Showing papers in "Journal of Chemical Engineering of Japan in 2008"

Gasification of Catalyst-Suspended Chicken Manure in Supercritical Water

Abstract: Chicken manure feedstocks containing a suspended fine activated carbon catalyst were gasified by supercritical water gasification in an experimental pilot plant. A chicken manure feedstock of 2 wt% with 0.4 wt% of activated carbon was completely gasified, whereas the same feedstock without activated carbon was gasified with a carbon gasification efficiency of only 0.8. A feedstock of 10 wt% with 5 wt% of activated carbon was completely gasified. Our results indicate that suspended fine activated carbon is effective as a gasification catalyst. The data also confirm that use of a suspended activated carbon catalyst helps to prevent plugging in the gasification reactor.

Catalysis Mechanism Study of Potassium Salts on Cellulose Pyrolysis by Using TGA-FTIR Analysis

Abstract: The catalytic effect of three kinds of potassium salts on cellulose pyrolysis kinetics and products was studied on a thermogravimetric analyzer coupled with a Fourier transform infrared spectroscopy. Experimental results showed that potassium salts catalyzed the dehydration and depolymerization reactions in the initial pyrolysis stage, enhanced the release of oxygenated gases, intensively catalyzed the formation of char, and restrained the production of volatiles. Kinetic modeling showed that the presence of potassium ions provided a mechanistic route with lower activation energy, and accelerated the pyrolysis rate. Both KCl and K2CO3 restrained the release of levoglucosan, glycoaldehyde and C=O containing compounds, while K2SO4 largely promoted the formation of levoglucosan. The presence of KCl and K2CO3 might have retarded the unzipping reaction at the terminal units of the cellulose chain, and thus restrained the formation of levoglucosan. K2SO4 exhibited different catalytic mechanisms, which uniquely catalyzed the formation of levoglucosan.

Activity Modeling for Integrating Environmental, Health and Safety (EHS) Consideration as a New Element in Industrial Chemical Process Design

Abstract: In this paper, we present activity models of chemical process design integrating environmental, health and safety (EHS) evaluation as a new element with conventional economic and technical considerations on the basis of the design framework, which defines different stages of early process design with appropriate indicators for multiobjective evaluation. The type-zero method of Integrated DEFinition language or IDEF0 is selected as an activity modeling method for the hierarchical and transparent description of complex design activities. The viewpoint of the activity model is the user of this design framework, i.e. a design-project manager who leads a group of process chemists and engineers. A set of template models is developed, which describes how a manager executes a project step by step with providing instructions and resources appropriately. According to this template, IDEF0 models of the design framework are created, and here EHS-related activities, tools and information are systematically defined as a part of the whole design activity. As further analysis, sub-activities are presented in detail, where the manager allocates resources appropriately to different design stages, including methods of environmental Life Cycle Assessment (LCA) and EHS hazard evaluation. Another detailed analysis is on how design constraints, e.g., market situation, competitors’ patents and company culture, affect different decision-making within the framework. The actual development of methyl methacrylate (MMA) processes is investigated as a case study. The paper finally presents important know-how for the design manager in executing the integrated design framework.

The Effect of Voidage on the CO2 Sorption Capacity of K-Based Sorbent in a Dual Circulating Fluidized Bed Process

Abstract: The performance of the CO2 capture of a potassium-based dry sorbent was investigated in a dual circulating fluidized bed process. The dual circulating fluidized bed process consisted of a carbonation reactor and a regeneration reactor. It was operated in the continuous solid circulation mode between a fast fluidized-bed carbonator of 6 m in height and a bubbling fluidized-bed regenerator. As the solid circulation rate increased from 7 to 36 kg/m2/s, the CO2 removal of the potassium sorbent, sorbKX40, increased from 25 to 55% and the mean voidage was maintained from 0.94 to 0.99 representing the dilute phase in the fluidization regime. The continuous solid circulation behavior in a dual fluidized bed process was well expressed by a single closed loop in a pressure balance curve that indirectly explained the direction of the sorbent flow and the mean bulk densities of the gas–solid mixture. The information on hydrodynamics and sorption capacity will be used for the conceptual and scale-up design of the system.

