Document VyRG7oy07bwqbopJyQpNoDjp

\\ Contains confid Resipon^bilitMT\^E \tfe^SrpTent. on. When/no longer*needed, destroy by burnii^g or shredding. Distribution on last page. CDP-ES-80-1 Issued 3/21/80 Copy No. Ik T. C MERCER, JR. C&F DEPT. INFORMATION SERVICES JACKSON LABORATORY EXPERIMENTAL STATION RESEARCH AND DEVELOPMENT DIVISION TECHNICAL REPORT CHEMICALS, DYES AND PIGMENTS DEPARTMENT ___________E. 1. DU PONT DE NEMOURS & COMPANY SURFACE CHEMISTRY OF TiOg * PART III work Done By: Report Written By: Approved By: Patent Situation Approved By: Previous Related Reports: Project Code: Type Technical Work: Period Covered: Notebook Nos.; Personnel: Lloyd Abrams Lloyd Abrams K. K. Bhatia J. W. Heberling, Jr, Date 1/7/80 PTD-SA-78-1B, CDP-EX-78-15 7053-184084, 7053-184082 IEB June 1978 - October 31, 1979 E13871, E16068, E16080, E16105, E16106 L. Abrams, R. E. Johnson, L. J. Janvier, J. V. Hughes, E. Z. Krams, P. R. Spring ABSTRACT We continued our research on the direct preparation of slurry from reactor discharge material; improved our understanding of the effects of surface alumina on colloidal properties and defined the restructuring of co-oxidized alumina on contact with water. Significant differences in pigment surface chemistry were determined by adsorption/desorption of aluminum onto pigments in aqueous suspension. R-900 CD (base) adsorbs aluminum from >20 ppm solutions. N40792 - II - CDP-ES-80-1 but R-960 does not adsorb any. This work indicates that modification of the alumina deposition on R-960 is a possible route to a high gloss, durable pigment permitting grade reduction/consolidation. i in related work, we found that R-960 has the same aggregate size as R-900 after micronizing, but it gradually agglomerates in sus pension because of limited surfactant adsorption and surface coating * solubility. Research has continued to better understand the interactions between a pigment's surface and end-use systems. We have related pigment flocculation to surface chemistry, equilibrium pH, zeta potential and surfactant adsorption. As little as 1/4 of a monolayer of a strong anionic surfactant has a large influence on colloid stability. Adsorp tion of Tamol 731, which behaves like a simple anion, decreases with increasing pH and depends on pigment surface chemistry. m' DUP050059347 - Ill CDP-ES-80-1 I, INTRODUCTION The primary use of Ti02 is to provide opacification which is related to its index of refraction and controlled particle size. Because TiOj pigments are composed of small particles with high surface area, surface chemistry governs their end-use performance. For example, our durable pigment grades are coated with silica to effectively eliminate photo-reactivity problems. Some pigments are coated with alumina to make them more dispersible in many end-use systems. Some customer formulations require high volume loadings of our pigments. For these crowded systems, we coat our pigments with combinations of oxides to prevent the pigment particles from getting too close together. Such crowding would result in a loss of lightscattering efficiency. We alter the surface chemistry of some pigments during their manufacture to improve their processability. For example, small amounts of alumina are used to control agglomeration of slurries and improve their filtration rates. Knowledge of pigment surface chemistry is therefore important to TiOo production and its end-uses. Previous work in this area is reported in PTD-SA-78-1B and CDP-EX-78-15. My program is to learn how to control the surface chemistry of our Ti-Pure pigments and maximize their end-use performance. The motivation for this program is: to provide guidance and methods of product control to our process and product groups to resolve customer problems more efficiently to meet anticipated customer needs of future end-use chemical systems to provide our customers with counter-offerings that out-perform our competition to support our cost reduction program by reducing the number of grades, make the remaining grades compatible with more end-uses, and reduce mill-costs by making slurry directly from cyclone discharge. II. OBJECTIVE The objective of this study is to gain further insight into the surface chemistry of Ti02 pigments and apply it to support the cost reduction and product improvement programs of White Pigments and Minerals R&D. DUP050059348 - IV CDP-ES-80-1 III. SUMMARY AND CONCLUSIONS Developed a working hypothesis describing the effects of surface alumina on pigment colloidal properties and then developed an improved understanding of co-oxidized alumina associated with TiOjj and how it restructures upon contact with water. Measured the desorption/adsorbtion of aluminum by pigments in aqueous suspension. Pound that R-900 CD (base) adsorbs soluble aluminum in concentrations >20 ppm whereas R-960 showed no sorption. This work indicates that