A novel chelating resin bearing amidinothiourea (ADTU) moieties was prepared by chloroethyl crosslinked polystyrene (CMPS) with ADTU in the presence of a phase transfer catalyst. Fourier transform infrared spectra (FT-IR) and scanning electron microscopy (SEM) were used to characterized the resulting chelating resin. The saturated adsorption capacity of Hg(II) ions estimated from the Langmuir model was up to 1215 mg g?1at 313 K. Furthermore, the resin was able to selectively separate Hg(II) from multicomponent solutions with Cd(II), Co(II), Cu(II), Zn(II), Mg(II) and Pb(II). The desorption process showed the mercury recovery reached to 99.2% under eluting condition of 1 M HCl + 8% thiourea. 相似文献
Currently, relatively large errors are found in numerical results in some low-specific-speed centrifugal pumps with unshrouded impeller because the effect of clearances and holes are not accurately modeled. Establishing an accurate analytical model to improve performance prediction accuracy is therefore necessary. In this paper, a three-dimensional numerical simulation is conducted to predict the performance of a low-specific-speed centrifugal pump, and the modeling, numerical scheme, and turbulent selection methods are discussed. The pump performance is tested in a model pump test bench, and flow rate, head, power and efficiency of the pump are obtained. The effect of taking into consideration the back-out vane passage, clearance, and balance holes is analyzed by comparing it with experimental results, and the performance prediction methods are validated by experiments. The analysis results show that the pump performance can be accurately predicted by the improved method. Ignoring the back-out vane passage in the calculation model of unshrouded impeller is found to generate better numerical results. Further, the calculation model with the clearances and balance holes can obviously enhance the numerical accuracy. The application of disconnect interface can reduce meshing difficulty but increase the calculation error at the off-design operating point at the same time. Compared with the standard k-ε, renormalization group k-ε, and Spalart-Allmars models, the Realizable k-ε model demonstrates the fastest convergent speed and the highest precision for the unshrouded impeller flow simulation. The proposed modeling and numerical simulation methods can improve the performance prediction accuracy of the low-specific-speed centrifugal pumps, and the modeling method is especially suitable for the centrifugal pump with unshrouded impeller. 相似文献
A highly efficient protocol for the synthesis of pyrrolidones by the copper‐catalyzed alkynylation/annulation of aliphatic amides with alkynyl carboxylic acids is discussed in this paper. A broad range of easily accessible alkynyl carboxylic acids were introduced at the β‐methyl group of aliphatic amides with the assistance of an 8‐aminoquinolyl auxiliary group via decarboxylation to achieve the subsequent cyclic C N bond formation within one hour. High selectivity of β‐methyl groups over methylene groups was observed, and the extension of this catalytic system to the activation of methylene C H bonds failed. The substrates with two different groups at the α‐position of the aliphatic amides lead to the formation of diastereoisomers which is determined by 1H NMR spectroscopy. The initially produced products with Z‐configurations can be easily transformed to the corresponding products with E‐configurations by the treatment with dilute p‐toluenesulfonic acid after the reaction. This catalytic tandem decarboxylative cyclization provides a new opportunity for the direct functionalization of sp3 C H bonds.
