This paper investigates the solid–liquid phase equilibria of ternary system (CsCl+Cs₂SO₄+H₂O) at 288.15 and 308.15 K with isothermal dissolution method. The solubilities and physicochemical properties (refractive index, density and pH value) of the ternary system were determined, and the corresponding phase diagrams and physicochemical property versus compositions at two temperatures were plotted. It was found that there are all one invariant point, two univariant curves, and two crystallization regions corresponding to cesium chloride and cesium sulfate at both temperatures. There are no double salts or solid solution in this system and it belongs to the simple type of salt–water ternary system. The physicochemical properties of the ternary system at the two temperatures showed a regular variation with the changing of cesium chloride concentration in the solution. Moreover, on the basis of empirical equations of density and refractive index, the calculation values of density and refractive index for the ternary system at two temperatures were in consistent with the experimental data.

The carbothermal reduction of barite is a complex multi-component and multi-phase reaction process. In this study, the HSC thermodynamic software and atomic matrix method were used to analyze the carbothermal reduction of barite. Furthermore, a systematic kinetics validation experiment was conducted. The effects of the reaction temperature, reaction time, and barite particle size on the phase composition and conversion of barite clinker into BaS were investigated experimentally. In addition, the kinetics of the carbothermal reduction process was studied using a modified kinetics model. The results indicated that 10 independent reactions occurred during the carbothermal reduction of barite. During the reduction of barite, SiO₂ underwent crystal transition from the quartz phase into tridymite and cristobalite phases. Consequently, SiO₂ could easily react with barium salts to form BaSiO₃ and Ba₂SiO₄, which caused the conversion to BaS to decrease. Kinetics studies indicated that the carbothermal reduction of barite was mainly controlled by a gas–solid topochemical reaction, and the kinetics equation could be expressed using the Erofeev equation.

A mathematical model describing the drying behavior of solution droplets deposited on a substrate is numerically solved to predict the morphology of the formed solid layer. The model includes the fluid dynamics, heat transfer, and mass transfer, and also considers wettability of the substrate and deformation of the free surface. The calculated morphologies of solid films agree reasonably with those formed experimentally from polystyrene/anisole solution droplets. The model predicts drying behavior that has not been previously reported. First, when a coffee ring is formed, solutal Marangoni forces deform the free surface while the solvent fully remains. Second, the deformation yields an outward bulk flow, enhancing solute transport toward the edge. Third, the effect of droplet size on the receding distance is related to the deformation. Consequently, the effects of droplet size, surface tension, viscosity, evaporation rate and wettability on film morphology can be explained by the deformation behavior.

Coating is one of the key technologies used for reducing drag in marine applications. Newly developed paints containing porous hydrogel polymers reduce drag. The present work investigates the effects of the thickness and roughness of such porous coatings by using direct numerical simulations of turbulent channel flow. Smooth permeable layers with different thicknesses have been simulated. It was found that smooth thin layers of thickness equal to or less than 20% of the fluid region cannot affect drag significantly, and the resultant changes in drag were below 1%. Next, to study the effect of roughness on the flow, two types of rectilinear rough surfaces were simulated in both permeable and impermeable states: (i) isotropic roughness with equal lengths in the streamwise and spanwise directions and random height, and (ii) anisotropic roughness with streamwise length equal to ten times the spanwise length and random height. In the impermeable state, both roughness patterns increased drag, with 33% and 3% increases with isotropic roughness and with anisotropic roughness, respectively. In the permeable state, drag increased further by 41.9% and by 9% with isotropic and anisotropic permeable roughness, respectively.

