Separation of water-in-oil emulsion with microfiber glass coalescing bed

Water-in-oil emulsion separation through a fibrous media bed is a complex and challenging process in industries. In this article, we used a vertical column separator to investigate the effects of the height and porosity of the fiber bed, the structure arrangement (the mixed or the layered fibrous bed), the superficial velocity of the water-in-oil emulsion through the bed, and the influent water content of the emulsion on water removal. Four kinds of glass microfibers (GF1-GF4) with mean diameters of 0.6, 2.6, 4.6, and 8.0?µm, respectively, acted as the coalescence medium and composed the fibrous bed with different structure types. The separation efficiency could reach 97.1% with a relatively low pressure drop under the optimal bed structure and operational conditions. It also showed that the mixed bed had higher separation performance compared to the layered fibrous bed.     

Filtration application from recycled expanded polystyrene

Water-in-oil emulsion with drop size less than 100 mum is difficult to separate. Coalescence filtration is economical and effective for separation of secondary dispersions. Coalescence performance depends on flow rate, bed depth, fiber surface properties, and drop size. The amount of surface area of the fibers directly affects the efficiency. A new recycling method was investigated in the previous work in which polystyrene (PS) sub-mum fibers were electro-spun from recycled expanded polystyrene (EPS). These fibers are mixed with micro glass fibers to modify the glass fiber filter media. The filter media are tested in the separation of water droplets from an emulsion of water droplets in oil. The experimental results in this work show that adding nanofibers to conventional micron sized fibrous filter media improves the separation efficiency of the filter media but also increases the pressure drop. An optimum in the performance occurs (significant increase in efficiency with minimal increase in pressure drop) with the addition of about 4% by mass of 500 nm diameter PS nanofibers to glass fibers for the filters.     

Oil and Water Separation Using a Glass Microfiber Coalescing Bed

A vertical sleeve separator using glass microfiber with a mean diameter of 4 µm as coalescence medium was explored to remove oil from the oil-in-water (O/W) emulsions. The artificial emulsions were prepared by mixing diesel oil and water to obtain oil droplets with a mean diameter about 7 µm. A series of experiments were performed to investigate the effect of such parameters as bed porosity (0.850–0.925), bed height (2.0–20.0 mm), flow velocity (1.0–20.0 mL/s), and influent oil concentration (200.0–3000.0 mg/L) on the effluent oil concentration and oil removal efficiency. The obtained effluent oil concentration was from 4.98 to 53.04 mg/L, and the oil removal efficiency was 96.4–99.8%. In addition, the article identifies the interaction between bed porosity and height, explains the mutual influences between the emulsion velocity and concentration, and quantitatively derives the appropriate ranges of bed characteristics and operating conditions.     

Hydrodynamic Characteristics and Adsorption Particularity of Nanobiological Feedstock Along the Bed Height in a Novel Chromatography Column

Expanded bed adsorption (EBA) is a practical method for the separation of nanoparticulates. In order to analysis the local hydrodynamic and adsorption behavior of nanoparticle (NP)-based biological feedstock, a modified Nano Biotechnology Group EBA column with a 26-mm inner diameter was used to withdraw liquid from different axial positions of the column. Fabricated egg albumin (EA) NPs with an average size of 70?nm were employed as a model system and viral size/charge mimic to assess the relationship between hydrodynamic and adsorption performance of NPs at the different column regions. The effects of influential factors, including flow velocity and initial concentration of NPs, on NP hydrodynamic behavior and adsorption kinetics along the bed height were investigated. NP hydrodynamic studies confirmed that non-uniform behavior dominated the system and a decreasing trend of liquid mixing/dispersion with increase of bed height was observed in this column. The results demonstrated an increase in the mixing/dispersion at certain bed heights with the increase in both the velocity and feed initial concentration. Breakthrough curves were measured at various column points to determine the adsorption performance [dynamic binding capacity (DBC) and yield] in different bed positions/zones. Yield and DBC of NPs were improved along the bed height, whereas liquid velocity had the opposite effect. Increasing the initial concentration of NPs enhanced only the DBC. Separation of EA NPs under optimal conditions was 87?%, which is an excellent result for a one-pass frontal chromatography method.     

