Separation of gallium and indium by supported liquid membranes containing 2-bromodecanoic acid as carrier: design of supported liquid membrane module based on batch permeation experiments

Hydrometallurgy, 33 (1993) 1-15

1

Elsevier Science Publishers B.V., Amsterdam

Separation of gallium and indium by supported liquid membranes containing 2-bromodecanoic acid as carrier: design of supported liquid membrane module based on batch permeation experiments Masaaki Teramoto, Ayao Kariya, Tomokichi Yonehara, Masaya Tokunaga, Nobuaki Ohnishi, Hideto Matsuyama and Yoshikazu Miyake Department of Chemistry and Materials Technology, Faculty of Engineering and Design, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606, Japan (Received November 26, 1990; revised version accepted July 15, 1992)

ABSTRACT Teramoto, M., Kariya, A., Yonehara, T., Tokunaga, M., Ohnishi, N., Matsuyama, H. and Miyake Y., 1993, Separation of gallium and indium by supported liquid membrane containing 2-bromodecanoic acid as carrier: design of supported liquid membrane module based on batch permeation experiments. Hydrometallurgy, 33: 1-15. The recovery of gallium and indium from sulfate media by supported liquid membranes containing 2-bromodecanoic acid (2-BDA) as a carrier was performed by using both a batch type stirred permeation cell and a continuous-typesupported liquid membrane module with flat geometry. The effect of various experimental conditions on the permeation rates of gallium and indium were studied. A simple method is proposed for designing continuous supported liquid membrane modules from the data obtained with the batch type permeation cell on the basis of the correspondence of the parameters in batch operation to those of continuous operation. By this method, the membrane area required for given feed flow rate and the percentage recovery can be easily determined even for the case of multi-componentseparation.

INTRODUCTION

Although separation by supported liquid membranes (SLM) has received increased attention as an alternative to solvent extraction and ion exchange, it has not been used commercially. This is due to the disadvantage of SLMs, such as instability and the high cost of SLM modules, and is also due to very Correspondence to." M. Teramoto, Kyoto Institute of Technology, Faculty of Engineering and Design, Department of Chemistry and Materials Technology, Matsugasaki, Sakyo-ku, Kyoto 606, Japan.

0304-386X/93/$06.00 © 1993 Elsevier Science Publishers B.V. All rights reserved.

2

M. TERAMOTO ET AL.

few feasibility studies on the applicability of SLMs for commercial processes [1,2]. In the feasibility study of SLM processes, it is very important to estimate the membrane area required to meet given separation conditions, such as feed flow rates and percentage recoveries, since the cost of an SLM process is mainly determined by that of the SLM module, which is approximately proportional to the membrane area. In the hydrometallurgical zinc recovery process which is operated at Dowa Mining Co, Ltd., zinc is recovered from the black ore which is produced in Akita, Japan. In this process, gallium and indium are also recovered by three stages of ion exchange columns (H. Masuda, personal communication, 198 7 ). The feed solution to the third ion exchange column contains relatively low concentrations of metal ions: Ga: 0.26, In: 0.11, Zn: 1.0, AI: 1.0 g / d m 3. Gallium and indium are separated from zinc and aluminium and are concentrated. It seems worthwhile to examine the possibility of replacement of the third ion exchange column by SLM modules since SLMs are suitable for the recovery of metal ions from dilute solutions. In the present work, the recovery by SLM of gallium and indium from mixed solutions of gallium, indium, zinc and aluminium was investigated as a study of the feasibility of the industrial application of SLMs. In this study, a series of experiments on the permeation of gallium and indium through a SLM, using a batch type SLM permeation cell, was first performed to investigate the effect of various experimental conditions on the permeation rates of metal ions. 2-Bromodecanoic acid was used as a carrier since it was found to be effective for the extraction [3] and also as a carrier [4] of gallium and indium. Second, a simple method was proposed for estimating the membrane area required for a given separation from the data obtained with a batch type permeation cell. The operating parameters for continuous operation were related to those obtained using a batch-type stirred permeation cell. The usefulness of this design method was confirmed by the experiments with a continuous-type SLM module. EXPERIMENTAL

