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Removal and recovery of boron from geothermal wastewater by selective ion exchange resins. I. Laboratory tests
Reactive & Functional Polymers 60 (2004) 163–170
REACTIVE & FUNCTIONAL POLYMERS www.elsevier.com/locate/react
Removal and recovery of boron from geothermal wastewater by selective ion exchange resins. I. Laboratory tests q N. Kabay a,*, I. Yılmaz a, S. Yamac b, S. Samatya b, M. Yuksel a, U. Yuksel b, M. Arda b, M. Sa glam a, T. Iwanaga c, K. Hirowatari d a
Chemical Engineering Department, Faculty of Engineering, Ege University, 35100 Izmir, Turkey b Chemistry Department, Faculty of Science, Ege University, 35100 Izmir, Turkey c Kyuden Sangyo Co. Inc., Fukuoka, Japan d West-Jec Co., Fukuoka, Japan Received 14 November 2003; accepted 16 February 2004 Available online 5 June 2004
Abstract Boron removal from wastewaters of geothermal plant was studied using N-glucamine type chelating resins so-called Diaion CRB 01, Diaion CRB 02, Purolite S 108. The batch-mode sorption studies was performed to obtain the optimum amount of resins for boron removal from geothermal wastewater. The boron on the resin was quantitatively eluted with 5% H2 SO4 . A column-mode study was performed using weak base ion exchange resin Diaion WA 30 for the separation of boron from H2 SO4 solution. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Boron; Geothermal water; Ion exchange; Chelating resins
1. Introduction Well waters or springs occasionally contain boron at toxic amounts, especially near geother-
q
The authors wish to dedicate this paper to Emeritus Professor Michael Streat, who is a pioneering scientist in the field of ion exchange and adsorption, upon his retirement from Loughborough University, UK. * Corresponding author. Tel.: +90-232-388-7600; fax: +90232-388-7776. E-mail address: [email protected] (N. Kabay).
mal areas and earthquake faults. Boron concentration in irrigation waters which is only slightly higher than the minimum will be negative for plant growth [1–4]. There are several methods suggested for boron removal from aqueous solution. Among those methods, ion exchange process is most extensively used. It was reported that chelating resins containing functional groups in which hydroxyl groups are in the cis position show a high selectivity for boron removal [3–12]. Chelating fibers having polyol groups have been also used for
1381-5148/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.reactfunctpolym.2004.02.020
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N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170
boron removal [13]. Ooi et al. [14] reported that some hydrous oxide of tetravalent metals (CeO2 Æ nH2 O, ZrO2 Æ nH2 O, HfO2 Æ nH2 O) or pentavalent metals (Ta2 O5 Æ nH2 O) are promising adsorbents for boron removal. Solvent extraction method was suggested for the recovery of boric acid using diol containing compounds [15]. Some membrane processes were tested for boron removal. Taniguchi et al. [16] used reverse osmosis process for boron reduction in seawater. Selective ion exchange resins have been employed for boron removal from reverse osmosis permeate [17]. Polymer-assisted ultrafiltration was reported as a method for boron removal that is compatible with other treatment methods [18,19]. Electrodialysis is another membrane process used for boron removal from seawater [20]. In our previous papers, we have reported the preliminary results of batch-mode and columnmode studies for boron removal from geothermal wastewaters using N-glucamine type resins [3,4]. In this paper, the comparative results obtained using N-glucamine type resins (Purolite S108, Diaion CRB 01, Diaion CRB 02) to obtain the optimum
amount of resins for boron removal from geothermal wastewater was presented. Column performances of these resins for boron removal from geothermal wastewater were compared. A columnmode study for the separation of boron from H2 SO4 solution was carried out using a weak base anion exchange resin Diaion WA 30.
2. Experimental 2.1. Materials Mitsubishi Co., Japan kindly provided Diaion CRB 01 and CRB 02 resins. The resins Purolite S108 (1) and Purolite S108 (2) were kindly sent by Purolite International Ltd. as a gift. The chemical and physical properties of chelating resins are given in Tables 1 and 2. The weak-base anion exchange resin Diaion WA 30 was provided by Mitsubishi Co., Japan. The geothermal wastewater was obtained from the field of Kizildere Geothermal Power Plant, Turkey. The chemical composition of geothermal wastewater is summarized in Table 3.
Table 1 Typical chemical and physical characteristics of Diaion CRB 01 an Diaion CRB 02 resins
Constitutional type Ion form as shipped Shipping density (g/l) (app.) Moisture content (%) Exchange capacity (meq/ml) Total capacity meq/ml R (FB) meq/g R (FB) Screen grading Effective size (mm) Operating temperature Effective pH range Specific surface area (m2 /g) Degree of swelling (ml/dry g) Structure
Diaion CRB 01
Diaion CRB 02
Highly porous OH-form 706 45.6 ND
Highly porous OH-form 635 50–60 Acid 0.6 (min)
1.13 2.95 ND ND ND ND ND 2.60
ND 118–300 l (through 300 l: max 1%) 0.355–0.550 100 °C (max) OH form 6–10 27 ND
-CH - CH2 -CH - CH2 -
CH3 -CH-CH2- CH2 NCH2 - (CH(OH))4 - CH2OH ND, not determined.
