Journal of Particle Science and Technology
https://jpst.irost.ir/
Journal of Particle Science and Technologyendaily1Wed, 01 Nov 2023 00:00:00 +0330Wed, 01 Nov 2023 00:00:00 +0330Heavy metal removal using SnO2 nanoparticles prepared in a grape extract media
https://jpst.irost.ir/article_1336.html
SnO2 nanoparticles were first synthesized using a grape extract media, then characterized by XRD, FE-SEM, TEM, BET, and DLS techniques, and finally used as an efficient adsorbent for the removal of Pb2+ and Cd2+ ions from wastewater. The prepared sample had a tetragonal phase with an average crystallite size of 41 nm (XRD analysis), a specific surface area of 47.08 m2.g-1 (BET method)/46.25 m2.g-1 (BJH method), and a pore diameter of 6.49 nm (BJH method). The best conditions for adsorbing were a 30 ppm concentration of metal ions, ambient temperature, pH of 6, and 0.025 g of an adsorbent. The maximum adsorption for Pb and Cd ions was 97 and 93%, respectively. The Elovich model was matched as the most suitable kinetic model, indicating that the adsorption mechanism is chemical adsorption. The negative values of &Delta;G (Pb: -6.38 kJ.mol-1; Cd: -4.16 kJ.mol-1) represent the spontaneousness of the adsorption process. The negative values of the parameters &Delta;H (Pb: -63.0 kJ.mol-1; Cd: -42.95 &nbsp;kJ.mol-1) and &Delta;S (Pb: -188.8 J.mol-1; Cd: -128.4 J.mol-1) represent the exothermic nature of the adsorption.Fabrication method, microstructural characteristics, and hardness behavior of an interpenetrating phases hybrid aluminum/alumina-nanodiamond composite
https://jpst.irost.ir/article_1338.html
In the present work, the addition effects of nanodiamond (ND) on the microstructure and hardness behavior of interpenetrating phases hybrid Al/Al2O3 metal matrix composites were investigated. The fabrication of the composites was done via a two-step process. In the first step, hybrid Al2O3-ND preforms were prepared, and then molten pure Al alloy was infiltrated into the preforms. The preforms were fabricated by the replica method using a polyurethane foam and an Al2O3-ND slurry with various ND contents (0, 1, 3, and 10 vol%). The preforms were sintered at 1500 &deg;C for 4 h under argon gas protection. Finally, the composites were fabricated by Al melt infiltration into the preforms via the squeeze casting method. The microstructure of the fabricated composites was analyzed using optical and scanning electron microscopes. The hardness of the composites was measured using a Vickers hardness tester. The results of the microstructural evaluations demonstrated a good distribution of ND in the preform. By increasing the ND content from 0 to 10 vol%, the matrix average grain size decreased from 143 &mu;m to 76 &mu;m. The results of the Vickers hardness test showed that increasing the volume percentage of ND increased the composite hardness to 263.8 Vickers at 10 vol%. The two main strengthening mechanisms for these composites are the Orowwn mechanism (volume fraction of ND particles) and the Hal-Petch mechanism (grain size), which affect the hardness behavior.Numerical investigation of the effect of nanoparticle sedimentation on the thermal behavior of cavities with different cross-sectional shapes
https://jpst.irost.ir/article_1353.html
In this paper, the thermal behavior of nanofluids was numerically simulated during nanoparticle sedimentation. A new solver was developed in the open-source framework, i.e. openFoam, using the finite volume method by combining appropriate solvers. Free convection flow was transiently modeled using this solver during the second phases (nanoparticles) sedimentation. A relative velocity term from the Vesilind relation was added to the momentum equation to model the sedimentation. Boussinesq and Maiga&rsquo;s relations were used to calculate the density changes with temperature and effective conductivity, respectively. Simulations were performed for square, triangular, and circular cross-sections with the same hydraulic diameter at three different Rayleigh numbers. In addition, the changes in Nusselt number over time and the distribution of nanoparticles under different conditions were studied. The results showed that the formation of the sediment layers at the bottom of the enclosure reduced the streamlines and decreased natural convection and rotational flow. In addition, it contributed to conductive heat transfer, leading to a rapid decrease in the Nusselt number of cavities. Moreover, by increasing the Rayleigh number, the square, and triangular cross sections had the highest and lowest heat transfer, respectively.Approximation and analytical study of the relativistic confined two particles state within the complex potential in the isotropic medium
https://jpst.irost.ir/article_1355.html
We have studied the dissociation of particle-antiparticle confined systems through a complex potential, which comes from adjusting and correcting both the perturbative and nonperturbative terms at finite temperatures. The real component of the confining nonperturbative potential makes the bound state stronger; in contrast, the absolute value of the imaginary component contributes more significantly to the thermal width at higher temperatures. The results are presented using the relativistic Bethe-Salpeter equation for the real and imaginary parts of the given potential within the framework of the asymptotic pattern and characteristics of the real and imaginary-time Green&rsquo;s functions of the bound state as charged particles that couple to a gauge field in any external field. The relativistic behavior of interaction within the Sturmian representation for two intertwined spaces was extracted based on the mathematical quantum field theory technique in the perturbative calculation of the quantum field theory. The expectation value of the vacuum of field operators is defined as a sum of operator product expansion methods. The results are applied to predict the masses of the charmonium confined state and study the heat dynamics and attributes of the system. The expectation values agree with the experimental and theoretical data found within scholarly works and among academic researchers.Fabrication and optimization of superhydrophobic ZnO-SA/PVC/PVP nanocomposite membrane distillation for highly saline RO brine recovery
https://jpst.irost.ir/article_1360.html
The induced phase separation method was used to fabricate polyvinyl chloride (PVC) flat sheets for membrane distillation (MD) of RO brine feed, by using Dimethylformamide (DMF) and water as solvent and non-solvent, respectively. In order to improve the membrane structure and modify pore surfaces, polyvinylpyrrolidone (PVP) and zinc oxide (ZnO) nanoparticles were utilized. Taguchi experimental design approach was employed to investigate the impacts of concentrations of PVP, and ZnO nanoparticles on the membrane structural characteristics and its performance.SEM, XRD, and FT-IR were used to characterize the surface and cross sectional morphology, as well as the presence of crystalline phases and cross-linked organic groups, respectively. Water contact angle was measured to determine the wettability of the surface membrane, and the impact of ZnO nanoparticles on its hydrophobicity. The membrane synthesis and MD process parameters were optimized for a Persian Gulf feed brine to obtain a maximum contact angle 148&deg;, under 80&deg;C and 12 L/min circulating feed water, and resulted in high salt rejection (96.4%) and proper permeability water flux (4.2 L/m2h).