Equilibria of extraction of In, Ga and Zn with 2-bromodecanoic acid Aqueous solutions of metal ions were prepared by dissolving their nitrate salts in de-ionized water. The pH was adjusted by sulphuric acid and the total sulfate concentration, [S]T, which is defined by eqn. ( 1 ), was adjusted by adding sodium sulfate: [S]x----- [5024 - ] 4- [HSO4 ] 4- ~ [Mm(SO4)n]/n

(1)

The organic solution was prepared by dissolving 2-BDA in n-dodecane. 2-

SEPARATION OF Ga AND IN BY SUPPORTED LIQUID MEMBRANES

3

Bromodecanoic acid (2-BDA) was synthesized according to methods described elsewhere [ 5 ]. The distribution ratios of metal ions DM were measured as follows. Equal volumes of the aqueous and organic solutions of known concentrations were shaken in a glass vessel and allowed to attain equilibrium. After about 4 h, the phases were separated and then aliquots of both phases were pipetted to determine the distribution ratios of metal ions. The metal ions in the organic phase were stripped with 3 m o l / d m 3 nitric acid. The metal concentrations were determined by atomic absorption spectrophotometry.

Supported liquid membrane permeation experiments The batch-type stirred permeation cell used in the experiments is similar to that described in a previous paper [ 6 ]. The membrane area was 20 cm 3, and the volumes of the feed solution and the strip solution were 50 cm 3 and 45 c m 3, respectively. Each aqueous solution was stirred by a magnetic stirring bar. Fluoropore ® FP-010 made of polytetrafluoroethylene (Sumitomo Electric Co., Ltd. ) was used as the microporous support membrane. Its thickness, porosity and pore diameter are 60 ~tm, 0.5 and 0.1 ~tm, respectively. Membrane solutions were prepared by dissolving 2-BDA in n-dodecane at concentrations of 1.20 or 0.72 m o l / d m 3, and were absorbed on the support memfeed solution

/

/

i r

~

s t r i p solution

Fig. 1. S c h e m a t i c d i a g r a m o f s u p p o r t e d l i q u i d m e m b r a n e m o d u l e . 1 = s u p p o r t e d l i q u i d m e m b r a n e ; 2 = gasket; 3 = m e s h spacer; c h a n n e l w i d t h = 1.5 c m ; c h a n n e l l e n g t h = 97 c m .

4

M. TERAMOTOET AL.

branes to prepare SLMs. The composition of the feed solution was as follows; Ga:260 ppm, In: 110 ppm, Zn: 1000 ppm, Al: 1000 ppm, [S]a-=0.2 m o l / d m 3. The stripping solution was 1 m o l / d m 3 H2SO4 solution. A small amount of organic membrane solution was added to the stripping solution to prevent the degradation of the SLM due to the dissolution of the membrane solution in aqueous solutions. Figure 1 shows the schematic diagram of the SLM module used in continuous experiments. The length, width and depth of the channels of both the feed and the strip solution were 97, 1.5 and 0.1 cm, respectively. In each channel one of two mesh spacers, A (opening: 89%, thickness: 0.08 m m ) or B (opening: 86%, thickness: 10 m m ) was inserted. The module was operated in a once-through mode for the feed solution, and a recycling mode for the strip solution ( 1 m o l / d m 3 H2SO4 solution). The volume of the stripping solution was 200 ml, and about 10 ml of the organic membrane solution was added to the strip solution to prevent the membrane degradation. RESULTS AND DISCUSSION