N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170
165
Table 2 Typical chemical and physical characteristics of Purolite S 108 (1) and Purolite S108 (2)
Polymer structure Optical appearance Functional groups Ionic form, as shipped Total capacity (Cl form) (eq/l) Total boron capacity (Cl form) (eq/l) Selective boron capacity (Cl form) (eq/l) Moisture retention (Cl form) (%) Reversible swelling ðFB ! Cl Þ (%) Specific gravity (Cl form) Temperature limit (Cl form) (°C) pH limits (operating) Structure
Purolite S 108 (1)
Purolite S 108 (2)
Macroporous polystyrene crosslinked with divinylbenzene Spherical beads Complex amino Free base-FB 0.8 (min) 0.35 0.20 (min) 45–55 10 (max) 1.1 60 1–13
Macroporous polystyrene crosslinked with divinylbenzene Spherical beads Complex amino Free base-FB 0.8 (min) ND ND 52–58 6 (max) 1.06 60 1–13
n
OH OH
OH OH
N Me
OH
OH
ND, not determined.
2.2. Batch-mode sorption studies Various amounts of N-glucamine type resins (0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 g) was contacted with 100 ml of geothermal wastewater at 30 °C for 48 h with continuous shaking in order to find the optimum amount of resin concentration for boron removal from geothermal wastewater.
2.3. Column-mode sorption–elution studies The resin in the 0.355–0.250 mm particle size range was selected for the column tests. The resin beads were immersed in deionized water for 24 h before being packed into the column. The columns were made of glass and had an internal diameter of 0.7 cm. The column was packed with 0.5 ml of wet-settled volume of resin. Geothermal wastewater was delivered down-flow to the column at a flow rate of SV 15 h1 (SV: so called space velocity defined as bed volumes per hour) using a peristaltic pump (Atto SJ 1211H). From the outlet of the column, each successive 3 cm3 fractions of the effluent were
Table 3 Chemical composition of geothermal wastewater Ionic species
Concentration (mg/l)
TSM Na K Li Ca Mg Al Fe F Cl SO4 HCO3 CO3 As B T-SiO2 S-SiO2 Mn
3720 1190 142 3.78 0.51 0.42 – – 15.36 94.2 646 1660 224 0.853 18–20 330 287 –
pH ¼ 9.0–9.2; EC ¼ 504 mS/m.
collected using a fraction collector (Advantec SF 2120 Model). Breakthrough curves were obtained by analysis of each fractions. After the sorption,
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N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170
the resin was washed with deionized water. The elution of boron from the resin was performed with 5% of H2 SO4 solution passed through the column at SV 10 h1 . The elution profile was obtained by analysing the 2 ml of fractions collected with the fraction collector. 2.4. Column-mode study for boron separation from acidic solution In order to separate boron from 5% H2 SO4 solution containing 1000 mg B/L, laboratory-scale column-mode tests were conducted using a weak base anion exchange resin Diaion WA 30 at different ionic forms obtained by means of various conditioning steps. The methods of conditionings were as follows: Method 1: 2.0 ml of Diaion WA 30 was conditioned with 2 M HCl first and then with 2 M NaOH. Method 2: 4.0 ml of Diaion WA 30 was conditioned with 2 M HCl first and then with 2 M NaOH (conditioning was repeated twice). Method 3: 3.8 ml of Diaion WA 30 was conditioned with 1 M Na2 SO4 following the conditioning explained as Method 2. The solution containing boron at a concentration of 1000 mg/l prepared in 5% H2 SO4 was passed down-flow through the resin packed into a glass column with an inner diameter of 0.95 cm using a peristaltic pump at SV 2 h1 . Each successive 2 ml fractions of the effluent were collected using a fraction collector. Breakthrough curves were obtained by analysis of these successive fractions for boron and sulfate. The effect of pH on separation of boron from H2 SO4 solution was investigated by using solutions at pH 0.31 (5% H2 SO4 ), 1.0, and 2.0. The pHs of the solutions at pH 1.0 and 2.0 were adjusted by precipitating CaSO4 from H2 SO4 solution (5%) containing 1000 mg B/L sulfate using Ca(OH)2 . 2.5. Boron analysis The analysis of boron in the solution was carried our spectrophotometrically using the Curcumine Method (kmax : 543 nm) [21].
2.6. Sulfate analysis The analysis of sulfate in the solution was performed by titration method using Ba(ClO4 )2 solution in the presence of thorin and methylene blue indicators [21].
