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Microfiltration of suspensions of microparticulate ion exchanger through ceramic membrane
Desalination 200 (2006) 343–345
Microfiltration of suspensions of microparticulate ion exchanger through ceramic membrane Barbora Onderkováa, Štefan Schlosserb*, Tomáš Bakalára, Milan Búgela a
Technical University of Košice, Department of Mineralurgy and Environmental Technologies, Letná 9, 04200, Košice, Slovakia b Slovak University of Technology, Department of Chemical and Biochemical Engineering, Radlinského 9, 81237, Bratislava, Slovakia Tel. +421 2 52496743; Fax +421 2 52496920; email: [email protected] Received 22 October 2005; accepted 4 March 2006
1. Introduction Removal of xenobiotics present at low concentrations in water and wastewater is frequent and sometimes not an easy task, which can be solved in many cases by application of adsorption techniques. Application of microparticulate suspensions of adsorbents can be an effective way of intensification of the adsorption process [1]. The aim of this work was to study microfiltration (MF) characteristics of microparticulate ion exchanger suspensions in NaCl aqueous solution to gain data for the design of a hybrid adsorption–microfiltration process. 2. Experimental Suspensions of the ground ion-exchange resin Lewatit MonoPlus S100 (Lanxess Deutschland GmbH, Leverkusen, De) with the mean particle size of d32 = 5.25 mm in aqueous solution with 0.05 kmol m–3 of NaCl were used. MF unit with recirculation of permeate used is described in *Corresponding author.
ref. [2]. The mean pore size of the ceramic tubular membrane (SCT, F) was 200 nm with the flux of distilled water and aqueous solution with 0.05 kmol m–3 NaCl at 43.3 kPa of 2259 and 429 l m–2 h–1, respectively. Analysis of the flux decline with time for the 1 and 6 wt.% suspensions according to the modified model of Hermia revealed that the dominant membrane fouling mechanism is an intermediate pore blocking — partial blocking of pores with particles. The feed velocity in the tubular membrane is one of the dominant parameters influencing the permeate flux. With increasing velocity, the permeate flux significantly increases (Fig. 1). This suggests that the velocity of suspension above 2 m s–1 should be used in crossflow MF. The transmembrane pressure, Dp, increases the permeate flux greatly at lower suspension concentrations with mass fraction of dry sorbent, wa, below about 0.2, but at higher mass fraction the flux is nearly independent of Dp (Fig. 2). The critical permeate flux is achieved at a relatively low transmembrane pressure difference, below about 50 kPa. The limiting flux was reached at
Presented at EUROMEMBRANE 2006, 24–28 September 2006, Giardini Naxos, Italy. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2006.03.374
344
B. Onderková et al. / Desalination 200 (2006) 343–345 70
50
40
0.06 50
0.19
30
0.22 0.25 20
Jv 106, m s–1
0.13 Jv 106, m s–1
47.6 kPa, v = 3.1 m s–1 68.2 kPa, v = 3.2 m s–1 42.9 kPa, v = 1.2 m s–1
60
wa
40 30 20
10 10 0
0 0
1
2
3
4
5
0
ν, m.s–1
Fig. 1. Permeate flux vs. velocity of suspension in tubular membrane for suspensions with various mass fractions of the dry sorbent shown in the legend. Dp = 46.2 kPa, pH = 6.
0.08
0.16 wa
0.24
Fig. 3. Permeate flux vs. mass fraction of the dry adsorbent in suspension of Lewatite. v = 3.25 m s–1.
a pressure of about 100 kPa, but at higher suspension concentrations even at about 60 kPa. Concentration of the suspension influenced the permeate flux, but there is no significant difference in permeate flux at low suspension velocities of about 1 m s–1 (triangles in Fig. 3).
80
3. Conclusions wa 0.13
60 Jv 106, m s–1
0.16 0.19 0.22
40
0.25
20
0 0
40
80 ΔpTM, kPa
120
160
Fig. 2. Permeate flux vs. transmembrane pressure difference for suspensions with various mass fractions of the dry sorbent in suspension at v @ 3 m s–1.
These results show that the resistance of the particle cake is decisive and at low velocities, when thinning of the cake is not actual, the flux is not influenced by the particle concentration. Surprisingly, at higher suspension velocities the dependence of the flux vs. the suspension concentration goes through a maximum at the mass fraction of the dry sorbent of about 0.13 (Fig. 3). At higher adsorbent concentrations, a further accumulation in the cake starts to be dominant. Increase of flux with the suspension concentration can be interpreted as a result of shear introduced by particles of the suspension. Even at higher particle concentrations above 20 wt.% and velocity of about 3 m s–1, the permeate flux has a reasonable value of about 70 l m–2 h–1.
B. Onderková et al. / Desalination 200 (2006) 343–345
Acknowledgement The supports of the grant MEDRC 04-AS-004, grant of the Ministry of Education of Slovak Republic and grant VEGA No. 2468/05 are acknowledged. References [1]
T. Bakalár, Š. Schlosser and M. Búgel, Hybrid Adsorption and Microfiltration Process for
[2]
345
Removal of Metals from Aqueous Solutions, J. Markoš and V. Štefuca, Eds., Proc. CHISA 2004, full text on CD ROM, Praha (CZ), August 22–26, 2004, 15 p. J. Stopka, S.G. Bugan, L. Broussous, S. Schlosser and A. Larbot, Microfiltration of beer yeast suspensions through stamped ceramic membranes, Sep. Purif. Technol. 25 (2001) 535.
