Analytical Sciences

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

Mikiro HIRAYAMA, Takashi GOSHIMA, Kei MIZUTA, and Susumu NII

Department of Chemical Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima, Kagoshima 890-0065, Japan

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, N_th. Resulting HTU values ranged from 0.15 to 0.78 m and N_th 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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