3. Results and discussion 3.1. Batch-mode sorption studies for boron removal The mechanism for boron sorption by glucamine type resins are given as follows [14]: P-CH2-N(CH3)-CH2-[CH(OH)-]4-CH2OH + B(OH)3 → P-CH2-N(CH3)-CH2-[CH(OH)-]2-CHO-CHO-CH2OH + 2H2O B(OH)
In this study, glucamine type resins such as Diaion CRB 01, Diaion CRB 02, Purolite S108 (1) and Purolite S108 (2) were employed for boron removal from geothermal wastewaters. To find the optimum amount of resin concentration, which can completely remove boron from geothermal wastewater, a batch-mode sorption study was performed using various amounts of resin. For this, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 g of resins were contacted with 100 ml of geothermal wastewater at 30 °C for 48 h with a continuous shaking. As shown in Fig. 1, boron removal increased with an increase in resin concentration. A resin concentration of 3 g-resin/l-wastewater was needed to remove more than 90% of boron for all chelating resins. 3.2. Column-mode sorption–elution studies for boron The breaktrough profiles of boron obtained using Diaion CRB 01 and Purolite S 108 (1) at SV 10 h1 are given in Fig. 2. Breakthrough appeared more quickly with Purolite S108 (1) than Diaion CRB 01. As shown in Fig. 3, breakthrough per-
N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170
Concentration of Boron (mg/L)
Removal of Boron (%)
100 80 60 Diaion CRB 01 Diaion CRB 02 Purolite S 108 (1) Purolite S 108 (2)
40 20
500 Diaion CRB 01 400 PuroliteS 108 (1) 300 200 100 0 0
0 0
0.1
0.2
0.3
0.4
167
5
10 15 20 25 Bed Volume (mL-solution/mL-resin)
30
35
0.5
Fig. 4. Elution profiles of boron by Diaion CRB 01 and Purolite S 108 (1).
Resin Amount (g)/100 mL-wastewater
Fig. 1. Effect of resin amount on boron removal from geothermal wastewater by the chelating resins.
1.0
C/Co
0.8
0.6
0.4 Diaion CRB 01 0.2 PuroliteS 108 (1) 0.0 0
100
200 300 BV (mL-solution/mL-resin)
400
500
Fig. 2. Breakthrough curves of boron by Diaion CRB 01 and Purolite S 108 (1) (SV ¼ 10 h1 ).
1.0
C/C0
0.8 0.6 0.4
formance of Diaion CRB 02 was better than that of Purolite S 108 (2) at SV 15 h1 . Respective elution curves are illustrated in Figs. 4 and 5. Elution of boron from the resins was completed between 15 and 20 BV using 5% H2 SO4 solution. Breakthrough and total capacities of each resin are summarized in Table 4. According to these results, it is clear that the resin Diaion CRB 02 has the highest breakthrough capacity among the resins tested. In order to see the effect of acid concentration on elution performance of boron, elution of boron from Diaion CRB 01 and Purolite S 108 (1) resins was studied using HCl and H2 SO4 at different concentrations with batch method. Table 5 summarizes the results obtained. A complete stripping of boron was obtained with H2 SO4 as low as 0.05 M in concentration. The effect of eluting agent concentration on elution of boron from the resin Diaion CRB 01 was also studied using column method. As shown in Fig. 6, elution profile of boron was sharp with 0.5 M H2 SO4 and elution was completed in a shorter period compared with the lower concentration of acids. 3.3. Separation of boron from H2 SO4 solution
Diaion CRB 02
0.2
Purolite S 108 (2) 0.0 0
50
100 150 200 250 300 Bed Volume (mL-solution/mL-resin)
350
400
Fig. 3. Breakthrough curves of boron by Diaion CRB 02 and Purolite S 108 (2) (SV ¼ 15 h1 ).
The eluted boron could be precipitated as boric acid crystals after further recovery and concentration processes. In this study, a weak-base anion exchange resin Diaion WA 30 was employed for the column-mode separation of boron from
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N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170
2R–OH þ Na2 SO4 $ R2 SO4 þ 2NaOH
Concentration of Boron (mg/L)
600
(b) adsorption mechanism for H2 SO4 by the resin in SO2 4 form
Diaion CRB 02
500
Purolite S 108 (2) 400
þ H2 SO4 ! HSO 4 þH
300
R2 SO4 þ Hþ $ RHSO4 þ Rþ
200 100
500
0
5
10 15 20 25 Bed Volume (mL-solution/mL-resin)
30
Concentration of Boron (mg/L)
0 35
Fig. 5. Elution profiles of boron by Diaion CRB 02 and Purolite S 108 (2).
H2 SO4 . To find out the conversion of the resin from OH form into SO2 4 form thereby adsorption of H2 SO4 on the resin, following site-sharing mechanism could be considered: (a) conversion of resin from OH form into SO2 4 form:
0.05 M H2SO4 400
0.1 M H2SO4 0.5 M H2SO4
300
200
100
0 0
5
10
15
20
25
30
35
Fig. 6. Effect of eluting agent concentration on elution of boron.
