Association of Water Technologies, Inc. 19 th Annual Convention & Exposition November 7 to 10, 2007 The Broadmoor Hotel Colorado Springs, Colorado

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1 AWT-7 (Nov-7) Association of Water Technologies, Inc. 19 th Annual Convention & Exposition November 7 to 1, 7 The Broadmoor Hotel Colorado Springs, Colorado Selection and Application of Deposit Control Polymers as Iron Stabilization Agents in Industrial Water Treatment Programs Zahid Amjad, Ph.D. and Robert W. Zuhl, P.E. Lubrizol Advanced Materials, Inc Brecksville Road Cleveland, OH Carbosperse K-7 Water Treatment Polymers 7, The Lubrizol Corporation. All rights reserved.

2 Introduction Aluminum and iron based compounds (e.g., alum, sodium aluminate, ferric chloride) have been used for years as flocculating/coagulant aids to clarify municipal and industrial waters. 1 These compounds neutralize the charge of suspended particles in the water and they hydrolyze to form insoluble hydroxide precipitates that entrap additional particles. In most cases, these large particles (or flocs) are removed via settling in a clarifier and are collected as sludge. Occasionally, clarifier upsets cause the metal containing flocs to carry over. Among the various dissolved impurities present in natural waters, iron-based compounds present the most serious problems in many domestic and industrial applications. In the reduced state, iron (II) or ferrous (Fe 2+ ) ions are very stable and pose no serious problems, especially at low ph values. However, upon contact with air, ferrous ions are oxidized to higher valence state and readily undergo hydrolysis to form insoluble hydroxides as shown below air Fe 2+ Fe +3 Fe H 2 O Fe(OH) 3 + 3H + In addition to feed water, sources that may contribute to iron fouling include boiler condensate, corrosion products from pumps and pipes, and biological activity (transformation of iron during bacterial processes). The solubility of iron compounds in industrial water systems is determined by their form as well as their solubility product constant. The amount of the dissolved iron containing compounds in water is dependent on several factors including ph, temperature, total dissolved solids, and type and concentrations of anions. When ferric or ferrous ions precipitate in water, an amorphous or gelatinous solid is usually formed. At low corrosion rates, the iron hydroxide formed may deposit on the heat exchanger surface as a permeable or impermeable film at the corrosion site. Iron hydroxides that form under these conditions are colloidal and form stable suspensions. Other types of iron-based compounds that can potentially deposit on the heat exchanger surfaces include iron carbonate, iron silicate, iron sulfide, etc. Additionally, it has been reported that soluble metal ions (i.e., Cu, Fe, Zn, Mn) interfere with the performance of calcium carbonate and calcium phosphate scale inhibitors. 2,3 The use of synthetic polymers (i.e., polyacrylates, polymethacrylates, hydrolyzed polyacrylamides, acrylic acid/acrylamide copolymers) dates back to the 195s. The early synthetic polymers used were high (>1,) molecular weight (MW) homopolymers of acrylic acid. With the passage of time, lower molecular weight (<1,) polyacrylates as well as polymethacrylates and polymaleic acids were found to be more efficacious. Researchers have shown that polyacrylate MW is an important consideration relative to performance. 4 Eventually, copolymers of acrylic acid, methacrylic acid, and/or maleic acids with a variety of other co-monomers [e.g., sulfonated styrene (SS), 2-acrylamido-2-methyl propane sulfonic acid (SA), substituted acrylamides] were found to provide improved performance characteristics in various 2

