Journal of Particle Science and Technology
Volume:6 Issue: 1, Spring 2020

Photodegradation of methyl orange was investigated using synthesized TiO2:Mg2+/zeolite as the photocatalyst. The photocatalyst was characterized by X-ray, XRF, FT-IR, and SEM. The photocatalytic activities of TiO2:Mg2+/zeolite samples were evaluated in the degradation of methyl orange under visible light irradiation. The appropriate content of Mg in the composite was obtained as 4.711 wt% with 100% removal of methyl orange in 50 minutes. The influence of irradiation time, catalyst concentration, pH, and calcination temperature on the photodegradation of methyl orange was investigated, and the appropriate amounts obtained for these parameters were 60 min, 5 g/l, 10, and 450 °C, respectively. The degradation of methyl orange over TiO2:Mg2+/zeolite was about 82% after five cycles, confirming the suitable reusability of the photocatalyst.

Since the Population Balance Model (PBM)  poses a significant problem (due to the effect of droplets size distribution on the mass transfer phenomenon) in mixers, researchers face difficulties during a Population Balance Equation (PBE) numerical investigation. Therefore, investigating PBM in mixers became more considerate in recent researches. In this study, the droplet size distribution of the organic phase, which is discrete in the aqueous phase, was obtained using experimental methods and experimental data analysis. A variance function, which produces different values between PBEs and experimental data, was used to obtain the constants of breakage and coalescence kernels. Results showed that the impeller speed and clearance had no effect on the PBEs constants. In addition to these operation parameters, impeller diameter and baffle width had very little effect on these constants. In contrast, the impeller type and the number of baffles had a large specific effect on the contents by deformation of the vortex configurations.

Superhydrophobicity is the tendency of a surface to repel water drops. Due to this unique property, superhydrophobic surfaces can be used in many applications, such as water-resistant surfaces, antifogging surfaces, anti-icing surfaces, and anti-corrosion surfaces. In this study, superhydrophobic surfaces were fabricated by a spray pyrolysis method with water contact angles ˃ 160° and contact angle hysteresis less than 3°. For this purpose, the alumina nanoparticle modified by a fatty acid was dispersed in an alcohol solvent and coated on the substrate. Palmitic acid and stearic acid were selected as the modifying hydrophobic agents on the alumina surface. The chemical bonding between the surface of the alumina and the fatty acid was confirmed by Fourier-transform infrared spectroscopy (FT-IR) patterns. The influences of alcohol solvents on spray pyrolysis deposition of the modified-alumina were also studied by altering alcohol solvents (methanol, ethanol, and 2-propanol). Dynamic light scattering (DLS), scanning electron microscopy (SEM), and roughness analysis results showed that the increase in stability of spray suspension can enhance the coverage of films, which consequently increase the roughness and hydrophobicity of the layers. Wetting measurements showed that stearic acid is a better hydrophobic agent for modifying the surface of alumina, and 2-propanol is a convenient alcohol solvent for the fabrication of a superhydrophobic surface due to the highest water contact angle and lowest surface free energy of its film. The method is both easy and inexpensive, and we propose that this work has potential industrial applications for the fabrication of superhydrophobic surfaces on the various scale of copper substrates.

In this study, the effects of adding erbium and graphene (separately and in combination) on the microstructure and mechanical properties of Al-7.5Si-0.5Mg alloy were investigated. Initially, the primary alloy was produced by casting in the form of ingots. To add graphene to the molten alloy, these particles were milled with aluminum powder for 3 h. Then 0.2, 0.4, and 0.6 wt% graphene, 0.2 wt% erbium, and finally, a combination of 0.2 wt% erbium with 0.4 wt% graphene were incorporated into the Al-7.5Si-0.5Mg alloy. The microstructure of the produced samples was examined using optical and electron microscopes, then the tensile and wear behaviors of the produced samples were examined. Finally, scanning electron microscopy (SEM) images were used to investigate the mechanisms of wear and failure. The results of this study showed that the addition of erbium and graphene modified the microstructure of the alloy and reduced the grain size of the alpha-aluminum. The best tensile and wear properties were obtained for the sample containing 0.2 wt% erbium + 0.4 wt% graphene. By adding this value to the Al-7.5Si-0.5Mg alloy, tensile strength and wear resistance were increased by 56% and 67%, respectively, compared to the control sample.

In this study, the effect of the ultrasound process on the dispersion of kaolinite and sepiolite suspensions in the absence and presence of sodium silicate was investigated. The effects of ultrasonic device-dependent parameters such as power, treatment time, and application method (batch and continuous) on the dispersion of kaolinite and sepiolite suspensions were determined. Results of the studies carried out without sodium silicate showed the suspension stability values of kaolinite and sepiolite minerals presented some differences. While the stability of the kaolinite suspension decreased at high power ultrasonic values, it increased slightly for the mineral sepiolite. Also, the stability of the kaolinite suspension decreased, while the stability of sepiolite increased with a prolonged ultrasonic treatment time. It was also found that the application of ultrasound did not affect the isoelectric point (iep) of these clay minerals. In the presence of sodium silicate as a dispersant, the dispersion of these mineral suspensions increased depending on ultrasonic power and treatment time. Moreover, higher suspension stability values were obtained with the ultrasound application. In addition, the negative zeta potential values of clays after ultrasonic treatment were higher than those without ultrasound. The findings obtained showed that kaolinite and sepiolite suspensions were more successfully dispersed by ultrasonic treatment.

The aim of this study was to examine dacarbazine tautomerization with the density functional theory, where two tautomer structures have been indicated. The B3LYP/ 6-311G++ (d, p) , 6-311(d, p), and 6-311 quantum methods were considered to calculate the relative energies transferred between two structures. Also, calculations of the HOMO, LUMO, as well as the structures’ band gap energy were performed. Estimation of electronic parameters, such as electrophilicity, electronegativity, softness, and hardness, were also investigated to determine the compound’s reactivity in a biological media.