A New Approach for the Prediction of Gas Holdup in Bubble Columns Operated under Various Pressures in the Homogeneous Regime

Abstract: A new semi-theoretical approach for prediction of gas holdups in the homogeneous flow regime is suggested. The model is based on two different expressions for the gas–liquid interfacial area. It is argued that in the case of oblate ellipsoidal bubbles (formed in the homogeneous regime) some correction factor should be introduced in order to render both expressions equivalent. The correction term is correlated to Eotvos number and a dimensionless gas density ratio. The method was capable of predicting 386 experimental gas holdups measured in 21 organic liquids, 17 liquid mixtures and tap water with an average relative error of 9.6%.

Characterization of Various TiO2 Powders Used for Complete Decomposition of Organic Wastes by Means of Thermally Excited Holes at High Temperatures

Abstract: Disposal of organic wastes is a social problem of high importance. We previously reported on a decomposition system of organic wastes by the use of thermally excited holes in TiO2 at high temperatures. An appealing feature of our system is that it makes use of a great number of holes formed at, for example, 350°C. In the present investigation, characterization has been carried out on various TiO2 powders that have nearly the same composition but differ in specific surface and particle size in an attempt to screen and select the most powerful powder. The decomposition ability of TiO2 has been evaluated using previously investigated polycarbonate (PC)-coated TiO2 as the model system, with special attention to the interaction between the adsorbate (PC) and the adsorbent (TiO2). As a result, the specific surface was found to play the most important role, and is closely linked to the adsorption amount of PC on TiO2, released energy, spin concentration, deep coloration, as well as to the Raman peak-shift. In addition, the crystallinity is also found to be effective in connection with the lifetime of holes.

Hydrodynamic Properties in a Cold-Model Dual Fluidized-Bed Gasifier

Abstract: A cold model dual fluidized bed gasifier was designed and constructed to determine the hydrodynamic properties in a bubbling fluidized bed and in a riser using silica sand (260 μm) as the bed material to determine the optimum operating conditions for stable heat supply between the two reactors for the biomass gasifer operation. Solid circulation rate was measured as a function of gas velocity and solid inventory and the obtained data was correlated in terms of Froude number and a ratio of aeration and particle terminal velocities. Flow regimes and the axial solid holdup distribution in the riser were determined as a function of gas velocity and solid circulation rate.

Ibuprofen Racemate Separation by Simulated Moving Bed

Abstract: Ibuprofen racemates were separated in a SMB system with 4 chromatographic columns packed with TBB gels. Retention times of R- and S-enantiomers of ibuprofen were measured in batch chromatography experiments with hexane/TBME/acetic acid mixed solvent. Isotherm parameters of SMB were calculated from the batch chromatography data, and operation flow parameters obtained from m2 and m3 plane of Morbidelli and coworkers (Abel et al., 2004). Experimental results are summarized as purities of raffinate. In order to compare experiments with simulations, ASPEN Chromatography Simulator was adopted. Isotherm and operation parameters were inserted to the dialog box of the simulator and output display data was cropped for comparison of experiments and simulations.

Detailed Analysis of Heat and Mass Balance for Supercritical Water Gasification

Abstract: The process energy efficiency of supercritical water gasification was determined by a detailed calculation of the energy balance. Ten tons (wet) per day of chicken manure, the moisture content of which was adjusted, was employed as the model feedstock. An efficiency ratio of 70% was obtained for chicken manure having a water content of 80%. The key operating parameters for ensuring high process energy efficiency were the heating value of feedstock and heat recovery efficiency. This result, along with the heat exchanger efficiency measured in the pilot plant, clearly indicates the high potential of supercritical water gasification technology as a wet biomass gasification process.

A Plate-Type Anodic Alumina Supported Nickel Catalyst for Methane Steam Reforming

Abstract: An anodic alumina supported nickel catalyst (Ni/Al2O3/Alloy) was synthesized using a double impregnation method with a high temperature calcination in between, to investigate reactivity performance thereof during steam reforming of methane (SRM) reactions in continuous and daily start-up and shut-down (DSS)-like operations. The catalyst was structurally characterized using X-ray diffraction (XRD), BET and temperature programmed reduction (TPR) technologies. The TPR results showed that almost all nickel content from the first impregnation was transformed into nickel aluminate, whereas nickel from the second impregnation predominantly existed in the more reducible forms of NiO and xNiO·Al2O3 (x < 1). The existence of these NiO and NiAl2O4 phases was identified by XRD.The catalyst provided high and stable SRM reactivity near the equilibrium value, while no deactivation was observed in continuous durability testing for 200 h at 800°C and 130 h at 700°C, and in DSS-like mode operation at 700°C. The investigation of the influence of methane and/or steam treatments on the reactivity of Ni/Al2O3/Alloy showed the catalyst is not disturbed by the methane treatment, whereas it is remarkably deactivated by the steam treatment. In addition, no differences in the reduction effect were found when using hydrogen or methane to regenerate a steamed catalyst.

