A model for gas-liquid annular and stratified flow through a horizontal pipe is investigated, using the two-phase hydrokinetics theory. Taking into consideration the flow factors including the void fraction, the friction between the two phases and the entrainment in the gas core, the one-dimensional momentum equation for gas has been solved. The differential pressure of the wet gas between the two tapings in the straight pipe has been modeled in the pressure range of 0.1-0.8 MPa. In addition a more objective iteration approach to determine the local void fraction is proposed. Compared with the experimental data, more than 83% deviation of the test data distributed evenly within the band of ±10%. Since the model is less dependent on the specific empirical apparatus and data, it forms the foundation for further establishing a flow measurement model of wet gas which will produce fewer biases in results when it is extrapolated.

Bubble motions and bubble-wall interactions in stagnant liquid were experimentally investigated by high-speed CCD and PIV technique with the main feature parameters such as Eötvös numbers Eo=0.98-1.10, Morton number Mo=3.21×10^-9 and Reynolds numbers Re=180~190. The effect of bubble injecting frequency and the distance S between the gas injection nozzle and the wall on the statistical trajectory of bubbles, average velocity distribution of flow field and Reynolds shear stress were studied in detail. It was shown that the combination of bubble injecting frequency and the distance S caused different bubble motion forms and hydrodynamic characteristics. When the normalized initial distance was very little, like S^* ≈ 1.2 (here S^*=2S/d_e, and d_e is the bubble equivalent diameter), bubbles ascended in a zigzag trajectory with alternant structure of high and low speed flow field around the bubbles, and the distribution of positive and negative Reynolds shear stress looked like a blob. With the increase of distance S^*, bubbles' trajectory would tend to be smooth and straight from the zigzag curve. Meanwhile, with the increase of bubble injecting frequency, the camber of bubble trajectory at 20 < y < 60 mm had a slight increase due to the inhibitory effect from the vertical wall. Under larger spacing, such as S^* ≈ 3.6, the low-frequency bubbles gradually moved away from the vertical plane wall in a straight trajectory and the high-frequency bubbles gradually moved close to the vertical wall in a similar straight trajectory after an unstable camber motion. Under the circumstances, high-speed fluid was mainly distributed in the region between the wall and the bubbles, while the relative large Reynolds shear stress mainly existed in the region far away from the wall.

In a rectangular fluidized bed combustor, the tracer gas is injected continuously into the bed from a point source at the center of the distributor plate. In this study, a general governing equation is formulated for tracer gas dispersion in the bed. An analytical solution is derived to estimate the dispersion coefficients, D_x and D_y, in a horizontal plane. The concentration profiles at different sampling heights with various gas velocities are plotted. Subsequently, to estimate the dispersion coefficients, surface fitting of the obtained analytical solution to the experimental data is performed. The dispersion coefficients obtained from this model are compared with those of a conventional model. Additionally, the effect of walls, bed height and gas injection rate on the dispersion coefficients in a horizontal plane is investigated, and the effect of distributor design on the dispersion coefficients in a horizontal plane is investigated with different tracer positions. It is found that D_x and D_y are nearly equivalent at a lower tracer gas ratio of the injected gas to the total gas flow rate. It is also demonstrated that the effect of bed height on D_x is minor. This model is also able to estimate the dispersion coefficients in the case of a multihorizontal nozzle distributor.

An analysis of the solute dispersion in the liquid flowing through a pipe by means of Aris-Barton's ‘method of moments’, under the joint effect of some finite yield stress and irreversible absorption into the wall is presented in this paper. The liquid is considered as a three-layer liquid where the center region is Casson liquid surrounded by Newtonian liquid layer. A significant change from previous modelling exercises in the study of hydrodynamic dispersion, different molecular diffusivity has been considered for the different region yet to be constant. For all time period, finite difference implicit scheme has been adopted to solve the integral moment equation arising from the unsteady convective diffusion equation. The purpose of the study is to find the dependency of solute transport coefficients on absorption parameter, yield stress, viscosity ratio, peripheral layer variation and in addition with various diffusivity coefficients in different liquid layers. This kind of study may be useful for understanding the dispersion process in the blood flow analysis.

Gas-liquid flow in serpentine microchannel with different surface properties exhibits drastically different flow behavior. With water and air as working fluids, the method of numerical simulation was adopted in this paper based on CLSVOF (coupled level set and volume of fluid method) multiphase model. After verifying the reasonability of the model through experiment, by changing wall properties and Re number (Re < 1500), the influences of contact angle and surface roughness on flow regime and Po number were discussed. Moreover, the difference of pressure drop between curve and straight microchannel was also calculated. Beyond that, the combined effect of curve channel and wall properties on flow resistance was analyzed. This paper finds that wall properties have great influence on gas-liquid flow in microchannels not only on flow regime but also flow characteristics. Meanwhile, the pressure drop in curve microchannels is larger than straight. It is more beneficial for fluid flowing when the straight part of microchannel is hydrophilic smooth wall and curve part is hydrophobic with large roughness.

