[en] A study of the phenomenon of quantum sieving was carried out, referring at the main application of this process in the separation of isotopes field. Nanotubes, carbonic materials and zeolites seem to be very good candidates as adsorbents in the case of quantum sieving. Starting with the properties of these materials, especially their porosities, a mathematic model has been constructed for the calculus of the separation factor. (authors)

[en] Investigations were conducted in a batch reactor system to study the adsorption behavior of four anionic dyes (Methyl orange (MO), Orange IV (OIV), Reactive brilliant red X-3B (X-3B), and Acid fuchsine (AF)) on ammonium-functionalized MCM-41 (NH₃⁺-MCM-41) from aqueous medium by varying the parameters such as contact time, initial dye concentration, pH and competitive anions. Dye adsorption was broadly independent of initial dye concentration. The intraparticle diffusion model was the best in describing the adsorption kinetics for the four anionic dyes on NH₃⁺-MCM-41. The adsorption data for the four dyes were well fitted with the Langmuir model. The electrostatic interaction was considered to be the main mechanism for the dye adsorption. Finally, it was observed that the anion of soft acid inhibited the adsorption capacity significantly

[en] The Peluit is a conceptual design of a power reactor based on High Temperature Gas-cooled Reactor (HTGR) with indirect power conversion. The primary coolant of Peluit is helium and its purity must be maintained from CO₂ below 0.6 parts per million by volume (ppmv) by its requirements. CO₂ is formed due to the reaction of oxygen or water with a carbon in the core during the water/air ingress. The impact of CO₂ to systems, structures and components (SSC) is steam generator tubes decarburization. In the helium purification system (HPS) of Peluit, the CO₂ removal component is a 5A type molecular sieve bed. This research aims to demonstrate the simulation of CO₂ adsorption in the molecular sieve bed along its design to achieve below its requirement limits. The Matlab software is used to simulate the adsorption process with the Henry method. The height of the column bed is assumed to be 200 cm, the diameter of the column is 50 cm, the flow rate of helium gas is 5 % of the main primary coolant mass flow rate equivalent to 3.0 kg/s, and the concentration of CO₂ is 40 ppmv. Based on the simulation it is known that after 5 seconds, the pure helium has come out at the end of the column with the remaining CO₂ concentration of 4.0 × 10^-5 ppmv. These results indicate that the molecular sieve bed is capable of removing CO₂ with an efficiency of 99.99 % and it concluded that molecular sieve 5A suitable for helium purification of Peluit. (author)

[en] The results are presented of the sorptive properties investigations of the molecular sieves with respect to krypton-85. The investigations have been done for impravement of the methodology for measuring of krypton-85 concentration in the atmosphere air and for determination of small volumes of concentrate activity. The molecular sieve with the grain size of 1.0 - 1.5 mm was used. Krypton adsorption was going on at the liquid nitrogene temperature (-196 deg C). Description is given of the devices for krypton-85 adsorption and measuring of the gases activity and also of the methodology for the experiment conducting. Dependances are given of the desorbed krypton amounts on different factors of the process proceeding. (I.T.)

No abstract available

No abstract available

[en] Carbon deposition process on activated carbon (AC) in order to produce carbon molecular sieve (CMS) was simulated using molecular dynamics simulation. The proposed activated carbon for simulation includes micropores with different characteristic diameters and lengths. Three different temperatures of 773 K, 973 K, and 1,273 K were selected to investigate the optimum deposition temperature. Simulation results show that the carbon deposition process at 973 K creates the best adsorbent structure. While at lower temperature some micropore openings are blocked with carbon atoms, at higher temperature the number of deposited carbons on the micropores does not change significantly. Also, carbon deposition process confirms the pseudo-second-order kinetic model with an endothermic behavior. To evaluate the sieving property of adsorbent products, nitrogen and oxygen adsorption on the initial and final adsorbent products are examined. Results show that there is not any considerable difference between the equilibrium adsorption amounts of nitrogen and oxygen on the initial and final adsorbents especially at low pressure (P<10 atm). Although, adsorption kinetics curves of these gases change significantly after the carbon deposition process in comparison with the initial sample. These observations indicate that the final adsorbent has high selectivity towards oxygen compared with the nitrogen, so it can be called a carbon molecular sieve. All simulated results are in good agreement with experiments

[en] Precisely controlling the deformation of carbon nanotubes (CNTs) has practical application in the development of nanoscale functional devices, although it is a challenging task. Here, we propose a novel method to guide the deformation of CNTs through filling them with salt water and applying an electric field. With the electric field along the axial direction, the height of CNTs is enlarged by the axial electric force due to the internal ions and polar water molecules. Under an electric field with two mutually orthogonal components, the transverse electric force could further induce the bending deformation of CNTs. Based on the classical rod and beam theories, two mechanical models are constructed to verify and quantitatively describe the relationships between the tension and bending deformations of CNTs and the electric field intensity. Moreover, by means of the electric field-driven tension behavior of CNTs, we design a stretchable molecular sieve to control the flow rate of mixed gas and collect a single high-purity gas. The present work opens up new avenues in the design and fabrication of nanoscale controlling units. (paper)

[en] Highlights: • The tritium removal performance and failure rate of the exhaust detritiation system (EDS) was evaluated for four years. • The detritiation factor (DF) of the molecular sieves type system was achieved to be more than 10³. • The DF of the polymer membrane type system was less than 10³, because the tritium concentration at the inlet of system was extremely low of less than 10³ Bq/m³. • The overall failure rate in EDS was on the order of 10⁻⁵ events/hour. The exhaust detritiation system (EDS) has been operating for the deuterium plasma experiment in large fusion test device since 2016. The EDS consists of two systems: the molecular sieves (MS) type for plasma exhaust gas, the polymer membrane (PM) type for vacuum vessel purge gas during the maintenance activity. The tritium removal performance of the EDS was evaluated for four years. As the operation results, the maximum detritiation factor (DF) of the MS system was achieved to be more than 10³ even though the average tritium concentration in the process gas was less than 10⁴ Bq/m³. On the other hand, the DF of the PM system was less than 10³, because the average tritium concentration during the vacuum vessel maintenance activity was at the order of less than 10³ Bq/m³. Throughout the initial phase of the deuterium plasma experiment, the tritium concentration at the outlet of EDS was maintained to be less than the order of 10² Bq/m³. Also, a failure analysis was performed to evaluate the reliability of the EDS in the initial phase of the operation. Over the four years of operation, the overall failure rate of the MS system was on the order of 10⁻⁵ events/hour.

[en] Molecular sieve driers have been included in the design of tritium handling systems for fusion reactors. In these systems there is a need to maintain extremely low exit dew points from the driers as well as a capability to rapidly reduce tritium concentrations following an accident. The required capacity of the driers is very high. The conventional method of regenerating these sieves after a water adsorption cycle is with hot air. However, because water is rapidly heated by microwave energy, this technology may be suitable for decreasing the bed regeneration time and hence may allow reduced capital and operating costs associated with a smaller bed. The present study was conducted to obtain preliminary information on the technical feasibility of regenerating molecular sieves with microwave energy. The study concentrated on Type 4A molecular sieve with a few tests on Type 13X sieve and also a silica gel adsorbent