Table 4 Evaluation of column-mode performances of N-glucamine resins for boron removal Resin
Breakthrough capacity (mg B/ml resin)
(BV)
Diaion CRB 01 Diaion CRB 02 Purolite S 108 (1) Purolite S 108 (2)
1.73 2.25 1.24 1.49
101 122 73 80
Total capacity (mg B/ml resin)
Column utilization efficiency (%)
Elution efficiency (%)
3.43 3.23 2.32 2.44
50 70 54 61
96 99 100 100
Table 5 Elution of boron from chelating resins Eluting agent
Elution of boron Diaion CRB 01
0.05 M H2 SO4 0.10 M H2 SO4 0.25 M H2 SO4 0.50 M H2 SO4 0.1 M HCl 0.2 M HCl 0.5 M HCl 1.0 M HCl
40
Bed Volume (mL-solution/mL-resin)
Purolite S 108 (1)
mg B adsorbed
mg B eluted
Elution (%)
mg B adsorbed
mg B eluted
Elution (%)
1.81 1.80 1.81 1.80 1.93 1.93 1.94 1.93
1.82 1.81 1.82 1.82 1.77 1.79 1.84 1.85
100 100 100 100 92 93 95 96
1.97 1.96 1.97 1.97 1.87 1.87 1.87 1.87
1.97 1.97 1.95 1.96 1.70 1.72 1.77 1.78
100 99 100 100 91 92 94 96
N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170 1.2 B
500
1.0
H2SO4
400
0.8
300
0.6
200
0.4
100
0.2
0
0.0 0
1
2 3 4 5 Bed Volume (mLsolution/mLresin)
6
7
Fig. 8. Breakthrough curves of Boron and H2 SO4 by Diaion WA 30 conditioned with Method 2. 1400
1.2 B
1200
1.0
H2SO4 1000
0.8 800 0.6 600 0.4 400
Concentartion of H2SO4 (N)
Concentration of Boron (mg/L)
(R: resin) Figs. 7–9 illustrate the breakthrough curves of B and H2 SO4 by Diaion WA 30 conditioned according to Methods 1–3. As illustrated in Figs. 7–9, the separation of B from H2 SO4 was achieved at a larger ratio when Method 3 was applied for conditioning. Since the separation of boron from H2 SO4 by using only ion exchange method was not so effective, a precipitation method was considered for removal H2 SO4 from boron. For this, Ca(OH)2 was considered as precipitating agent for sulphate. The addition of Ca(OH)2 was performed until pH of the solutions became 1.0 and 2.0. As summarized in Table 6, some decrease was observed in boron concentration of solution after adding Ca(OH)2 into H2 SO4 solution. This could be due to the adsorption of boron on CaSO4 precipitated. It was considered that boric acid could be produced from the eluate by further crystallizations following the precipitation of CaSO4 using Ca(OH)2 . In order to make a comment on the efficiency of this separation, we need to know the maximum concentration of sulphate accepted as impurity in the boric acid crystals. Indeed, the sulphate content of A.G. H3 BO3 (Merck-zur Analyse) was given as 5 mg/kg. The economical process for the recovery of boron from acidic eluates are now under investigation.
Concentration of Boron (mg/L)
600
Concentartion of H2SO4 (N)
Rþ þ HSO 4 $ RHSO4
169
0.2
200 0
0.0 0
1
2 3 4 Bed Volume (mLsolution/mLresin)
5
6
Fig. 9. Breakthrough curves of boron and H2 SO4 by Diaion WA 30 conditioned with Method 3. Table 6 Separation of B from H2 SO4 by precipitation
1.2 B
1200
1.0
H2SO4 1000
0.8 800 0.6 600 0.4 400 0.2
200 0
Concentration of H2SO4 (N)
Concentration of Boron (mg/L)
1400
0.0 0
1
2
3
4
5
6
7
8
Bed Volume (mL solution / mL resin)
Fig. 7. Breakthrough curves of Boron and H2 SO4 by Diaion WA 30 conditioned with Method 1.
pH
[B]i (mg B/L)
[SO2 4 ]i (N)
0.31 1.00 2.00
998.33 938.75 955.00
1.055 0.255 0.064
[B]i , initial concentration of B; [SO2 4 ]i , initial concentration of SO2 4 .
Acknowledgements The research study reported here was financially supported by NEDO (New Energy Development Organization of Japan) and Ege University Research Foundation (Project Nos. EU-2001-FEN041; EU-2001-FEN-042; EU-2003 MUH-013). We acknowledge the donations of some equipments
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N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170
which are offered by Kyuden-Sangyo Co. Inc., Japan to our Avicenne Project Laboratory at Ege University. We are grateful to General Directorate of MTA (Mineral Research and Exploration Institute), Ankara and Izmir-Region Directorate of MTA for their collaborations and support during the project. We also thank TEAS, Kizildere for providing us with geothermal water.
References [1] R.M. Adams, Boron, Metallo-Boron Compounds and Boranes, Wiley, New York, NY, 1964. [2] R.S. Ayers, Water Quality for Agriculture (Report of FAO Irrigation and Drainage, M-56 ISBN, 92-5-102263-1), Rome 1994. [3] M. Badruk, N. Kabay, M. Demircioglu, H. Mordogan, U. _ Ipeko glu, Sep. Sci. Technol. 34 (13) (1999) 2553. [4] M. Badruk, N. Kabay, M. Demircioglu, H. Mordogan, U. _ Ipeko glu, Sep. Sci. Technol. 34 (15) (1999) 2981. [5] R. Kunin, A.F. Preus, Ind. Eng. Chem. Prod. Res. Dev. 3 (1964) 304. [6] U. Schilde, E. Uhlemann, React. Func. Polym. 18 (1992) 155.