振动分离流化床中沉积组分的运动速度

本文在槽式振动流化床中研究沉积组分的运动特性，分别考察了振动参数，振动角度及床体倾角对运动速度的影响，根据碰撞理论推导出沉积组分的抛掷高度和物料运动速度的计算式，同时与实验值进行了比较，且研究了振动参数和物料的运动速度对焦渣混合物的分选效率的影响。     

High-resolution monolithic columns—a new tool for effective and quick separation

This work describes a comparison of three types of commercial high-performance liquid chromatography silica monolithic columns with different inner diameters and generations of monolithic sorbent: a “classic” monolithic column, the first generation (Onyx? monolithic C₁₈, 100 mm?×?4.6 mm, Phenomenex); a “narrow” monolithic column for fast separation at lower flow rates (Chromolith® Performance RP-18e, 100 mm?×?3 mm, Merck); and a recently introduced “high-resolution” monolithic column, the next generation (Chromolith® HighResolution RP-18e, 100 mm?×?4.6 mm, Merck). Separation efficiency (number of theoretical plates, height equivalent to a theoretical plate and van Deemter curves), working pressure, the symmetry factor and resolution were critical aspects of the comparison in the case of the separation of ascorbic acid, paracetamol and caffeine. The separations were performed under isocratic conditions with a mobile phase consisting of 10:90 (v/v) acetonitrile–phosphoric acid (pH 2.80). Detailed comparison of the newest-generation monolithic column (Chromolith® HighResolution) with the previously introduced monolithic sorbents was performed and proved the advantages of the Chromolith® HighResolution column.

Enantioselective analysis of cetirizine in pharmaceuticals by cyclodextrin-mediated capillary electrophoresis

The present paper demonstrates the potential of cyclodextrin (CD)-mediated CE for the chiral analysis of a drug of zwitterionic nature, viz. cetirizine (CET). Various separation mechanisms were applied and several parameters affecting the separation were studied, including the type and concentration of chiral selector, coselector, and carrier ion, and pH of buffer. The optimal separation conditions were based on a medium buffer pH (approximately 5.2) (migration velocity of CET molecule was near to zero) and a highly substituted CD derivative, sulfated-beta-CD, serving as an analyte carrier in the anionic regime of the separation with suppressed electroosmotic flow. In this way, a baseline enantioseparation, reasonable separation efficiency, and short analysis time could be easily achieved. Acceptable validation criteria for sensitivity, linearity, precision, accuracy, and robustness were obtained using a hydrodynamically closed CE separation system. The proposed method was successfully applied to the enantioselective assay of CET in pharmaceutical formulations using fexofenadine (FEX) as an internal standard.     

Synchronized extraction and purification of L-lactic acid from fermentation broth by emulsion liquid membrane technique

This study aims to investigate the recovery of L-lactic acid from fermentation broth by an emulsion liquid membrane (ELM), made up of sunflower oil as the diluent, Sorbitan monooleate (Span 80) as the surfactant, Aliquat 336 as the carrier, and sodium hydroxide (NaOH) solution as the internal aqueous phase. Particularly, the ELM process was properly set up, through the identification of the optimal ELM operating parameters on the final extraction efficiency of L-lactic acid, including Span 80 concentration, NaOH concentration, Aliquat 336 concentration, stirring speed, phase ratio, and treatment ratio. The obtained results showed that the extraction efficiency of L-lactic acid reached up to 99% under the following optimal conditions: 10 minutes after contact time, 4% w/w Span 80, 3% w/w Aliquat 336, 0.1?N solution of NaOH, stirring speed of 300?rpm, phase ratio 1, and treatment ratio 0.25. A stable system without considerable emulsion swelling and breakage was monitored using a dynamic light scattering (DLS) apparatus for the selected optimal ELM operating parameters.     

Process diagnosis of coalescence separation of oil-in-water emulsions-two case studies

Coalescence separation is a widely applied technology for oil/water emulsion separation. In this paper, we first review the existing coalescence theories regarding droplet capture, attachment and release. Two case studies are considered, dealing with the separation of oil-in-water emulsions using our recently developed coalescing filters. The first case (Case I) is associated with the separation of surfactant-stabilized hexadecane/water emulsions. The second case (Case II) addresses the separation of sulfonated kerosene/water emulsions in a continuous bench operation. In Case I, known wetting and collision theories were applied to understand the complex coalescence process occurring on the surface of the fibers. For this, the detrimental effect of surfactants on coalescence separation was taken into account. It was found that the best oil wetting coalescing material under water was not the most desired for coalescence, contradicting the existing theory. In addition, once the materials were pre-saturated with surfactant-containing emulsions, the oil wetting was enhanced significantly. However, the separation efficiency was maintained at the same level, unless the material adsorbed surfactant, resulting in minor reductions in the wetting angle. In Case II, based on the fiber properties and operation conditions, the droplet capture efficiency and released droplet size were calculated using the existing models. Fiber diameter and medium face velocity were found to affect not only the capture, but also drop release. Based on model predictions, the dominant capture mechanism was identified as interception followed by van der Waals forces. Overall, this work offers insights about the influencing parameters on oil/water emulsion separation for better designing coalescence systems.     

