- Email: [email protected]
Capacity loss in an organically fouled anion exchanger
Desalination 189 (2006) 303–307
Capacity loss in an organically fouled anion exchanger Z. Beril Gönder*, Yasemin Kaya, Ilda Vergili, Hulusi Barlas Environmental Engineering Department, Faculty of Engineering, Istanbul University, 34320 Avcilar-Istanbul, Turkey email: [email protected] Received 27 April 2005; accepted 29 July 2005
Abstract One of the most important contaminants that ion-exchange resins are exposed to is fouling by organic materials. Especially, anion-exchange resins are more sensitive to fouling by organic materials. The fouling of anion-exchange resins by organic materials is primarily caused by the degradation of products of cation ion exchangers and humic and fulvic acids. Organic fouling causes product water with low quality and few anion exchangers and shortens the service time. Also the need for rinsing water and the use of regeneration chemicals increase. Operating capacity losses occurring due to the fouling of anion-exchange resin by humic acid were quantitatively determined. SAK254 (Spektraler Absorptions Koeffizient = spectral absorption coefficient), DFZ436 (DurchsichtsFarbZahl = indexes of transparency), conductivity and sulfate measurements were made to determine capacity losses, which were obtained as 21%, 23%, 25% and 30% after the fouling studies of anion-exchange resin by the amounts of 0.13, 0.25, 0.5 and 1.0 mg/L humic acid, respectively. It was found that even small concentrations of humic acid resulted in a considerable amount of capacity losses in anion-exchange resin. Keywords: Organic fouling; Humic acid; DFZ436; SAK254; Operating capacity
1. Introduction Very high quality water is needed through various stages of processing in many industries (e.g., semiconductor, pharmaceutical, chemical, etc.). Ion-exchanger systems currently have widespread use for this purpose. Some problems are encountered during their use (loading, backwashing and regeneration), which affect the
performance of ion-exchange resins. The most important one amongst these problems is the fouling of ion-exchange resins [1,2]. Fouling with organic materials is the most important one that ion-exchange resins encounter. Organic fouling is an irreversible fixation of organic materials to the ion-exchange resin. Especially, anion exchange resins are more sensitive to fouling with organic materials [3].
*Corresponding author. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved
doi:10.1016/j.desal.2005.07.012
304
Z. Beril Gönder et al. / Desalination 189 (2006) 303–307
The fouling of anion-exchange resins by organic materials is primarily caused by the degradation products of cation exchangers and humic and fulvic acids. Organic fouling results in production of low-quality (high conductivity, low pH), low amounts of water and some great problems such as early breakthrough and long washing periods after regeneration. The capacity of the ion-exchanger bed decreases and water with desired quality is not produced due to the fouling that was not removed fully by means of regeneration and backwashing [3,4]. Natural waters contain organic, inorganic and biological compounds in various ratios. Organic materials have a high share amongst these compounds. Sources of organic materials in these waters are decomposition products of wood and leaves or industrial and domestic wastes [5]. Organic materials are largely composed of humic materials. Humic materials are classified into three groups according to their solubilities in water [6]: (1) humin, that is the part which is not soluble at any pH value; (2) humic acid, that is the part which is not soluble in (pH <2) acidic medium but is soluble at high pH values; (3) fulvic acid, that is the part which is soluble in all pH values. It is believed that the chemical structure of these three fractions are alike. They appear to differ in molecular weight and functional group content. Fulvic acid probably has a lower molecular weight but more hydrophilic functional groups than humic acid [7]. According to McCoy [8], soluble organic materials such as humic and fulvic acids foul anion-exchange resins primarily with ion exchange. The chloride ions or hydroxyl anions within the humic acid structure are exchanged with the chloride, sulfate or hydroxyl anion on the quarternary amine that is grafted to the backbone of the anion-exchange resin molecule [9]. These fouling materials do not diffuse into the resin due to their molecular dimensions. They rather prevent ions moving into the resin by