[7] U. Schilde, E. Uhlemann, React. Func. Polym. 20 (1993) 181. [8] U. Schilde, E. Uhlemann, Int. J. Miner. Process 32 (1991) 295. [9] S. Yasuda, Y. Inukai, H. Ohba, Bunseki Kagaku 42 (1993) 713. [10] O. Recepoglu, U. Beker, Geothermics 20 (1991) 83. [11] N. Bicßak, N. Bulutcßu, B.F. S ß enkal, M. Gazi, React. Func. Polym. 47 (2001) 175. [12] T. Qi, A. Sonoda, Y. Makita, H. Kanoh, K. Ooi, T. Hirotsu, Ind. Eng. Chem. Res. 41 (2002) 133. [13] A. Jyo, S. Aoki, M. Uchimura, K. Yamabe, T. Sugo, Anal. Sci. 17 (2001) 1211. [14] K. Ooi, H. Katoh, A. Sonoda, T. Hirotsu, J. Ion Exchange 7 (3) (1996) 166. [15] M. Matsumoto, K. Kondo, M. Hirata, S. Kokubu, T. Hano, T. Takada, Sep. Sci. Technol. 32 (5) (1997) 983. [16] M. Taniguchi, M. Kurihara, S. Kimura, J. Membrane Sci. 183 (2001) 259. [17] N. Nadav, Desalination 124 (1999) 131. [18] B.M. Smith, P. Todd, C.N. Bowman, Sep. Sci. Technol. 30 (20) (1995) 3849. [19] C. Dilek, O. Ozbelge, N. Bcak, L. Yilmaz, Sep. Sci. Technol. 37 (6) (2002) 1257. [20] L. Melnik, O. Vysotskaja, B. Kornilovich, Desalination 124 (1999) 125. [21] I. Yilmaz, M.Sc. Thesis, Ege University, 2003.
REACTIVE & FUNCTIONAL POLYMERS www.elsevier.com/locate/react
Removal and recovery of boron from geothermal wastewater by selective ion exchange resins. I. Laboratory tests q N. Kabay a,*, I. Yılmaz a, S. Yamac b, S. Samatya b, M. Yuksel a, U. Yuksel b, M. Arda b, M. Sa glam a, T. Iwanaga c, K. Hirowatari d a
Chemical Engineering Department, Faculty of Engineering, Ege University, 35100 Izmir, Turkey b Chemistry Department, Faculty of Science, Ege University, 35100 Izmir, Turkey c Kyuden Sangyo Co. Inc., Fukuoka, Japan d West-Jec Co., Fukuoka, Japan Received 14 November 2003; accepted 16 February 2004 Available online 5 June 2004
Abstract Boron removal from wastewaters of geothermal plant was studied using N-glucamine type chelating resins so-called Diaion CRB 01, Diaion CRB 02, Purolite S 108. The batch-mode sorption studies was performed to obtain the optimum amount of resins for boron removal from geothermal wastewater. The boron on the resin was quantitatively eluted with 5% H2 SO4 . A column-mode study was performed using weak base ion exchange resin Diaion WA 30 for the separation of boron from H2 SO4 solution. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Boron; Geothermal water; Ion exchange; Chelating resins
1. Introduction Well waters or springs occasionally contain boron at toxic amounts, especially near geother-
q
The authors wish to dedicate this paper to Emeritus Professor Michael Streat, who is a pioneering scientist in the field of ion exchange and adsorption, upon his retirement from Loughborough University, UK. * Corresponding author. Tel.: +90-232-388-7600; fax: +90232-388-7776. E-mail address: [email protected] (N. Kabay).
mal areas and earthquake faults. Boron concentration in irrigation waters which is only slightly higher than the minimum will be negative for plant growth [1–4]. There are several methods suggested for boron removal from aqueous solution. Among those methods, ion exchange process is most extensively used. It was reported that chelating resins containing functional groups in which hydroxyl groups are in the cis position show a high selectivity for boron removal [3–12]. Chelating fibers having polyol groups have been also used for
1381-5148/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.reactfunctpolym.2004.02.020
164
N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170
boron removal [13]. Ooi et al. [14] reported that some hydrous oxide of tetravalent metals (CeO2 Æ nH2 O, ZrO2 Æ nH2 O, HfO2 Æ nH2 O) or pentavalent metals (Ta2 O5 Æ nH2 O) are promising adsorbents for boron removal. Solvent extraction method was suggested for the recovery of boric acid using diol containing compounds [15]. Some membrane processes were tested for boron removal. Taniguchi et al. [16] used reverse osmosis process for boron reduction in seawater. Selective ion exchange resins have been employed for boron removal from reverse osmosis permeate [17]. Polymer-assisted ultrafiltration was reported as a method for boron removal that is compatible with other treatment methods [18,19]. Electrodialysis is another membrane process used for boron removal from seawater [20]. In our previous papers, we have reported the preliminary results of batch-mode and columnmode studies for boron removal from geothermal wastewaters using N-glucamine type resins [3,4]. In this paper, the comparative results obtained using N-glucamine type resins (Purolite S108, Diaion CRB 01, Diaion CRB 02) to obtain the optimum
amount of resins for boron removal from geothermal wastewater was presented. Column performances of these resins for boron removal from geothermal wastewater were compared. A columnmode study for the separation of boron from H2 SO4 solution was carried out using a weak base anion exchange resin Diaion WA 30.