An Experimental Investigation of the Characteristics of the Secondary Atomization and Spray Combustion for Emulsified Fuel

Abstract: In this study, a single droplet experiment and a spray combustion experiment for an emulsified fuel were carried out. The purpose of the single droplet experiment was to investigate the characteristics of the secondary atomization and the dominant factor in determining micro-explosion or puffing. In the spray combustion experiment, the spray combustion characteristics of the emulsified fuel used in the single droplet experiment were investigated. In the single droplet experiment, individual emulsified fuel droplets suspended from a thermocouple were set into an electric furnace. As a result, many forms of secondary atomization were observed. While the superheat temperature ranged between 50 and 80 K at the occurrence of micro-explosion, it ranged between 20 and 50 K when puffing occurred. It was found that the probability of the micro-explosion increased with an increase in the superheat temperature. The emulsified fuel had a drastic effect on the spray combustion characteristics. When the emulsified fuel was used, the gas temperature was reduced in the upstream region. However, the gas temperature increased rapidly and there was no peak of the gas temperature in the axial direction, unlike kerosene. Moreover, the radial distribution of the gas temperature of the emulsified fuel became uniform, also unlike kerosene, as a result of the improvement of the evaporation and the mixing caused by the secondary atomization as shown in the single droplet experiment.

Degradation of 1,4-Dioxane by Photo-Fenton Processes

Abstract: 1,4-Dioxane is an EPA priority pollutant found in contaminated groundwater and industrial effluents. The common treatment techniques are not effective for 1,4-dioxane degradation. Thus there is a need to find an efficient degradation method such as a photo-Fenton process and understand the degradation mechanism of 1,4-dioxane during such reactions. In this study, the effect of the reaction parameters such as initial concentration of 1,4-dioxane, H2O2 and FeSO4 dosages, and UV light intensity on 1,4-dioxane degradation has been examined. Under optimal conditions, over 95% of 1,4-dioxane is degraded by photo-Fenton (UV with H2O2 and FeSO4), while little 1,4-dioxane is degraded by FeSO4 alone. It was proposed that 1,4-dioxane was oxidized by OH radicals and sequentially led to formation of malonic acid, formic acid and acrylic acid. Based on the experimental results of 1,4-dioxane, the application of advanced oxidation processes (AOPs) appears to be a promising alternative for 1,4-dioxane removal in various environment systems.

Hydrogen Protection from Methanol or Methane by the Use of Thermally Generated Holes in TiO2

Abstract: Previously involved in complete decomposition (H2O + CO2) of organic wastes (mainly thermoplastic and thermosetting polymers), as well as exhaust of diesel engines by the use of thermally generated holes in TiO2 at about 350–500°C under sufficient O2. Then, we struck on an idea that H2 can be produced in place of H2O under O2-deficient conditions. Because of this, an attempt has been made in the present investigation to produce hydrogen from methanol or methane. Hydrogen is found to be successfully produced from methanol at 350–400°C under 5–20% O2, or from methane at 450–500°C under 50% O2. The conversion efficiency amounts to about 70–85% for methanol while about 40% for methane.

Chemical Recycling of Poly(Ethylene Terephthalate) Using a New Hybrid Process

Abstract: In this study, we propose a new hybrid process consisting of glycolysis/methanolysis and then a vapor methanolysis process to obtain dimethyl terephthalate (DMT) and ethylene glycol (EG) in the depolymerization of waste poly(ethylene terephthalate) (PET). Zinc acetate was used to catalyze the reactions. We found that the depolymerization rate increased remarkably when glycolysis and methanolysis reactions were simultaneously carried out than when the glycolysis reaction was performed alone. We explored the possibility of the hybrid process and examined optimal weighting between glycolysis and methanolysis in the glycolysis/methanolysis step to increase the DMT yield and production rate. We also investigated the effect of major process variables such as reaction pressure, reaction temperature, reaction time, amount of EG, and methanol feed rate on process performance. We found that methanolysis has a greater role than glycolysis in the glycolysis/methanolysis step and the DMT yield has a maximum at a reaction temperature of 513.15 K and EG/PET mole ratio of 0.52, and increases with reaction pressure.

