Dynamic properties on 99Mo adsorption and 99mTc elution with alumina columns

The Mo adsorption/99mTc elution properties of alumina used as Mo adsorbents are examined for the development of 99Mo/99mTc generators using 99Mo produced by the (n, γ) method. MoO3 is irradiated by the Kyoto University Research Reactor (KUR). The alumina columns are filled with three types of alumina made from different raw materials. In this paper, elongated tubes are used as columns and the properties under Mo dynamic adsorption conditions on alumina are compared with those under static adsorption conditions. The results obtained suggest that the 99Mo/99mTc ratio specified by the Minimum Requirements for Radiopharmaceuticals of Japan (MRRP) is greatly affected by the method of adsorbing Mo on alumina.

Purification of Hydrogen from CO with Cu/ZSM-5 Adsorbents

The transition to a hydrogen economy requires the development of cost-effective methods for purifying hydrogen from CO. In this study, we explore the possibilities of Cu/ZSM-5 as an adsorbent for this purpose. Samples obtained by cation exchange from aqueous solution (AE) and solid-state exchange with CuCl (SE) were characterized by in situ EPR and FTIR, H2-TPR, CO-TPD, etc. The AE samples possess mainly isolated Cu2+ cations not adsorbing CO. Reduction generates Cu+ sites demonstrating different affinity to CO, with the strongest centres desorbing CO at about 350 °C. The SE samples have about twice higher Cu/Al ratios, as one H+ is exchanged with one Cu+ cation. Although some of the introduced Cu+ sites are oxidized to Cu2+ upon contact with air, they easily recover their original oxidation state after thermal treatment in vacuum or under inert gas stream. In addition, these Cu+ centres regenerate at relatively low temperatures. It is important that water does not block the CO adsorption sites because of the formation of Cu+(CO)(H2O)x complexes. Dynamic adsorption studies show that Cu/ZSM-5 selectively adsorbs CO in the presence of hydrogen. The results indicate that the SE samples are very perspective materials for purification of H2 from CO.

Studies on the CO2 Capture by Coal Fly Ash Zeolites: Process Design and Simulation

At present, mitigating carbon emissions from energy production and industrial processes is more relevant than ever to limit climate change. The widespread implementation of carbon capture technologies requires the development of cost-effective and selective adsorbents with high CO2 capture capacity and low thermal recovery. Coal fly ash has been extensively studied as a raw material for the synthesis of low-cost zeolite-like adsorbents for CO2 capture. Laboratory tests for CO2 adsorption onto coal fly ash zeolites (CFAZ) reveal promising results, but detailed computational studies are required to clarify the applicability of these materials as CO2 adsorbents on a pilot and industrial scale. The present study provides results for the validation of a simulation model for the design of adsorption columns for CO2 capture on CFAZ based on the experimental equilibrium and dynamic adsorption on a laboratory scale. The simulations were performed using ProSim DAC dynamic adsorption software to study mass transfer and energy balance in the thermal swing adsorption mode and in the most widely operated adsorption unit configuration.

Preliminary experimental research of metal-organic frameworks (MOFs) for formaldehyde dynamic adsorption

Formaldehyde is a common emission from furniture and indoor decorations. Although the concentration of formaldehyde gas is not too high in the indoor environment, it is highly toxic and carcinogenic. The formaldehyde removal potential of a novel type of green and safe nano-porous materials, Metal-Organic Frameworks (MOFs), with a high surface-to-volume ratio, strong adsorption capacity, and low regeneration temperature was investigated. To date, researchers are mainly focusing on formaldehyde selectivity and detection using MOFs in low moisture circumstances. This study carried out a series of experiments to compare breakthrough curves of formaldehyde dynamic adsorption on MIL-100(Fe), MIL-160(Al), and aluminum fumarate with activated carbon. In experiments, the formaldehyde was evaporated from diluted formalin solution, dried to 30±5 % RH, and driven through different adsorbents by nitrogen. The results indicated that MOFs showed great potential for indoor air formaldehyde removal.

Wastewater treatment by adsorption process on mineral actived carbon: modeling and prediction using an intelligent artificial approach

Currently there are several wastewater treatments processes, and several adsorbent materials consist of separating and purifying the various industrial effluents. In this work an artificial neural network (ANN) was developed to describe the dynamic adsorption of sodium decanesulfonate using actived carbon obtained by the calcination of mineral biomass under different conditions. Three inputs (time, mass of adsorbent and fixed bed height) were used in the input layer, three neurons in the hidden layer and one in the output layer for the reduced concentration. The Levenberg Marquardt back-propagation algorithm was applied. The tangent sigmoid and linear transfer functions are used for the hidden layer and the output layer respectively. The results showed a correlation coefficient R2 = 0.9965 with root mean squared error RMSE = 0.0276. An interpolation and an extrapolation stage are made to test the accuracy of the network. The results showed a high correlation coefficient R2 = 0.9969 and 0.984 respectively for the interpolation and the extrapolation. These results show the robustness and the high capacity of ANN to describe the dynamic adsorption of sodium decanesulfonate onto actived carbon.