Use of 120-nm deep channels for liquid chromatographic separations

The present study reports on the exploration of the separation speed limits of RPLC chromatography in open-tubular channels. Applying the shear-driven chromatography principle in a 120-nm deep open channel, and using an improved detection set-up, the separation of three coumarin dyes was detectable 8mm downstream of the injection point. At this distance, separation efficiencies of N = 17,900 - 24,100 plates were obtained at a velocity of 10 mm s(-1), corresponding to a plate generation velocity of 21,100 to 28,300 plates per second for the most and least retained component, respectively.     

Effects of nebulizing and drying gas flow on capillary electrophoresis/mass spectrometry

This study was focused on examining the influence of gas flow parameters on capillary electrophoresis/mass spectrometry (CE /MS) performance using sheath-liquid CE /MS interfaces. The effects of nebulizing and drying gas velocity and drying gas temperature on CE separation and MS detection sensitivity were systematically determined. Nebulizing gas velocity was observed to be a critical parameter in the optimization of CE /MS method, since it affected both MS detection sensitivity, and also CE separation efficiency for one interface design tested. Better detection sensitivity was obtained when the nebulizing gas velocity was increased. However, high velocity of the nebulizing gas flow can cause a hydrodynamic bulk flow inside the CE capillary, thus clearly increasing the apparent mobility and decreasing the resolution obtained for the compounds studied. Increasing the drying gas velocity or temperature did not affect the apparent mobility or the separation efficiency and the temperature could be increased to achieve the optimal detection sensitivity in the CE /MS analysis. For comparison, the effects of nebulizing gas flow were studied using a different design of the coaxial sheath-liquid CE /MS interface, and in this case better detection sensitivity but no effect on CE separation efficiency was observed with increased nebulizing gas velocity. These different effects of nebulizing gas flow on the CE bulk flow were concluded to result from pressure differences at the tip of the CE capillaries for the different CE /MS interface arrangements. It is therefore recommended that the cross-sectional dimensions of the fused-silica and steel capillaries, and the gas streamlines, should be optimized when CE /MS interfaces are built. Moreover, the effect of gas flow on CE separation should be studied when optimizing the CE /MS operation parameters.     

PREDICTION OF PREDOMINANT MECHANISMS IN THE SEPARATION OF SECONDARY DISPERSIONS IN A FIBROUS BED

The different drop capture mechanisms for secondary dispersions in fibrous beds are reviewed. A quantitative analysis showed that interception and sedimentation are the predominant mechanisms in fibrous bed coalescers. The selection of operating parameters, e.g. velocity, fibre size and drop size depends upon these mechanisms. A 3 cm deep fibrous bed of glass wool, with a fibre diameter of 25 pm, was found to capture more than 80% of the dispersed phase from an inlet secondary dispersion of 15 Mm drop size. Almost 70% of these drops were captured due to the interception mechanism.     

Evaluation of new high-density ion exchange adsorbents for expanded bed adsorption chromatography

New adsorbents Q HyperZ and CM HyperZ composed of hydrogel-filled porous zirconium oxide particles were evaluated for expanded bed adsorption applications in the present work. The HyperZ adsorbents have wet density of 3.16 g ml(-1), particle size of 44.5-100.8 microm and average sphere diameter of 67 microm. The bed expansion as the function of flow velocity and fluid viscosity was measured and correlated with Richardson-Zaki equation. The suitable expansion factor was considered less than 2.5, while the corresponding flow velocity was about 450 cmh(-1). Liquid mixing in the bed was determined to evaluate the stability of expanded bed. The Bodenstein numbers tested were higher than 40 and the axial mixing coefficients (D(ax)) were between 0.5 and 9.7x10(-6)m(2)s(-1), which demonstrated that a stable expanded bed could be formed under suitable operation conditions. Bovine serum albumin (BSA) and lysozyme were used as model proteins to estimate the adsorption capacities of Q and CM HyperZ, respectively. The maximum equilibrium adsorption of Q and CM HyperZ could reach 45.7 and 27.2 mg g(-1) drained adsorbents, respectively. It was found that yeast cells had little influence on the adsorption capacities of the two adsorbents tested. The dynamic adsorption capacity of BSA at 10% breakthrough with Q HyperZ was 35.9 mg g(-1) drained adsorbent at flow velocity of 100 cm h(-1) for packed bed adsorption. The values for expanded bed adsorption were 34.4 mg g(-1) drained adsorbent at flow velocity of 200 cm h(-1), 33.6 mg g(-1) drained adsorbent at 300 cm h(-1) and 31.7 mg g(-1) drained adsorbent 400 cm h(-1). The results demonstrated that Q HyperZ and CM HyperZ are suitable for expanded bed adsorption of biomolecules.     

