SALT EFFECT IN HEAT OF MIXING: EFFECT OF DISSOLVED SALTS ON THE HEAT OF MIXING OF 2-PROPANOL-BENZENE SYSTEM

The effect of three dissolved salts namely sodium chloride, calcium chloride and zinc chloride on the heat of mixing (endothermic) of the binary system 2-propanol-benzene has been experimentally investigated. The salts were dissolved in the component in which they were preferentially soluble to concentrations up to 15% by weight wherever possible. The experimentation was done at 30°C using a standard type calorimeter attached to a micro-processor based control unit M1PROC The established experimental procedure was followed. The salts sodium chloride and zinc chloride brought about an enhancement in the heat of mixing values. Calcium chloride on the other hand has been found to produce an opposite effect.     

THE VAPOR-LIQUID EQUILIBRIUM OF ETHANOL-WATER MIXTURE IN THE PRESENCE OF BENZYLTRIETHYLAMMONIUM CHLORIDE SALT AT ATMOSPHERIC PRESSURE

The phase transfer catalysis reaction is gaining more and more attention in chemical industry. Usually, the chemicals used as phase transfer catalyst are organic salts. Unfortunately, the effect of an organic salt on the vapor-liquid equilibrium (VLE) of a mixture has hardly been reported in literature. In this study, the effect of the benzyltriethylammonium chloride organic salt on the VLE of ethanol-water mixture was obtained experimentally. It is observed that this organic salt can shift and even break away the azeotrope of ethanol -water mixture as an inorganic salt does. The experimental data were correlated with the models or Tan (1987, 1990) and Ohe (1991). The results were not satisfactory probably due to the complicated interactions among ions and molecules and the big different particle sizes or ion, solvent molecule, and salt molecule.

The vapor pressures of benzyltriethylammonium chloride-ethanol mixtures needed in this study for determining solvent-salt interaction parameters in the correlation model were also measured and regressed by the Patil model (1990).     

STUDY OF THE PARAMETERS CONTROLLING THE ALTERNATING COPOLYMERIZATION OF METHYL METHACRYLATE AND STYRENE

The copolymerization of methyl methacrylate and styrene, in the presence of zinc chloride, was conducted in the aqueous phase. The zinc chloride acting as a complexing agent

Among the factors affecting the polymerization yield, we have; the level of complexing agents, the monomer ratio and the temperature

The polymers were characterized for their molecular weight (G.P.C.) and analyzed by N.MR, and D.T.A

A model taking into account the various parameters is proposed.     

APPLICATION OF UF TECHNOLOGY TO LARGE-SCALE SYNTHESIS OF GT 267-004, A SEQUESTRANT FOR C. DIFFICILE TOXIN

GT 267-004 is a nonabsorbed, nonantibiotic, high molecular weight anionic polymer that is undergoing clinical evaluation as a Clostridium difficile toxin sequestrant. The API is a mixed salt form that consists of approximately 30 to 50% potassium and 70 to 50% sodium as the counterions on the polymer.

The initial polymerization process results in an aqueous polymer solution with the polymer in the 100% sodium form. It also contains some oligomeric impurities. UF technology was applied in a novel way to convert the single-salt polymer to the mixed salt form and to simultaneously remove the oligomers below the required specification limits in a single-unit operation.

Experiments with a UF lab unit validated the concept of simultaneously performing ion exchange and purification. An appropriate amount of potassium chloride was added to the polymer solution to carry out the ion exchange considering the selectivity of the polymer for the potassium ion over the sodium ion. The resulting mixed salts in solution were removed using ultrafiltration membranes. The process produced the API in excellent purity.

The lab data were used to scale up the process to produce several hundred kg of the API. The engineering analysis of the large-scale UF operation was carried out to run the UF process in the cyclic mode and in the diafiltration mode. The UF operation was optimized with respect to time, water usage, operability, and the concentration of product solution required for the subsequent processing.

The optimized UF process was found to be a very cost-effective and time-efficient route to produce the new API.     

SODIUM SULPHATE FROM BITTERN BY METHANOL

Sodium sulphate is produced mainly from land ores by conventional crystallization methods of evaporation and dehydration; these sources are fast being exhausted and new processes should be found which do not use the conventional sources. Seawater bittern produced as by-product from solar halite plants contains about 6% by weight of sodium sulphate, the recovery of which by conventional methods, is made difficult by the presence of other salts.

