Recently, demands for raw materials like rare earth elements (REEs) have increased considerably due to their high potential applications in modern industry. Additionally, REEs’ similar chemical and physical properties caused their separation to be difficult. Numerous strategies for REEs separation such as precipitation, adsorption and solvent extraction have been applied. However, these strategies have various disadvantages such as low selectivity and purity of desired elements, high cost, vast consumption of chemicals and creation of many pollutions due to remaining large amounts of acidic and alkaline wastes. Membrane separation technology (MST), as an environmentally friendly approach, has recently attracted much attention for the extraction of REEs. The separation of REEs by membranes usually occurs through three mechanisms: (1) complexation of REE ions with extractant that is embedded in the membrane matrix, (2) adsorption of REE ions on the surface created-active sites on the membrane and (3) the rejection of REE ions or REEs complex with organic materials from the membrane. In this review, we investigated the effect of these mechanisms on the selectivity and efficiency of the membrane separation process. Finally, potential directions for future studies were recommended at the end of the review.

The COVID-19 pandemic, known as coronavirus pandemic, a global pandemic, emerged from the beginning of 2020 and became dominant in many countries. As COVID-19 is one of the deadliest pandemics in history and has a high rate of distribution, a fast and extensive reaction was needed. Considering its composition, revealing the infection mechanism is beneficial for effective decisions against the spread and attack of COVID-19. Investigating data from numerous studies confirms that the penetration of SARS-CoV-2 occurs along with bonding spike protein (S protein) and through ACE2; Therefore, these two parts were the focus of research on the suppression and control of the infection. Performing lab research on all promising candidates requires years of experimental study, which is time-consuming and not an acceptable solution. Molecular dynamic simulation can decipher the performance of nano-structures in preventing the spread of coronavirus in a shorter time. This study surveyed the effect of three nano-perovskite structures (SrTiO₃, CaTiO₃, and BaTiO₃), a cutting-edge group of perovskite materials with outstanding properties on coronavirus. Various computational parameters evaluate the effectiveness of these structures. Results of the simulation indicated that SrTiO₃ performs better in SARS-CoV-2 suppression.

The objective of this study was to simulate the flow of graphene oxide (GO) dispersions, a discotic nematic liquid crystal (DNLC), using the Ericksen-Leslie (EL) theory. GO aqueous suspension, as a lubricant, effectively reduces the friction between solid surfaces. The geometry considered in this study was two cylinders with a small gap size, which is the preliminary geometry for journal bearings. The Leslie viscosity coefficients calculated in our previous study were used to calculate the stress tensor in the EL theory. The behavior of GO dispersions in the concentration range of 15 mg/mL to 30 mg/mL, shown in our recent experiments to be in the nematic phase, was investigated to obtain the orientation and the viscosity profile. The viscosities of GO dispersions obtained from numerical simulations were compared with those from our recent experimental study, and we observed that the values are within the range of experimental uncertainty. In addition, the alignment angles of GO dispersions at different concentrations were calculated numerically using EL theory and compared with the respective theoretical values, which were within 1% error. The anchoring angles corresponding to viscosity values closest to the experimental results were between 114 and 118 degrees. Moreover, a sensitivity analysis was performed to determine the effects of different ratios of the elasticity coefficients in EL theory. Using this procedure, the same study could be extended for other DNLCs in different geometries.