3 applications including, boiler, cooling, geothermal, oil field, and desalination (thermal and membrane based) processes. 5,6 Thermal degradation of polymers is a well studied area but limited information of practical value is available to water technologists pertaining to the use of thermally degraded low molecular weight polymers. Polymers used in geothermal and boiler water treatment programs should be able to sustain high temperature and pressure environments normally associated with high temperature processes. Denman and Salutsky 7 briefly examined the thermal stability of a sodium poly(methacrylate) under dry conditions and they found no change to 316 C after one (1) hour but some charring at 371 C. In 1982, Masler presented Lubrizol s initial research efforts on the thermal stability of several homopolymers [i.e., polyacrylic acids (PAAs), polymethacrylic acids (PMAAs), polymaleic acid (PMAs)] commonly used in boiler applications. 8 These homopolymers were (before and after thermal stress) (a) characterized by various analytical techniques and (b) evaluated for their performance. It was demonstrated under the conditions employed [ph 1.5, 25 C (592 psig), 18 hr] that PAA, PMAA, and PMA all underwent some degradation. In terms of MW loss, PMAA lost slightly less MW than PAA which lost considerably less than PMA. Additionally, PAA and PMAA had minimal performance changes whereas PMA displayed a substantial loss in performance. Several years latter, Amjad used a similar test methodology to evaluate the thermal stability of several co-polymers. The results of this study, 9 showed that the performance of polymers subjected to thermal stress is affected both by temperature level and exposure time. Over the last two decades, the performance of polymers as scale inhibitors and dispersants has attracted the attention of academic researchers and industrial technologists It has been reported that water chemistry and polymer architecture play important roles in inhibiting the precipitation of scale forming salts and also in dispersing suspended matter under stressed system conditions (i.e., high hardness, high alkaline ph, high temperature). However, the role of polymer architecture in stabilizing various metal ions has been the subject of limited research. The results presented in this paper is a part of Lubrizol s broader research efforts to understand the impact of polymer architecture (i.e., polymer composition, molecular weight, ionic charge) in stabilizing metal ions (e.g., aluminum, copper, iron, manganese, zinc). The focus of the present paper is to investigate the performance of several commercially available deposit control polymers as stabilizing agents for ferric ions. In addition, we also conducted experiments to study the impact of thermal treatment on polymer performance. 3

4 Experimental The polymers used in this study were commercial polymers and their characteristics are shown in Table 1. The polymers tested fall into the following three categories: Homopolymers of acrylic, maleic, and sulfonic acids Copolymers of acrylic/maleic acid and sulfonic acids Terpolymers containing combinations of carboxyl (e.g., acrylic acid, maleic acid), sulfonic acid, and/or non-ionic groups. Sample Preparation A 1% polymer solution (as active solids) was prepared at ph 1.5 using sodium hydroxide as the neutralization agent. Sodium sulfite was added as an oxygen scavenger. A known amount of polymer solution was retained for characterization and performance testing. The balance was charged to a stainless steel tube. The headspace was purged with nitrogen followed by tightening the fittings. The tube was then placed in the oven maintained at the required temperature [either 15ºC (84 psig), ºC (241 psig), or 2 o C (47 psig)]. After hr, the tube was removed from the oven, cooled to room temperature, and solution transferred to vials for characterization and performance testing. Ferric Ion Stabilization Test Method A known amount of Fe +3 as Fe(NO 3 ) 3 was added to a known volume of synthetic water containing varying amounts of iron stabilizing stock solution in 125 ml glass bottles. The synthetic water (14 mg/l Ca, 31 mg/l Mg, 361 mg/l Na, 2 mg/l SO 4, mg/l Cl, and 146 mg/l HCO 3 ) was prepared by mixing standard solutions of calcium chloride, magnesium chloride, sodium sulfate, sodium chloride, and sodium bicarbonate. After adding the Fe +3 solution to the synthetic water, the solution ph was adjusted to 7. with dilute sodium hydroxide. The experimental solutions were then stored at 23 C without stirring. At 2 hr, the solutions were filtered through.22 micron filter and the filtrate analyzed for iron by Inductively Coupled Plasma Optical Emission Spectroscopy. The experimental set-up used in the present investigation is shown in Figure 1. The polymer performance for iron ion stabilization was calculated according to the following equation: [Fe] sample --- [Fe] blank S = x 1% [Fe] initial --- [Fe] blank Where: S = Stabilization (%) or %S [Fe] sample = Fe concentration in the presence of stabilizing agent at 2 hr [Fe] blank = Fe concentration in the absence of stabilizing agent at 2 hr [Fe] initial = Fe concentration in the beginning of experiment 4