accumulating physically onto the resin surface and blocking the ion-exchange points [4]. Organic materials make ion-exchange resin hydrophobic. Because of this, the moisture content of resins which fouled by organic materials decreases. This is a case which is to be avoided because it results in the decrease of porosity volume. As a result, the diffusion rate of counter ions and operating capacity decrease while the washing period and rinse water needed increase. Organic materials may also cause silicate leakage in anion exchangers where the silicate removal process is carried on. Silicate accumulates at the bottom of the anion-exchanger bed because the flow of water into resin is slowed down due to the blockage of resin pores by organic materials having high molecular weights [10]. There are some methods used for the purpose of cleaning of anion-exchange resins fouled by organic metarials. Washing with a caustic salt solution is the most used amongst other methods. This cleaning procedure is implemented by using 10% salt solution containing 2% NaOH of three times volume of bed volume [11]. The application of pretreatment processes is proposed before the ion-exchange system in order to protect the resins against organic fouling. Coagulation–flocculation, adsorption with actived carbon, membrane processes and oxidation/ biofiltration processes are used as pretreatment processes in the removal of organic materials [12]. In addition, the most resistant resin type must be chosen against fouling with organic materials. Acrylic-based resins are more resistant than styrene-based resins because they have a larger hydrophilic structure and ease the passage of high molecular organic materials from the resin due to their aliphatic structure. Organic materials could be removed effectively from the acrylic-based resins during regeneration [13]. 2. Materials and methods Changes in resin capacity were determined
Z. Beril Gönder et al. / Desalination 189 (2006) 303–307
quantitatively by searching fouling of resin with humic acid which is a fraction of humic material. Lewatit M 500, frequently used in demineralisation applications, was chosen as the strongly basic anion exchanger. Technical specifications of the resin (Lewatit M 500), provided from Bayer Leverkusen, are given in Table 1. A laboratory-scale glass column with a 2 cm diameter and 45 cm height was used throughout the experiments. The column was filled with a strong anion-exchange resin of 50 mL in volume. Synthetic water, prepared by dissolving Na2SO4 in distilled water with appropriate amounts resulting 150 mg/L SO42! content, was used. The synthetic water was supplied to the system by using a peristaltic pump (Prominent) and the feed rate was adjusted to V = 5.0 m/h (specific flow rate = 31 bed volume/h). A humic acid solution was used in the fouling studies. This solution was prepared according to the Urano method: 1 g humic acid was dissolved in 100 mL 0.1 N NaOH solution and then distilled water was added up to 1 L after waiting for 1 day [14]. The following method was used for the determination of changes occuring in ion-exchange capacity in the studies performed for the fouling Table 1 Technical specifications of the strongly basic anion exchanger (Lewatit M 500) Properties
Strongly basic anion exchanger
Ionic form Functional group
Cl! Quarternary amine, Type 1 Gel 1.4 0.47 40 NaOH 100 2–4
Structure Total capacity, min. eq /L Bead size, mm Flow rate, max. m/h Regenerant Regenerant level, g/L Regenerant con., %
305
of ion-exchange resins. The method is based upon the comparison of resin after being regenerated with a new resin sample [15,16]. In this study this method is taken as a reference. Changes in resin capacity during the fouling of the anion-exchange resin were determined by using humic acid in the amounts of 0.13, 0.25, 0.5 and 1.0 mg/L. The amount of 15 mg/L SO42! value was taken as the breakthrough point and column loading was continued until this value was reached at the outlet. SAK254 (Spektraler AbsorptionsKoeffizient = spectral absorption coefficient) [17], DFZ (Durchsichts Farbzahl = indexes of transparency) [18] and conductivity measurements were performed for the samples taken from the column outlet during fouling. SAK254 and DFZ436 measurements were made by using Jenway UV-Vis (model 6105) and Pharmacia LKB-Novaspec II spectrophotometers, respectively. Conductivity measurements were carried out by a WPA CM35 conductivity device. Sulphate measurements were implemented according to the turbidimetric method as defined in Standard Methods [19]. A 4% NaOH (12 bed volume/h) solution of 300 mL (6 bed volume) in volume was used for the strong anion-exchange resin regeneration. Cocurrent regeneration was carried out in the study. The regenerated resin was backwashed with distilled water until the conductivity of the effluent was less than 1 µS/cm.