Extraction equilibria It was found by vapor pressure osmometry at 313 K that the dimerization constant of 2-BDA in n-hexane was 2000 dm3/mol. Since this value is sufficiently large, 2-BDA was assumed to exist as its dimer, (HL) 2, in n-dodecane. Figure 2 shows the proton concentration dependencies of the distribution ratios of Ga, In and Zn at different total sulfate concentrations. It is seen that the presence of sulfate ion considerably lowers the distribution ratio, since it forms complexes with these metal ions. The slopes for In and Zn are approximately - 3 and - 2 , respectively, in accordance with their valences. However, the slopes for Ga are lower than - 3. Tanaka et al. [ 7 ] found that, in the extraction of A1 with capric acid, the slope of DA~ against proton concentration was less than - 3. They concluded that such a strong dependence of DA~ on proton concentration can be attributed to the formation of polynuclear complexes. The present result may also be due to the similar extraction behavior of 2-bromodecanoic acid. As pH increases, sulfate ion concentration increases, due to dissociation of HSO~- into SO ] - . This lowers free metal ion concentrations and also increases the ionic strength of the feed solution. Therefore, it is difficult to explain quantitatively the slopes of the plots in Fig. 2. As the values of D~n and DGa are much higher than Dzn, it is expected that Ga and In can be separated from Zn by the SLM containing 2-BDA. From the experiments on the 2-BDA concentration dependence of the distribution ratio, the values of the exponent q in the relation DMoc [ (HL)2 ]q were found to be approximately 1.5 and 2 for Ga and In, respectively.

SEPARATION OF Ga AND IN BY SUPPORTED LIQUID MEMBRANES

5

10 3

I

I I I I1[

I

i

t

i

[S] T [ m o l / d m 3 ]

0

0

II)

0,12 0,53

•

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I

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I I III11

'

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= cm o

101 i00

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~..... I

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10 1

, i

(a)

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-rltll

[H + ]

(b)

i0 -2 [mol/dm 3 ]

i I II

0

10-2

\

i 0 -3

• ....

I

10-3 [H+]

,

,

, ,~,,,,

It)

10-2 [mo]/dm 3]

Fig. 2. Distribution ratios of metal ions. [(HL)2] =0.72 mol/dm 3, 298 K. (a) Gallium. (b) Indium. (c) Zinc.

Effect of experimental conditions on permeation rates in batch permeation experimen ts In this liquid membrane system, the counter-transport of metal ions and protons takes place and the metal ions can be driven from the feed to the strip solution by the chemical potential difference of protons between the two aqueous phases. In all experiments, the permeation rate o f Zn was very small

6

M. TERAMOTO ET AL.

compared to that of Ga or In. First, the effect of [ S ] T in the feed phase on the variation with time of the dimensionless metal concentrations, [Mi]F/ [Mi]v,o, and of the pH of the feed phase was examined in the range of [S]T from 0.1 to 0.4 m o l / d m 3. The results are shown in Fig. 3. An increase in [S]T lowers the distribution ratios and is unfavorable to metal permeation. On the other hand, when [S]T is high the decrease in the pH of the feed solution is small, due to the increase in the buffer capacity, and this is favorable to metal permeation. On the basis of this result, [S ]v was adjusted at 0.20 m o l / d m 3 by adding Na2SO4 to the feed solution. The effect of temperature is shown in Fig. 4. It should be noted that higher temperatures are favorable to the permeation of Ga, while the permeation rate of In is almost independent of temperature. This may be partly explained by the temperature dependence of the distribution ratios of Ga and In as shown in Fig. 5. It can be seen that both DGa and Din increase with temperature; however, the degree of the increase in DGa is larger. It was also found that the increase of [ (HL)2 ] from 0.72 to 1.20 m o l / d m 3 increased the permeation rate. Figure 6 shows the effect of the stirring speed in the feed phase, nv. The permeation rates of both Ga and In were strongly influenced by nF, suggesting

• 2,~

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,

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(a)

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A

0 Q []

0,20 0.30

O

A

0,4o A

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0,2 0 t

60 [mini

I

I 120

[c)

Fig. 3. The effect f total sulfate concentration in the feed phase on the permeation rate of Ga and In. pHvo= 3.1; [ (HL)2 ] =0.72 mol/dm3; [HzSO4]s= 1 m o l / d m 3, 298 K, nv= 300 min -1. ( a ) pHv against time. (b) [ Ga ] F~ [ Ga ] v,o against time. (c) [ In ] v/[ In ] v,o against time.