Membrane-based CO₂ separation is a promising alternative in terms of energy and environmental issues to other conventional techniques. Polyether-polyamide block copolymer (Pebax) membranes are promising for CO₂ separation because of their excellent selectivity, but limited by their moderate gas permeability. In this study, fresh-prepared zeolitic imidazolate framework-8 (ZIF-8) nanocrystals were integrated into the Pebax^®1657 matrices to form mixed matrix membranes. The resulting membrane exhibits significantly improved CO₂ permeability (as high as 300% increase), without the sacrifice of the selectivity, to the pristine polymer membrane. Several physical characterization techniques were employed to confirm the good interfacial interaction between ZIF-8 fillers and Pebax matrices. The effect of added ZIF-8 fillers on the transport mechanism through MMMs is also explored. Mixed-gas permeation for both CO₂/N₂ and CO₂/CH₄ was also evaluated. The separation performance for CO₂/CH₄ mixtures on the ZIF-8/Pebax MMMs is very close to the Roberson upper bound, and thus is technologically attractive for purification of natural gas.

A mathematic model is developed for the perovskite-type mixed ionic-electronic conducting (MIEC) membrane, which makes it possible to simulate the process of oxygen separation in the U-shaped Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ hollow-fiber membrane. The model correlates the oxygen permeation flux to the measurable variables. The trends of calculated results for purge operation coincide well with the experimental data, therefore the model is considerable for flux prediction under vacuum operation. Higher oxygen separation efficiency can be achieved with vacuum operation than purge operation. Parameter study with vacuum operation reveals that oxygen permeation flux increases with higher vacuum levels, and vacuum pressure of around 1.013×10³ Pa is the optimal. Also, vacuum operation on the lumen side is much more efficient to achieve higher oxygen permeation flux compared with compression mode on the shell side.

Five tryptophan analogues with a hydrophobic indole ring and an amino group on each molecule were used as functional ligands of mixed-mode resins for human serum albumin (HSA) purification. Their adsorption performance was evaluated and the effects of pH and salt addition on HSA adsorption were studied. The resins prepared showed typical pH-dependent adsorption and the highest adsorption capacity and affinity were found at pH 5.0 for all the resins tested. The saturated adsorption capacity was 138.02 mg·g^-1 with the tryptaminefunctionalized resin, which significantly decreased at pH below 4.0 due to electrostatic repulsion between ligands and HSA. Moreover, the addition of NaCl or (NH₄)₂SO₄ in media reduced HSA adsorption capacity, although the two salts showed different affecting profiles. The tryptamine-functionalized resin showed the best salt-tolerant performance, and its high adsorption capacity was maintained under high salt concentrations. In addition, the five resins prepared showed good adsorption selectivity for recombinant HSA from Pichia pastoris broth. Molecular docking results between tryptamine and HSA indicated that tryptamine was favorable to bind on Site Ⅱ (indole-binding site) of HSA.

Our previous studies have reported the presence of "chain delivery" effects of protein adsorption onto ion exchangers with polymer-grafted ion-exchange groups, such as dextran-grafted and poly(ethylenimine)-modified Sepharose gels. However, it is unclear if the "chain delivery" occurs on affinity adsorption with specific interactions. This work is designed to address this issue. A dextran-grafted Sepharose gel was prepared, and then the matrix was modified using diethylaminoethyl, a typical ion-exchange group, or octapeptide (FYCHWQDE), an affinity ligand for human immunoglobulin G (hIgG) to prepare ion-exchange or affinity adsorbents, respectively. Results of hIgG adsorption showed that the uptake rate represented by the effective diffusivity of hIgG onto the dextran-grafted ion exchangers was obviously enhanced by the dextran grafting, indicating the presence of "chain delivery" of the bound proteins on the charged groups on the dextran chains. By contrast, the effective diffusivity of hIgG changed little as ligand density increased on the dextran-grafted FYCHWQDE adsorbents. Their adsorption capacities decreased and effective diffusivities were not accelerated by the dextran grafting. Thus, this work clarified that grafted dextran could not accelerate hIgG uptake rate on the affinity resins, or in other words, chain delivery did not occur on the specific interaction-based affinity adsorption.