Flow Characteristics in Cocurrent Upflow Bubble Column Dispersed with Micro-Bubbles

Abstract: The flow characteristics and decomposition performance in the cocurrent upflow bubble column dispersed with micro-bubbles were experimentally examined. A micro-bubble generator was installed at the bottom of the column, and for comparison the sintered glass gas sparger was set at the lower part of the column.When milli-bubbles coexist with dispersed micro-bubbles, micro-bubbles disappear. This is considered because micro-bubbles are absorbed into the wake of milli-bubbles. The volumetric mass transfer coefficient is higher for micro-bubbles than for milli-bubbles, but the mass transfer coefficient is much lower for the former than for the latter. The apparent decomposition rate constant strongly depends on the volumetric coefficient. When the volumetric coefficient is higher, the rate constant of micro-bubbles is higher than that of milli-bubbles.

Fault Detection in Chemical Processes Using Discriminant Analysis and Control Chart

Abstract: This paper presents a fault detection methodology based on the Fisher discriminant analysis (FDA) and individuals control charts (XmR control charts). As the first step, FDA is used to find the optimal discriminant direction between the normal operation data and the fault data. In the next step, XmR control charts on the discriminant direction are used to monitor the process. To reduce the amount of false alarms, we also used a variable selection technique based on the contribution plot of FDA. The performance of the proposed technique is demonstrated through application to the monitoring of the Tennessee Eastman challenge process.

Removal of Hexavalent Chromium from Model Tannery Wastewater by Adsorption Using Mongolian Natural Zeolite

Abstract: We applied Mongolian natural zeolite to adsorptive removal of hexavalent chromium contained in tannery wastewater. At first, characterization was carried out for various kinds of natural zeolites obtained from Tsagaan Tsav and Urgon deposits in Dornogovi province, southeast part of Mongolia. From the X-ray diffractometry analysis, the zeolite samples were composed of mordenite, quartz, gismondine, clinoptilolite, and chabazite, and many of the samples contained clinoptilolite, which is the most abundant natural zeolite. The BET surface areas and the pore volumes of the samples were much lower than those of pure zeolites, and ranged from 15 to 160 m2·g–1 and from 0.03 × 10–6 to 0.1 × 10–6 m3·g–1, respectively. A part of the zeolite samples were modified by a metal cation, barium cation, in order to adsorb hexavalent chromium, which is anion of chromate in aqueous solution. The content of barium in the modified zeolite was much higher than that in the unmodified one, so that the successful zeolite modification could be confirmed. Secondly, batch equilibrium adsorptions of hexavalent chromium from aqueous solution, the model tannery wastewater, by the natural zeolites were carried out. Although the adsorption performances varied with the natural zeolite, all of the zeolites modified by barium cation could adsorb hexavalent chromium favorably and the fractional removal was over 0.9 at maximum, while the unmodified ones could not almost at all. The higher solution pH gave the higher adsorption performance and, then, main adsorbate was CrO42–, since this species is dominant in higher pH according to the speciation of hexavalent chromate anion. Consequently, we proposed to utilize Mongolian natural zeolite to treat the tannery wastewater containing hexavalent chromium.

Analysis and Optimization of a CSTR by Direct Entropy Minimization

Abstract: Determination of optimal operating conditions of chemical processes is difficult. Minimization of entropy generation is a simpler option for standard, either numerical or analytical, optimization techniques. This paper illustrates how entropy generation minimization can simplify the analysis and optimization of the operation of a CSTR. A typical irreversible, exothermic, first order chemical reaction taken from the literature has been considered. For this system, the entropy generation rate has been derived based on mass, energy and entropy balances. Using analytical derivatives it was found that entropy generation can be minimized if the inlet stream temperature is the same as the operating temperature of the reactor. Additionally, it was easy to draw from the analysis the operating temperature that achieved maximum conversion. Finally, the procedure proposed was compared with an indirect entropy minimization method, and shown to be simpler and clearer.

Carbonization of Cellulose Using the Hydrothermal Method

Abstract: Cellulose was treated at 423–623 K under hydrothermal conditions without a catalyst to produce charcoal. The charcoal generated under hydrothermal conditions was mainly analyzed by FT-IR in order to investigate changes in its chemical structures occurring during the carbonization process. Increasing reaction temperatures decreased charcoal yield, increased its carbon-to-oxygen ratio, and promoted cellulose carbonization. Furthermore, increasing reaction temperature during hydrothermal treatment of cellulose weakened FT-IR peaks from –OH and –CH groups, showing that dehydrogenation and deoxygenation had occurred. These studies confirmed that hydrothermal conditions promoted carbonization of cellulose.

