Direct extraction of Mo(Ⅵ) from sulfate solution by synergistic extractants in the rotation column

Direct extraction of molybdenum from sulfate solution with synergistic extractants(mixture of D2EHPA and TBP)was studied in the rotation column.The influence of extractant concentration and initial pH of aqueous phase was studied in the bench scale experiments.The outcomes demonstrated that the synergistic solvent extraction enhances the constancy of the extracted complexes for transfer into the organic phase.In the continuous experiments,the effect of different operating parameters such as speed of agitation,inlet solvent flow rate and inlet aqueous flow rate on the holdup,mean drop size,drop size distribution,slip and characteristic velocities and extraction percentage were examined.Modified correlations were proposed for prediction of hydrodynamic parameters with consideration of reaction extraction condition in the rotation column.Furthermore,these correlations were compared with the experimental data.According to the results,the direct extraction of Mo(Ⅵ)from aqueous solution and sulfuric media with extraction efficiency of 90.4%was obtained at higher rotor speed(240 r·min–1 rpm)in this column.

Prediction of dispersed phase holdup in pulsed disc and doughnut solvent extraction columns under different mass transfer conditions

Using experimental data from a number of pulsed disc and doughnut solvent extraction columns,a unified correlation for the prediction of dispersed phase holdup that considers the effects of mass transfer is presented.Pulsed disc and doughnut solvent extraction columns(PDDC) have been used for a range of important applications such as uranium extraction and nuclear fuel recycling.Although the dispersed phase holdup in a PDDC has been presented by some researchers,there is still the need to develop a robust correlation that can predict the experimental dispersed phase holdup over a range of operating conditions including the effects of mass transfer direction.In this study,dispersed phase holdup data from different literature sources for a PDDC were used to refit constants for the correlation presented by Kumar and Hartland [Ind.Eng.Chem.Res.,27(1988),131–138] which did not consider the effect of column geometry.In order to incorporate the characteristic length of the PDDC(i.e.the plate spacing),the unified correlation for holdup proposed by Kumar and Hartland based on data from eight different types of columns [Ind.Eng.Chem.Res.,34(1995) 3925–3940] was refitted to the PDDC data.New constants have been presented for each holdup correlation for a PDDC based on regression analysis using published holdup data from PDDCs that cover a range of operating conditions and physical properties and consider the direction of mass transfer.

Comparison of the Reynolds-averaged Turbulence Models on Single Phase Flow Simulation in Agitated Extraction Columns

The flow field of liquid phase (water) of agitated extraction columns is simulated with the help of computational fluid dynamics (CFD). Four kinds of Reynolds-averaged turbulence models, i.e. the standard k-ε model, the RNG (renormaiization group) k-ε model, the realizable k-ε model and the Reynolds stress model, are compared in detail in order to judge which is the best model in terms of the accuracy, less CPU time and memory required. The performance of the realizable k-ε model is obviously improved by reducing the model constant from c2 = 1.90 to c2 = 1.61. It is concluded that the improved realizable k-ε model is the optimal model.

Mass Transfer and Axial Mixing Characteristics in a Coalescence-Dispersion Pulsed-Sieve-Plate Extraction Column

A new configuration of coalescence-dispersed pulsed-sieve-plate extraction column (CDPSEC) was developed, and the mass transfer and axial mixing characteristics were evaluated with the two-point dynamic method.The influence of operation conditions was discussed with experimental results, showing that the mass transfer performance of CDPSEC mainly depends on the energy input and the holdup of dispersed phase. Higher energy input results in higher holdup of the dispersed phase, the axial mixing of the continuous phase is suppressed, and the true height of mass transfer unit decreases markedly. On the other hand, higher energy input leads to more serious forward mixing of the dispersed phase, so the energy input should be limited. Accordingly the operation conditions were divided into two regions, and empirical correlations for predicting the mass transfer and axial mixing characteristics in different regions with a satisfactory accuracy were suggested.

Recovery of Caprolactam from Waste Water in Caprolactam Production Using Pulsed-sieve-plate Extraction Column

Recovery of caprolactam from waste water of caprolactam production factory was investigated using benzence as solvent in a small-scale pulsed-sieve-plate column.First,liquid-liquid equilibrium (LLE) deta were measured,including water-caprolactam-benzene system at low caprolactam concentrations,and waste water-benzene system.Then,the operating regions and mass transfer of the pulsed-sieve-plate column were measured.Finally,the overall apparent heights of a transfer unit based on continuous phase are correlated in terms of the column operation variables.

Extraction of Caprolactam from Aqueous Ammonium Sulfate Solution in Pulsed Packed Column Using 250Y Mellapak Packings

Liquid-liquid equilibrium (LLE) data of water-caprolactam-benzene-(NH4)2SO4 system at 303 K were measured for extraction of caprolactam from aqueous ammonium sulfate solution. The influence of fluid flow rate, pulsation intensity on flooding velocity and mass transfer was studied for extraction of caprolactam from ammonium sulfate solution in a laboratory pulsed packed column. The flooding velocities and overall apparent height of a transfer unit were given under various operation conditions. An industrial column developed based on above study is operated well. The scale-up effect is discussed.