2. Experimental 2.1. Materials Mitsubishi Co., Japan kindly provided Diaion CRB 01 and CRB 02 resins. The resins Purolite S108 (1) and Purolite S108 (2) were kindly sent by Purolite International Ltd. as a gift. The chemical and physical properties of chelating resins are given in Tables 1 and 2. The weak-base anion exchange resin Diaion WA 30 was provided by Mitsubishi Co., Japan. The geothermal wastewater was obtained from the field of Kizildere Geothermal Power Plant, Turkey. The chemical composition of geothermal wastewater is summarized in Table 3.
Table 1 Typical chemical and physical characteristics of Diaion CRB 01 an Diaion CRB 02 resins
Constitutional type Ion form as shipped Shipping density (g/l) (app.) Moisture content (%) Exchange capacity (meq/ml) Total capacity meq/ml R (FB) meq/g R (FB) Screen grading Effective size (mm) Operating temperature Effective pH range Specific surface area (m2 /g) Degree of swelling (ml/dry g) Structure
Diaion CRB 01
Diaion CRB 02
Highly porous OH-form 706 45.6 ND
Highly porous OH-form 635 50–60 Acid 0.6 (min)
1.13 2.95 ND ND ND ND ND 2.60
ND 118–300 l (through 300 l: max 1%) 0.355–0.550 100 °C (max) OH form 6–10 27 ND
-CH - CH2 -CH - CH2 -
CH3 -CH-CH2- CH2 NCH2 - (CH(OH))4 - CH2OH ND, not determined.
N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170
165
Table 2 Typical chemical and physical characteristics of Purolite S 108 (1) and Purolite S108 (2)
Polymer structure Optical appearance Functional groups Ionic form, as shipped Total capacity (Cl form) (eq/l) Total boron capacity (Cl form) (eq/l) Selective boron capacity (Cl form) (eq/l) Moisture retention (Cl form) (%) Reversible swelling ðFB ! Cl Þ (%) Specific gravity (Cl form) Temperature limit (Cl form) (°C) pH limits (operating) Structure
Purolite S 108 (1)
Purolite S 108 (2)
Macroporous polystyrene crosslinked with divinylbenzene Spherical beads Complex amino Free base-FB 0.8 (min) 0.35 0.20 (min) 45–55 10 (max) 1.1 60 1–13
Macroporous polystyrene crosslinked with divinylbenzene Spherical beads Complex amino Free base-FB 0.8 (min) ND ND 52–58 6 (max) 1.06 60 1–13
n
OH OH
OH OH
N Me
OH
OH
ND, not determined.
2.2. Batch-mode sorption studies Various amounts of N-glucamine type resins (0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 g) was contacted with 100 ml of geothermal wastewater at 30 °C for 48 h with continuous shaking in order to find the optimum amount of resin concentration for boron removal from geothermal wastewater.
2.3. Column-mode sorption–elution studies The resin in the 0.355–0.250 mm particle size range was selected for the column tests. The resin beads were immersed in deionized water for 24 h before being packed into the column. The columns were made of glass and had an internal diameter of 0.7 cm. The column was packed with 0.5 ml of wet-settled volume of resin. Geothermal wastewater was delivered down-flow to the column at a flow rate of SV 15 h1 (SV: so called space velocity defined as bed volumes per hour) using a peristaltic pump (Atto SJ 1211H). From the outlet of the column, each successive 3 cm3 fractions of the effluent were
Table 3 Chemical composition of geothermal wastewater Ionic species
Concentration (mg/l)
TSM Na K Li Ca Mg Al Fe F Cl SO4 HCO3 CO3 As B T-SiO2 S-SiO2 Mn
3720 1190 142 3.78 0.51 0.42 – – 15.36 94.2 646 1660 224 0.853 18–20 330 287 –
pH ¼ 9.0–9.2; EC ¼ 504 mS/m.
collected using a fraction collector (Advantec SF 2120 Model). Breakthrough curves were obtained by analysis of each fractions. After the sorption,
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the resin was washed with deionized water. The elution of boron from the resin was performed with 5% of H2 SO4 solution passed through the column at SV 10 h1 . The elution profile was obtained by analysing the 2 ml of fractions collected with the fraction collector. 2.4. Column-mode study for boron separation from acidic solution In order to separate boron from 5% H2 SO4 solution containing 1000 mg B/L, laboratory-scale column-mode tests were conducted using a weak base anion exchange resin Diaion WA 30 at different ionic forms obtained by means of various conditioning steps. The methods of conditionings were as follows: Method 1: 2.0 ml of Diaion WA 30 was conditioned with 2 M HCl first and then with 2 M NaOH. Method 2: 4.0 ml of Diaion WA 30 was conditioned with 2 M HCl first and then with 2 M NaOH (conditioning was repeated twice). Method 3: 3.8 ml of Diaion WA 30 was conditioned with 1 M Na2 SO4 following the conditioning explained as Method 2. The solution containing boron at a concentration of 1000 mg/l prepared in 5% H2 SO4 was passed down-flow through the resin packed into a glass column with an inner diameter of 0.95 cm using a peristaltic pump at SV 2 h1 . Each successive 2 ml fractions of the effluent were collected using a fraction collector. Breakthrough curves were obtained by analysis of these successive fractions for boron and sulfate. The effect of pH on separation of boron from H2 SO4 solution was investigated by using solutions at pH 0.31 (5% H2 SO4 ), 1.0, and 2.0. The pHs of the solutions at pH 1.0 and 2.0 were adjusted by precipitating CaSO4 from H2 SO4 solution (5%) containing 1000 mg B/L sulfate using Ca(OH)2 . 2.5. Boron analysis The analysis of boron in the solution was carried our spectrophotometrically using the Curcumine Method (kmax : 543 nm) [21].