3. Results and discussion A strong basic anion-exchanger was fouled with 0.13, 0.25, 0.5 and 1.0 mg/L humic acid and raw water was passed through after regeneration. The capacity of the ion exchanger was calculated by obtaining breakthrough curves belonging to the cycles of raw water passed through fresh ionexchanger resin and through ion-exchanger resin fouled with humic acid and subsequently regenerated (see Figs. 1–4).
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Fig. 1. Breakthrough curves obtained from the fouling of strong anion exchanger with 0.13 mg/L humic acid. (a) raw water, (b) raw water containing 0.13 mg/L humic acid, (c) raw water after regeneration.
Fig. 2. Breakthrough curves obtained from the fouling of strong anion exchanger with 0.25 mg/L humic acid. (a) raw water, (b) raw water containing 0.25 mg/L humic acid, (c) raw water after regeneration.
Fig. 3. Breakthrough curves obtained from the fouling of strong anion exchanger with 0.5 mg/L humic acid. (a) raw water, (b) raw water containing 0.5 mg/L humic acid, (c) raw water after regeneration.
Fig. 4. Breakthrough curves obtained from the fouling of strong anion exchanger with 1.0 mg/L humic acid. (a) raw water, (b) raw water containing 1.0 mg/L humic acid, (c) raw water after regeneration.
The capacity loss was found to be 21% for the fouling of anion-exchange resin with 0.13 mg/L humic acid. In this case, organic material causes high capacity losses even in small amounts. The capacity losses were found to be 23% and 25% for the humic acid amounts of 0.25 and 0.5 mg/L, respectively. A 30% capacity loss was observed as the humic acid amount reached 1.0 mg/L value. The capacity losses are shown in Fig. 5. Capacity losses increased as the humic acid amounts increased. The reason for this is that humic acid which is a high molecular organic material blocks the pores of anion exchange resin which in turn prevents ions moving into the resin.
This situation could not to be ceased even by the regeneration process [4]. DFZ436 and SAK254 parameters measured for the samples taken from the outlet of the ionexchange column were evaluated during fouling studies. DFZ was measured as zero for the samples taken up to 15 mg/L SO4= value which was chosen as the breakthrough point during the fouling studies made with 0.13, 0.25, 0.5 and 1.0 mg/L humic acid values. In other words, no colour was observed in the samples taken from the column outlet. SAK254 values were determined to be zero for samples taken up to the breakthrough point during the fouling of anion-
Z. Beril Gönder et al. / Desalination 189 (2006) 303–307
Fig. 5. Capacity losses occurring in strong anion exchange.
exchange resin with 0.13 and 0.25 mg/L humic acid. When the humic acid amount was 0.5 mg/L, SAK254 values were observed for the samples taken from column outlet after the passage of 15.3 L water fouled by humic acid (bed volume = 306). SAK254 value was measured as 0.9 m!1 at the breakthrough point. When the humic acid amount was 1.0 mg/L, SAK254 values were observed for the samples from the column outlet after the passage of 14.5 L water fouled by humic acid (bed volume = 290), and this value became 2.6 m!1 at the breakthrough point. The reason for this is the blockage of ion-exchange points existing in ion-exchanger’s structure by a large amount of humic acid. As a result, the capacity of resin decreases.
References [1] F.N. Kemmer, Ion Exchange, Nalco Water Handbook, 2nd ed., Mc Graw-Hill, New York, 1988, pp. 12.1–12.45. [2] P.N. Cheremisinoff and N.P. Cheremisinoff, Water Treatment and Waste Recovery: Advanced Technology and Applications, Prentice Hall, Englewood, NJ, 1993, pp. 288–289. [3] K. Dorfner, Ion Exchange Types, Ion Exchangers Properties and Applications, 2nd ed., Ann Arbor Science, Michigan, 1972, pp. 168–170.