5 The term stabilization used in this paper refers to an ability of the polymer to inhibit metal ion hydrolysis/precipitation and/or form soluble complexes. 14 In practice, it may be difficult to differentiate between truly soluble and very finely dispersed particles. Under the conditions employed in the present work, % stabilization or %S is defined as that concentration of the ionic species which is not removed by filtration through a.22 micron membrane filter. It should be noted that the terms complexation, chelation, and sequestration are generally applied to phenomena where ions or complex species are maintained in a soluble form. On the other hand, dispersion of particles is generally recognized as de-agglomeration of pre-formed large particles. Ferric Ion Stabilization Results and Discussion Effect of Polymer Dosage: The Fe +3 stabilization performance of a 2, MW PAA (HPAA1 or Carbosperse K-752 polyacrylate) as a function of polymer dosage was investigated by a series of experiments. The results in Figure 2 show that HPAA1 exhibits poor iron stabilization at low concentrations (e.g., 4% and 25% stabilization in presence of 5 ppm and 1 ppm of K-752, respectively) whereas doubling the HPAA1 concentration (i.e., from 1 to ppm) yields 9% iron stabilization (a 3.5x increase). Effect of Polymerization Solvent: Previous investigations have shown that polymerization solvent plays an important role in the performance of poly(acrylic acids) or PAAs as both precipitation inhibitors for sparingly soluble salts and suspended matter dispersants. 15,16 It was also reported 17 that solvent polymerized PAAs are more tolerant to calcium ions than the water polymerized PAAs of similar MW. A series of experiments were conducted to understand the impact of manufacturing process polymerization solvent (organic and water) on iron stabilization using ppm PAA dosages. Figure 3 shows that the solvent polymerized PAAs (i.e., HPAA1 [K-752] and HPAA2 [K-732]) exhibit ~1.5x better performance than comparable MW water polymerized PAAs (i.e., HPAA4 [K-728] and HPAA5 [K-758]). In addition, Figure 3 illustrates that PAA performance decreases as the PAA MW increases from 2k for HPAA1 (K-752) to 6k for HPAA2 (K-732]. The influence of MW on the performance of PAAs as observed for iron stabilization is consistent with previous reports on the performance of PAAs as scale inhibitors for calcium carbonate, calcium sulfate, and calcium fluoride. 18- Homopolymer Performance: Figure 4 shows the performance of several homopolymers. In the presence of ppm PAAs, the %S varies from 34% to 9% depending upon the MW and polymerization solvents. The iron stabilization of homopolymers containing several different functional groups (i.e., carboxylic acid, phosphino and carboxylic acid, sulfonic acid, and sulfonated styrene) was also investigated. The results show that the polymaleic acid (HPMA) or the homopolymer containing two (2) carboxylic acid groups on adjacent carbon atoms exhibited poor performance compared to single carboxylic acid containing polyacrylates (e.g., HPAA1). This is noteworthy because the HPMA compared to HPAA1 (K-752) is touted as a 5

6 better calcium carbonate inhibitor but as shown herein is a poorer iron stabilization agent than HPAA1. Furthermore, the poly(sulfonic acid) homopolymer (HPSA), poly(sulfonated styrene) homopolymer (HPSS), and poly(aa) with phosphinate groups (HPAAP touted as an iron stabilizer for boiler water applications), are ineffective iron stabilization agents under these test conditions. The data presented in Figure 4 clearly point out the importance of homopolymer functional groups. Copolymer Performance: Incorporating other functional groups of varying chain length and ionic charge such as 2-acrylamido-2-methylpropane sulfonic acid (SA) and/or sulfonated styrene (SS) into carboxyl-based polymers creates polymers that exhibit varying Fe +3 stabilization properties. As shown in Figure 5, the homopolymers of acrylic acid (AA) and sulfonic acid (SA) or HPAA2 and HPSA, respectively provide poor performance. However, all three (3) of the copolymers of AA and SA monomer groups provide significantly greater iron stabilization than the comparable MW homopolymers of the component monomers; the %S values in the presence of 1 ppm CPAS1 (AA:SA), HPAA2 (AA), and HPSA (SA) were 84%, 4%, and 2%, respectively. Similarly, maleic acid (MA) and sulfonated styrene (SS) hompolymers or HPMA and HPSS, respectively provide poor iron stabilization performance. However, a copolymer of MA and SS monomer groups (CPMS) provides excellent iron stabilization. In summary, whereas homopolymers of AA (HPAA2), MA (HPMA), SA (HPSA), and SS (HPSS) show poor performance, the incorporation of a sulfonated monomer (SA or SS) with a carboxylate monomer (AA or MA) significantly improves iron stabilization performance. Figure 5 also shows that the three (3) AA:SA copolymers of similar monomer ratios and molecular weights (i.e., CPASx where x is 1, 2, or 3) have different iron stabilization properties with CPAS1 (K-775) outperforming the other two (2) comparable copolymers. This suggests that more than monomer combinations impacts performance. Figure 6 compares the performance of homo-, co-, and ter-polymers as Fe +3 ion stabilizing agents. The data indicate that %S values increase with increasing polymer dosages and increasing polymer sulfonate group (SA and/or SS) content. The positive influence of combining AA and SA was shown previously in Figure 5 and is further enhanced by the addition of a second sulfonate group (SS). As shown in Figure 6, %S values obtained in the presence of 7.5 ppm dosages of HPAA1 (K-752), CPAS1 (K-775), and TPASS1 (K-781) are 6%, 42%, and 98%, respectively indicating a dramatic performance improvement by incorporating the second sulfonated monomer group (or SS). The iron stabilization performance of polymers containing three (3) or more different functional groups was investigated. The data in Figure 7 indicate that the AA:SA-based terpolymers (TPASS [K-781] and TPASN containing SS and NI groups, respectively) provide much better iron stabilization performance than the other polymers tested. In addition, the AA:SA copolymers (CPAS1 and CPAS4 or K-775 [75:25] and K-776 [:], respectively) slightly provide better performance than the two (2) MA-acrylatesbased copolymers (MCP and MFP). Based on its higher SA content, one would expect CPAS4 to provide better iron stabilization performance than CPAS1 but values are 6