SEPARATIONOF Ga AND IN BY SUPPORTEDLIQUIDMEMBRANES

3.0

L

A 298K

[] 308K

O 303K @

• 313K

B 2.4[-

,

l

6[]

A

7

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[]

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0 ~o,5

8

8

L,

o

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30

60

@llc) 120

90 [mini

t

150

Fig. 4. Effect of temperatureon the permeationrates of Ga and In. [ (HL)2 ] =0.72 tool/din 3, [H2SO4]s= 1 mol/dm3;nv=200 rain-1. (a) pHv againsttime. (b) [Ga]v/[Ga]v,o againsttime. (c) [In]F/[In]v,o againsttime. 10~

........

I

1[i

iii

i

i

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[

,

L iii

In

Ga

i0 ~

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313 K •

•

[]

,,,,,,,l ,,,,,,,,I , ,,,,, 10-2 L , ,,.,,] i0 -I i 0 -2 i0 -I 1O -3 10 .2 [H+] [molldm 3] [H+] [mol/dm 3]

Fig. 5. Effect o f temperature on the distribution ratios o f Ga and In. [ ( H L ) 2 ]

=

0, 72 m o l / d m 3.

a considerable contribution of the diffusional resistance in the feed phase to the overall resistance due to high distribution ratio of both Ga and In. In the above experiments, the pH decreased during the permeation, and the permeation rates also decreased. To prevent such a decrease in permeability,

8

M. TERAMOTOET AL.

3.0 T

I

2,6

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'

]L'OI!

~

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t I

I

a)

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o~ •

0

~7

v --0,2

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{mini

Fig. 6. Effect of stirring speed on the permeation rates of Ga and In. [ (HL)2 ] =0.72 mol/dm3; [H2SO4]s--1 mol/dm3; 313 K. (a) PHF against time. (b) [Ga]F/[Ga]F,o against time. (c) [In]r/[In]F,0 against time.

pH adjustment

L {:z

(a) 1,0

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i

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i

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i

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o

~0.5

30

60 90 t [min]

i ~

120

(b) 150

Fig. 7. Effect o f p H adjustment during the permeation on the permeation rate. [ (HL)2 ] = 1.20 mol/dm 3, [H2SO4]s= | mol/dm3; nv= 200 m i n - l ; 313 K.

SEPARATIONOF Ga AND IN BY SUPPORTED LIQUID MEMBRANES

9

Go InpH F [[TTI~722]spacer Temp. calc, 0

[] ~ [] qr . V

•

3,0

0,72M 1,20M 1.2OM

i

A A B

298K 313K 313K

.... .... - -

i ~ _v'_=.,~..~_:.:,~__ _

c

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''~

'

't

D- ~ D- ~ll-~rn.---[

//.1,,

I

i

i0

i J(c) 20

vF [cm3/min] Fig. 8. Recovery of Ga and In by the continuous SLM module. [H2SO4]s = l m o l / d m 3. (a) PHv,out against vv. (b) [ Ga ] v,ouJ [ Ga ] v,i. against vv. (c) [ In ] v,o,,/[ In ] v,i, against vv.

the pH of the feed solution was adjusted every 30 min. The result is shown in Fig. 7. More than 96% of both Ga and In was recovered within 135 min. EFFECT OF EXPERIMENTAL C O N D I T I O N S ON PERMEATION RATES IN C O N T I N U O U S PERMEATION BY THE SLM M O D U L E

A series of experiments on the recovery of Ga and In was performed using the continuous-type SLM module shown in Fig. 1. The support membrane, the carrier and the feed and strip solutions used were the same as used in the batch experiments. The results are shown in Fig. 8 as the plots of dimensionless metal concentration, [ Mi ] F, out/[ Mi ] F. in, and of PHF, out against vv, the volumetric flow rate. It is seen that recovery at high temperatures and high carrier concentrations is better than at low temperatures and low carrier concentrations, as in the case of the batch permeation. It is also seen that spacer B gives a higher permeation rate than spacer A, indicating that selection of the correct spacer is important for obtaining high permeation rates. RELATION BETWEEN BATCH O P E R A T I O N A N D C O N T I N U O U S OPERATION