307
[4] G.C. Lee, G.L. Foutch and A. Aranuchalam, Reactive Func. Polym., 35(10) (1997) 55–73. [5] H. Yıldırım, Contribution of ionic strength to the interaction of natural organic matter and metal oxide surface, Masters Thesis, Bogazici University, Istanbul, Turkey, 2000. [6] APHA-AWWA-WEF, Standard Methods for the Examination of Water and Wastewater, 19th ed., Washington, 1995, pp. 5.27–5.28. [7] S.A. Suphandag, Adsorption capacity of natural organic matter on semi-conductor powders, Master Thesis, Bogazici University, Istanbul, Turkey, 1998. [8] M. McCoy, Ion Exchange, Ultrapure Water, Tall Oaks, Littleton, CO, 1996, pp. 20–31. [9] R.G. Alther, Preventing Resin and Membrane Fouling with Clay Prepolish, Biomin, MI, 2000. [10] W. Bornak, Resin Analysis and Chemical Cleaning, 39th Liberty Bell Water Treatment Course, Atlantic City, New Jersey, 2001. [11] Purolite Company, The fouling of ion exchange resins and methods of cleaning, Purolite Technical Bulletin, 1998. [12] H. Ødegard, B. Eikbrokk and R. Storhaug, Water Sci. Technol., 40 (1999) 37–46. [13] J.F. Desilva, Removing organics with ion exchange resin, Water Conditioning Purification, (1997) 1–3. [14] S.C. Uyguner, Trace-level metals and natural organic matter interactions: Oxidative/adsorptive removal pathways, Master Thesis, Bogazici University, Istanbul, Turkey, 1999. [15] Deutsche norm, DIN 54 402: Bestimmung der Totalen Kapazität von Anionenaustauschern, Beuth, Berlin, 1982. [16] Deutsche norm, DIN 54 403: Bestimmung der Totalen Kapazität von Kationenaustauschern, Beuth, Berlin, 1982. [17] DIN 38404, Deutsche einheitsverfahren zur wasser-, abwasser-und schlammuntersuchung- physikalischchemische kenngröβen (gruppe C), Teil 3: Bestimmung der absorption im bereich der UV-strahlung; spektraler absorptionskoeffizient (C3), Beuth, Berlin, 2003. [18] H. Barlas and T. Akgun, Fresenius Environ. Bull., 9 (2000) 597–602. [19] APHA-AWWA-WEF, Standard Methods for the Examination of Water and Wastewater, 19th ed., Washington, 1995, pp. 4.136–4.137.
Capacity loss in an organically fouled anion exchanger Z. Beril Gönder*, Yasemin Kaya, Ilda Vergili, Hulusi Barlas Environmental Engineering Department, Faculty of Engineering, Istanbul University, 34320 Avcilar-Istanbul, Turkey email: [email protected] Received 27 April 2005; accepted 29 July 2005
Abstract One of the most important contaminants that ion-exchange resins are exposed to is fouling by organic materials. Especially, anion-exchange resins are more sensitive to fouling by organic materials. The fouling of anion-exchange resins by organic materials is primarily caused by the degradation of products of cation ion exchangers and humic and fulvic acids. Organic fouling causes product water with low quality and few anion exchangers and shortens the service time. Also the need for rinsing water and the use of regeneration chemicals increase. Operating capacity losses occurring due to the fouling of anion-exchange resin by humic acid were quantitatively determined. SAK254 (Spektraler Absorptions Koeffizient = spectral absorption coefficient), DFZ436 (DurchsichtsFarbZahl = indexes of transparency), conductivity and sulfate measurements were made to determine capacity losses, which were obtained as 21%, 23%, 25% and 30% after the fouling studies of anion-exchange resin by the amounts of 0.13, 0.25, 0.5 and 1.0 mg/L humic acid, respectively. It was found that even small concentrations of humic acid resulted in a considerable amount of capacity losses in anion-exchange resin. Keywords: Organic fouling; Humic acid; DFZ436; SAK254; Operating capacity
1. Introduction Very high quality water is needed through various stages of processing in many industries (e.g., semiconductor, pharmaceutical, chemical, etc.). Ion-exchanger systems currently have widespread use for this purpose. Some problems are encountered during their use (loading, backwashing and regeneration), which affect the
performance of ion-exchange resins. The most important one amongst these problems is the fouling of ion-exchange resins [1,2]. Fouling with organic materials is the most important one that ion-exchange resins encounter. Organic fouling is an irreversible fixation of organic materials to the ion-exchange resin. Especially, anion exchange resins are more sensitive to fouling with organic materials [3].