The effects of two different hydrophilic additives and two solvents on the membrane morphological structure, permeability property and anti-fouling performances of cellulose acetate (CA) ultrafiltration membranes were investigated. During the phase-inversion process, cellulose acetate was selected as a membrane forming polymer; polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) were used as additives; acetone (Ac):N, N-Dimethylacetamide (DMAc) and N, N-Dimethylformamide (DMF) were used as solvents; and deionized (DI) water was used in the coagulation bath. All the prepared membranes were characterized in terms of hydraulic permeability (P_m), membrane resistance, average pore radius, and hydrophilicity. The top surface and crosssectional view of the prepared membranes were also observed by using field emission scanning electron microscopy. Membrane fouling and rejection experimentations were done using a stirred batch-cell filtration set-up. The experimental studies of fouling/rinsing cycles, rejection, and permeate fluxes were used to investigate the effect of PEG and PVP additives and effect of the two solvents on the fabricated membranes using bovine serum albumin (BSA) as a model protein.

This study addresses the synthesis of nanoscale zero-valent iron (nZVI) in the presence of natural bentonite (B-nZVI) using green tea extract. The natural bentonite and B-nZVI were then applied for the removal of phosphorus from aqueous solutions at various concentrations, pH levels and contact time. The desorption of phosphorus (P) from adsorbents was done immediately after sorption at the maximum initial concentration using the successive dilution method. The characterization of FTIR, SEM, and XRD indicated that nZVI was successfully loaded to the surface of natural bentonite. The sorption of phosphorus on B-nZVI was observed to be pH-dependent, with maximum phosphorus removal occurring at the pH range of 2 to 5. The results demonstrate that the maximum sorption capacities of natural bentonite and B-nZVI were 4.61 and 27.63 mg·g^-1, respectively. Langmuir, Freundlich, and Redlich-Peterson models properly described the sorption isotherm data. For either adsorbent, desorption isotherms did not coincide with their corresponding sorption isotherms, suggesting the occurrence of irreversibility and hysteresis. The average percentages of retained phosphorus released from natural bentonite and B-nZVI were 80% and 9%, respectively. The results indicated that sorption kinetics was best described by the pseudo-second-order model. The present study suggests that B-nZVI could be used as a suitable adsorbent for the removal of phosphorus from aqueous solutions.

Use of ultraporous nylon membrane is one of the most widely employed techniques for removal of hard and soft nanoparticles in the semiconductor industry, and the accurate determination of membrane pore size is necessary in order to avoid manufacturing defects caused by contamination. The gold nanoparticle has several benefits for the evaluation of polymeric membranes; however, the nanoparticles agglomerate easily on the nylon membrane and make it difficult to evaluate the membrane precisely. The properties of 2-amino-2-hydroxymethyl-1,3-propanediol (ADP) ligand in gold nanoparticle solution were systematically investigated, and ADP was utilized for improved evaluation of the nylon membranes. Nylon membrane used in this study was prepared by phase inversion techniques. Ultrathin dense layer on top of the membrane surface and Darcy structures in the microporous membrane support were observed. The gold particle rejection was carried out at various pH values from 4 to 14 and higher rejection was observed at pH 4 and 8. The suppression of gold colloid agglomeration using ADP and monodispersity of gold colloids was also analyzed by confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). van der Waals interaction energy of the particles was reduced in the addition of ADP. The presence of ADP ligand in the gold solutions prevented the agglomeration of gold nanoparticles and reduced the adsorption of the particles on the nylon membrane surface, leading to precise evaluation of membrane pore sizes.

Modifying polypropylene membranes with interpenetrating polymer networks (IPNs) through the incorporation of poly(glycidyl methacrylate-N-methyl-D-glucamine) (P(GMA-NMG)) was performed by in situ synthesis via radical polymerization. The surface of the polypropylene membrane was activated by hydrophilic grafted polyelectrolyte, and then, pressure injection was used for the impregnation of the reactive solution in the membrane. Two types of pore-filled membranes were synthesized, chelating interpenetrating homopolymer networks of P(GMA-NMG), and chelating-ion exchange interpenetrating polymer networks (e.g., P(GMA-NMG)/P(AA), P(GMA-NMG)/P(AMPSA), and P(GMA-NMG)/P(ClVBTA)). After their synthesis, the modified polypropylene membranes were characterized using techniques such as the electrokinetic potential, SEM, FT-IR, and Donnan dialysis to corroborate the chromium ion transport. The P(GMA-NMG) and complex network membranes exhibited a hydrophilic character with a water-uptake capacity between 20% and 35% and a percentage of modification between 4.0% and 7.0% in comparison with the behavior of the unmodified polypropylene membrane. Hexavalent chromium ions were efficiently transported from the food chamber at pH 9.0 when the 65.2% MTA1 P(ClVBTA) homopolymer IPN membrane and 48.5% MTAG P(GMA-NMG)/P(ClVBTA) IPN membrane were used. Similarly, hexavalent chromium ions were removed from the food chamber at pH 3.0 when MTAG (63.30%) and MTA1 (35.68%) were used in 1 mol·L^-1 NaCl solution as the extraction reagent.

