Li Liu,Jingshuai Wang,Xingyi Wu,Hui Kong,Rui Wang,Zhaoyang Wu
Herein, the composite powder with a core–shell heterostructure (Fe–Si–Cr magnetic particles as the core and ZnSO 4 as the shell) was synthesized using hydrothermal method, and Fe–Si–Cr-based soft magnetic composites (SMCs) with an insulation layer of ZnO·SiO 2 ·Cr 2 O 3 (ZSC) composites were successfully prepared via powder heat treatment and cold pressing. The formation mechanism of the ZSC composite insulation layer was thoroughly investigated, and the impact of varying amounts of ZnSO 4 on the Fe-Si-Cr/ZSC SMCs’ microstructure and magnetic properties was analyzed. ZnSO 4 released oxygen during thermal decomposition and oxidation reaction occurred at the core–shell heterogeneous interface, forming ZSC composite insulation layer. The incorporation of ZnSO 4 significantly influenced the homogeneity and thickness of the composite insulation layer, effectively modulating the magnetic properties of Fe–Si–Cr/ZSC SMCs. This SMCs had the best magnetic properties after the addition of 2 wt% ZnSO 4 . Under 10 mT and 300 kHz, the relative permeability was 37.7, with a total loss of 248.8 kW/m 3 The method proposed in this study is beneficial for facilitating the advancement of SMCs towards high frequency and further optimizing its performance.
Ziying Wang,Yisheng Shao,Naiyun Gao,Bin Xu,Na An,Xian Lu
Applying the highly oxidative sulfate radical ( SO 4 - · ) to pollutant degradation may cause it to react with the coexisting bromide (Br − ) to form undesired byproducts. This study investigated the transformation of Br − during the degradation process of a contaminant (diethyl phthalate (DEP)) via heat-activated persulfate (PS). Dibromoacetonitrile and bromoform formed with Br − and natural organic matter (NOM) in the solution, while only bromoform was detected without NOM. The formation of these brominated disinfection byproducts (Br-DBPs) can be ascribed to the reactions between the phenolic groups of DEP degradation intermediates or NOM and reactive bromine species (free bromine and radical bromine) generated through the oxidation of Br − by SO 4 - · . Br-DBPs were degraded by excessive SO 4 - · , which indicates that organic bromine is a temporary phase during the turnover of Br − . The time-dependent formation of organic and inorganic bromines suggests that Br − may have cycled several times between organic and inorganic forms before eventually turning into bromate. The bromate formation showed a lag phase before continuously increasing. Generally, increasing the temperature, PS dosage, and Br − and organic matter (DEP and NOM) concentrations increased the maximum concentration of Br-DBPs. Additionally, these reaction parameters facilitated bromate formation except for organic matter, whose inhibitory effect is probably due to the consumption of reactive species by organic matter and the generated superoxide anion. The total organic carbon concentration of the solution exhibited a relatively quick reduction followed by a slow decrease. These results highlight the potential risks of PS activation technologies and can help prevent such risks in actual practice.
In this study, the degradation of ofloxacin (OFX) over Cu–Ce tyre carbon catalysts by the microwave assisted persulfate process was examined for the first time. The results showed that the Cu–Ce tyre carbon catalysts dramatically improved OFX decay efficiency. The optimal reaction conditions were the Cu–Ce tyre carbon catalysts of 2.0 g/L and the persulfate dosage of 12.0 g/L under microwave power of 400 W at 60 °C. The OFX conversion and total organic carbon (TOC) removal reached 95.8% and 87.6%, respectively, after 60 min catalytic oxidation under optimal conditions. To identify the properties of Cu–Ce tyre carbon catalyst, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), the Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and the ultraviolet–visible (UV–vis) diffuse reflectance spectra studies have been carried out. Eleven kinds of degradation products and five pathways during degradation process of OFX and degradation products were identified by GC–MS and HRMS.
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