Synergistic Effect of Sonophoresis and Iontophoresis in Transdermal Drug Delivery

Abstract: Synergistic effects of sonophoresis and iontophoresis on skin penetration were investigated using vitamin B12 (VB12, molecular weight 1355.4 and non-ionized compound at pH 7.4) as a model drug in the stratum corneum (SC) of hairless mice. Under passive penetration, SC acts as an effective diffusion barrier for VB12 and physical treatment is necessary to enhance skin penetration flux. Ultrasound (US) treatment (frequency of 300 kHz, intensity of 5.21 W/cm2, and pulse mode of 5.4% duty cycle) under sonophoresis increased both VB12 solubility and diffusivity in the skin according to its energy flux [J/cm2] (intensity × treatment time × duty cycle). The penetration flux of VB12 treated with US of 510 J/cm2 was 12 times larger than that through intact skin. Iontophoresis (IP) application increased the convective water flow due to electro-osmosis, and resulted in an increase in the flux of non-electrolyte VB12 with IP (0.3 mA/cm2) by 20 times compared to the flux of passive experiments. Using US and IP combination, a synergistic effect on the penetration flux of VB12 was achieved. This synergistic effect may be caused by a different mechanism than the one responsible for enhancing skin penetration with only US or IP. Thus, the combination of US and IP treatment is an effective method for skin penetration of large molecules which enter into systematic circulation with great difficulty.

High Temperature Preparation of Core and Core/Shell Composite Nanocrystals in a Multiphase Microreactor

Abstract: Microreactors can be used for continuous operation and precise control of heating conditions in chemical synthesis. Therefore, microreactors are expected to offer a more efficient strategy for obtaining homogeneous nanocrystals and easier of size control than the general batch reaction system. CdSe nanocrystals can be turned into emission color by controlling the size of nanocrystals. In this study, we synthesized CdSe nanocrystals by a multiphase microreactor. The CdSe nanocrystals were coated with ZnSe and ZnS by using the multiphase microreactor. The nanocrystals are coated on their surface with a shell of a larger band gap semiconductor, which can improve luminescence efficiency. Furthermore, we investigated the residence time in relation to size of nanocrystals and optimized the coating layer thickness.

CO2 Recovery at High Temperatures Using Ba2TiO4

Abstract: We investigated the use of Ba2TiO4 to remove CO2 from a flow gas at high temperatures. Experiments using a CO2/N2 gas and a vertical reaction tube showed that the CO2 concentration of the exit gas can be reduced to 1% or less at 500 to 800°C (and to even 0.1% or less at 600°C) when the space velocity (SV) of the flow is 2000 h–1. Also, the CO2 concentration changes for the gas mass flow at 700°C or lower. From the results of reaction rate analysis of Ba2TiO4 and CO2, at temperatures of 550°C and higher, the activation energy was 12.5 kJ/mol, indicating that this range is a diffusion-rate controlled area. The reaction rate had a linear correlation with the CO2 concentration from 500 to 800°C, and the estimated reaction degree was 0.96. These results indicate that Ba2TiO4 can effectively remove CO2 from exhaust gas at high temperatures.

Classification and Diagnostic Output Prediction of Cancer Using Gene Expression Profiling and Supervised Machine Learning Algorithms

Abstract: In this paper, a new supervised clustering and classification method is proposed. First, the application of discriminant partial least squares (DPLS) for the selection of a minimum number of key genes is applied on a gene expression microarray data set. Second, supervised hierarchical clustering based on the information of the cancer type is subsequently proposed to find key gene groups and to group the cancer samples into different subclasses. Here, the weights of the genes in the DPLS are proportional to their importance in the determination of the class labels, that is, the variable importance in the projection (VIP) information of the DPLS method. The power of the gene selection method and the proposed supervised hierarchical clustering method is illustrated on a three microarray data sets of leukemia, breast, and colon cancer. Supervised machine learning algorithms thus enable the subtype classification 3 data sets solely on the basis of molecular-level monitoring. Compared to unsupervised clustering, the supervised method performed better for discriminating between cancer types and cancer subtypes for the leukemia data set. The performance of the proposed method, using only a limited set of informative genes, is demonstrated to be comparable or better than results reported in the literature for the three data sets. Furthermore the method was successful in predicting the outcome of medical treatment (success or failure) based on the microarray data, which could make the method an important tool for clinical doctors.