Because of the complicated interplay between the prefractionator and main distillation column involved, the black-hole problem might occur and prohibit the assignment of four specifications to dividing-wall distillation columns (DWDCs) (e.g., the three main product compositions plus an impurity ratio in the intermediate product), which lowers terribly process flexibility and operability. In this paper, a feed thermal condition adjustment strategy, achieved by the installation of a pre-heater in feed pipeline, is employed to eliminate the black-hole problem and serve to enhance process flexibility and operability. Through the strong influence to the overall mass and energy balance of the DWDC, the feed thermal condition adjustment can alter the interlinking flows between the thermally coupled prefractionator and main distillation column and work effectively to coordinate their relationship. A DWDC separating a benzene, toluene, and o-xylene mixture is chosen to ascertain the feasibility of the philosophy proposed. The static and dynamic studies demonstrate that the feed thermal condition adjustment is an effective way to refine process design and can completely eliminate the black-hole problem and elevate consequently process flexibility and operability.

The pseudo-ternary system (NaCl + Na₂SO₄ + H₂O) of coal gasification wastewater was studied at T=(268.15 to 373.15) K. The solubility and density of the equilibrium liquid phase were determined by the isothermal solution saturation method. The equilibrium solids were also investigated by the Schreinemaker's method of wet residues and X-ray powder diffraction (XRD). According to the experimental data, the phase diagrams were determined. It was found that there was no significant solubility difference on the NaCl-rich side between the ternary system (NaCl + Na₂SO₄ + H₂O) in coal gasification wastewater and in pure water. However, the solubility on the Na₂SO₄-rich side of coal gasification wastewater was apparently higher than that of pure water. The increase in the solubility of Na₂SO₄ was most likely caused by the effects of other impurities apart from NaCl and Na₂SO₄ in coal gasification wastewater. The measured data and phase equilibrium diagrams can provide fundamental basis for salt recovery in coal gasification wastewater.

Nylon 10T and Nylon 10T/1010 samples were synthesized by direct melt polymerization. The non-isothermal crystallization kinetics of Nylon 10T and Nylon 10T/1010 was investigated by means of differential scanning calorimetry (DSC). Jeziorny equation and Mo equation were applied to describe the non-isothermal crystallization kinetics of the Nylon 10T and the Nylon 10T/1010. The activation energies for non-isothermal crystallization were obtained by Vyazovkin's method and Friedman's method, respectively. These results showed that Jeziorny equation and Mo equation well described the non-isothermal crystallization kinetics of the Nylon 10T and the Nylon 10T/1010. It was found that the values of the activation energy for non-isothermal crystallization of the Nylon 10T/1010 were lower than those of the Nylon 10T at a given temperature or relative crystallinity degree, which revealed that crystallization ability of the Nylon 10T/1010 was higher. The crystal morphology was observed by means of a polarized optical microscope (POM) and X-ray diffraction (XRD). It was found that the addition of sebacic acid comonomer not only did not change the crystal form of the Nylon 10T, but also significantly increased the number and decreased the size of spherulites. Comparing with the Nylon 10T, the crystallization rate was increased with the addition of the sebacic acid comonomer.

In this work, the group contribution method of Chickos et al. was applied to estimate the fusion enthalpy of isonicotinic acid, and the obtained result (29.2 kJ·mol^-1) showed a large difference with the value (135 kJ·mol^-1) as reported from literatures and as determined by differential scanning calorimetry (DSC). The results of DSC/TG measurement showed that the phase transition of isonicotinic acid from 187.27℃ to 277.47℃ underwent a sublimation process, with a sublimation enthalpy of 128.03 kJ·mol^-1. An efficient analytical technique combining pyrolysis and gas chromatography/mass spectrometry (Py-GC/MS) was used to prove this conclusion.

It has been known that the productivity of artesian wells is strongly dependent on the rheological properties of crude oils. This work targets two deep artesian wells (>5000 m) that are producing heavy crude oil. The impacts of well conditions including temperature, pressure and shear rate, on the crude oil rheology were comprehensively investigated and correlated using several empirical rheological models. The experimental data indicate that this heavy oil is very sensitive to temperature as result of microstructure change caused by hydrogen bonding. The rheological behavior of the heavy oil is also significantly impacted by the imposed pressure, i.e., the viscosity flow activation energy (E_μ) gently increases with the increasing pressure. The viscosity-shear rate data are well fitted to the power law model at low temperature. However, due to the transition of fluid feature at high temperature (Newtonian fluid), the measured viscosity was found to slightly deviate from the fitting data. Combining the evaluated correlations, the viscosity profile of the heavy crude oil in these two deep artesian wells as a function of well depth was predicted using the oilfield producing data.