we should be able to make slurry directly using reactor discharge material. Developed rationale to relate pigment flocculation behavior to information about surface chmistry, equilibrium pH, zeta potential-pH character and surfactant adsorption. As little as 1/4 of a monolayer of a strong anionic adsorbent was observed to have a large effect on colloid stability. Measured adsorption of Tamol 731, a widely used anionic sur factant, and found adsorption decreased with increasing pH. Found that this drop-off trend relates to the pigment surface chemistry. Adsorption mechanism for Tampl appears similar to mechanism for simple anion adsorption. This work provides the basis for understanding how a pigment surface interacts with end-use chemical systems. Found that R-960 (durable silica/alumina coated pigment) has the same aggregate size as R-900 (alumina coated) after micronizing. Determined that R-960 agglomerates in suspension with time because of the slow rate of surfactant adsorption. This work indicates that the deposition conditions for alumina should be modified. If accomplished, a high-gloss, durable pigment can be made and grades consolidated. Began program to accelerate settling of Florida humate and eliminate need for extensive settling ponds. Found an alternate route to 'wet' R-101 using F- as floccu lating agent instead of alumina. Began study of competitive pigments to identify micro-physical and chemical surface properties that determine end-use performance. This information would direct studies to making pigments with surfaces permitting broad acceptance in end-use classes, thereby permitting grade consolidation without loss of sales. A study of the surface modification of SDG was begun to improve gloss and viscosity stability of R-950 slurry. DUP050059349 V - CDP-ES-80-1 IV. PATENT SITUATION None yet. V.PROGRAM J H. Boughton will continue portions of this study. VI. PUBLICATION STATUS None. VII. SPECIAL SAFETY PRECAUTIONS None. VIII. ENVIRONMENTAL CONSIDERATIONS None IX. ACKNOWLEDGEMENT The author gratefully acknowledges the close collaboration with R. E. 'Ted' Johnson (CR&DD) in doing most of this research. Discussions with John Boughton, Luis Matienzo and Dave Schussler were quite helpful. The excellent lab work of Dolly Janvier, Jerry Hughes, Ed Krams and Paul Spring in doing the described experiments were indispensable to the author. DUP050059350 - vi TABLE OF CONTENTS I. Introduction .... II. Objectives ..... III. Summary & Conclusions IV. Patent Situation . . V. Program ....... VI. Publication Status VII. Special Safety Precautions VIII. Environmental Considerations IX. Acknowledgement . ...... X. Experimental and Discussion . A. Restructuring of Surface Alumina B. Zeta Potential Histograms ... C. Analysis of Soluble Aluminum , . D. R--950 Slurry .... . ..... E. Particle Size Measurements of Pigment Dispersions . . . . . F. Competitive Pigments . . G. Tamo! Adsorption Studies H. Miscellaneous studies XI. References . . XII. Appendix . . . XIII. Indexing Terms Figures 1 thru 31 . Distribution . . . CBP-ES-80-1 Page . Ill . Ill . IV V .V V .V V V 1 1 3 3 6 8 13 15 18 19 20 23 24-54 55 DUP050059351 1 CDP-ES-SO-1 X, EXPERIMENTAL AND DISCUSSION A. Restructuring of Surface Alumina While using zeta potential as one of the techniques to characterize R-900 cyclone discharge, R. E, Johnson and I observed that the zeta potentials shifted with time. This phenomenon is illustrated in Figure 1. The "initial1* curve is the zeta potential-ph curve for the R-900 CD (cyclone discharge) "as received". After some time (hours) in aqueous suspension (at the pH's indicated, room temp., and in plastic containers) the zeta potential values climbed to give the curve "after exposure". By combining this observation with the information from the open literature (for example, Healy, Parfitt, etc.) and the work of Prof. L. L. Bench (consultant), J. H. Boughton and others, we developed a definitive picture of the chemistry involved for understanding the effect of A1 (from co-oxidation) on the behavior of aqueous slurried R-900 CD. In essence, we observed that aluminum dissolves from pigment surfaces. Depending upon the suspension (slurry) conditions (pH, temperature, ions and other chemical species present, time of contact, etc.), we discovered that the aluminum in solution will polymerize to some degree and the polymeric alumina adsorbs back onto the particles. This process (surface aluminum dissolution, polymerization and adsorption of polymer) allows the aluminacontaining-surface to restructure and accounts for most of the pre viously reported differences in measurements shown in Table I. TABLE I EFFECTS OF SURFACE ALUMINA RESTRUCTURING Heterogeneous Distribution of A1 from Coox (JHBo, R.Davies) Change of Zeta Potential with Time (REJ) Heating Effects on Zeta Potential (LLH & AA) Bi-Modal zeta Potential (LLH) precipitation Order for coatings (AA) DUP050059352 -2 - CDP-ES-80-1 ...Heterogeneous Al distribution. John Boughton has observed that a significant fraction of pigment base (1% co-oxidized AI2Q3) particles have little or no surface aluminum, when Al-free TiC>2 particles are put into an aqueous suspension containing a few ppm Of A1 ions, they readily adsorb aluminum species (Parfitt, TWHealy). Soluble A1 species coming from Al-rich Ti02 particles are present in ample supply (as shown by our previous work) to adsorb and raise the IEP of Al-free TiC>2 (rutile) particles (5.4) to that reported for R-900 cyclone discharge (7.0). If slurry conditions are such that more A1 is available for adsorption, larger zeta potential shifts are observed. For example. Figure 2 shows the zeta potential histrogram of R-900 cyclone dis charge particles in pH 5 water. The distribution in zeta potentials is, at the least, bi-modal. By far, the largest number of particles are centered around a potential of +20 mv with a distinct 2nd distribution at 35-40 mv. The histogram was obtained within 4 minutes after making the aqueous suspension. If the same particles were suspended in the supernatent of a more concentrated slurry or if sufficient Al+3 were added, the bi-modal (or tri-etc.) histogram shown in Figure 2 would disappear with the lower zeta potential peaks shifting upwards to the 35-40 mv range. The shifts in zeta potentials were monitored over the entire pH range and the new zeta potential histogram values vs. pH approached those obtained for R-900 (3% alumina coated product) as shown in Figure 1. At higher pH's, bi-modal zeta-potential distri butions were not observed. The dissolution/adsorption process at pH >7 may be too fast for the present zeta meter (Pen Kern, System 3000) to follow. Figure 4 shows a comparison of Zeta Potential measurements for R-900 CD with those for a chemically cleaned R-900 CD as described in a previous report (1) . Curves C<|>/24A*REJ and C<J>24A*LLH are the zeta potential-pH measurements reported by R. E. Johnson and L. L. Hench for the same R-900 CD (C<t>24A) sample. Curve *REJ represents samples obtained by dispersing the R-900 CD in water at the desired pH and diluting the suspension in water at that pH. Curve *LLH represents R-900 CD dispersions that were first centri fuged and then a small portion of the sediment was redispersed in the supernatent. By invoking the A1 solution/adsorption mechanism, the difference in zeta potential-pH curves is readily explained. The data points (*) for the chemically cleaned B-900 CD are for particles remaining in the supernatent of a concentrated slurry at that pH. The Al in solution is sufficient to adsorb onto the particles and reproduce the *LLH curve. The zeta potential pH curve for the sediment duplicated the *REJ curve because of an insufficient Al supply. DUP050059353 -3- CDP-ES-80-1 ...Change of Zeta potential with time. R. E. Johnson has observed changes occurring on the order of weeks and months. Such changes are measurable in terms of modifications in structure of polymeric alumina gels on the particle surface. ...Heating effects on Zeta potential. These affects were observed by L. L. Hench and A. Allen. Pronounced changes in alumina chemistry (gel --* transition oxide - stable oxide) are known to occur upon heating. Shifting in zp-pH curves, therefore, seems reasonable; furthermore, the alumina-gel structures readily take up transition metals which the R-900 CD has (2) and the slow zeta potential shift with time may reflect the slow incorporation of these metals. ...Bi-Modal Zeta Potential. Prof. L. L. Hench has reported bi-modal zeta potential distributions. As shown in Figures 2 & 3, a bi-or maybe tri-) modal distribution was observed at pH 5. These distributions were not observed for higher pH preparations, possibly because the measuring speed of the zeta meter is too slow. A bi-modal system might be observed for a non-aqueous system or with shorter measuring times of the zeta potential for the pH range >7. ...Precipitation order for coatings. making quality pigments by first depositing an alumina coating followed by a silicate coating. The 'first' alumina coating may homogenize the surface presented and make subsequent coating operations more uniform. B. Zeta Potential Histograms Reliable histograms of the number of particles (several thousand) at a zp vs pH are now available'using the Pen-Kem system 3000 and Figure 5 shows the effect of pH on the histogram shape and position for the 'clean' R-900 CD. The width of the histogram may provide information concerning the uniformity of the surface. The width was ^ 5-7 mv for R-900 CD in the pH 6-7.5 range and increased to 15-25 mv outside that range. For R-900 (3% hydrated alumina content), the histogram widths were much narrower (less than 1/2 of the R-900 CD values) and may reflect its