Characterization of a novel diol column for high-performance liquid chromatography

For the investigation of a diol phase (Inertsil Diol column) in hydrophilic interaction chromatography, urea, sucrose and glycine were used as test compounds. The chromatographic conditions were investigated for optimal column efficiency. The column temperature used in common reversed-phase liquid chromatography could also be used for the separation and the flow-rate should be adjusted to 0.3-0.5 ml/min to optimize column efficiency. It is suggested that the velocity of the hydrophilic interaction is slower than the hydrophobic interaction in RPLC. The addition of trifluoroacetic acid is effective for the retention of glycine, but ineffective for urea and sucrose. The diol phase exhibited sufficient chemical stability even if exposed to water in high percentage, and could be applied with isocratic elution for the separation/analysis of amino acids and glucose.     

Non-particulate (continuous bed or monolithic) acrylate-based capillary columns for reversed-phase liquid chromatography and electrochromatography

Three approaches are described to synthesize acrylic non-particulate beds (also called continuous beds or monoliths) in aqueous polymerization media for reversed-phase capillary liquid chromatography/electrochromatography. In the first, hexyl acrylate comonomer was dissolved together with water soluble polar comonomers using a non-ionic detergent. In the second, a new alkyl ammonium salt comonomer, (3-allylamino-2-hydroxypropyl)dodecyldimethylammonium chloride was used, which is water soluble and has detergent properties itself. The alkyl group of this comonomer provides hydrophobicity while the ionic groups generate electroosmosis in the non-particulate bed. In the third approach, the alkyl comonomer was used as a detergent to dissolve another hydrophobic comonomer in an aqueous polymerization medium. All three approaches were evaluated with respect to hydrophobicity, efficiency and electroosmotic properties of the beds. Hydrophobicity expressed as methylene group selectivity for the three types of the beds in 50% methanol mobile phase was 1.86, 1.16 and 1.78, electroosmotic mobility -5.14 x 10(-5), 6.89 x 10(-5) and 6.37 x 10(-5) cm2 V(-1) s(-1) and efficiency for the retained compound (methylparabene) 67,000, 93,000 and 110,000 plates m(-1) correspondingly. The columns were tested using pressure driven capillary chromatography and capillary electrochromatography. The influence of polymerization temperature on hydrodynamic permeability, separation impedance and inverse size exclusion porosimetry characteristics were used to evaluate the separation columns. The increase of the polymerization temperature resulted higher permeability of the bed, separation impedance and lower polymeric skeleton porosity. Further characterisation was provided by examining the separation efficiency observed for a series of benzoic acid esters and alkyl parabens.     

Evaluation of tertiary pyridine resin for the separation of lanthanides by simulated moving‐bed chromatography

Lanthanide separation by simulated moving‐bed chromatography was studied as a model system for separating lanthanide fission products and minor actinides from used nuclear fuels. The simulated moving‐bed system was modeled for a tertiary pyridine anion‐exchange resin supported on silica particles as the stationary phase and a mixture of methanol and 1M nitric acid as the mobile phase. Pulse injection tests using a single packed column were used to obtain chromatographic parameters for mathematical modeling of the simulated moving‐bed system. Higher concentrations of methanol improved the separation, but the chromatograms showed evidence of nonlinearity of the isotherms. The mathematical model of the simulated moving‐bed process predicted a production rate of purified samarium and neodymium at 118 g solute/L resin/day and a purity of 99.5%. The optimal methanol ratio for the production rate for various product purities was determined from the model. The excellent separation of Nd and Sm suggests that the simulated moving‐bed system could be applied to the separation of minor actinides such as americium and curium.     

