Jiao Liu,Jinhu Hu,Xukang Han,Zhenyu Sheng,Yonglei Chi,Fangjiang Chi,Mingliang Ma
The rapid expansion of 5 G technology and the proliferation of electronic devices have exacerbated electromagnetic radiation pollution of urban building space and pose significant risks to human health, necessitating the development of efficient electromagnetic wave (EMW) absorbing materials for use in buildings to address this challenge. Carbon nanotubes (CNT) and magnetic materials such as Fe are widely used in this field due to their unique electromagnetic properties. In this study, γ-Fe 2 O 3 /C/CNT magnetic nanofibers were successfully prepared, exhibiting synergistic di-electric and magnetic capabilities through electrospinning and mechanical blending methods. Compared to γ-Fe 2 O 3 /C fibers and CNT, the CNT-modified composite material exhibited superior EMW absorption performance. At a low loading of 15 wt %, the γ-Fe 2 O 3 /C/CNT composite fibers achieved a minimum reflection loss (RL min ) of -78.89 dB (2.61 mm) and an effective absorption bandwidth (EAB) of 4.12 GHz (1.52 mm, 13.6-17.72 GHz). The superior EMW absorbing performance is primarily attributed to the three-dimensional network structure created by the intertwined nanofibers and CNT, through the synergy of two one-dimensional structures, which achieved good impedance matching and multiple loss mechanisms. As high-efficiency absorbing agents, γ-Fe 2 O 3 /C/CNT magnetic nanocomposite fibers have broad application prospects, serving as low-loading polymer coatings and cement-based materials absorbent to absorb radiation from electronic devices within buildings, reducing indoor electromagnetic pollution, and they can also be used in the field of military stealth. This work provides new insights into the development of efficient EMW absorbing materials.
Tao Chen,Yuhao Xiong,Yuemei Qin,Haiguan Yang,Peng Zhang,Fanggui Ye
In this study, a novel and low-cost method was developed for synthesizing magnetic porous γ-Fe2O3/C as an adsorbent and catalyst for removal of methylene blue (MB) from aqueous solution. Using FeCl3·6H2O and bagasse as the precursor, the biomass-based material was synthesized rapidly using a microwave heating process. Fe ions were introduced to achieve both adsorption and catalytic degradation by the Fenton reaction. Characterization by BET, XRD, SEM, and TEM indicated that the prepared γ-Fe2O3/C material exhibited homogeneous mesoporosity with a BET surface area, mesoporous volume, and saturation magnetization of 764.116 m2 g−1, 0.54 cm3 g−1, and 17.1 emu g−1, respectively. The material exhibited excellent adsorption and catalytic degradation abilities for removal of MB from aqueous solution (up to 352.96 mg g−1), with complete degradation of MB within 30 min. Moreover, γ-Fe2O3/C had good stability over 5 cycles. Therefore, this biomass-based γ-Fe2O3/C material can be used as a highly effective and low-cost adsorbent and catalyst and has great potential application in clean-up processes for environmental pollutants.
A novel and inexpensive approach was adopted to develop magnetic porous γ-Fe2O3/C@HKUST-1 composites for the adsorption of dyes and heavy metal ions from aqueous solution. The γ-Fe2O3/C with unique functional groups present such as –OH and –NH2 was used as the support to directly grow HKUST-1 by a stepwise liquid-phase epitaxy process. The crystallographic, morphology, and magnetic properties as well as porosity of the as-synthesized γ-Fe2O3/C @HKUST-1 composites were carefully studied by XRD, SEM, TEM, XPS, TGA, and BET. The results indicated that the BET surface area, micropore volume, and saturation magnetization of the γ-Fe2O3/C @HKUST-1 are 993.4 m2 g−1, 0.69 cm3 g−1, and 12.6 emu g−1, respectively. In addition, a uniform distribution of ultrafine γ-Fe2O3 nanoparticles with an average diameter of 2–3 nm was observed in the γ-Fe2O3/C@HKUST-1 composites. Our results showed that methylene blue (MB) and Cr(VI) (used as a model for typical dye pollutants and heavy metal ions) are effectively removed from aqueous solutions by γ-Fe2O3/C@HKUST-1. The maximum adsorption capacities were 370.2 and 101.4 mg g−1 of adsorbent for MB and Cr(VI), respectively. Moreover, a removal efficiency of about 90% was retained after five cycles of consecutive adsorption–desorption. The adsorption kinetics data were well described by a pseudo-second-order model (R2 > 0.99), and equilibrium data were well fitted to the Langmuir isotherm model (R2 > 0.99). Finally, our results suggested that the γ-Fe2O3/C@HKUST-1 composites have a great potential to be employed for treatment of wastewater containing MB and Cr(VI).
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