Methanol has the property of markedly depressing the solubility of certain inorganic salts while hardly affecting the solubilities of others, because of this property, it can be used to promote various crystallization processes and some double decomposition reactions between inorganic salts. This paper examines one example of the second type of application in which magnesium sulphate and sodium chloride present in the bittern interact in the presence of methanol resulting in the formation and selective crystallization of anhydrous sodium sulphate.

Experimental work is described which follows the progress of the reaction under wide range of conditions some given above 94% recovery of high purity sodium sulphate with a crystallizer reactor residence time of 20 minutes. SEM photographs reveal rhombic shapes crystals of size varying between about 1 to 5 μrn. The results presented give promise of forming the basis of a commercially viable process for the fabrication of sodium sulphate.     

醋酸甲酯-甲醇-水体系的盐效应

在20℃的条件下研究了加入氯化钙对醋酸甲酯-甲醇-水体系产生的盐效应。实验结果表明,随着初始水相中氯化钙质量分数的增加,两相区逐渐扩大,醋酸甲酯在水相的溶解度和水在有机相中的溶解度均有所降低。在有机相中甲醇质量分数一定的条件下,随着初始水相中氯化钙质量分数的增加,甲醇在有机相和水相间的分配系数减小,甲醇的选择性系数而增大。这些结论表明,采用加盐萃取对醋酸甲酯和甲醇进行分离十分有利。对该含盐体系的液—液平衡数据采用Eisen-Joffe方程进行了关联,关联值与实验值的平均相对偏差为4 08%。     

SOLAR DRYING OF RAISING

The drying of Sultana seedless grapes was investigated under intermittent and continuous operating conditions in a laboratory solar installation involving a thermal storage bed and an auxiliary heater. The effect of pretreatment, and of the a i r velocity on the drying rate of the grapes at constant temperature was also studied in relation t o the quality of the dried product.

Solar drying of the grapes was accomplished in 30.5 to 60.5 h of intermittent operation, or 19 to 60 h of continuous drying, involving the thermal storage bed and the auxiliary heater. The shortest drying time (19 h ) and the highest quality dried product were obtained with grapes dipped in a hot (80 C ) solution of sodium hydroxide and ethyl oleate, which were dried continuously at 42°C and 2m/s, air temperature and velocity respectively.

The mean apparent diffusivity of moisture in raisins at 6o°C and air velocity 2m/s was estimated as 1.0.10-10 m2/s.     

303.15 K下氯化钙和氯化铵盐的溶解对甲醇+苯混合物焓的影响(英文)

The effect of two dissolved inorganic salts, cadmium chloride CdCl2 and ammonium chloride NH4Cl, on the excess enthalpy of mixing (HE) of the binary system methanol + benzene measured at 303.15 K using an isothermal displacement calorimeter with vapor space is investigated in the present work. Compared to the salt-free system, a decreasing trend in the endothermicity of HE values is significant with the addition of CdCl2 salt but the decrease in the HE values is insignificantly smaller with the addition of NH4Cl salt. The experimental values of the enthalpy of mixing are fitted into a Redlich-Kister equation and the deviations in the val-ues and the parameters are reported. The importance of the solute-solvent interactions and the solvent-solvent interactions are dem-onstrated from the increasing excess enthalpy of mixing values in the positive direction with the increase of salt concentration.     

BENZYL ALCOHOL FROM PHASE TRANSFER CATALYZED WEAKLY ALKALINE HYDROLYSIS OF BENZYL CHLORIDE

The chemical and mass transfer processes were formulated and explained for the system initially composed of BzCl/BzR₃”NCI, R'COONa, H₂O. The effects of the size of the alkyl group of benzyltrialkylammonium chloride, the pH of the aqueous phase, the concentration of the pH controlling agent, aqueous NaOH, the stirring speed, the reaction temperature, the amounts of the cocatalysts, sodium formate and sodium acetate, and the initial volume-ratio of benzyl chloride to water on the product distribution and the production rate of benzyl alcohol were investigated experimentally.

The experimental results show that the pH of the aqueous phase is the most important factor. With sodium formate as the cocatalyst it should be controlled within 7.2-7.7, while with sodium acetate it should be within 9.5-10. Under the suitable pH and 110°C and other suitable conditions, 95% yield of benzyl alcohol can be obtained within 3 hrs of reaction time.     