Enhanced performance of expanded bed chromatography on rigid superporous adsorbent matrix

Rigid spherical macroporous adsorbent beads with surface hydroxyl groups were prepared by cross-linking of cellulose. These beads had diameter in the range 100-200 microm and a mean pore size of about 3 microm with about 60% pore volume. The matrix (bulk density approximately 1600 kg m(-3)) could be expanded into a stable bed and used for protein chromatography. Chromatographic runs were performed on a 10 mm diameter column under non-retaining and retaining conditions on the prepared matrix (called Celbeads) and performance of the runs was measured in terms of the height equivalent to a theoretical plate (HETP). The HETP curves in both packed and expanded bed modes followed profiles typical of macroporous adsorbents, i.e. increasing and levelling with velocity. Unimpaired performance of the matrix at increasing flow-rates permitted expanded bed elution of adsorbed solutes without loss of efficiency in terms of purification factor and product concentration. As a model system, Celbeads was used to purify lactate dehydrogenase from porcine muscle homogenate by dye-affinity chromatography. The prepared matrix provided about 100 theoretical plates per meter for the enzyme system at a linear flow velocity of 1.27 cm x min(-1) in an expanded bed elution mode, and gave enzyme yields of 100% with a purification factor of 31 using an optimized procedure. The adsorbent could be cleaned in place with 5 M urea and used repeatedly without loss of performance.     

Analyzing small samples with high efficiency: capillary batch injection–capillary electrophoresis–mass spectrometry

We present an experimental approach to conducting fast capillary electrophoresis-mass spectrometry (CE-MS) measurements of very small samples in the nanoliter range. This is achieved by injecting sample very efficiently into a CE-MS system. Injection efficiency represents the ratio of injected sample to the amount of sample needed for carrying out the injection process (v/v). In order to increase this injection efficiency from typical values of 10(-3) to 10(-7), the concept of capillary batch injection is used to build an automated, small-footprint injection device for CE-MS. This device is capable of running true multi-sample measurement series, using minimal sample volumes and delivering an injection efficiency of up to 100?%. It is compatible with both aqueous and non-aqueous background electrolytes. As an additional benefit, CE-MS separations of a catecholamine model system in capillaries of 15?cm length under conditions of high electric field strength could be accomplished in 20?s with high separation efficiency. This report details design and specifications of the injection device and shows optimal parameter choices for injections with both high injection efficiency and high separation efficiency. Furthermore, a procedure is presented to coat the tip of a fused silica capillary with a silicone elastomer which acts as a seal between two capillaries.     

Expansion and hydrodynamic properties of cellulose-stainless steel powder composite matrix for expanded bed adsorption

For better understanding the influences of solid phase properties on the performance of the expanded bed, the expansion and hydrodynamic properties of cellulose-stainless steel powder composite matrix with a series of densities was investigated and analyzed in an expanded bed. Two kinds of matrix particle diameter fractions, the small one (60-125 microm) and the large (125-300 microm), were used in the present work. In general, the expansion factors decreased obviously with the increase of matrix density. A linear relation between the mean density of matrix and superficial velocity at expansion factor of 2.5 was found for same series of matrices. The Richardson-Zaki equation could correlate the bed expansion and operation fluid velocity for all matrices tested. The theoretical prediction of correlation parameters (the terminal settling velocity U(t) and expansion index n) was improved with the modification of equations in the literature. The residence time distributions were investigated to characterize the hydrodynamic property in expanded bed. Compared with three evaluation factors (the height equivalent of theoretical plate, Bo number and axial distribution coefficient D(ax)), the results indicated that D(ax) is the best parameter to analyze the bed stability of expanded bed under various operation conditions and matrix properties. In addition, it was found that fluid velocity is the most essential factor to influence the hydrodynamic properties in the bed. A linear relation between the D(ax) and superficial fluid velocity for all matrices tested was established.     

含氧煤层气流化床催化燃烧脱氧特性研究

利用自制的铜基球形甲烷催化燃烧催化剂,在小型流化床反应器中对模拟含氧煤层气进行了流化床催化燃烧脱氧的实验研究,考察了床层温度、催化剂粒径、空速对脱氧效率和CO₂选择性的影响。结果表明,较高的反应床层温度使催化剂活性增强,进而提高催化脱氧效率。床层温度在450 ℃以上,脱氧效率可稳定保持在95%以上。较小的催化剂粒径降低了内扩散阻力对催化反应的影响,提高催化反应的CO₂选择性。床层温度在450 ℃以下时,降低空速可提高氧气转化率,但温度高于450 ℃时,脱氧反应速率加快,空速变化对脱氧效率影响不明显。此外,通过调节CH₄/Air比例模拟不同含氧量的煤层气,考察流化床反应器及催化剂对含氧煤层气中O₂浓度变化的适应性。模拟含氧煤层气中氧气体积分数在5%~15%,该催化剂均表现出高的脱氧活性和选择性,反应器出口气体中氧气体积分数低于0.2%,CO₂选择性高于98%。