl Orange (MO) and Congo Red (CR). Alginic acid was firstly oxidized through an easy addition of KMnO4 as an oxidizing agent. A carboxylated alginic acid (CAA) has been interacted with selected metal ions (Sn, Fe, Ni, and Zr) through coordination bonds at the value of pH = 4 to form the corresponding metal complexes namely: Sn-CAA, Fe-CAA, Ni-CAA and Zr-CAA. The consistency of the coordination was confirmed by several spectroscopic techniques including FT-IR, XRD, SEM, and EDX. The catalytic reduction of these metal ion-based products was carried out against MO and CR in the presence of NaBH4 as a reducing agent under UV irradiation. All catalysts based metal complexes showed enhanced catalytic reduction against CR compared to MO. Among all those mentioned metal complexes Sn-CAA showed the best catalytic reduction of these dyes. The time taken by the Sn-CAA for CR, and MO is 5 and 7min respectively. Ni-CAA was classified as the second efficient product against both dyes, where the reduction process took 20 and 9 min respectively. The other two catalysts took a long time for CR and MO reduction. Zr-CAA showed more than 80 % reduction of only CR dye within 20 min. Whereas, Fe-CAA did not show any significant sign of reduction against both the dyes after the same time. The order of higher catalytic reduction was illustrated as: Sn-CAA > Ni-CAA > Zr-CAA = Fe-CAA.

Electrochemical Mechanism of Recovery of Nickel Metal from Waste Lithium Ion Batteries by Molten Salt Electrolysis

With the widespread use of lithium-ion batteries, the cumulative amount of used lithium-ion batteries is also increasing year by year. Since waste lithium-ion batteries contain a large amount of valuable metals, the recovery of valuable metals has become one of the current research hotspots. The research uses electrometallurgical technology, and the main methods used are cyclic voltammetry, square wave voltammetry, chronoamperometry and open circuit potential. The electrochemical reduction behavior of Ni3+ in NaCl-CaCl2 molten salt was studied, and the electrochemical reduction behavior was further verified by using a Mo cavity electrode. It is determined that the reduction process of Ni3+ in LiNiO2 is mainly divided into two steps: LiNiO2 → NiO → Ni. Through the analysis of electrolysis products under different conditions, when the current value of LiNiO2 is not less than 0.03 A, the electrolysis product after 10 h is metallic Ni. When the current reaches 0.07 A, the current efficiency is 77.9%, while the Li+ in LiNiO2 is enriched in NaCl-CaCl2 molten salt. The method realizes the separation and extraction of the valuable metal Ni in the waste lithium-ion battery.