7 close and MW (is lower for the latter) is more important in this case). It s clear that the types of functional groups, relative ratios of monomer groups, and MW all play roles in a polymer s iron stabilization performance. Effect of Solution ph It is generally accepted that increasing the recirculating water ph has a two-fold effect on system performance: (a) tends to decrease metal corrosion rate and (b) increases scaling tendencies by increasing the supersaturation of scale forming salts. It is well recognized that the degree of de-protonation explains polymer performance improvements observed with increasing solution ph (from 4.5 to 9.) for polymeric inhibitors such as PAA and AA and/or MA-based co- and ter-polymers. 21 Figure 8 shows iron stabilization data for three (3) commonly used polymers with different compositions: HPAA1 (K-752), CPAS1 (K-775), and TPASS (K-781). As illustrated, solution ph in the range 7. to 8.5 range influences to varying degrees the Fe +3 ion stabilization power of these polymers; i.e., the %S values for homo-, co-, and ter-polymers tested decrease by a factor of 1.5 to 2 as ph increases. A similar polymer performance trend was observed in an earlier study on the interactions of hardness ions with polymeric scale inhibitors. 22 Effect of Heat Treatment on Polymer Performance The before and after thermal treatment ( C for hr) iron stabilization performance data for two (2) homopolymers [acrylic acid (HPAA1) and sulfonic acid (HPSA)] and an P-AA:SA copolymer (CPAS4) are shown in Figure 9. It is evident that heat treatment exposure causes a small but measurable effect on the performance of HPAA1 (K-752); e.g., the %S values decreased from 99% to 93% before and after heat treatment, respectively. A similar decrease in performance was also observed (but is not shown herein) for the other PAAs evaluated. In contrast, thermal exposure increases the iron stabilization property of P-SA (HPSA). The data in Figure 9, indicate %S values for HPSA are 32% after thermal treatment compared to 4% before heat treatment. The performance improvement observed for heat treated HPSA may be attributed to the conversion of P-SA to P-AA. A similar heat treated P-SA performance improvement was observed in our earlier study on calcium carbonate inhibition in aqueous solutions. 11 The data in Figure 9 show that heat treatment ( C for hr) has a negative influence on the iron stabilization performance of CPAS4 (P-AA:SA copolymer). Specifically, the %S values obtained in the presence of 25 ppm of the non-heat treated CPAS4 was 99% compared to 83% after heat treatment; a >16% performance loss attributable to degradation of SA groups to AA groups. A similar performance decrease was observed for other P-AA:SA copolymers tested as part of this study and previously when evaluated as calcium phosphate inhibitors. 9 The influence of temperature on the thermal stability of polymers was investigated at C (241 psig). Figure 1 shows a comparison of the two (2) acrylate terpolymers 7

