Yingying Fang,Wenbo Zhou,Yihuan Cheng,Yuge Zhang,Tingting Yu,Shaoxian Song
The high-value utilization of steel pickling waste liquid (SPWL) is an important direction in the resourceful utilization of hazardous waste. In this study, nano-Fe 3 O 4 prepared from SPWL (S-Fe 3 O 4 ) was hydrothermally compounded with MnO 2 as Fe 3 O 4 -MnO 2 (SFM), which were compared with Fe 3 O 4 -MnO 2 (CFM) prepared by chemical reagents. The synthetic materials were evaluated by SEM, VSM, BET, XRD, and zeta potential, the results show that the spherical S-Fe 3 O 4 was encapsulated by spiny spherical shell-like MnO 2 , and the SFM has a high saturation magnetization and specific surface area (159.91 m 2 /g). The adsorption experiments demonstrated that the adsorption effect of SFM on Pb 2+ is highly similar to that of CFM. The maximal adsorption capacity of SFM reached 129.74 mg/g under ideal composite ratio and pH conditions, and the adsorption process was unaffected by competing heavy metal ions coexisting in the environment. Moreover, the high saturation magnetization strength of the SFM makes it simple to separate materials under a magnetic field. The pseudo-second-order kinetics and Langmuir isotherm models provided a good description of the Pb 2+ adsorption on SFM. XPS and FTIR analysis provided evidence that the adsorbent surface has a high concentration of -OH functional groups, and that O atoms serve as Pb 2+ binding sites, suggesting that ion exchange occurs during the SFM adsorption process. In this paper, we developed a cheap SFM with high adsorption performance and provided a novel approach to the high-value application of SPWL.
In this work, a novel 2D Fe 3 O 4 -MnO 2 hollow fiber ceramic membrane (HFCM) with both excellent separation performance and high catalytic activity was constructed. The Fe 3 O 4 nanoparticles were deposited on 2D MnO 2 nanoplates to increase the Mn 3+ content, and then the nanoplates were pressure-driven and sintered on the surface of the hollow fiber ceramic supports to obtain 2D Fe 3 O 4 -MnO 2 -HFCMs. Electron spin resonance analysis confirmed that hydroxyl radicals and superoxide radicals played a major role in oxidative degradation and tetracycline hydrochloride (TCH) removal was 86.9 %. Noteworthily, TCH was concentrated on the membrane interface due to the concentration polarization effect, which increases the probability of binding free radicals from the catalytic membrane layer, thus enhancing the catalytic performance and the anti-fouling capability of the membrane. The 2D Fe 3 O 4 -MnO 2 -HFCM can be applied in wastewater treatment due to its superior catalytic ozonation activity and high separation performance.
Cross and secondary electromagnetic pollution is a major challenge in current electromagnetic interference (EMI) mitigation. In this study, Fe3O4@MnO2 composite microspheres and AgNWs were prepared using modified solvothermal and hydrothermal methods. By optimizing the fabrication process and structural design of electromagnetic shielding composite films, we successfully constructed a composite film with superior shielding performance and reduced thickness. The Fe3O4@MnO2 composite exhibited an SEA/SET ratio of 83.32%, along with a high absorption coefficient A, indicating its dominant role in electromagnetic wave absorption, thereby mitigating excessive reflection. Results demonstrated that the gradient network-structured film possessed significantly enhanced electromagnetic wave absorption and attenuation capabilities compared to other three composite materials. The SEA/SET of the gradient network-structured film reached 86%, with a maximum SET of 58.65 dB. This hierarchical structure not only improves shielding effectiveness at reduced thickness but also enhances absorption, achieving the ultimate goal of high absorption with low reflection while minimizing resource consumption.
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