2.6. Sulfate analysis The analysis of sulfate in the solution was performed by titration method using Ba(ClO4 )2 solution in the presence of thorin and methylene blue indicators [21].
3. Results and discussion 3.1. Batch-mode sorption studies for boron removal The mechanism for boron sorption by glucamine type resins are given as follows [14]: P-CH2-N(CH3)-CH2-[CH(OH)-]4-CH2OH + B(OH)3 → P-CH2-N(CH3)-CH2-[CH(OH)-]2-CHO-CHO-CH2OH + 2H2O B(OH)
In this study, glucamine type resins such as Diaion CRB 01, Diaion CRB 02, Purolite S108 (1) and Purolite S108 (2) were employed for boron removal from geothermal wastewaters. To find the optimum amount of resin concentration, which can completely remove boron from geothermal wastewater, a batch-mode sorption study was performed using various amounts of resin. For this, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 g of resins were contacted with 100 ml of geothermal wastewater at 30 °C for 48 h with a continuous shaking. As shown in Fig. 1, boron removal increased with an increase in resin concentration. A resin concentration of 3 g-resin/l-wastewater was needed to remove more than 90% of boron for all chelating resins. 3.2. Column-mode sorption–elution studies for boron The breaktrough profiles of boron obtained using Diaion CRB 01 and Purolite S 108 (1) at SV 10 h1 are given in Fig. 2. Breakthrough appeared more quickly with Purolite S108 (1) than Diaion CRB 01. As shown in Fig. 3, breakthrough per-
N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170
Concentration of Boron (mg/L)
Removal of Boron (%)
100 80 60 Diaion CRB 01 Diaion CRB 02 Purolite S 108 (1) Purolite S 108 (2)
40 20
500 Diaion CRB 01 400 PuroliteS 108 (1) 300 200 100 0 0
0 0
0.1
0.2
0.3
0.4
167
5
10 15 20 25 Bed Volume (mL-solution/mL-resin)
30
35
0.5
Fig. 4. Elution profiles of boron by Diaion CRB 01 and Purolite S 108 (1).
Resin Amount (g)/100 mL-wastewater
Fig. 1. Effect of resin amount on boron removal from geothermal wastewater by the chelating resins.
1.0
C/Co
0.8
0.6
0.4 Diaion CRB 01 0.2 PuroliteS 108 (1) 0.0 0
100
200 300 BV (mL-solution/mL-resin)
400
500
Fig. 2. Breakthrough curves of boron by Diaion CRB 01 and Purolite S 108 (1) (SV ¼ 10 h1 ).
1.0
C/C0
0.8 0.6 0.4
formance of Diaion CRB 02 was better than that of Purolite S 108 (2) at SV 15 h1 . Respective elution curves are illustrated in Figs. 4 and 5. Elution of boron from the resins was completed between 15 and 20 BV using 5% H2 SO4 solution. Breakthrough and total capacities of each resin are summarized in Table 4. According to these results, it is clear that the resin Diaion CRB 02 has the highest breakthrough capacity among the resins tested. In order to see the effect of acid concentration on elution performance of boron, elution of boron from Diaion CRB 01 and Purolite S 108 (1) resins was studied using HCl and H2 SO4 at different concentrations with batch method. Table 5 summarizes the results obtained. A complete stripping of boron was obtained with H2 SO4 as low as 0.05 M in concentration. The effect of eluting agent concentration on elution of boron from the resin Diaion CRB 01 was also studied using column method. As shown in Fig. 6, elution profile of boron was sharp with 0.5 M H2 SO4 and elution was completed in a shorter period compared with the lower concentration of acids. 3.3. Separation of boron from H2 SO4 solution
Diaion CRB 02
0.2
Purolite S 108 (2) 0.0 0
50
100 150 200 250 300 Bed Volume (mL-solution/mL-resin)
350
400
Fig. 3. Breakthrough curves of boron by Diaion CRB 02 and Purolite S 108 (2) (SV ¼ 15 h1 ).
The eluted boron could be precipitated as boric acid crystals after further recovery and concentration processes. In this study, a weak-base anion exchange resin Diaion WA 30 was employed for the column-mode separation of boron from
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2R–OH þ Na2 SO4 $ R2 SO4 þ 2NaOH
Concentration of Boron (mg/L)
600
(b) adsorption mechanism for H2 SO4 by the resin in SO2 4 form
Diaion CRB 02
500
Purolite S 108 (2) 400
þ H2 SO4 ! HSO 4 þH
300
R2 SO4 þ Hþ $ RHSO4 þ Rþ
200 100
500
0
5
10 15 20 25 Bed Volume (mL-solution/mL-resin)
30
Concentration of Boron (mg/L)
0 35
Fig. 5. Elution profiles of boron by Diaion CRB 02 and Purolite S 108 (2).