Microfiltration of suspensions of microparticulate ion exchanger through ceramic membrane Barbora Onderkováa, Štefan Schlosserb*, Tomáš Bakalára, Milan Búgela a
Technical University of Košice, Department of Mineralurgy and Environmental Technologies, Letná 9, 04200, Košice, Slovakia b Slovak University of Technology, Department of Chemical and Biochemical Engineering, Radlinského 9, 81237, Bratislava, Slovakia Tel. +421 2 52496743; Fax +421 2 52496920; email: [email protected] Received 22 October 2005; accepted 4 March 2006
1. Introduction Removal of xenobiotics present at low concentrations in water and wastewater is frequent and sometimes not an easy task, which can be solved in many cases by application of adsorption techniques. Application of microparticulate suspensions of adsorbents can be an effective way of intensification of the adsorption process [1]. The aim of this work was to study microfiltration (MF) characteristics of microparticulate ion exchanger suspensions in NaCl aqueous solution to gain data for the design of a hybrid adsorption–microfiltration process. 2. Experimental Suspensions of the ground ion-exchange resin Lewatit MonoPlus S100 (Lanxess Deutschland GmbH, Leverkusen, De) with the mean particle size of d32 = 5.25 mm in aqueous solution with 0.05 kmol m–3 of NaCl were used. MF unit with recirculation of permeate used is described in *Corresponding author.
ref. [2]. The mean pore size of the ceramic tubular membrane (SCT, F) was 200 nm with the flux of distilled water and aqueous solution with 0.05 kmol m–3 NaCl at 43.3 kPa of 2259 and 429 l m–2 h–1, respectively. Analysis of the flux decline with time for the 1 and 6 wt.% suspensions according to the modified model of Hermia revealed that the dominant membrane fouling mechanism is an intermediate pore blocking — partial blocking of pores with particles. The feed velocity in the tubular membrane is one of the dominant parameters influencing the permeate flux. With increasing velocity, the permeate flux significantly increases (Fig. 1). This suggests that the velocity of suspension above 2 m s–1 should be used in crossflow MF. The transmembrane pressure, Dp, increases the permeate flux greatly at lower suspension concentrations with mass fraction of dry sorbent, wa, below about 0.2, but at higher mass fraction the flux is nearly independent of Dp (Fig. 2). The critical permeate flux is achieved at a relatively low transmembrane pressure difference, below about 50 kPa. The limiting flux was reached at
Presented at EUROMEMBRANE 2006, 24–28 September 2006, Giardini Naxos, Italy. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2006.03.374
344
B. Onderková et al. / Desalination 200 (2006) 343–345 70
50
40
0.06 50
0.19
30
0.22 0.25 20
Jv 106, m s–1
0.13 Jv 106, m s–1
47.6 kPa, v = 3.1 m s–1 68.2 kPa, v = 3.2 m s–1 42.9 kPa, v = 1.2 m s–1
60
wa
40 30 20
10 10 0
0 0
1
2
3
4
5
0
ν, m.s–1
Fig. 1. Permeate flux vs. velocity of suspension in tubular membrane for suspensions with various mass fractions of the dry sorbent shown in the legend. Dp = 46.2 kPa, pH = 6.
0.08
0.16 wa
0.24
Fig. 3. Permeate flux vs. mass fraction of the dry adsorbent in suspension of Lewatite. v = 3.25 m s–1.
a pressure of about 100 kPa, but at higher suspension concentrations even at about 60 kPa. Concentration of the suspension influenced the permeate flux, but there is no significant difference in permeate flux at low suspension velocities of about 1 m s–1 (triangles in Fig. 3).
80
3. Conclusions wa 0.13
60 Jv 106, m s–1
0.16 0.19 0.22
40
0.25
20
0 0
40
80 ΔpTM, kPa
120
160
Fig. 2. Permeate flux vs. transmembrane pressure difference for suspensions with various mass fractions of the dry sorbent in suspension at v @ 3 m s–1.
These results show that the resistance of the particle cake is decisive and at low velocities, when thinning of the cake is not actual, the flux is not influenced by the particle concentration. Surprisingly, at higher suspension velocities the dependence of the flux vs. the suspension concentration goes through a maximum at the mass fraction of the dry sorbent of about 0.13 (Fig. 3). At higher adsorbent concentrations, a further accumulation in the cake starts to be dominant. Increase of flux with the suspension concentration can be interpreted as a result of shear introduced by particles of the suspension. Even at higher particle concentrations above 20 wt.% and velocity of about 3 m s–1, the permeate flux has a reasonable value of about 70 l m–2 h–1.
B. Onderková et al. / Desalination 200 (2006) 343–345
Acknowledgement The supports of the grant MEDRC 04-AS-004, grant of the Ministry of Education of Slovak Republic and grant VEGA No. 2468/05 are acknowledged. References [1]
T. Bakalár, Š. Schlosser and M. Búgel, Hybrid Adsorption and Microfiltration Process for
[2]
345
Removal of Metals from Aqueous Solutions, J. Markoš and V. Štefuca, Eds., Proc. CHISA 2004, full text on CD ROM, Praha (CZ), August 22–26, 2004, 15 p. J. Stopka, S.G. Bugan, L. Broussous, S. Schlosser and A. Larbot, Microfiltration of beer yeast suspensions through stamped ceramic membranes, Sep. Purif. Technol. 25 (2001) 535.