Thermodynamic modeling of the solubilities of various acetylacetonate-type metal precursors in supercritical carbon dioxide was performed using the PC-SAFT (perturbed-chain statistical associating fluid theory) equation of state. Pure component parameters for the metal precursors (segment number, segment diameter, and dispersion energy) were determined by fitting to solubility data obtained from the literature. The PC-SAFT equation of state could correlate the literature data over wide temperature and pressure ranges for various precursors. The pure component PC-SAFT parameters obtained from these correlations were found to vary systematically with changes in the properties of the metal precursors, such as the molar masses of the precursors and of the metal centers, which could be generalized based on the physical meaning of each parameter. The generalized PC-SAFT parameters could reproduce the solubilities of the metal precursors in supercritical carbon dioxide to within 30% average relative deviation under almost all conditions, especially at temperature below 393 K.
Three-dimensional (3-D) simulations on entire slot coating systems including regions inside the slot die and in coating bead are performed for correlating die internal and external flow fields. A CFD solver based on the finite volume method with a volume of fluid scheme is employed to investigate coating flow dynamics with free surfaces and menisci in the coating bead region. Operability windows for a Newtonian coating liquid in this process are determined using the simplified viscocapillary model and experiments, and then some flows states are quantitatively verified with 3-D model. The results from the 3-D model show that the final coating thickness with edge beads is satisfactorily predicted, and agree with experimental observation and the relationship between die internal and external flow features is closely linked.
A novel method of emulsion preparation by intramembrane premix membrane emulsification without preliminary emulsification was developed for the preparation of monodispersed oil-in-water (O/W) and water-in-oil-in-water (W/O/W) emulsions with small droplet size and high disperse phase content at high productivity. The dispersed phase and the continuous phases were simultaneously permeated through Shirasu Porous Glass (SPG) membranes with mean pore sizes of 5, 10, and 20 µm at a membrane permeation rate over 50 m3/m2 h. Monodispersed emulsions with disperse phase content of 25 to 95% by volume, mean droplet size to the mean pore size ratio of 1.2 to 0.26, and with droplet size distribution (span) of 0.4 to 0.6 were prepared. The emulsion droplet size decreased with membrane permeation rate, continuous phase viscosity and the number of membrane permeation cycles. A composite W/O/W emulsion with an average droplet size of 10.4 µm, a span of 0.5 and of disperse phase content of 50% by volume was also prepared in a sequence of consecutive steps without integrating the preliminary emulsification step by high-shear homogenization.
How to greenly and economically extract high-value elements from a complex matrix is the focus of current separation techniques. The combination between solvent extraction and electrodeposition technique was proposed in this work. In order to realize the electrodeposition of metal ions from the extraction organic phase, the electroconductivities of the commonly used extraction system containing di-(2-ethylhexyl) phosphoric acid (P204) were investigated in detail. The results showed that the traditional P204 extraction system is not electroconductive even after the extraction of metal ions, but this problem was effectively solved by the addition of ionic liquids (ILs) especially the tributylhexylphosphonium bis(trifluoromethyl sulfonyl)imide ([P4446][NTf2]). Different diluents have significant effects on the electroconductivity, among which methyl isobutyl ketone (MIBK) is the best to obtain a high electroconductivity. The electroconductivity-composition diagram of the P204+MIBK+[P4446][NTf2] system at room temperature indicates that both the MIBK and [P4446][NTf2] contribute to improving the electroconductivity of this system. All these findings provide the feasibility of electrodeposition from the extraction organic system containing P204.
It is known MnO2 ion sieve is an excellent adsorbent for Li+ recovery from low lithium grade brine containing a high ratio of Mg to Li. However, the concentration of manganese ions dissolved along with Li+, during the desorption process with hydrochloric acid is very high and its mechanism of desorption has still not be elucidates. Here, acetic acid in aqueous solution is evaluated by the first time as an eluent in the desorption process of Li4Mn5O12 powder. A desorption mechanism of Li4Mn5O12 is proposed for the first time throughout analyses and correlations of experimental data, the construction of ε-pH diagram for the Mn–H2O system, and changes in its crystalline structures for the first time. The Mn dissolved in acetic acid 0.5 mol·L−1 has been just 0.01%, which was less than that eluted with hydrochloric acid carried out for the sake of comparison. The desorption process of Li+ from Li4Mn5O12 was successfully achieved with a pH around 2.0. Meanwhile, the mechanism found is described by the simple H+–Li+ ion-exchange mainly occurring in the eluent with a high pH value, while both H+–Li+ ion-exchange and redox reactions occur in the eluent with low pH value. The Mn dissolution is mainly caused by the redox reactions.