Simulations were performed for seeded batch cooling crystallization. In industry, partial seeding is often utilized, where a small amount of seed crystal is added to trigger secondary nucleation and grown secondary nuclei are obtained as the product. Partial seeding was investigated by computer simulation in this study. First, the coefficient of variation (CV) of the product crystal size distribution (CSD) was proven to take two local minima, one in the partial seeding range and the other in the range in which the product was mainly composed of seed-grown crystals. The local minimum point in the partial seeding range was considered as an optimum condition for partial seeding. Then, CSDs of grown seed crystals and nuclei were simulated at the optimum seed-loading ratio. As a result, the product was found to be composed mainly of grown secondary nuclei induced by grown seed crystals and grown secondary nuclei themselves. Partial seeding performed at the optimum seed-loading ratio yielded a reasonably good product of unimodal size distribution. Finally, the optimum seed-loading ratio was correlated with the cooling rate and seed crystal size and was found to depend on the cooling rate and more strongly on the seed crystal size. As the cooling rate was decreased, the minimum CV was shown to decrease and the mean size at the optimum seed-loading ratio was shown to increase.

A co-extraction system of tributyl phosphate (TBP) and KPF₆ was used for lithium ion extraction from brine containing a high ratio of magnesium and lithium. The effects of the phase ratio R(organic/aqueous), aqueous phase pH, and PF₆⁻/Li⁺ molar ratio on the extraction of lithium were studied. The single-stage extraction efficiency of lithium was 82.29% under optimal conditions, and the back-extraction efficiency was 93.99% when using 1 mol/L HCl +3 mol/L NaCl as the stripping agents at R(O/A)=1. The stoichiometry of the extraction complex was investigated by nuclear magnetic resonance spectroscopy and slope analysis.

CHA-type SAPO-34 and SSZ-13 zeolites with different homogeneous crystal sizes were prepared and used as fillers for fabricating polyethersulfone (PESU) based mixed matrix membranes (MMMs). These CHA-type crystals and the obtained MMMs were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). H₂, N₂, CO₂ and CH₄ gas permeation properties of MMMs with 20% and 30% zeolite weight loadings were investigated at 35°C under the pressure drop of 0.3 MPa. All gas permeabilities were enhanced after filling these zeolites into PESU polymer. The defective MMMs were formed when using the smallest 100 nm SAPO-34 crystals. High permselectivity MMMs were obtained with 200 nm SAPO-34 crystals, and high gas permeability MMMs were obtained when filled with 400 nm SSZ-13 zeolites.

In the oxidative dehydrogenation of isobutane to isobutene, selectivity and stability were improved by introducing chromium and molybdenum into SBA-15. The direct synthesis method (DM) was used to introduce these binary elements into SBA-15. Use of the DM resulted in a higher specific surface area of the catalyst and a greater dispersion of chromium and molybdenum species compared with a corresponding binary catalyst prepared using the incipient wetness impregnation method (IM). Selectivity to isobutene was improved, along with a decrease in the selectivities to CO and CO₂ with the introduction of greater amounts of molybdenum, which suggests that molybdenum must suppress the tendency of isobutene to over-oxidate to either CO or CO₂. The molybdenum species must be in close proximity to the chromium species, which results in the formation of an active Cr–O–Mo site.

In this paper, TiO₂ and Fe doped TiO₂ (Fe–TiO₂) photocatalysts were prepared by a sol–gel method, and the catalyst was immobilized on the surface of a spinning disk reactor (SDR) turntable by a dip-immobilizing method. The synthesized TiO₂ film and Fe–TiO₂ film were characterized using X-ray diffraction, Raman spectra, ultraviolet and visible spectra and scanning electron microscopy. The results proved that the prepared TiO₂ and Fe–TiO₂ nanoparticles were anatase phase and the average crystallite sizes were 20 nm and 10 nm, respectively. The effect of rotational speed and flow rate on the photocatalytic efficiency of TiO₂ and the degradation performance of phenol wastewater by three systems of TiO₂, Fe–TiO₂ and TiO₂/H₂O₂ were investigated. The results showed that the rotational speed and flow rate are the main factors affecting the thickness and residence time of the surface of the turntable, and then the degradation efficiency of phenol wastewater was affected; in the three catalytic systems, the degradation rate of TiO₂ was 41%, Fe–TiO₂ increased to 70%, and TiO₂/H₂O₂ reached 99%.