Permeation rates are determined by many parameters, such as chemical equilibrium constants, mass transfer coefficients and concentrations of chem-

10

M. TERAMOTO ET AL.

ical species. Therefore, to design the SLM module theoretically, a great number of experiments are necessary to determine such system parameters, especially in the case of multi-component separations. Here, a simple method has been developed for estimating the membrane area or the extent of recovery from the data obtained with a batch permeation cell. In the analysis, it was assumed that at the SLM-stripping interface the metal-carrier complex is completely decomposed to release metal ion into the stripping solution. The material balance equation of metal ion, Mi; that is, Ga, In or Zn for a batch operation is expressed by:

Vv(d[M~]v/dt) = - P i S [ M i ] F

(2)

Initial conditions: t=0

[ M i ] v = [Mi]v,o

(3)

On the other hand, for a continuous operation in an SLM module, the design equation is expressed by eq. (4) if the flow pattern of the feed solution is plug flow:

vv(d[Mi]F/dS')= - P I [ M i ] F

(4)

Boundary conditions: S' = 0

[MiIF-- [Mi]v, in

(5)

where, Pi and P~ are the permeabilities of Mi for the batch and the continuous operation, respectively, and are defined by flux/[Mi] v- S and s' are the membrane areas of the batch permeation cell and the continuous module, and VF and Vvare the volume of feed solution and volumetric feed rate per one feed channel, respectively. It is evident, from a comparison of eqs. (2) and (3) with eqs. (4) and (5) that, ifP~=Pi, [Mi]v,0 = [Mi]F, in and PHv,0=PHv, in, the following relations hold for the same extent of recovery in both operations:

t=S' Vv/vvS

(6)

S' =Stvv/ Vv

(6')

where, S' is the total effective membrane area per feed channel of the module. The permeability is dependent upon various experimental parameters. If the composition of the feed solution and the stripping solution, the support membrane, the carrier solution and the feed phase mass transfer coefficient, kv. Mi, are identical in both operations, then the permeabilities of the SLMs in both operations become identical, and eq. (6) or (6') holds. Generally, the equation for the change in proton concentration in the feed phase is necessary since it influences the permeabilities greatly. However, because those changes are identical in both operations for the same metal recovery, the equation expressing the change in proton concentration is not considered here.

SEPARATION OF Ga AND IN BY SUPPORTED LIQUID MEMBRANES

11

DESIGN OF SUPPORTED LIQUID MEMBRANE MODULE BASED ON BATCH PERMEATION EXPERIMENTS

Estimation of degree of recovery by continuous S L M module of known membrane area The recovery of metal ions by the continuous operation at various feed flow rates can be estimated using eq. (6) from the data obtained in the batch experiments. Equation (6) holds when Pi=PI. For this equality to hold, the values of kv in both batch and continuous operations must be identical. Therefore, when we apply the proposed method to the estimation of metal recoveries, we need the relation between nF, the stirring speed of the feed phase in the batch operation and uv, the linear velocity of the feed solution in the module, which give the same value of kF. Figure 9 shows the relation of kF,M against nv, and that of kF, Mi against uv. These data were obtained by experiments carried out under conditions where the diffusion of indium in the feed phase was rate-determining; that is, at high pHv and low indium concentration (pHv, in= 3.2, [In]F, in= 50 ppm, [S iT=0 mol/dm3). It can be seen that, in the continuous operation, spacer B gives higher kF, In than spacer A, and also that a higher temperature gives a higher kF, in. By using Figs. 6 and 9, and eq. (6), the values of [Mi]v, out/[Mi]v, in and PHv, out for a given linear velocity uv can be estimated as follows: ( 1 ) Using Fig. 9, kv, In for the given value of uv is obtained, and then the value of nv that gives the same kv, in value can be obtained. (2) Time t is calculated using eq. (6) from the known values of S, S', Vv and vv( = uFWd). n F [mln "1] 102 104

lO s

' '''l

'

'

'

' ' '"[

298K 313K cell 0 • module(spacerA) [] [] module(SpacerB) stirred

~ io-5I

~

-

iO-3

10-2 UF

[ CIII/S }

Fig. 9. T h e relation ofkv, In against r/v a n d kv, In against uF.