The Resident Time Distribution of Injected Dispersed Drops in Stirred Extraction Columns

一个居民时间模型被建议评估鼓动的抽提塔的表演。在这个模型，驱散的落下的居民时间被模仿，分散相当模特儿，在连续相和分散相(落下)被thesingle阶段海军司烧(骚乱)描述的地方模型和 Lagrangian 模型，分散相和连续相的 respectively.The 相互作用在 casesstudied.The 为落下的低集中被忽视在不同操作条件下面的落下(普通居民时间和标准误差)的统计参数为四列被计算。有列的表演的上述统计参数的关系被讨论，为最佳的分隔空间的标准被构画出。我们的结果显示居民时间模型是有用的评估表演并且优化抽提塔的设计。

HYDRODYNAMICS AND MASS TRANSFER IN A NEW TYPE(FG)STACK PACKED EXTRACTION COLUMN

1 INTRODUCTIONOne of the major objectives in the study of extraction column is to minimize column di-mensions to fulfill a certain specific separation process.This has led to the intensiveemployment of structured packings in extraction columns [1].One of the recentdevelopments targeted for greater interfacial areas without excessive dispersion is the useof structure packings contactive claiming advantages,such as lower fluid flow

GRAVITY SETTLING OF DISPERSED PHASE DROP SWARMS IN EXTRACTION COLUMNS IN ABSENCE OF MASS TRANSFER

Taking into account the effect of velocity profiles of the continuous phase in interstices of drops,dragcoefficient and relative motion correlations for dispersed liquid-liquid two-phase flow in absence of mass transferwere developed in terms of the pseudo-fluid concept based on the simple similarity criteria and the mixtureviscosity model suggested by Ishii and Zuber.The present model was compared with the experimental data fromfive(different sources and also with seven other pertinent correlations available in literature.Fairly goodpredictions were obtained under wide ranges of the dispersed phase holdup and Reynolds number.The validity ofthe present model has also been checked against the experimental slip velocity data and holdup data obtained ina Karr reciprocating plate extraction column by the author of the present paper and satisfactory agreement isachieved、The results show that the equations of the motion of a multi-droplet system can be formulated in aform identical with those for a single

A General Equation for Calculating the‘True’Height of Transfer Unit in Extraction Columns

Based on single drop mass transfer models and two phase flow equation,a general equationfor calculating the‘true’height of transfer unit of extraction columns was derived and tested withfour types of extraction columns with some different working systems.The calculated results fittedwell with those obtained by experiments.

STUDY ON THE INFLUENCE OF ANNULAR SPACE WIDTH ON THE AXIAL MIXING IN PULSED-SIEVE-PLATE EXTRACTION COLUMN

1 INTRODUCTIONAnnular pulsed-sieve-plate extraction column is an unique extraction equipment that can beused to ensure critical safety in reprocssing of irradiated nuclear fuel,The study of this kind ofextraction column has been carried out and some results were published in resent years [1—9]. It is known that axial mixing is one of most important parameters effecting column be-

Design aspect of a novel L-shaped pulsed column for liquid–liquid extraction applications: Energy consumption and the characteristics velocity concept

This article deals with the evaluation of the consumption of energy for a steady state solvent extraction in a novel L-shaped pulsed sieve-plate column, which is highly required for design and optimization of the periodic flow processes for industrial applications. In this regard, a comprehensive evaluation on the energy consumption in case of a pulsed flow for three different chemical systems is conducted and besides the influence of pulsation intensity, the effect of geometrical parameters including the plate spacing and the plate free area is investigated as well. Moreover, the concept of characteristic velocity models at flooding points is evaluated with respect to the variation of pressure drop along the column at different operational conditions.

Measurement of Mass Transfer Coefficients and Their Modelling of Continuous Counter-Current Aqueous Two-Phase System in a Packed Extraction Column

Overall dispersed side volumetric mare transfer coeffcieats for protein and amino acids were measured in continuous countercurreat PEG4000/KHP aqueous two-phase systems in a 57 mm I.D. packed extraction column. A model for overall dispersed side volumetric mass transfer coefficients was derived by describing the motion of the drops based upon Navier-Stokes equation combined with the relationship between mass transfer coefficients and the drop velocity. The model provides good predictions and can be successfully used in aqueous two-phase extraction. The awrage relative deviation between calculated values and experimental date ranges from 8% to 14%.

