Size Distribution of Droplets in a Two Liquid-phase Mixture Compared between Liquid Spraying and Mechanical Stirring

Shimogouchi, Taisuke; Naganawa, Hirochika; Nagano, Tetsushi; Grambow, Bernd; Nagame, Y.

doi:10.2116/analsci.18p508

Cited by 11 publications

(8 citation statements)

References 14 publications

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“…The larger k and the shorter time in microscale are mainly caused by the large surface-to-volume (S/V) ratio because the S/V ratio in the present microchannel could be estimated to be 12.5 mm −1 , which is somewhat larger than S/V ratios in bulk (about 1−10 mm −1 ), given that bulk-scale droplets for a mechanical mixer are usually about 0.1−0.8 mm in size. 53 These results show that the developed microsystem consisting rates. Increased fluorescence intensities in the cyclohexane phase were observed by a fluorescence microscope along the flow direction in the microchannel because the extraction of BPS progressed with increasing residence times.…”

Section: ■ Results and Discussionmentioning

confidence: 64%

Development of Real-Time Analysis System of Selenium Ion in Solutions by Using Microextraction and Fluorescence Microscopy

Brandt

Tsukahara

2021

ACS Earth Space Chem.

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The development of advanced analytical methods for trace amounts of selenium (Se) ions in wastewater become a matter of great importance in avoiding biological and environmental burdens due to Se pollution. In this study, a simple microanalytical methodology was developed, enabling the rapid and highly efficient extraction, real-time monitoring in situ, and extraction kinetic analysis of Se(IV) ions. The microscale extraction and analysis was verified by means of fluorescence intensity changes of fluorogenic complex 4,5-benzopiazselenol (BPS) consisting of the coordination of Se(IV) with 2,3-diaminonaphthalene (DAN). After the optimal BPS formation conditions, including pH, temperature, and Se(IV)/DAN concentration ratio, were examined, the microscale extraction of BPS was carried out under aqueous and organic two-phase parallel flow regimes in Y-shaped microchannels. The fluorescence intensity profiles of BPS in the organic phase were scanned in situ along the flow direction in the microchannel by a fluorescence microscope. The residence time dependence of the BPS concentrations could be precisely detected in real time. The results show that the developed microsystem has not only a detection limit of a submicromolar level for Se(IV), which is sufficiently lower than the permeable limit concentration of selenium in wastewater, but also a large apparent extraction rate constant of approximately 0.3 s–1 and a short time to reach equilibrium of approximately 20 s, compared to those of bulk-scale extraction. This would indicate a valuable technique for elucidating microfluidic extraction kinetics and for applying real-time, environmentally friendly monitoring of toxic selenium ions.

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Section: ■ Results and Discussionmentioning

confidence: 64%

Development of Real-Time Analysis System of Selenium Ion in Solutions by Using Microextraction and Fluorescence Microscopy

Brandt

Tsukahara

2021

ACS Earth Space Chem.

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“…After reaching a steady-state, the height of the droplet layer, (emulsion-phase), becomes constant. The height of emulsion phase was smaller than the former studies 6,10 aiming to achieve a high extraction ratio. While in the present study, the smaller height was chosen to avoid establishing extraction equilibrium in the column for enhancing the precision in determining both HTU values and the number of theoretical plates.…”

Section: Methodsmentioning

confidence: 78%

“…Stability is maintained even when feeding crude materials containing Al2O3 particles of approximately 20 to 25 micrometer in diameter 2 . As was pointed out by Shimogouchi et al 6 , keeping uniform droplet size in the region near a porous sintered glass nozzle is key to achieve high operability with an emulsion-flow column. Furthermore, the simple column structure without any agitating mechanism, minimizes the exposure of organic solvents to the atmosphere.…”

Section: Introductionmentioning

confidence: 98%

Evaluation of Mass-transfer Performance of Emulsion-flow Column with Height of Transfer Unit (HTU) and Number of Theoretical Plates, and Comparison of HTU with Column-type Extractors

et al. 2020

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The performance of iodine extraction in the emulsion-flow column was evaluated using an indicator of difficulty in separation, height of transfer unit, HTU and of the number of theoretical plates, Nth. Resulting HTU values ranged from 0.15 to 0.78 m and Nth changed from 0.58 to 1.3. HTU values were formulated in accordance with operating liquid velocities. Despite a 30% margin of error, HTU values were found to be useful in predicting column performance. Observed HTU values were compared with those of conventional extraction columns with or without mechanical agitation. The emulsion-flow column meets the top-level performance of extractors without mechanical agitation, such as packed and spray columns, and performs in the middle range of agitated extractors, although these sacrifice the structure simplicity to assure stable counter-current operation. The advantage of the emulsion-flow column is better HTU values with stable counter-current operation in a simple column structure.

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“…A novel operation mode of extraction, "emulsion-flow" allows for both stable counter-current operation and a high extraction ratio [1][2][3][4][5]. The method is characterized by supplying aqueous and organic phases in the form of droplets with uniformly controlled sizes.…”

Section: Introductionmentioning

confidence: 99%

“…The method is characterized by supplying aqueous and organic phases in the form of droplets with uniformly controlled sizes. Extraction proceeds in the stacked layer of droplets called the "emulsion phase" [3,5]. Our previous study quantified the mass-transfer characteristics of iodine extraction in emulsion-flow column operation [6].…”

Section: Introductionmentioning

confidence: 99%

Axial Mixing in Emulsion-flow Column under Iodine Extraction

Hirayama

Goshima

Mizuta

et al. 2021

SERDJ

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Strength of axial mixing in the emulsion phase during the progress of extraction was evaluated using the Peclet number under various flow conditions. The Peclet numbers were determined with the established tracer technology which applies inert species for iodine extraction. Very little effect of operating velocities of either aqueous and organic phases was found on the Peclet numbers. This fact indicates that an almost constant degree of axial mixing was kept in this column for different flow velocities of both phases. Furthermore, the degree of axial mixing of the emulsion-flow column was compared with conventional spray and packed columns by plotting the droplet Peclet number against the droplet Reynolds number. Points of the Peclet numbers of emulsion-flow column located in the middle of the spray and the packed columns, which suggests that the strength of axial mixing in the present column is in between spray and packed columns.

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Size Distribution of Droplets in a Two Liquid-phase Mixture Compared between Liquid Spraying and Mechanical Stirring

Cited by 11 publications

References 14 publications

Development of Real-Time Analysis System of Selenium Ion in Solutions by Using Microextraction and Fluorescence Microscopy

Development of Real-Time Analysis System of Selenium Ion in Solutions by Using Microextraction and Fluorescence Microscopy

Evaluation of Mass-transfer Performance of Emulsion-flow Column with Height of Transfer Unit (HTU) and Number of Theoretical Plates, and Comparison of HTU with Column-type Extractors

Axial Mixing in Emulsion-flow Column under Iodine Extraction

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