8 that have the same baseline performance before thermal stress. These data indicate that the thermal stability (as determined by retention of performance after thermal treatment) of TPASS (K-781) is better than TPASN. Although two (i.e., AA and SA) of the three (3) monomers used to manufacture these acrylate terpolymers are the same, the dissimilar third monomer or functional group plays a key role in explaining the performance difference between these terpolymers. The influence of temperature (i.e., 15, and 2 C) on the thermal stability of polymers was also investigated. Figure 11 shows a comparison of the terpolymers TPASS and TPASN that have the same baseline performance before heat treatment. However, as the polymers are exposed to 15 C, C, and 2 C a marked decrease in iron stabilization is observed. As noted in Figure 11, increasing solution temperature from 15 to C resulted in a significant decrease in performance for each of the terpolymers. It is worth noting the results at 2 C, TPASS (K-781) lost 67% of its performance compared to TPASN which lost of >85% of its performance. The data presented in Figure 11 clearly show that TPASS (K-781) is more tolerant to heat treatment than TPASN. Influence of polymers on iron hydroxide particles stabilization The impact of polymers on iron hydroxide particles was investigated. Figure 12 shows optical micrographs of iron hydroxide particles collected on the filter papers at the end of experiments for HPAA1 (K-752), CPAS1 (K-775), and TPASS (K-781). As shown, K-781 is an effective Fe +3 ions stabilizer (the darker the yellow color, the more iron hydroxide precipitated from solution). Summary A wide variety of deposit control polymers are available to technologists that are involved in developing new water treatment programs to achieve desired performance objective. The key to successful operation of industrial water systems largely depends upon selecting formulation additives that deliver performance under stressed operating conditions. This paper has shown that polymer architecture plays an important in stabilizing ferric ions in aqueous systems. The conclusions from this study appear below: 1. Homopolymers of acrylic acid, maleic acid, sulfonic acid, and sulfonated styrene are ineffective ferric ions stabilization agents. 2. Polyacrylates made in organic solvent perform better that water polymerized polyacrylates. 3. Compared to homopolymers, co- and ter-polymers containing sulfonic acid and/or sulfonated styrene groups exhibit excellent Fe +3 stabilization performance. 4. Solution ph markedly affects the performance of homo-, co-, and ter-polymers. 8

9 5. Thermal treatment of polymers (1% polymer solutions stored for hr; ph 1.5; in the absence of oxygen; for 15ºC, ºC or 2ºC) has pronounced and varied effects on a polymer s Fe +3 stabilization performance as follows: a. PAAs (e.g., HPAA1) experienced some (<15%) performance loss. b. The performance of a poly(sulfonic acid) homopolymer (HPSA) exposed to heat improved presumably due to the formation of poly(acrylic acid). c. P-AA:SA copolymers (e.g., CPAS4) experienced degradation of the SA group and corresponding performance decreases. d. Terpolymers experience varying degrees of performance loss depending upon the degree of thermal stress and polymer composition. However, among the two (2) AA:SA-containing terpolymers, TPASS (containing SS) is more stable than TPASN (containing a non-ionic monomer). Acknowledgements The authors wish to thank The Lubrizol Corporation for permission to carry out the studies and present the results to the Association of Water Technologies. References 1. J. C. Cowan and D. J. Weintritt, Water Formed Scale Deposit, Gulf Publishing Company, Houston, Texas (1976). 2. Z. Amjad, J. F. Zibrida, and R. W. Zuhl, Performance of Polymers in Industrial Water Systems: The Influence of Process Variables, Materials Performance, 36 (1), 32 (Jan-97). 3. Z. Amjad, D. Butala, and J. Pugh, The Influence of Re-circulating Water Impurities on the Performance of Calcium Phosphate Inhibiting Polymers, CORROSION/99, Paper No. 118, NACE International, Houston, TX (1999). 4. Z. Amjad, Development of Calcium Phosphate Inhibiting Polymers for Cooling Water Application, Chapter No. 16, Calcium Phosphates in Biological and Industrial Systems, Z. Amjad (Ed.) Kluwer Academic Publishers, Boston, MA (1998). 5. Z. Amjad, R. W. Zuhl, and J. F. Zibrida, The Use of Polymers to Improve Control of Calcium Phosphonate and Calcium Carbonate in High Stressed Cooling Water Systems, Association of Water Technologies 4 Annual Convention, Nashville, TN, November (4). 6. W. F. Masler and Z. Amjad, Advances in the Control of Calcium Phosphonate with a Novel Polymeric Inhibitor, CORROSION/1988, Paper No. 11, NACE International, Houston, TX (1988). 7. W. L. Denman and M. L. Salutsky, Boiler Scale Control with Polyacrylates and Polymethacrylates, Proceedings of the 28 th International Water Conference, Pittsburgh, PA (1967). 9