*Corresponding author. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved
doi:10.1016/j.desal.2005.07.012
304
Z. Beril Gönder et al. / Desalination 189 (2006) 303–307
The fouling of anion-exchange resins by organic materials is primarily caused by the degradation products of cation exchangers and humic and fulvic acids. Organic fouling results in production of low-quality (high conductivity, low pH), low amounts of water and some great problems such as early breakthrough and long washing periods after regeneration. The capacity of the ion-exchanger bed decreases and water with desired quality is not produced due to the fouling that was not removed fully by means of regeneration and backwashing [3,4]. Natural waters contain organic, inorganic and biological compounds in various ratios. Organic materials have a high share amongst these compounds. Sources of organic materials in these waters are decomposition products of wood and leaves or industrial and domestic wastes [5]. Organic materials are largely composed of humic materials. Humic materials are classified into three groups according to their solubilities in water [6]: (1) humin, that is the part which is not soluble at any pH value; (2) humic acid, that is the part which is not soluble in (pH <2) acidic medium but is soluble at high pH values; (3) fulvic acid, that is the part which is soluble in all pH values. It is believed that the chemical structure of these three fractions are alike. They appear to differ in molecular weight and functional group content. Fulvic acid probably has a lower molecular weight but more hydrophilic functional groups than humic acid [7]. According to McCoy [8], soluble organic materials such as humic and fulvic acids foul anion-exchange resins primarily with ion exchange. The chloride ions or hydroxyl anions within the humic acid structure are exchanged with the chloride, sulfate or hydroxyl anion on the quarternary amine that is grafted to the backbone of the anion-exchange resin molecule [9]. These fouling materials do not diffuse into the resin due to their molecular dimensions. They rather prevent ions moving into the resin by
accumulating physically onto the resin surface and blocking the ion-exchange points [4]. Organic materials make ion-exchange resin hydrophobic. Because of this, the moisture content of resins which fouled by organic materials decreases. This is a case which is to be avoided because it results in the decrease of porosity volume. As a result, the diffusion rate of counter ions and operating capacity decrease while the washing period and rinse water needed increase. Organic materials may also cause silicate leakage in anion exchangers where the silicate removal process is carried on. Silicate accumulates at the bottom of the anion-exchanger bed because the flow of water into resin is slowed down due to the blockage of resin pores by organic materials having high molecular weights [10]. There are some methods used for the purpose of cleaning of anion-exchange resins fouled by organic metarials. Washing with a caustic salt solution is the most used amongst other methods. This cleaning procedure is implemented by using 10% salt solution containing 2% NaOH of three times volume of bed volume [11]. The application of pretreatment processes is proposed before the ion-exchange system in order to protect the resins against organic fouling. Coagulation–flocculation, adsorption with actived carbon, membrane processes and oxidation/ biofiltration processes are used as pretreatment processes in the removal of organic materials [12]. In addition, the most resistant resin type must be chosen against fouling with organic materials. Acrylic-based resins are more resistant than styrene-based resins because they have a larger hydrophilic structure and ease the passage of high molecular organic materials from the resin due to their aliphatic structure. Organic materials could be removed effectively from the acrylic-based resins during regeneration [13]. 2. Materials and methods Changes in resin capacity were determined
Z. Beril Gönder et al. / Desalination 189 (2006) 303–307