Distribution of Solid Particles Lighter than Liquid in an Agitated Vessel Stirred by Dual Impellers

Abstract: In the present study, we investigated the influences of diameter and impeller position on drawing from the liquid surface and on the dispersion of solid particles lighter than liquid in a vessel stirred by dual impellers. We defined the just drawdown condition as the state in which there are no floating lighter-than-liquid particles on the liquid surface at the just suspension speed for heavier-than-liquid particles. The best type of upper stage impeller, which drew floating particles on liquid surface into the liquid efficiently, was found to be the pitched paddle pumping up and the best impeller-diameter-to-vessel-diameter ratio was 0.5. In addition, the optimal position of the upper side impeller to minimize the just drawdown speed was located at 0.85 of the total liquid level from the bottom of the vessel. We examined the influence of the clearance of dual impellers on the distribution of solid particles in the vessel. The obtained results indicated that the best type of lower stage impeller is the pitched paddle pumping down and the impeller-diameter-to-vessel-diameter ratio is 0.5. The standard deviation of the dispersion of solid particles was found to be lowest when the clearance of the dual impellers to vessel diameter ratio was 0.83.

Water Pool pH of AOT-Based W/O Microemulsions at Various Water Contents Estimated by Absorbance Ratio of Pyranine

Abstract: The dependence of water pool pH on the water content of the W/O microemulsions was investigated by using the absorbance ratio of pH-sensitive probe pyranine. The W/O microemulsions were prepared with a mixture of an aqueous solution of pH 1–13 containing pyranine, AOT and isooctane at w0 = [water]/[AOT] = 10, 20, 30 and 40. The water pool pH was estimated by comparing the absorbance ratios given by the W/O microemulsions and the aqueous solutions of pH 1–13. The experimental results suggest that the water pool pH is kept approximately constant as a buffer regardless of the solution pH 4–11, and that the water pool pH increases with decreasing w0. As an additive factor to affect the absorbance ratio of pyranine, high Na+ counterion concentration in the water pool was focused on because the roughly estimated Na+ concentration increases from 1.4 to 5.6 M with decreasing w0. It was found by the ratio measurements for NaOH aqueous solutions that the ratio increases at NaOH concentration > 5 M, which suggests that the ratio given by the W/O microemulsions is affected by not only pH, but also high Na+ concentration in the water pool. It would be correct to assume that the AOT-based W/O microemulsions play a role of the buffer, and that the water pool pH depends on w0. However, attention should be paid to the possibility that the water pool pH estimated by the absorbance ratio of pyranine may include the effect of high Na+ concentration in the water pool.

Effect of Pore Widening Treatment on BET Surface Area of Rapidly Anodized Alumina Support

Abstract: In this study, to reduce the preparation time and production cost of anodic alumina support, the rapid anodization in sulfuric acid solution and at a high electric current density was employed to synthesize the rapidly anodized alumina support. After rapid anodization, the alumina support was soaked in sulfuric acid solution to widen its pore size (pore widening treatment, PWT). PWT conducted at 293–298 K for 45–60 min in 15.0 wt% sulfuric acid solution is considered to be effective to widen pore radius. PWT slightly changed its BET surface area, but it caused a substantial increase in BET surface area after subsequent HWT (hot water treatment) and high-temperature calcination. It is believed that PWT that it effectively reduces the inhibitory pore-sealing effect caused by HWT, and allows more alumina to react with hot water to form hydrated alumina, and obviously eventually increases its BET surface area.

Perspectives on Intensification of Ethanol–Water Separation Process in a High Frequency Ultrasound System

Abstract: Application of high frequency ultrasound for generating a fine droplet mist has been recently applied for fine chemical manufacturing, pharmaceutical production, cleaning and agitation/mixing. A recent development is the enrichment of alcohols from miscible alcohol–water mixtures using ultrasonic atomization. In this work, the effect of high frequency ultrasonic atomization at 1.6 MHz on the separation of ethanol from ethanol–water feed mixtures has been studied. Experiments for evaluating this novel separation process were conducted in a constant volume separation system. Well-controlled experiments were performed to analyze the separation of ethanol–water feed mixture at different temperatures (between 283 and 313 K). An interesting aspect of the separation process is the concentration of ethanol above the vapor–liquid equilibrium curve above 40 mol% ethanol feed concentration. It was found that the enrichment ratio was not affected by feed solution temperature. However, mist generation rate increased with increasing feed temperature. An understanding of the role of the ultrasonic jet formed at the surface of the feed solution combined with the separation characteristics of ethanol–water feed mixtures has been discussed here and the dependence of the process on acoustic cavitation has been elucidated.