Reduction of concentration polarization at feeding interphase of a hollow fiber supported liquid membrane by using periodic operation

Abstract

An experimental investigation was carried out to reduce the concentration polarization at feeding interphase between feed solution and liquid membrane imposing flow instabilities. The periodic operation of the hollow fiber supported liquid membrane for separation of lanthanide metal by using D2EHPA as extractant dissolved in kerosene. The operating flow rate of the feed solution was varied according to a symmetric square wave function around time-average values of 200, 300 and 400 ml/min. Time periods ranging from 18 to 3 minutes and amplitudes of 50 and 100 ml/min were investigated. The results of these periodic tests were compared with results obtained from the conventional steadystate mode of operation. It has been found that the periodic operation leads to higher stripping concentration or higher ion flux than that obtained from the corresponding steady state operating conditions. This is because periodic operation disturbs concentration polarization in the boundary layer between the feed solution and liquid membrane. It has also been found that the ion flux increases with increasing amplitudes and decreasing time periods of the forcing function. However, when the period is less than 3 minutes the flux decreases because the liquid membrane is peeled out from the pores of hollow fiber.

Separation of yttrium from rare earth using hollow fiber-supported liquid membrane: factorial design analysis

“…As shown, the flow rates of feed solution are highly effective on the extractability of hollow fiber-supported LM. When flow rate increased, %Ex of yttrium and other rare earth decreased because the LM at the pore mouth deteriorated when the flow rate was higher [26].…”

Study of cyclic operation of RO desalination process

“…In another work, Al-Bastaki and Abbas (1999) found that the maximum improvement in permeate flow rate was around 6.5%. Ramakul et al (2009b), on the other hand, obtained an increase in permeate flux from 1% to 17%. In the same figure the average ratio of wall to bulk salt concentrations (C w /C b ) is plotted.…”

“…Al-Bastaki and Abbas (2001) also reviewed the different methods used to enhance membranes performance while Abufayed (2003) reported the experience gained from the periodic operation of a sea-water reverse osmosis plant in Libya. Recently, Ramakul et al (2009a) studied the effect of periodic variation of feed flow rate in a hollow fibre supported liquid membrane process. The authors reported an increase in the flux through the membrane when either the cycle amplitude or frequency was increased.…”

“…The second objective is to investigate the effect of symmetric and asymmetric shapes of pulsing associated with square waves. Both shapes are commonly used in experimental studies (Al-Bastaki and Abbas, 1998Abbas, , 1999Abbas and Al-Bastaki, 2000;Ramakul et al, 2009b). The third objective of this work is to compare between the effect of amplitude and frequency of both pulse shapes.…”

Mass transport modeling and analysis on the mutual separation of lanthanum(III) and cerium(IV) through a hollow fiber supported liquid membrane

“…3. We focus on the feed-membrane interface layer because in most liquid membrane systems the mass transfer controlling step occurs here [24]. We assume, in accordance with the film model, that bulk lanthanum ions come in contact with a stagnant organic liquid membrane of film thickness (d).…”