H2 SO4 . To find out the conversion of the resin from OH form into SO2 4 form thereby adsorption of H2 SO4 on the resin, following site-sharing mechanism could be considered: (a) conversion of resin from OH form into SO2 4 form:
0.05 M H2SO4 400
0.1 M H2SO4 0.5 M H2SO4
300
200
100
0 0
5
10
15
20
25
30
35
Fig. 6. Effect of eluting agent concentration on elution of boron.
Table 4 Evaluation of column-mode performances of N-glucamine resins for boron removal Resin
Breakthrough capacity (mg B/ml resin)
(BV)
Diaion CRB 01 Diaion CRB 02 Purolite S 108 (1) Purolite S 108 (2)
1.73 2.25 1.24 1.49
101 122 73 80
Total capacity (mg B/ml resin)
Column utilization efficiency (%)
Elution efficiency (%)
3.43 3.23 2.32 2.44
50 70 54 61
96 99 100 100
Table 5 Elution of boron from chelating resins Eluting agent
Elution of boron Diaion CRB 01
0.05 M H2 SO4 0.10 M H2 SO4 0.25 M H2 SO4 0.50 M H2 SO4 0.1 M HCl 0.2 M HCl 0.5 M HCl 1.0 M HCl
40
Bed Volume (mL-solution/mL-resin)
Purolite S 108 (1)
mg B adsorbed
mg B eluted
Elution (%)
mg B adsorbed
mg B eluted
Elution (%)
1.81 1.80 1.81 1.80 1.93 1.93 1.94 1.93
1.82 1.81 1.82 1.82 1.77 1.79 1.84 1.85
100 100 100 100 92 93 95 96
1.97 1.96 1.97 1.97 1.87 1.87 1.87 1.87
1.97 1.97 1.95 1.96 1.70 1.72 1.77 1.78
100 99 100 100 91 92 94 96
N. Kabay et al. / Reactive & Functional Polymers 60 (2004) 163–170 1.2 B
500
1.0
H2SO4
400
0.8
300
0.6
200
0.4
100
0.2
0
0.0 0
1
2 3 4 5 Bed Volume (mLsolution/mLresin)
6
7
Fig. 8. Breakthrough curves of Boron and H2 SO4 by Diaion WA 30 conditioned with Method 2. 1400
1.2 B
1200
1.0
H2SO4 1000
0.8 800 0.6 600 0.4 400
Concentartion of H2SO4 (N)
Concentration of Boron (mg/L)
(R: resin) Figs. 7–9 illustrate the breakthrough curves of B and H2 SO4 by Diaion WA 30 conditioned according to Methods 1–3. As illustrated in Figs. 7–9, the separation of B from H2 SO4 was achieved at a larger ratio when Method 3 was applied for conditioning. Since the separation of boron from H2 SO4 by using only ion exchange method was not so effective, a precipitation method was considered for removal H2 SO4 from boron. For this, Ca(OH)2 was considered as precipitating agent for sulphate. The addition of Ca(OH)2 was performed until pH of the solutions became 1.0 and 2.0. As summarized in Table 6, some decrease was observed in boron concentration of solution after adding Ca(OH)2 into H2 SO4 solution. This could be due to the adsorption of boron on CaSO4 precipitated. It was considered that boric acid could be produced from the eluate by further crystallizations following the precipitation of CaSO4 using Ca(OH)2 . In order to make a comment on the efficiency of this separation, we need to know the maximum concentration of sulphate accepted as impurity in the boric acid crystals. Indeed, the sulphate content of A.G. H3 BO3 (Merck-zur Analyse) was given as 5 mg/kg. The economical process for the recovery of boron from acidic eluates are now under investigation.
Concentration of Boron (mg/L)
600
Concentartion of H2SO4 (N)
Rþ þ HSO 4 $ RHSO4
169
0.2
200 0
0.0 0
1
2 3 4 Bed Volume (mLsolution/mLresin)
5
6
Fig. 9. Breakthrough curves of boron and H2 SO4 by Diaion WA 30 conditioned with Method 3. Table 6 Separation of B from H2 SO4 by precipitation
1.2 B
1200
1.0
H2SO4 1000
0.8 800 0.6 600 0.4 400 0.2
200 0
Concentration of H2SO4 (N)
Concentration of Boron (mg/L)
1400
0.0 0
1
2
3
4
5
6
7
8
Bed Volume (mL solution / mL resin)
Fig. 7. Breakthrough curves of Boron and H2 SO4 by Diaion WA 30 conditioned with Method 1.
pH
[B]i (mg B/L)
[SO2 4 ]i (N)
0.31 1.00 2.00
998.33 938.75 955.00
1.055 0.255 0.064
[B]i , initial concentration of B; [SO2 4 ]i , initial concentration of SO2 4 .
Acknowledgements The research study reported here was financially supported by NEDO (New Energy Development Organization of Japan) and Ege University Research Foundation (Project Nos. EU-2001-FEN041; EU-2001-FEN-042; EU-2003 MUH-013). We acknowledge the donations of some equipments
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which are offered by Kyuden-Sangyo Co. Inc., Japan to our Avicenne Project Laboratory at Ege University. We are grateful to General Directorate of MTA (Mineral Research and Exploration Institute), Ankara and Izmir-Region Directorate of MTA for their collaborations and support during the project. We also thank TEAS, Kizildere for providing us with geothermal water.
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