We theoretically investigated the relationship between the activity of the supported Pt catalyst and the oxide support type. The activation energies (E_a) of the propylene (C₃H₆) oxidation reaction with Pt catalysts using different oxide supports were estimated by an Arrhenius plot. The minimum and maximum E_a values were 99 kJ/mol for Pt/TiO₂ and 121 kJ/mol for Pt/La₂O₃, respectively. The chemical potentials of the oxide support (μ_MOx) were estimated by the density functional theory (DFT) calculations. The calculation results showed that the μ_MOx values varied depending on the thickness of the oxide support, but they were not strongly dependent on the crystal structure of the oxide. It was found that E_a can be expressed by the quadratic equation of μ_MOx, and E_a assumes the minimum value when μ_MOx is close to the chemical potential of the O₂ molecule (approx. −6 eV). We succeeded in expressing E_a as a quadratic expression of μ_MOx by theoretical consideration using the Brønsted–Evans–Polanyi (BEP) principle and the hard–soft-acid-base (HSAB) concept, i.e., the E_a value for the C₃H₆ oxidation reaction depends on the binding energy of the catalyst and oxygen. It was also determined that the μ_MOx value is one of the descriptors affecting the activity of the supported Pt catalyst.

The present study investigates a spinning disc reactor (SDR) as a process intensification technology for continuous biodiesel production. Refined palm oil (RPO) and waste cooking oil (WCO) were transesterified with methanol in the presence of NaOH as a homogeneous catalyst. The effects of operating temperature, methanol to oil molar ratio, catalyst loading, and rotational speed were investigated. The highest fatty acid methyl ester (FAME) yields as high as 97.0% and 90.9% could be achieved at a very short residence time of 2–3 s when using RPO and WCO, respectively, as feedstocks. It was found that the grooved disc surface plays an important role in increasing FAME yield obtained from WCO to 97.7% compared to the conventional mechanical stirring. This FAME yield also conforms to the EN 14103 standard. Moreover, the calculated values of activation energy based on the first order reaction kinetics were 57.5 and 43.4 kJ mol⁻¹ for RPO and WCO, respectively. The performance of SDR in terms of yield efficiency was also compared with other reactors. The use of SDR offers a significant reduction in the reaction time for the transesterification, especially when compared with the reaction time of 90 min required for the conventional mechanical stirred reactor. It was demonstrated that the SDR is the most promising intensification reactor for continuous biodiesel production from waste cooking oil.

Just-in-time modeling methods, such as locally weighted regression, construct a local model using samples stored in a database each time when the output estimation is required. To reduce the computational burden of online estimation, the number of samples stored in the database should be limited. Thus, a database management method that selects an appropriate set of samples from all the historical samples is required. We propose a new database management method that takes into account the strength of the nonlinearity as well as the sample density in order to realize the systematic sample selection. Locally weighted linear regression models with different degrees of localization are used to evaluate the strength of the nonlinearity. We compared the proposed method and conventional methods, such as first-in first-out methods, through a numerical example and a case study of an industrial distillation process. It was confirmed that, using the proposed method, 7 to 48% less estimation error is accomplished when the number of samples in the database is the same.

Automatic fault detection techniques for chemical processes are critical to process safety and reliability. Support vector data description (SVDD) has been widely used in the fault detection areas because of its fast calculation speed and low classification error. However, for incipient faults with slight changes of characteristics, the SVDD model has high complexity, and in addition, the feature sample selection of SVDD has a great impact on the effectiveness of fault detection. In the paper, the complexity of the SVDD model is not only reduced based on process exergy-data abstraction using the mutual information method, but also the proposed method presents great fault detectability and isolability. Meanwhile, the proposed method can detect incipient faults with different severity and indicate the evolution direction of faults. Therefore, the main contribution of this paper is to provide a novel fault detection method based on the EESVDD for incipient fault, in which the advantages of exergy data is combined with the SVDD method. Finally, the effectiveness of the proposed method is illustrated by a numerical simulation case and an industry distillation column, respectively.

