Titanium oxide (TiO2) semiconducting materials attracted great interest in photocatalytic degradation of organic pollutants in the treatment of textile wastewater in recent days. The present study focuses on a sol-gel method for synthesizing nano-Fe doped TiO2 photocatalyst, and employs the advanced oxidation technique termed photocatalytic activation of persulfate to degrade azo dye. The degradation performance of targeted degradant acid orange dye (AO7) was analyzed regarding the impacts of PDS concentration, solution pH, and catalyst dose. Results showed that under visible light irradiation, the removal rate of AO7 can reach a peak of 98.40% within 40 min at an optimal initial concentration of 0.05 g·L-1, a pH of 5, a PDS concentration of 4 mM, and a catalyst dosage of 0.4 g·L-1, accompanied by a reaction rate constant of 0.1152 min-1. Moreover, the higher photocatalytic activity of nano-Fe/TiO2 in comparison to pure TiO2 is attributed to a higher specific surface area, smaller crystalline size, reduced band gap (2.54 eV), and increased efficiency for the electron-hole generation according to SEM, XRD, FTIR and DRS characterization measurements. The nano-Fe/TiO2 photocatalytic efficiency persisted robustly after 4 runs. The photocatalytic mechanism revealed that the persulfate radical (·SO4-) and the hole (h+) followed by superoxide radicals (·O2-) played an crucial role in providing a better photocatalytic activity under visible light irradiation. The outcomes demonstrate future possibilities of applying nano-Fe/TiO2 photocatalyst in the treatment of azo dye wastewater under visible light.
ABSTRACT The corrosion behaviors of austenitic stainless steels 304 and 316 were systematically examined in a 60 wt. % NaOH solution at 240°C under an oxygen partial pressure of 3.2 MPa. After 168h of immersion corrosion, the steady corrosion rates of 304SS and 316SS were determined as 6.60 mm/y and 4.28 mm/y, respectively, with 304SS showing higher corrosion rates under these conditions. Corrosion tests conducted at different durations helped to reveal the migration and transformation patterns of key elements in stainless steel in this aggressive environment. The corrosion mechanism was identified as a multi-stage process. Firstly, during corrosion, a metallic nickel layer forms near the surface, thus preventing the formation of a stable passive protective film. Secondly, chromium (Cr) and molybdenum (Mo) dissolve and convert into their respective soluble products, CrO42− and MoO42−, thereby destroying the integrity of the material. Finally, surface corrosion products tend to crack, leading to delamination and exposure of fresh surfaces to the corrosive medium, therefore accelerating the corrosion process. The investigation results in this work demonstrated the difference in corrosion resistance between 304SS and 316SS, revealing the reasons for the lack of corrosion resistance of stainless steels in oxidative high-concentration alkaline solutions.
The phase transitions, dielectric properties, and polarization versus electric field (P-E) hysteresis loops of Pb0.97La0.02(Zr0.42Sn0.58-xTix)O-3 (0.13 < x < 0.18) (PLZST) bulk ceramics were systematically investigated. This study exhibited a sequence of phase transitions by analyzing the change of the P-E hysteresis loops with increasing temperature. The antiferroelectric (AFE) to ferroelectric (FE) phase boundary of PLZST with the Zr content of 0.42 was found to locate at the Ti content between 0.14 and 0.15. This work is aimed to improve the ternary phase diagram of lanthanum-doped PZST with the Zr content of 0.42 and will be a good reference for seeking high energy storage density in the PLZST system with low-Zr content.
A novel method to prepare high-purity vanadium pentoxide (V2O5) was proposed, and V2O5 with a purity of above 99.95 wt %, in which the concentration of Fe was at 0.0060%, the concentration of Al was at 0.0040%, and Si, K, Na, and other impurities were under the determination limit, was obtained. In this method, anhydrous aluminum chloride (AlCl3) was adopted, which replaced toxic and corrosive Cl2 in the traditional chlorination method. Moreover, the reaction temperature was relatively low at 160 °C compared to Cl2 chlorination method. A novel method to prepare high-purity vanadium pentoxide (V2O5) was proposed. V2O5 with a high-purity of 99.95% was obtained. Anhydrous aluminium chloride (AlCl3) was adopted as chlorination agent to achieve the separation vanadium from impurities at low temperature of 160 °C. This method enables a lower cost, shortened process, a higher selectivity, and simpler and cleaner operation to prepare high-purity V2O5.
Autoimmune Th1 and Th17 responses are critical for the development of central nervous system (CNS) pathology in experimental autoimmune encephalomyelitis (EAE), an animal model for human multiple sclerosis. Although macrophages play important roles in the development of Th1 and Th17 responses, whether modulating macrophage gene transcription can diminish the Th1- and Th17 cell-induced CNS pathology is unclear. In this study, we successfully silenced the expression of the transcription factor c-Rel in macrophages of mice with EAE (including those infiltrating the CNS) using chemically modified c-Rel-specific siRNAs delivered by nanoparticles. Knocking down c-Rel in macrophages in vitro inhibited expression of NF-κB targets, such as pro-inflammatory cytokines interleukin 1β (IL-1β) and p40 of interleukin 12 (IL-12)/interleukin 23 (IL-23), in macrophages, leading to reduced interferon γ (IFN-γ) and interleukin 17A (IL-17A) production by co-cultured MOG-specific T cells from EAE mice. Such effects correlated with diminished T-cell infiltration in the CNS, reduced clinical symptoms, as well as downregulated pathogenic Th1 and Th17 responses in EAE mice. Taken together, our findings indicate that targeting c-Rel in macrophages dampens CNS-specific Th1 and Th17 immune responses, and can be effective for treating autoimmune diseases of the CNS.
The scaling behaviors of dynamic hysteresis were investigated in serial rhombohedral Nb-doped Pb(Zr1-xTix)O3 (PZT) bulk ceramics as a function of frequency (f) and field amplitude (E0). Three distinct regions were plotted including linear loops, minor loops, and saturated loops with an increase of E0. When the external fields were over ∼1.5 times of coercive field (Ec), the scaling relations of saturated loops for these PZT ceramics could be expressed with an identical form as hysteresis area ⟨A⟩ ∝ f 0.01E00.10, which indicated that similar ferroelectric systems with different compositions could display a uniform scaling law under high-E0 and low-f regions.
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