The effect of venturi tube shape on reaction rate by hydrodynamic cavitation was investigated. The apparatus mainly composed of the venturi tube, a liquid pump, a tank, a pipe arrangement, and a heat exchanger. The upstream and downstream pressures of the venturi tube were measured. The sample was an aqueous solution containing potassium iodine and chloroform. The generation rate of triiodide ion increased with increasing upstream pressure. This is because liquid velocity at the venturi tube is high and the amount of cavitation bubbles increases. When the throat diameter of the venturi tube was 2.5 mm, the generation rate of triiodide ion reached a maximum value. As the throat diameter of the venturi tube became smaller, the generation rate of triiodide ion per pass of venturi tube increased and the pass number of venturi tube decreased. Both low cavitation number and large pass number are important for high reaction performance.
A process monitoring method based on the dissimilarity (DISSIM) of slow feature (SF) analysis is proposed for effective fault detection in the process industry. The useful information from this method is mainly contained in low-frequency data signals. The sensitive slow features (SSFs) of a single fault status with maximum dissimilarity between normal data SFs and fault data SFs are initially selected by a dissimilarity analysis and are used to construct monitoring statistics and obtain the control limits of the corresponding fault status. The most probable fault status for online monitoring is selected by addressing the smallest Euclidean distance between the SSFs of the online data and the corresponding SFs of the fault data. Subsequently, the SSFs are redefined according to the corresponding fault status, and the statistics and corresponding control limits are compared to detect faults. A simulation of the Tennessee Eastman process demonstrates that the proposed method outperforms conventional methods.
The subway station is an easy target for terrorists. In this paper, AUTODYN software is used to simulate the characteristics of shock wave propagation in the subway station. Further, the effects of walls, standing columns and stairs on the shock wave propagation are analyzed quantitatively by setting reference points in the subway station. According to the overpressure distribution of the explosion at subway station, the casualty distances and the favorable positions for personnel to hide are determined. The results show that the shock wave in the subway station is affected not only by the reflection of the whole structure, but also by the diffraction and local reflection of the platform columns. Due to the pressure relief on the shock wave by the stair exit, the overpressure peak on the stair slope is greater than those at other locations near the stairs at the same explosion distance.
To ensure the reliability of reciprocating multiphase pumps, it is necessary to predict the flow rate curve of the discharge process under different multiphase transportation conditions. Unfortunately, an accurate model describing the complicated characteristics is still not available. A modeling method of automatically selecting a probabilistic model is proposed for prediction of the discharge flow rate. A posterior probability index is proposed to evaluate the trained local Gaussian process regression (GPR) models. Additionally, to enhance the prediction reliability, the prediction variance-based index is explored to automatically choose a more suitable model from the selected local GPR and just-in-time GPR models for each new sample. Consequently, with limited samples, an efficient probabilistic modeling method is developed for online prediction of the discharge flow rate curve. The experimental results for a reciprocating multiphase pump validate its superiority.
Introduction of a continuous production system to the pharmaceutical field has become realistic. In this field, many kinds of organic crystals with high anisotropic aspect are produced. Hence, crystal morphology affects the pharmaceutical productivity. Therefore, a high production method with crystal morphology improvement currently attracts attention by using a continuous crystallizer. In order to improve the production rate, it is necessary to enhance the crystal growth rate by increasing the mass transfer. The stirring method using Taylor Vortex has been developed in the crystallization research field. The objectives of this study are to design a double-cylinder shaped milli-size crystallizer in order to realize Taylor Vortex, and to evaluate the productivity and crystal morphology. As a result, it was clear that the proposed crystallizer had a productivity about 40 times greater than a conventional batch crystallizer and had a performance which improved the aspect ratio by 59%.
Polydiacetylene (PDA) shows a unique colorimetric response toward external stimuli, such as heat. Herein, self-assembled hydrogels were prepared by 10,12-tricosadiynoic acid (TCDA) and 1-oleoylglycerol (Monoolein, MO). The hydrogel of TCDA/MO (1/1) turned to blue by UV irradiation, and the color changed to red by heating. Although unpolymerized gel deformed within 3 h at 70°C, the polymerized hydrogel maintained its structure at least for 4 h. This method successfully produced hydrogel materials including the organized membranes composed of PDA precursor molecules.
An improved semi-batch cooling crystallization of potassium alum (AlK(SO4)2·12H2O) was developed to produce monodisperse crystals under the unseeded condition. The two-stage cooling was a useful method for the prevention of secondary nucleation and the size enlargement of generated fine crystals because supersaturation is successfully controlled by the selection of the optimal feed condition in each cooling stage. In this study, the calculation and validation of semi-empirical feed condition was carried out based on the seeding policy. Unseeded crystallization technique is particularly important in the field of foods and pharmaceuticals in a view of crystal purity. The semi-batch cooling crystallization is a simple and possible method to produce monodisperse crystals under the unseeded condition which contributes to these industrial fields.