In this research work, new composite materials based on magnesium phosphate cement (MPC) were developed to evaluate the retention of fluorine from wastewater. This material was prepared with dead burned magnesia oxide (MgO), ammonium dihydrogen phosphate (NH₄H₂PO₄), and some retarding agents. We chose to synthesize with hydrogen peroxide instead of water; alumina and zeolite were also added to the cement. The obtained optimal conditions were studied and analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), BET, and thermogravimetric analysis (TGA). The adsorbents showed a strong ability to remove fluoride from contaminated water, and the best defluoridation capacity was evaluated as 2.21 mg/g for the H₂O₂ cement. Equilibrium modeling was performed, and the experimental data were presented according to the isotherms of Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich.

In this study, we used a novel composite material based on magnesium phosphate cement (MPC) to explore the retention of fluoride from used water. Dead-burned magnesium oxide (MgO), ammonium dihydrogen phosphate (NH₄H₂PO₄), and a few retarders were used to create this particular substance. Several studies have corroborated the performance of using aluminum in the capture of fluoride. From this perspective, we attempted to reinforce our matrix with different quantities of aluminum, which increased the resistance of the composite in water. The optimal conditions that were obtained were evaluated and scrutinized using a range of techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transforms infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET). The adsorbents demonstrated a powerful ability to remove fluoride from contaminated water and the defluoridation capacity was evaluated at 4.84 mg/g. Equilibrium modeling was carried out, and the experimental data were expressed in accordance with the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms.

In the current study, X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer techniques were used to examine the impact of milling time on the microstructural and magnetic characteristics of Fe₃₀Co₂₀Ni₂₀Mn₂₀Ti₁₀ (at%) produced via mechanical alloying. Results demonstrate that phase change is dependent on up to 30 h of milling. In terms of the hcp-Fe₂Ti intermetallic and the BCC-FeCoNiMnTi supersaturated solid solution, the system maintains its two-phase structure at higher times. Additionally, the final average crystallite size was estimated to be approximately 10 nm, and the lattice strain was found to be between 0.95 and 1.15%. As a function of milling time, the magnetic properties are discussed with the microstructural and crystallographic alterations. The collected powder after 100 h of milling has an Ms value of 28 emu/g and a Hc value of 25 Am⁻¹, which is consistent with exceptional soft magnetics. This is essentially due to the Fe₂Ti intermetallic and the BCC-Fe-based solid solution production, together with the refinement of the crystallite size. Furthermore, the presence of paramagnetic Ti atoms in solid solution and the development of high densities of defects and interfaces have been connected to the low value of Ms.

In the present study, the hydrogen-absorption properties of the LaNi₅ and the La_0.7Ce_0.1Ga_0.3Ni₅ compounds were determined and compared. This work is therefore divided into two parts: an experimental part that presents and discusses the kinetics and isotherms of hydrogen absorption in the two compounds at two different temperatures (298 K and 318 K). In addition, the temperature variations inside the hydride bed were determined. In the second section, the experimental isotherms were compared to a numerical model processed using statistical physics. Following that, thanks to the perfect agreement between the experimental data and the proposed model, the stereographic and energetic parameters associated with the hydrogen absorption reaction, such as the number of hydrogen atoms per receptor site (n₁, n₂), the densities of the sites (N_m1, N_m2), the half-saturation pressures (P₁, P₂) and the absorption energies (ΔE₁, ΔE₂) for each receptor site, were calculated. All of these parameters are acquired by making numerical adjustments to the experimental data. Thermodynamic functions, such as internal energy and Gibbs energy, which regulate the absorption process, were then identified using these parameters. For both compounds, all of the aforementioned were compared and discussed in relation to initial temperature and pressure. The results demonstrated that the hydrogen-storage properties in LaNi₅ are enhanced by more than 30% of stored mass and kinetics when Ce and Ga are substituted at the La sites.

The sol-gel process was used to produce ferrite Ni_0.3Zn_0.7Cr_2−xFe_xO₄ compounds with x = 0, 0.4, and 1.6, which were then subsequently calcined at several temperatures up to 1448 K for 48 h in an air atmosphere. X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and ⁵⁷Fe Mössbauer spectrometry were used to examine the structure and magnetic characteristics of the produced nanoparticles. A single-phase pure Ni_0.3Zn_0.7Cr_2−xFe_xO₄ nanoparticle had formed. The cubic $Fd\overline{3}m$ spinel structure contained indexes for all diffraction peaks. The crystallite size is a perfect fit for a value of 165 ± 8 nm. Based on the Rietveld analysis and the VSM measurements, the low magnetization Ms of Ni_0.3Zn_0.7Cr_2−xFe_xO₄ samples was explained by the absence of ferromagnetic Ni²⁺ ions and the occupancy of Zn²⁺ ions with no magnetic moments in all tetrahedral locations. Moreover, because of the weak interactions between Fe³⁺ ions in the octahedral locations, the magnetization of the current nanocrystals is low or nonexistent. According to Mössbauer analyses, the complicated hyperfine structures are consistent with a number of different chemical atomic neighbors, such as Ni²⁺, Zn²⁺, Cr³⁺, and Fe³⁺ species that have various magnetic moments. A Fe-rich neighbor is known to have the highest values of the hyperfine field at Fe sites, while Ni- and Cr-rich neighbors are responsible for the intermediate values and Zn-rich neighbors are responsible for the quadrupolar component.