Application of a Particle Extraction Process at the Interface of Two Liquids in a Drop Column—Consideration of the Process Behavior and Kinetic Approach

The focus of this research is a new type of particle extraction process for the transfer of magnetite nanoparticles from an aqueous to an immiscible organic phase, directly through the liquid-liquid phase boundary in a drop column. The particle extraction process comprises several advantages such as a minimum amount of stabilizing surfactant, no exposure of the particles to a gas atmosphere and with it the avoidance of sintering by capillary forces and a high particle concentration in the receiving phase as well. The study presents experimental results of the characterization of the process environment and the transfer behavior in a drop column. The solution of surfactant in the continuous phase has been investigated during a particle-free phase transfer experiment including the measurements of the total organic carbon (TOC) content and analysis of the size of the stabilized droplets using the laser diffraction spectroscopy. The determination of the transfer fluxes, the mass flows as well as the yield of transferred magnetite by ICP-OES measurements provide information on the impact of interaction of the elementary processes at the phase boundary. Furthermore, the transfer kinetics of the process is described and compared with calculated theoretical values resulting from a kinetic approach.

Axial mixing and mass transfer characteristics of pulsed extraction column with discs and doughnuts

The axial mixing is a key factor for design and scaling up of the pulsed extraction column which has strong influence on the mass transfer performances of the pulsed extraction column with discs and doughnuts. A steady-state concentration profile measurement was used to evaluate the mass transfer and axial mixing coefficients for the nitric acid/water/30%TRPO (in kerosene) system in the pulsed extraction column with the diameter of 38 mm on the condition of the TRPO-kerosene solution as the continuous phase and the flow ratio of 1∶1. Experimental results indicate that Ey evaluated by the experiments is in good agreement with that given by Burratti’s correlation; the axial mixing is far smaller for the continuous phase than that for the dispersed phase. However the empirical correlation for HOX is only given based on the present data.

Separation and analysis of six fractions in low temperature coal tar by column chromatography

The low temperature coal tar(CT)is taken as the raw material,and the extraction and column chromatography are used for detailed and accurate characterization in this paper.The n-heptane soluble fraction(CT-HS)and insoluble fraction(CT-HI)were obtained by n-heptane Soxhlet extraction.The extraction rate of CT-HS reached 92.79%(mass),which indicated that there are few heavy compounds in it.Further,different solvents(methylbenzene,benzene,ethyl acetate,methylbenzene-ethanol)were used to elute CT-HS by chromatographic column to obtain five fractions(saturates,aromatics,heteroatoms,phenolics and resins,named CT-SA,CT-AR,CT-HE,CT-PH,CT-RE,respectively).The yields of CTSA,CT-AR,CT-HE,CT-PH,CT-RE are 42.12%,10.43%,2.19%,9.50%and 6.63%(mass),respectively.Gas chromatography-mass spectrometry analysis of eluting components show that alkanes are the main components in CT,followed by polycyclic aromatics,and the corresponding fractions are CT-SA and CT-AR,respectively.The relative content of aliphatics in CT-SA is 76.93%,and the relative content of aromatics in CT-AR is 75.05%.This separation technology effectively separates and enriches different components in CT,and the activation energy required for the pyrolysis process of a single eluting fraction is lower than that of CT,which is expected to provide an important reference for the separation,analysis and conversion of complex oil products such as coal-oil co-processing products,coal tar and other complex heavy carbon oil products.

基于在线柱切换液相色谱技术的红霉素软膏含量测定研究

目的建立在线柱切换高效液相色谱法测定红霉素软膏中主药含量的方法,为相关制剂的质量控制提供有效手段。方法样品经80℃提取后直接进样,柱切换系统下,采用C_(18)(50 mm×2.1 mm,5μm)色谱柱初步分离,2.5 min后转入C_(18)(150 mm×2.1 mm,5μm)柱进行分析,流速0.2 mL·min^(-1),柱温35℃。结果红霉素在1~100μg·mL^(-1)范围内线性关系良好(r=0.9994);平均加样回收率大于96.9%;日内和日间精密度小于1.29%(n=6)。结论本研究改进样品提取方法,并通过在线柱切换完成目标组分的净化和富集,该方法操作简单、准确灵敏、稳定性好,可用于红霉素软膏的含量测定。

PRiME HLB前处理技术联合超高效液相色谱-三重四极杆质谱系统检测水产品中17种磺胺类药物残留

使用通过型固相萃取小柱PRi ME HLB处理水产品样品,建立了一种水产品中17种磺胺类药物的简单、快速的筛选分析方法。水产品样品经80%乙腈水溶液(含0.2%甲酸)提取,过PRi ME HLB固相萃取柱净化,浓缩后经C_(18)色谱柱梯度洗脱分离,超高效液相色谱-三重四极杆质谱系统进行定量分析。结果表明,17种磺胺类药物在1.0~50.0 ng·mL^(-1)线性关系良好,相关系数R^(2)>0.99;该方法检出限为2μg·kg^(-1);添加浓度为10μg·kg^(-1)时方法回收率在71.3%~118.4%,RSD值均小于20%。