During ferrochromium alloy manufacturing, ferrochrome slag is an inevitable industrial residue. Its environmental impacts depend on chromium speciation rather than on total chromium content alone. This study investigates chromium speciation within a low-carbon ferrochrome slag aliquot from a large-scale production facility in the Ural Mountains, using high-energy-resolution laboratory von Hámos X-ray absorption spectroscopy (XAS), a novel technique only recently made accessible for routine characterization, designed to approach synchrotron-level performance. XANES analysis reveals the predominance of the trivalent oxidation state. LCF results indicate Cr occurs mainly in environments similar to FeCr2O4 (70.2%), Cr(0) (23.4%), and Cr2O3 (6.4%). EXAFS analysis shows that the first (Cr-O) and second (Cr-Cr) coordination shells are arranged in a chromite spinel-like Cr(III) structure. XPS findings confirm the predominance of Cr(III) in the slag. Finally, high-energy-resolution laboratory von Hámos XAS enabled the determination of the chromium oxidation state and the local coordination environment even in a poorly defined soil matrix, which parameters define the mobility, reactivity, and potential toxicity of the ferrochrome slag, and promotes this technique as an accessible and economical alternative for toxic metals speciation, with significant implications for the environmental risk classification and the safe reutilization of ferrochrome slag.
This research provides a comprehensive study on the adsorption behavior and mechanism of methylene blue (MB) using non-functionalized extracted cellulose derived from rice husks (ERH) prepared via ultrasound-assisted chemical extraction as a biosorbent. ERH exhibits enhanced structural properties and adsorption performance compared to raw rice husks and commercial cellulose. The adsorption performance was influenced by adsorbent dosage, contact time, initial dye concentration, pH, and temperature, achieving maximum adsorption capacity of 68.4 mg g−1. The adsorption of MB by ERH adsorbent followed pseudo-first-order (PFO) and Temkin model under non-linear fitting. Furthermore, thermodynamic parameters revealed that the adsorption process is favorable, exothermic, and spontaneous. This biosorbent maintained a removal efficiency approximately 70% after three regeneration cycles. These results demonstrate the potential of ERH as a biosorbent for MB removal and further clarifying insight into the adsorption mechanism.
Optimization of a hydrogen-fed solid oxide fuel cell (SOFC) by integrating the Taguchi design of experiments and computational fluid dynamics (CFD) simulations was conducted. Seven key parameters (including operational, geometrical, and property parameters) were analyzed using a two-stage orthogonal-array strategy (first-stage L27 orthogonal array and second-stage L9 array). Results indicated that voltage was the most influential factor, followed by temperature and GDE thickness, while oxidant composition, electrolyte thickness, porosity, and anode permeability showed comparatively lower marginal effects. The Taguchi-selected configuration yielded an average power density of 13,097.50 W/m2 and a current density of 26,194 A/m2 in the final CFD confirmation simulation. A direct voltage sweep at the final selected operating, material, and geometric conditions showed that the highest directly simulated power density was 13,406.36 W/m2 at 0.56 V, whereas the Taguchi-selected voltage level of 0.5 V yielded 13,097.50 W/m2. Under otherwise fixed conditions, increasing HE from 50 to 70 μm decreased the power density by 7.16%, confirming the expected increase in electrolyte transport loss with increasing thickness. Accordingly, the 70 μm electrolyte thickness identified by the Taguchi analysis should be interpreted as a design-space selection based on the marginal S/N response rather than as an intrinsic physical optimum.
