The efficient separation of ethane/ethene (C 2 H 6 / C 2 H 4 ) is imperative yet challenging in industrial processes. We herein combine machine learning (ML) and molecular simulation to predict optimal covalent organic frameworks (COFs) for reversed C 2 H 6 /C 2 H 4 separation before experimental efforts. Using molecular simulations, two out of 601 CoRE COFs were identified with excellent separation performance, and eight CoRE COFs exhibit high C 2 H 6 /C 2 H 4 selectivity surpassing all of the reported values, although these COFs have a relatively low working capacity. As for ML, we found that the random forest (RF) algorithm displays the highest accuracy (R 2 = 0.97) among the four different models, and the density (ρ) of COFs was identified as the key factor that influences the C 2 H 6 /C 2 H 4 selectivity. Moreover, the 10 best hypothetical COFs (hCOFs) with excellent selectivity were further predicted. Ultimately, the competitive adsorption behaviors of guests in COF-303 were disclosed, and the adsorption selectivity of COF-303 was enhanced by introducing the fluorine group. Results of this work could provide molecular-level insights for future design and synthesis of novel COFs that can directly remove low-concentration ethane from the C 2 H 4 /C 2 H 6 mixture.
PbTe-PbS/TiO 2 electrodes are produced via wet chemical routes for splitting water into hydrogen at the ambient temperatures. PbTe nano-crystals are firstly deposited via the successive ionic layer adsorption and reaction (SILAR) treatment onto TiO 2 nanotube arrays (TNAs) prepared by anodic oxidation of Ti substrates. Subsequently, linear sweep voltammetry (LSV) is employed to convert the outer PbTe into PbS, producing PbTe-PbS/TiO 2 electrodes with a gradient p-n-n band configuration. With the external electric field, the vector charge transfer effect of the TNAs and the gradient energy band structure of PbTe-PbS/TNAs, the two electrode system in which PbTe-PbS/TNAs functions as the anode illustrates excellent hydrogen production activities. The whole electrochemical system consisted of anode, cathode, electrolyte serves as a hot side while the endothermic electrochemical reactions in hydrogen production as an in situ cold side. At 70 °C and 1.0 V bath voltage, the system registers 6.1 mL cm-2 h-1 rate of hydrogen generation, consuming electric power of 26.2 kWh kg-1 H 2 , with an energy efficiency of 88.5% and a heat efficiency of 49.9%. This method demonstrates a novel pathway to produce chemical energy from low quality waste heat, benefitting from thermoelectric and electrocatalytic coupling.
Effective capture and recovery of sulfur hexafluoride (SF 6 ) from SF 6 /N 2 mixture is an urgent challenge. Considering the existence of a large number of metal− organic frameworks (MOFs), the computational screening of MOFs is strongly desired before experimental efforts. In this work, the top-performance MOF adsorbents were identified from the most recent computation-ready, experimental metal−organic frameworks (CoRE MOFs) based on various metrics. The degree of unsaturation (unsat) and the number of hydrogen per unit cell (H) revealed with the optimal machine learning (ML) model are important factors for effective SF 6 /N 2 separation. One of the screened MOF candidates, FIRNAX01(TKL-107), was synthesized and the separation performance exceeded all the reported MOFs. Our computational screening not only offers effective prediction but also paves the way for accelerating the development of novel MOFs.
TBP extraction in nitric acid system is the core purification process of the wet method for uranium refining and conversion. Reextraction for uranium refining based on fractionation extraction was proposed, according to the characteristics and requirements of uranium refining extraction. The operation line and step line of reextraction were obtained through mathematical model, and the control law is explained. The reextraction bench test was carried out to investigate the stable operation and the concentration variation of the related components. The study shows that the reextraction process can run stably. After extraction, the concentration of uranium in organic phase can reach 120g/L, the extraction saturation can reach 96.7%, the concentration of uranium in raffinate is less than 10mg/L, and the concentration of impurity components is greatly reduced. Reextraction technology can facility the control of uranium refining extraction, which maintains the state of high saturation vs. low raffinate concentration.
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