quantitatively by searching fouling of resin with humic acid which is a fraction of humic material. Lewatit M 500, frequently used in demineralisation applications, was chosen as the strongly basic anion exchanger. Technical specifications of the resin (Lewatit M 500), provided from Bayer Leverkusen, are given in Table 1. A laboratory-scale glass column with a 2 cm diameter and 45 cm height was used throughout the experiments. The column was filled with a strong anion-exchange resin of 50 mL in volume. Synthetic water, prepared by dissolving Na2SO4 in distilled water with appropriate amounts resulting 150 mg/L SO42! content, was used. The synthetic water was supplied to the system by using a peristaltic pump (Prominent) and the feed rate was adjusted to V = 5.0 m/h (specific flow rate = 31 bed volume/h). A humic acid solution was used in the fouling studies. This solution was prepared according to the Urano method: 1 g humic acid was dissolved in 100 mL 0.1 N NaOH solution and then distilled water was added up to 1 L after waiting for 1 day [14]. The following method was used for the determination of changes occuring in ion-exchange capacity in the studies performed for the fouling Table 1 Technical specifications of the strongly basic anion exchanger (Lewatit M 500) Properties
Strongly basic anion exchanger
Ionic form Functional group
Cl! Quarternary amine, Type 1 Gel 1.4 0.47 40 NaOH 100 2–4
Structure Total capacity, min. eq /L Bead size, mm Flow rate, max. m/h Regenerant Regenerant level, g/L Regenerant con., %
305
of ion-exchange resins. The method is based upon the comparison of resin after being regenerated with a new resin sample [15,16]. In this study this method is taken as a reference. Changes in resin capacity during the fouling of the anion-exchange resin were determined by using humic acid in the amounts of 0.13, 0.25, 0.5 and 1.0 mg/L. The amount of 15 mg/L SO42! value was taken as the breakthrough point and column loading was continued until this value was reached at the outlet. SAK254 (Spektraler AbsorptionsKoeffizient = spectral absorption coefficient) [17], DFZ (Durchsichts Farbzahl = indexes of transparency) [18] and conductivity measurements were performed for the samples taken from the column outlet during fouling. SAK254 and DFZ436 measurements were made by using Jenway UV-Vis (model 6105) and Pharmacia LKB-Novaspec II spectrophotometers, respectively. Conductivity measurements were carried out by a WPA CM35 conductivity device. Sulphate measurements were implemented according to the turbidimetric method as defined in Standard Methods [19]. A 4% NaOH (12 bed volume/h) solution of 300 mL (6 bed volume) in volume was used for the strong anion-exchange resin regeneration. Cocurrent regeneration was carried out in the study. The regenerated resin was backwashed with distilled water until the conductivity of the effluent was less than 1 µS/cm.
3. Results and discussion A strong basic anion-exchanger was fouled with 0.13, 0.25, 0.5 and 1.0 mg/L humic acid and raw water was passed through after regeneration. The capacity of the ion exchanger was calculated by obtaining breakthrough curves belonging to the cycles of raw water passed through fresh ionexchanger resin and through ion-exchanger resin fouled with humic acid and subsequently regenerated (see Figs. 1–4).
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Fig. 1. Breakthrough curves obtained from the fouling of strong anion exchanger with 0.13 mg/L humic acid. (a) raw water, (b) raw water containing 0.13 mg/L humic acid, (c) raw water after regeneration.
Fig. 2. Breakthrough curves obtained from the fouling of strong anion exchanger with 0.25 mg/L humic acid. (a) raw water, (b) raw water containing 0.25 mg/L humic acid, (c) raw water after regeneration.
Fig. 3. Breakthrough curves obtained from the fouling of strong anion exchanger with 0.5 mg/L humic acid. (a) raw water, (b) raw water containing 0.5 mg/L humic acid, (c) raw water after regeneration.
Fig. 4. Breakthrough curves obtained from the fouling of strong anion exchanger with 1.0 mg/L humic acid. (a) raw water, (b) raw water containing 1.0 mg/L humic acid, (c) raw water after regeneration.
The capacity loss was found to be 21% for the fouling of anion-exchange resin with 0.13 mg/L humic acid. In this case, organic material causes high capacity losses even in small amounts. The capacity losses were found to be 23% and 25% for the humic acid amounts of 0.25 and 0.5 mg/L, respectively. A 30% capacity loss was observed as the humic acid amount reached 1.0 mg/L value. The capacity losses are shown in Fig. 5. Capacity losses increased as the humic acid amounts increased. The reason for this is that humic acid which is a high molecular organic material blocks the pores of anion exchange resin which in turn prevents ions moving into the resin.