THE CHARACTERIZATION OF MICROMIXING USING FAST MULTIPLE REACTIONS

Micromixing (mixing at the molecular scale) may be characterized by following fast, competitive, consecutive reactions having the following stoichiometry:

A + B → R (1)

R + B → S (2)

provided that reaction mechanism and kinetics are known. This paper includes many results obtained within the last five years, in particular (a) diffusion-reaction equations for a sheared lamina within which (1) and (2) occur, and (b) comparisons of this and other diffusion-reaction models with measured product distributions.     

Synthesis of Thumba,Castor and Sal Fatty Ethanolamide-Based Anionic Surfactants

The study involved the preparation and evaluation of anionic surfactants from non-edible oil based thumba (containing unsaturated-rich fatty acids, 80.9 %), castor (containing ricinoleic acid, a hydroxy fatty acid 89.3 %) and sal (containing saturated-rich fatty acids, 56.5 %). The oils extracted from these seeds (using Soxhlet) were reacted with monoethanolamine and diethanolamine to get corresponding fatty mono- and diethanolamides. The ethanolamides were sulfated using chlorosulfonic acid and the sulfated sodium salts were evaluated for surfactant properties namely surface tension, critical micelle concentration (CMC), emulsifying property, wetting, foaming power and calcium tolerance. The properties were compared with sodium dodecyl sulfate (SDS) a well known anionic surfactant. Among the different sulfated sodium salts of ethanolamides, thumba showed superior surfactant properties compared to castor and sal. Sulfated sodium salt of thumba monoethanolamide showed better properties (CMC, 0.035 mmol/L, surface tension 30.2 mN/m and calcium tolerance >1,000 ml, 0.5 % calcium acetate solution) compared to sulfated sodium salts of thumba diethanolamides, followed by sulfated sodium salts of castor monoethanolamide (CMC 0.037 mmol/L, surface tension 35.3 mN/m and calcium tolerance >1,000 ml, 0.5 % calcium acetate solution). Sal being saturated rich was not properly soluble in water and showed poor surfactant properties compared to the other two. Also the sulfated sodium salts of thumba and castor ethanolamides exhibited superior properties compared to SDS.     

无机盐对三甘醇脱水及发泡性能影响研究

在天然气净化工艺过程中,三甘醇会受到天然气所携带高矿化度地层水的污染,影响生产。因此,通过实验分析了氯化钠、碳酸氢钠、氯化钙以及氯化铁等无机盐对三甘醇富液脱水和发泡、消泡的影响。研究结果表明,三甘醇富液含水量越大,脱水需要的时间越长,且不易脱除;三甘醇富液脱水率随氯化钠、氯化钙和碳酸氢钠浓度的增大而下降。钙离子对三甘醇富液脱水影响要大于钠离子,碳酸根离子的影响大于氯离子;对于发泡来说,氯化钙影响最小,但氯化钠、氯化钙和碳酸氢钠都存在一个引起三甘醇富液(含有十二烷基磺酸钠)发泡高度最大的浓度,碳酸氢钠的最大,氯化钙的最小;消泡方面,三种盐存在一个消泡最大时间对应的浓度范围,这个浓度范围氯化钙最小,碳酸氢钠最大。氯化铁浓度增大使三甘醇富液脱水率缓慢下降,在研究范围内,总体变化不大;三甘醇富液发泡高度及消泡时间随氯化铁加入浓度的增大而增大,在氯化铁浓度达到0.12%(重量浓度)趋于平缓。     

RECOVERY OF FATTY ACID FROM A SOLVATED HYDROCARBON MIXTURE APPLICABLE TO THE BEAVER-HERTER SOLVENT EXTRACTION PROCESS

The Herter process is a patented enhanced oil recovery process that proposes the use of a fatty acid as a solvent to recover petroleum from an oil reservoir or a tar sand. The fatty acid solvent is injected into a reservoir formation or mixed with a tar sand in order to reduce the viscosity and increase the mobility of the petroleum.

The recovery and recycle of the fatty acid solvent are fundamental parts of the process. The Herter process proposes to recover the fatty acid by saponification, migration of the soap to the aqueous phase, and desaponification of the resulting soap phase. However, the formation of a hydrocarbon-soap-water emulsion severely limits the proposed process. Addition of methanol limits emulsification to allow a meaningful separation to be accomplished.

An evaluation of two proposed revisions to the Herter process was made based on batch experiments involving the recovery of oleic acid, linolenic acid, and Georgia Pacific XTOL™304 fatty acid from solvated mixtures with n-heptane. In both of these methods, methanol was introduced to the process as a cosolvent for the saponifying base (sodium hydroxide). The two methods differed in the manner of methanol recovery. In method 1, the saponification heavy phase was distilled to recover methanol. In method 2, the desaponification heavy phase was distilled to recover methanol.