10 8. W. F. Masler, Characterization and Thermal Stability of Polymers for Boiler Treatment, 43 rd Annual Meeting, International Water Conference, Pittsburgh, PA, October, (1982). 9. Z. Amjad and R. W. Zuhl, The Impact of Thermal Stability on the Performance of Polymeric Dispersants for Boiler Water Systems, Association of Water Technologies 5 Annual Convention, Palm Springs, CA (5). 1. P. G. Klepetsanis, A. Kladi, P. G. Koutsoukos, and Z. Amjad, The Interaction of Water Soluble Polymers with Solid Substrates. Implications on the Kinetics of Crystal Growth, Progr. Colloid Poly Sci. 115, (). 11. Z. Amjad and R. W. Zuhl, Kinetic and Morphological Investigation on the Precipitation of Calcium Carbonate in the Presence of Inhibitors, CORROSION/6, Paper No. 6385, NACE International, Houston, TX (6). 12. L. Perez and D. Freese, Scale Prevention at High LSI, High Cycles, and High ph without the Need for Acid Feed, Paper No. 174, CORROSION/1997, NACE International, Houston, Texas (1997). 13. Z. Amjad, Dispersion of Iron Oxide Particles in Industrial Water Systems, Tenside Surfactants Detergents, 36 (1) 5-56 (1999). 14. K. P. Fivizzani, L. Dubin, B. E. Fair, and J. F. Hoots, Manganese Stabilization by Polymers for Cooling Water Systems, CORROSION/1989, Paper No. 433, NACE International, Houston, TX (1989). 15. R. W. Zuhl and Z. Amjad, The Role of Polymers in Water Treatment Applications and Criteria for Comparing Alternatives, Association of Water Technologies 1993 Annual Convention, Las Vegas, NV (1993). 16. Z. Amjad and R. W. Zuhl, The Influence of Water System Impurities on the Performance of Deposit Control Polymers as particulate Dispersants, Association of Water Technologies 1 Annual Convention, Dallas, TX (1). 17. Z. Amjad, R. W. Zuhl, and J. F. Zibrida, Factors Influencing the Precipitation of Calcium-Inhibitor Salts in Industrial Water Systems, Association of Water Technologies 3 Annual Convention, Phoenix, AZ (3). 18. Z. Amjad, Effect of Precipitation Inhibitors on Calcium Phosphate Scale Formation, Canadian Journal of Chemistry, 67, 85 (1988). 19. Z. Amjad and J. Hooley, Influence of Polyelectrolytes on the Crystal Growth of Calcium Sulfate Dihydrate, J. Colloid Interface Sci. 111 (2) (1986).. Z. Amjad, Inhibition of Calcium Fluoride Crystal Growth by Polyelectrolytes, Langmuir 7, (1991). 1

11 21. Z. Amjad, Kinetics of Crystal Growth of Calcium Sulfate Dihydrate. The Influence of Polymer Composition, Molecular Weight, and Solution ph, Can J. Chem. 66, (1988). 22. Z. Amjad, Interactions of Hardness Ions with Polymeric Scale Inhibitors in Aqueous Systems, Tenside Surfactants Detergents 42, (5). Table 1 Deposit Control Polymers Investigated Type* Mol. Wt. Acronym Solvent-based poly(aa) ~2,** HPAA1 (K-752) 1 Solvent-based poly(aa) ~6,** HPAA2 (K-732) 1 Solvent-based poly(aa) 2,*** HPAA3 Water-based poly(aa) ~2,** HPAA4 (K-728) 1 Water-based poly(aa) ~7,** HPAA5 (K-758) 1 Water-based poly(aa) 4,5*** HPAA6 Poly(AA) with phosphinate groups ~3,*** HPAAP Poly(MA) ~1,*** HPMA Poly(SA) ~7,5 HPSA Poly(SS) 25,** HPSS Poly(MA:SS),*** CPMS Poly(MA:EA:VAc) ~*** MCP Poly (AA:MA:MMA:SA)** 5,** MFP Poly(AA:SA) <15,** CPAS1 (K-775) 1 Poly(AA:SA) 4,5*** CPAS2 Poly(AA:SA) ~4,*** CPAS3 Poly(AA:SA) >1k & <k** CPAS4 Poly(AA:SA:SS) <1,** TPASS (K-781) 1 Poly(AA:SA:NI) 4,5*** TPASN * Key to abbreviations: AA = acrylic acid, MA = maleic acid, SA = sulfonic acid (2-acrylamido-2- methylpropane sulfonic acid), SS = sulfonated styrene, EA = ethyl acrylate, VAc = vinyl acetate, MMA = methylmethacrylate, NI = non-ionic monomer. ** Lubrizol Advanced Materials, Inc. measurement (molecular weight) 2 or analyses (e.g., composition). *** Product literature or industry publication value. 1 Lubrizol Advanced Materials, Inc. Carbosperse Polymer. 2 Lubrizol Advanced Materials, Inc. Test Procedure, Carbosperse K-7 Polymer Molecular Weight Determinations by Aqueous GPC Method (Equipment, Conditions, and Analyses), The Lubrizol Corporation (Jun-7). 11