This situation could not to be ceased even by the regeneration process [4]. DFZ436 and SAK254 parameters measured for the samples taken from the outlet of the ionexchange column were evaluated during fouling studies. DFZ was measured as zero for the samples taken up to 15 mg/L SO4= value which was chosen as the breakthrough point during the fouling studies made with 0.13, 0.25, 0.5 and 1.0 mg/L humic acid values. In other words, no colour was observed in the samples taken from the column outlet. SAK254 values were determined to be zero for samples taken up to the breakthrough point during the fouling of anion-
Z. Beril Gönder et al. / Desalination 189 (2006) 303–307
Fig. 5. Capacity losses occurring in strong anion exchange.
exchange resin with 0.13 and 0.25 mg/L humic acid. When the humic acid amount was 0.5 mg/L, SAK254 values were observed for the samples taken from column outlet after the passage of 15.3 L water fouled by humic acid (bed volume = 306). SAK254 value was measured as 0.9 m!1 at the breakthrough point. When the humic acid amount was 1.0 mg/L, SAK254 values were observed for the samples from the column outlet after the passage of 14.5 L water fouled by humic acid (bed volume = 290), and this value became 2.6 m!1 at the breakthrough point. The reason for this is the blockage of ion-exchange points existing in ion-exchanger’s structure by a large amount of humic acid. As a result, the capacity of resin decreases.
References [1] F.N. Kemmer, Ion Exchange, Nalco Water Handbook, 2nd ed., Mc Graw-Hill, New York, 1988, pp. 12.1–12.45. [2] P.N. Cheremisinoff and N.P. Cheremisinoff, Water Treatment and Waste Recovery: Advanced Technology and Applications, Prentice Hall, Englewood, NJ, 1993, pp. 288–289. [3] K. Dorfner, Ion Exchange Types, Ion Exchangers Properties and Applications, 2nd ed., Ann Arbor Science, Michigan, 1972, pp. 168–170.
307
[4] G.C. Lee, G.L. Foutch and A. Aranuchalam, Reactive Func. Polym., 35(10) (1997) 55–73. [5] H. Yıldırım, Contribution of ionic strength to the interaction of natural organic matter and metal oxide surface, Masters Thesis, Bogazici University, Istanbul, Turkey, 2000. [6] APHA-AWWA-WEF, Standard Methods for the Examination of Water and Wastewater, 19th ed., Washington, 1995, pp. 5.27–5.28. [7] S.A. Suphandag, Adsorption capacity of natural organic matter on semi-conductor powders, Master Thesis, Bogazici University, Istanbul, Turkey, 1998. [8] M. McCoy, Ion Exchange, Ultrapure Water, Tall Oaks, Littleton, CO, 1996, pp. 20–31. [9] R.G. Alther, Preventing Resin and Membrane Fouling with Clay Prepolish, Biomin, MI, 2000. [10] W. Bornak, Resin Analysis and Chemical Cleaning, 39th Liberty Bell Water Treatment Course, Atlantic City, New Jersey, 2001. [11] Purolite Company, The fouling of ion exchange resins and methods of cleaning, Purolite Technical Bulletin, 1998. [12] H. Ødegard, B. Eikbrokk and R. Storhaug, Water Sci. Technol., 40 (1999) 37–46. [13] J.F. Desilva, Removing organics with ion exchange resin, Water Conditioning Purification, (1997) 1–3. [14] S.C. Uyguner, Trace-level metals and natural organic matter interactions: Oxidative/adsorptive removal pathways, Master Thesis, Bogazici University, Istanbul, Turkey, 1999. [15] Deutsche norm, DIN 54 402: Bestimmung der Totalen Kapazität von Anionenaustauschern, Beuth, Berlin, 1982. [16] Deutsche norm, DIN 54 403: Bestimmung der Totalen Kapazität von Kationenaustauschern, Beuth, Berlin, 1982. [17] DIN 38404, Deutsche einheitsverfahren zur wasser-, abwasser-und schlammuntersuchung- physikalischchemische kenngröβen (gruppe C), Teil 3: Bestimmung der absorption im bereich der UV-strahlung; spektraler absorptionskoeffizient (C3), Beuth, Berlin, 2003. [18] H. Barlas and T. Akgun, Fresenius Environ. Bull., 9 (2000) 597–602. [19] APHA-AWWA-WEF, Standard Methods for the Examination of Water and Wastewater, 19th ed., Washington, 1995, pp. 4.136–4.137.