Synthesis of pure and lanthanum-doped barium ferrite nanoparticles for efficient removal of toxic pollutants

Treatment of wastewater for reuse is an important strategy undertaken to deal with water scarcity. In this study, pure and La-doped barium ferrites were produced using a facile hydrothermal technique. Lanthanum was doped at 1% and 2% molar ratio and the obtained product was analyzed for further confirmation of crystal structure, optical properties, vibrational properties, and morphology. X-ray powder diffraction pattern confirmed material formation. Bandgap energies were estimated from a Tauc plot. The vibrational properties of the pure and doped samples were examined by Fourier-transform infrared spectra. The pure barium ferrite sample showed a spherical agglomerated morphology. The 1% La-doped barium ferrite sample showed reduced agglomeration and the particles were attached together. The 2% La-doped barium ferrite sample showed small nanoballs with no agglomeration on the surface. The transmission electron microscopy images confirmed no agglomeration for the 2% La-BaFe₂O₄ sample. The M-H loop revealed the ferromagnetic behavior of the pristine and doped samples. The 2% La-BaFe₂O₄ sample had 24.53 m²/g surface area. The photocatalytic activity was examined employing degrading methylene blue under ultraviolet (UV) and visible light. Prepared product showed better efficiency on UV light exposure. The 2% La-doped barium ferrite sample exhibited almost 80% of efficiency under UV light and 85% efficiency under visible light toward toxic pollutants. The sample attained 0.02 min^-1 rate constant value. The main advantage of ferrite samples is that the particles can be separated by magnetic methods and the water will be fit for reuse. The sample will be a promising candidate for use in the wastewater treatment.

Hard magnetic membrane based on bacterial cellulose - Barium ferrite nanocomposites

Magnetic membranes based on bacterial cellulose (BC) nanocomposites have been extensively researched. However, most magnetic nanoparticles (NPs) incorporated in the BC matrix were focused on soft magnetic phases, which limited the extensive use of magnetic BC membranes. Therefore, this work proposes a method to fabricate hard magnetic membrane based on the BC matrix and magnetically hard phase barium ferrite (BFO) NPs. The nanocomposites showed the peaked tensile strength and modulus at the low concentration of BFO whereas the magnetization increased drastically with the BFO content. They also demonstrate the high flexibility up on bending and the sensitivity to external magnetic fields. Furthermore, unlike other magnetic BC membranes, the BC/BFO nanocomposites exhibited the hard magnetic properties, i.e. they could retain their magnetic attraction after being magnetized by a permanent magnet. These properties open the possibility to employ these materials in various fields, such as information storage, anti-couterfeit or electromagnetic shieldings.

PANI/BaFe12O19@Halloysite ternary composites as novel microwave absorbent

A three-phase PANI/BaFe₁₂O₁₉@Hal heterostructure was designed and fabricated in this paper as efficient lightweight electromagnetic wave absorbing material through the combination of citrate assisted sol-gel self-propagating combustion and in-situ oxidative polymerization of aniline. In addition, the effects of the weight ratio of different PANI to BF@Hal on the microwave absorption properties of the materials were studied. The results show that when the weight ratio of PANI is 40%, the material has the best microwave absorption performance. The frequency bandwidth below -5 dB reached 9.60 GHz and the minimum absorption peak at 11.92 GHz was -14.77 dB. The combination of the PANI and BF@Hal nanosheets take advantage of the interfacial polarization, natural resonance, dielectric polarization and trapping of EM waves by internal reflection in PANI/BaFe₁₂O₁₉@Hal. Taking advantage of the unique microscopic morphology and interface characteristics, halloysite was introduced to improve the microwave absorption performance and enrich the absorbing mechanism of the composite materials. This work may provide a reliable candidate for the synthesis of electromagnetic attenuation materials with fairly good performances.

Synthesis and application of magnetic materials-barium ferrite nanomaterial as an effective microwave catalyst for degradation of brilliant green

In this work, magnetic separably barium ferrite nanomaterial (BaFeO) was synthesized via citrate acid assisted sol-gel combustion method. Subsequently, X-ray diffraction (XRD), scanning electron microscopy-energy dispersion spectroscopy (SEM-EDS), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) were applied for its structural, morphological, and electromagnetic characterization. In addition, microwave (MW) absorption and thermal conversion test results indicated the BaFeO had electrothermal rather than magnetothermal conversion capacity. Meanwhile, the synthesized BaFeO showed satisfactory performance in both eliminating and mineralization of a typical triphenylmethane dye, brilliant green (BG), in MW-induced catalytic oxidation (MICO) process without extra oxidant addition. Besides, changes in element valence and content of BaFeO before and after MICO process investigated with XRD, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) showed its relatively stable properties. Furthermore, transition oxygen species involved in MICO process was deduced as lattice oxygen species. Then, the possible degradation pathway of BG was proposed as demethylation, open-loop of triphenylmethane, releasing one ring, formation of the benzene ring and the ultimate mineralization based on the degradation intermediates tentatively identified by gas chromatography mass spectrometry (GC/MS) and liquid chromatography mass spectrometry (LC/MS), respectively. Finally, ecotoxicity analysis by ecological structure activity relationships (ECOSAR) showed that both the acute and chronic toxicity of these intermediates were lower than that of parent BG. These findings are important regarding the development of efficient catalysts in MICO process for degradation of BG analogues in wastewater.