Both of these methods had fatty acid recoveries greater than 84%, n-heptane recoveries greater than 89%, and methanol recoveries greater than 67%. Method 1 recovered purer fatty acid and a slightly greater percentage of n-heptane. Method 2 recovered a greater percentage of both fatty acid and methanol. Method 2 was found to be superior when high purity of the recovered fatty acid product was not required.     

A THEORETICAL EVALUATION OF CATALYST DISTRIBUTION ON THE PERFORMANCE OF NON-IDEAL SLURRY REACTORS

A study has been made of the influence of catalyst concentration profiles on isothermal continuous slurry reactor performance. Solid catalyst behaviour was modelled with the one dimensional sedimentation-dispersion model and that of the liquid with the one dimensional dispersion model. The Power-law kinetic model as well as Michaelis-Menten and a form of Langmuir-Hinshelwood kinetics were considered.

The results of the computations are given in terms of departures of the exit concentration obtained with a selected, non-uniform, catalyst distribution with respect to constant catalyst profile (reference case). Only for intermediate mixing conditions were differences in the exit concentration found. These differences are usually negligible for power law and Michaelis-Menten kinetics (especially for conversion not very high); on the contrary, they became meaningful for the Langmuir-Hinshelwood—at least for some ranges of the parameters.

The existence of an optimal catalyst distribution was also discussed.     

MEASUREMENT OF INTERFACIAL AREA AND MASS TRANSFER COEFFICIENTS BY CHEMICAL METHOD OF C02 ABSORPTION INTO AQUEOUS SOLUTIONS OF NaOH IN A MODEL COLUMN WITH EXPANDED METAL SHEET PACKING

The theory of gas absorption accompanied by fast pseudo-fast order reaction which considered dependences of diffusivity, kinetic constant and Henry's law constant on absolute temperature and ionic strength was used to obtain values of effective interfacial areas and mass transfer coefficients in gas and liquid phase.

Experimental measurement of carbon dioxide absorption from mixture with air was performed in a pilot-plant column with expanded metal sheet packing irrigated with sodium hydroxide solution.

Resulting liquid and gas-side mass transfer coefficients are compared with values obtained from physical Absorption measurement of carbon dioxide into water and with measurement of gas-side mass transfer coefficient for sulphur dioxide in the same column.

The differences between determined values are discussed.     

APPLICATION OF TURBULENCE FUNDAMENTALS TO REACTOR MODELLING AND SCALEUP

Applications of the fundamentals of turbulent mixing become clear once those fundamentals are understood. The first article in this series presented those fundamentals, in order to show how to apply turbulent mixing fundamentals modelling and scaleup, this article covers the following topics:

1. reaction types and their interaction with mixing;

2. closure of the Reynolds equations for mixing and reactions;

3. application to complex geometries;

4. random coalescence-dispersion modelling;

5. application to complex chemistry.

The most difficult problem in applying our knowledge of turbulence to mixer modelling and scaleup is the choice of model complexity. The levels of model complexity available and how to apply them to various problems are presented following the introduction.     

Experimental results for the vapor–liquid equilibria of (formaldehyde+1,3,5-trioxane+methanol+salt+water) systems and comparison with predictions

The salt effect on the vapor–liquid phase equilibrium (VLE) of solvent mixtures is of significant interest in the industrial production of 1,3,5-trioxane. Experimental data for the VLE of quinary systems (formaldehyde + 1,3,5-trioxane + methanol + salt + water) and their ternary subsystems (formaldehyde+salt+water), (1,3,5-trioxane+salt+water), and (methanol+salt+water) were system-atic measured under atmospheric pressure. The salts considered included KBr, NaNO3, and CaCl2. The extended UNIFAC model was used to describe the VLE of the salt-containing reactive mixtures. The model parameters were determined from the experimental VLE data of ternary systems or obtained from the literature, and then were used to predict the VLE of systems (1,3,5-trioxane + KBr + water), (methanol+KBr+water), (formaldehyde+KBr+water), and (formaldehyde+1,3,5-trioxane+methanol+salt+water) with salt=KBr, NaNO3, and CaCl2. The predicted results showed good agreements with the measured results. Furthermore, the model was used to uncover the salt effect on the VLE of these multi-solvent reactive systems.     