12

M. TERAMOTO ET AL.

(3) Using Fig. 6, the values of [Mi]F/[Mi]F,0, and p H v at t and nF determ i n e d in ( 1 ) and (2) are obtained. These values correspond to [Mi ] F, out/ [ M~ ] F, in and PHF, out in the continuous operation, respectively. The estimated results are shown in Fig. 8. In the estimation of recoveries at 298 K, the batch permeation data obtained at 298 K, which is similar to Fig. 6, was used. Agreement between the estimated and experimental results is fairly good, indicating the usefulness of the present design method.

Estimation of membrane area required for given recovery W h e n the total volumetric feed flow rate va- and the extent of recovery are given, the total m e m b r a n e area and the d i m e n s i o n of the SLM module can be estimated from data such as that shown in Figs. 6 and 9 as follows. Here, a plate-and-frame type module with the channel configuration IS IF IS IF I S I .... I S IF I S I is considered. F and S are the channels of feed and strip solutions, respectively, and I denotes the SLM. This m e t h o d can also be applied to the design of hollow fiber modules: ( 1 ) An appropriate value of UF is assumed. High uF values result in large pressure drops, while low UF values give low permeability and large m e m brane area. (2) The value of nv, which gives the same kv, In value as that of the uv is d e t e r m i n e d using Fig. 9. ( 3 ) T i m e t is d e t e r m i n e d for a given recovery and nv from Fig. 6. (4) If r/is defined as the ratio of effective m e m b r a n e area to total m e m brane area, the following equations are obtained. Effective m e m b r a n e area per feed channel:

S' = 2 WLrl = Stvv/ Vv = StUF Wd/ Vv

(7 )

Channel length:

L = S ' / ( 2r/W) =Stuvd/2riV v

(8)

N u m b e r of channels of feed solution:

NF = vT/(UF Wd)

(9)

Total n u m b e r of channels:

N~ =2Nv + 1 = 2vv/ (Uv Wd) + 1

(10)

Total m e m b r a n e area:

ST =S'Nv/rl

( 11 )

Thickness of module:

dx = N x d = 2 v T / ( uv W) + d

(12)

SEPARATIONOF Ga AND IN BY SUPPORTEDLIQUIDMEMBRANES

13

Volume of module: VT = WLdT = WStuFd[ 2VT/(UF W) + d ] / 2 q VF = VTStd/rlVF + WStuFd2/(2r/VF)

(13)

where, d and Wdenote the depth and the width of each channel, respectively. This method can be applied to the case of multi-stage SLM operation where more than two modules are used in series. For example, in the batch permeation experiment shown in Fig. 7, pH of the feed solution was adjusted three times during the permeation. This corresponds to a continuous operation in which four modules are used in series and the pH of the feed solution was adjusted at the inlet of each module as shown in the upper part of Fig. 7. In this experiment, the stirring speed was 200 rain- 1, and the corresponding value of UF was found to be 2.0 cm/s from Fig. 9. The feed flow rate at Dowa Mining Co., Ltd. was reported as 0r=463 cm3/s. I f d a n d Ware taken as 0.1 cm, and 50 cm, respectively, and r/was taken as 0.74, which is the square of the opening of the mesh spacer B, the membrane area and the dimension of each module are determined as follows: total membrane area, ST= 48.4 m2; channel length, L = l . 0 3 m; total number of channels, NT=95; number of SLMs = 94; thickness of module, aCT= 9.5 cm; volume of module, VT= 0.0489 m 3. The module is very small compared with the two ion exchange columns (each having a volume of 1 m 3) which are used at Dowa Mining Co., Ltd. (H. Masuda, personal communication, 1987). The pressure drop in the channel was measured using water as the feed solution at 298 K, and the result is shown in Fig. 10. The pressure drop at UF=2.0 cm/s is about 4000 Pa, sug106

' ''""1

........