Graphene has been widely explored to reinforce polyimide (PI) composites for its excellent physical and chemical properties. However, previous works mainly focusing on functionalized reduced graphene oxide and thick graphene as additives have not been able to reveal the influences of intrinsic few-layer graphene without functional groups on performance enhancements, because of the limits in preparation technique of large quantity few-layer graphene nanosheets and poor dispersibility of graphene in a polymer matrix. Herein, we prepare highly uniform few-layer graphene/polyimide (G/PI) nanocomposite films through a solution mix procedure and thermal polymerization. The as-prepared G/PI nanocomposite films show obvious mechanics, thermotics and hydrophobicity enhancements. Compared with neat PI films, the tensile strength increases 30% from 113 to 147 MPa at 0.1% graphene content. The thermal conductivity at 0.05% graphene content reaches 0.2275 W/(m·K), 8.8% higher than that of neat PI. At 0.50% graphene content, water absorption decreases from 1.19 to 0.50% and water surface contact angle increases from 82.95 to 99.95°. The homogeneously dispersed few-layer graphene nanosheets effectively strengthen the interaction between graphene nanosheets and PI matrix, enhance the performances of nanocomposite films with less additive amount of filler, and have negligible effects on stability and electronic properties.

Cocrystals have attracted attention in the pharmaceutical field as a novel crystal form of solid drug substances. Crystalline particles with desired quality are required for practical use in industry. For the control of crystal qualities, supersaturation is the key. The supersaturation of cocrystal can be generated by an operation decreasing solubility such as anti-solvent addition or cooling as conventional crystallization of single component crystal. Moreover, the supersaturation of cocrystal also can be generated by the reaction of cocrystalline components. In this study, the effects of supersaturation including the viewpoint of supersaturation generation mechanisms are investigated. In the experiments, supersaturation was generated by using the two mechanisms in various distribution ratios in order to investigate the effect of the kinds of supersaturation during cocrystallization. The aspect ratios of obtained crystals were different by the distribution. There was a relationship between the aspect ratio and supersaturation ratio. The relationship was confirmed by an additional semi-batch experiment changing supersaturation generation speed. The aspect ratio distribution becomes narrower and average aspect ratio becomes smaller when the supersaturation generation speed was changed to be slower. Supersaturation ratio affects the shape of cocrystalline particles, while there are two kinds of supersaturation during cocrystallization.

The reaction of aluminum with water is of great interest to hydrogen production. However, it is very difficult to initiate the reaction owing to the oxide film covering the aluminum powder surface, especially for the reaction of micrometer-aluminum powder with water. Na₂CO₃ was invoked as a modifier to improve the hydrogen yield of the reaction of micrometer-aluminum with water at low temperatures. The effects of solution concentration and temperature on the hydrogen yield were studied. The results indicate that the hydrogen yield of the reaction of micrometer-aluminum powder with water without the addition of Na₂CO₃ is low owing to the low activity of micrometer-aluminum powder. Increasing the temperature, the hydrogen yield increases slightly. However, when Na₂CO₃ is added into the mixture of micrometer-aluminum powder and water, the hydrogen yield is significantly improved owing to the production of OH⁻ of Na₂CO₃ hydrolysis to destroy the oxide film on the micrometer-aluminum powder surface. The hydrogen yield of micrometer-aluminum powder and water with the addition of 3 wt% Na₂CO₃ reaches 89.90% at 70°C. There are two stages in the reaction process of micrometer-aluminum powder and water with the addition of Na₂CO_3: the fast reaction stage and slow reaction stage. The reaction activation energy of micrometer-aluminum powder with water increases with the increase of Na₂CO₃ concentration. Based on these results, the reaction mechanism is discussed.