12 Figure 1. Experimental Setup Sample.22 μ m filter Sampling Port Filtrate Soluble Fe Analysis Retentate Particle Characterization Thermostatted Water Out Thermostatted Water In Magnetic Stirrer ph Meter 1 Figure 2. Fe +3 Stabilization by HPAA1 (K-752) Synthetic w ater, 3 ppm Fe +3, ph 7., 23 C, 2 hr %S HPAA1 (K-752) dosage (ppm) 12

13 %S 1 Figure 3. Effect of PAA Mfg. Process on Fe +3 Stabilization Synthetic w ater, 3 ppm Fe +3, ppm polymer, ph 7., 23 C, 2 hr HPAA1 HPAA2 HPAA4 HPAA5 2k MW PAAs 6k to 7k MW PAAs Solvent Water %S 1 Figure 4. Fe +3 Stabilization by Homopolymers Synthetic w ater, 3 ppm Fe +3, ppm polymer, ph 7., 23 C, 2 hr Solvent-Based PAAs Water-Based PAAs HPAA1 HPAA2 HPAA3 HPAA4 HPAA5 HPAA6 HPAAP HPMA HPSA 13

14 1 Figure 5. Polymer Function Group Impact on Fe +3 Stabilization Synthetic w ater, 3 ppm Fe +3, 1 ppm polymer, ph 7., 23 C, 2 hr %S HPAA2 HPSA CPAS1 CPAS2 CPAS3 HPMA HPSS CPMS 1 Figure 6. Fe +3 Stabilization by Polymers Synthetic w ater, 3 ppm Fe +3, ph 7., 23 C, 2 hr %S Polymer Dosage (ppm) HPAA1 (K-752) CPAS1 (K-775) TPASS K-781) 14

15 1 Figure 7. Fe +3 Stabilization by Copolymers Synthetic w ater, 3 ppm Fe +3, 6 ppm polymer, ph 7., 23 C, 2 hr %S CPAS1 CPAS4 TPASN TPASS MCP MFP %S Figure 8. Solution ph Effect on Fe +3 Stabilization by Polymers Synthetic w ater, 3 ppm Fe +3, 1 ppm polymer, ph 7., 23 C, 2 hr 1 ph 7. ph 8.5 HPAA1 (K-752) CPAS1 (K-775) TPASS (K-781) 15

16 1 Figure 9. Heat Treatment Effect on Fe +3 Stabilization by Polymers (Synthetic w ater, 3 ppm Fe +3, 25 ppm polymer, ph 7., 2 hr) %S HPAA1 HPSA CPAS4 23 C C 1 Figure 1. Effect of Heat Treatment on Fe +3 Stabilization by Terpolymers Synthetic w ater, 3 ppm Fe +3, 6 ppm polymer, ph 7., 2 hr %S 23 C C TPASS TPASN 16

17 1 Figure 11. Heat Treatment Temperature Effect on Fe +3 Stabilization by Terpolymers Synthetic w ater, 3 ppm Fe +3, 6 ppm polymer, ph 7., 2 hr %S TPASS TPASN 23 C 15 C C 2 C Figure 12. Iron Hydroxide Precipitates Formed in the Absence and Presence of Polymers No Polymer HPAA1 (K-752) CPAS1 (K-775) TPASS (K-781) 17

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