I

.......

!

f i0q

103

oo I

iv10-3

I

I I]lll

I

10-2 i0-i u F [m/s]

i00

Fig. 10. Plot of pressure drop in the feed channel of the SLM module against linear velocity of feed solution UF. The solid line represents equation alP~L= ( 121a/d2)aF, which was derived for laminar flow in a thin channel without spacer.

14

M. TERAMOTO ET AL.

gesting that the c o s t o f the energy required for p u m p i n g feed and strip s o l u t i o n s is very s m a l l c o m p a r e d with the c o s t o f t h e S L M m o d u l e s .

CONCLUSION

From the above, the following conclusions can be drawn: ( 1 ) The effect of permeation conditions on the permeabilities of Ga and In through supported liquid membranes containing 2-bromodecanoic acid was investigated using a batch-type stirred permeation cell. High permeabilities were obtained at higher temperatures and higher stirring speeds in the feed phase. These results were qualitatively explained by the extraction equilibria of Ga and In with 2-bromodecanoic acid. (2) A simple method for designing supported liquid membrane modules from the permeation data obtained with a batch permeation cell was proposed. The recoveries of Ga and In by the continuous-type supported liquid membrane module could be successfully estimated by this method. This method is useful for examining the possibility of using supported liquid membranes in a given separation process, since the required module membrane area can easily be estimated. NOMENCLATURE

D d

distribution ratio thickness of channel, m

a~

total thickness of channel, m feed phase mass transfer coefficient, m / s length of feed channel of module, m stirring speed in feed phase, m i n number of channel permeability in batch operation, m / s permeability in continuous operation, m / s membrane area in batch operation, m 2 total membrane area of continuous-type module, m z membrane area per feed channel in continuous-type module, m 2 membrane area measured from inlet of channel, m 2 time, s linear velocity of feed solution in channel, m / s feed volume in batch operation, m 3 feed flow rate per channel, m3/s total volume of module, m 3 total flow rate to module, m3/s width of channel of module, m concentration of metal M i , m o l / m 3 total sulfate concentration, m o l / m 3 effective membrane area/total membrane area of module

kv L nF N P p, S

ST S' S' t

v~ vT L~r W

[Md

[S]T q

SEPARATION OF Ga AND IN BY SUPPORTED LIQUID MEMBRANES

~t

15

viscosity, Pa-s

Subscripts F in Out

S T 0

feed solution inlet of module outlet of module strip solution total initial value

REFERENCES 1 Babcock, W.C., Kelly, D.J. and Friesen, T.D., Uranium recovery with coupled-transport membranes. Proc. ISEC'83 (Denver, Colo.), Am. Inst. Chem. Eng. (1983), p. 373. 2 Perason, D., Supported liquid membranes for metal extraction from dilute solutions. In: D.S. Flett (Editor), Ion Exchange Membranes, Ellis Horwood, Chichester, UK (1983), pp. 55-73. 3 Preston, J.S., Solvent extraction of metals by carboxylic acids. Hydrometallurgy, 14 ( 1985 ): 171-188. 4 Fujinawa, K., Akiyama, M., Shono, A., lmaishi, N. and Hosawa, M., Application of supported liquid membrane to a hydrometallurgical process of gallium and indium. Kagaku Kogaku Ronbunshuu, 15 ( 1989): 381. 5 Preston, J.S., Solvent extraction of nickel and cobalt by mixtures of carboxylic acids and non-chelating oximes. Hydrometallurgy, 11: ( 1983 ): 105-124. 6 Matsuyama, H., Katayama, Y., Kojima, A., Washijima, I., Miyake, Y. and Teramoto, M., Permeation rate and selectivity in the separation of cobalt and nickel by supported liquid membranes. J. Chem. Eng. Jpn., 20 (1987) 213-220. 7 Tanaka, M., Nakasuka, N. and Yamada, H., Extraction of aluminium with capric acid. J. Inorg. Nucl. Chem., 32 (1970): 2791-2793.