Effect of dissolved inorganic salts on the isothermal vapor–liquid equilibrium of the propionic acid–water mixture

Propionic acid–water is one of the minimum boiling point azeotropic binary mixtures. Alteration of the vapor–liquid equilibrium (VLE) by addition of inorganic salts is of interest, since it allows bypassing the azeotropic point due to salt-in and salt-out effects. The effect of NaCl, NH₄Cl, CaCl₂, and AlCl₃ at salt concentrations of 1 m and the effect of NaCl molality (0.5–3 m) on the VLE of the binary propionic acid–water mixture has been experimentally investigated at 60 °C using the headspace gas chromatography (HSGC) technique. The alteration in the VLE of the system was salt type and salt concentration dependent. Salting out of the propionic acid was observed when salts were added and was most obvious in the case of AlCl₃ salt. The salt effect parameter, determined from the Furter's equation was a function of the liquid concentration.     

INVESTIGATIONS INTO PUMPING CHARACTERISTICS OF AXIAL FLOW IMPELLERS IN AN INTERNAL LOOP REACTOR FOR ANIMAL CELL CULTURE

This investigation was intended to aid in the selection of impeller design and operating conditions, which would exhibit minimum turbulence in an internal loop reactor for axial flow velocities up to 18 cm/s.

For this purpose we measured power consumption, liquid flow velocity and mixing time with two marine propellers (pitch ratio tan alpha =1 and 0.57, respectively) and with flat-blade fan-type impellers (blade angles 10 to 90°).

The present results showed that at flow velocities between 7 and 14 cm/s a reduction in the pitch ratio (tan alpha) of the marine propeller from 1 to 0.57 increased the mechanical flow efficiency.

In addition, the fan-type impeller with a blade angle of 20° displayed flow characteristics comparable to the marine propellers; therefore, owing to its simple design, the fan-type impeller offers a practical substitute for the marine propellers.

In cell culture, draft-tubes used in impeller-driven reactors (internal loop reactors) offer two important features:

1. They simplify the design and scale-up process over that of open-blade impellers (flow patterns are more uniform);

2. They provide a mechanical support for bubblte-free membrane oxygenators;

Furthermore, on the assumption that loop reactors display lower bulk turbulence than open blade impellers for similar power consumption, this investigation was intended to aid in the selection of impeller design and operating conditions which would exhibit maximum pumping efficiency (with minimum mixing).

For this purpose, using a pH tracer method, we determined mechanical flow efficiency and dimensionless mixing time, which served as parameters for pumping efficiency to establish the following specific design characteristics:

1. Bulk mixing decreases relative to bulk flow with increasing bulk flow (mixing therefore conforms to the flow-in-pipe model) for two marine propellers (pitch tan alpha = 1 and 0.57) and for fan-type impellers (variable pitch) up to a blade angle of 30°;

2. Liquid velocity increases directly proportional to impeller speed up to 17 cm/s for (above) propellers, as well as fan-type impellers with blade angles of less than 30°;

3. The mechanical efficiency of axial flow (liquid velocity/power input) increases by decreasing the impeller pitch of marine impellers from tan alpha = 1 to tan alpha = 0.57, in the range of 7-14 cm/s;

4. A fan-type impeller (variable pitch) with a pitch angle of 20° displayed flow velocity and mechanical efficiency values, which lay between those of the (above) two marine propellers.

Fan-type impellers are considerably simpler in construction and are simpler to modify than marine propellers; for this reason this impeller type serves as a useful investigational tool. In addition we have found that at an impeller of 20° this type of impeller may be used to substitute marine propellers with a pitch ratio between 1 and 0.57.

We also suggest that square pitch marine propellers are not the most suitable for reactors in which mechanical efficiency of axial flow is critical, such as those for “shear sensitive” animal and plant cells.     

DEVELOPMENT OF RANEY-TYPE LOW TEMPERATURE METHANOL SYNTHESIS CATALYSTS†

Catalysts prepared by caustic leaching of Cu—Zn—Al alloys are shown to have activities greater than those of a commercial copper-based catalyst.

Complete leaching of alloys containing 50 wt.% aluminium, with between 0 and 50 wt.% copper, and the balance zinc produced catalysts having a wide range of activities. The most active catalysts for methanol production were produced from alloys containing from 10 to 20 wt.% zinc.

The activities of catalysts prepared by the partial leaching of an alloy containing approximately 36% copper, 15% zinc and 48% aluminium were shown to pass through a maximum at a leaching time of 2.75 hours. This catalyst had more than double the activity of a commercial catalyst al reaction conditions similar to those employed industrially.