more homogeneous surface. Additional work needs to be done to get some use out of these histograms. C. Analysis Of Soluble Aluminum A modification of a CD&P analytical method, No. W200.015, Was used to measure soluble aluminum, and a copy of the modifica tion is included in the Appendix. Essentially, the aluminum in DUP050059354 - 4 CDP-ES-80-1 solution is converted to a colored-complex and the OV absorbance (optical density) is obtained as a function of A1 concentration. A linear calibration was obtained for the concentration range 0-7 ppm aluminum and is shown in Figure 6. R-900 and "clean1 R-900 CD suspensions were prepared in pH 4 water. The aluminum contents were measured 1 and 24 hours after suspension preparation and the results are summarized in Table II. Table II Al-Contents in Aqueous Suspensions of TiO? pH - 4 Pigment Time Hours ppm - Soluble A1 Suspension Concentration - % Ti2 1 0.1 0.01 R-900 R-900 1 1,292 0.505 0.188 24 1.019 0.492 0.236 R-900 CD R-900 CD 1' 24 1.220 1.369 0.338 0,467 0.133 0.176 These measurements show that considerable A1 dissolves from these pigment surfaces and supports the hypothesis for the Observed changes in surface alumina chemistry. Furthermore, the dissolution process is rapid (over in less than 1 hr) and similar for both mater ials (almost equivalent surface areas). This measurement shows that water provides the transfer medium for the alumina surface (from cooxidation) to restructure. By better definition of suspension conditions, a slurry product might be made directly from cyclone discharge material. Aluminum adsorption experiments were run using R-960 (C104E) and "as received" R-900 CD (C104C). The results are shown in Table III, 0-80 ppm of aluminum was added to a suspension containing 1% pigment. At 0 ppm added aluminum, both pigments show considerable A1 desorption: ^8 ppm from R-900 CD and 5+ ppm from R-960. For R-900 CD, the measured amount of soluble aluminum tracks the amount added + 8 ppm for the samples where 1 to 10 ppm A1 was added. For the samples where the amount of added aluminum was >20 ppm, adsorption of aluminum became significant at 80 ppm. DUP050059355 Table III Al Sorption (ppm) on R-900 CD and R-960 at pH 3 Room Temperature A1 Added(1) 0 1 2 4 10 20 40 80 R-900 CD (C104C) Total(2) 7.9 9.7 9.9 11.7 18.5 26.7 46.6 81.6 Diff.(3) 7.9 8.7 7.9 7.7 8.5 6.7 6.6 1.6 Amt. Sorbed(4) 0 0 0 0 0 1.2 1,3 6.3 R-960 (C104E) Total(2) 6.0 6.1 7.1 8.5 14.5 25.2 44.9 86,1 Diff. 6.0 5,1 5.1 4,5 4.5 5,2 4.9. 6.1 Note: (1) A1 cone., ppm, added to suspension (2) Measured Al cone, in supernatant (3) - (2) - (1) (4) Al, ppm, adsorbed onto surface: For R-900 CD, (4) * 7.9 - The measurements for R-960 show no aluminum adsorption for the 1-80 ppm range. The A1-desorption/adsorption behavior of R-900 CD and R-960 confirms that the surfaces are quite different chemically. The sorption of A1 by R-900 CD lends support to our concept of trans forming its surface in slurry form. On the other hand, the lack of sorption by R-960 shows that the presence of silica greatly influences its surface reactivity. The aluminum adsorption experiments should be continued at higher pH's, temperatures and loadings to determine if the surfaces of R-900 CD and R-960 can be restructured to one similar to that of R-900. The specific effects of anions, e.g. CO3, SO,}'8, Cl, etc., DUP050059356 -6- CDP-ES-80-1' should also he examined with respect to controlling surface coating chemistry (3), Another set of experiments should involve restruc turing of high 2-3% A1 co-ox containing material including a step for surface hydrolysis (H2O exposure at elevated temperatures) before slurrying. D. R-950 Slurry R-950 slurry is made from SDG (simultaneous drying and grind ing) base and exhibits gloss and viscosity instability upon aging. This instability may be caused, in part, by the lack of a stable surface coating on the SDG base such as the 3% hydrated alumina coating deposited on R-900. To check this hypothesis, TiC>2 pigment was recovered from R-950, washed, and, seta potential-pH measurements were made. Shown in Figure 7 are the seta potential-pH curves for: the recovered *pigment in Tamol suspension (solid line) the same pigment but washed with deionized water to 140,000 ohms (A) the same pigment, washed 6 times with 0.1 N NaOH and then with H2O to >5000 ohms (+) R-950 base (SDG pigment) The IEP curve (zeta potential vs pH) for the pigment/Tamol suspension shows that R-950 base (SDG) readily adsorbs this surfac tant, After water leaching, the Tamol SG-1 is still present on the surface and the IEP curve is shifted half-way between the curves for the pigment/Tamol and SDG suspensions. Drastic leaching, 0.IN NaOH, removes more of the Tamol as shown by the shift in IEP but does not remove it completely. It is possible that the strongly adsorbed Tamol SG-1 surfac tant may not be easily displaced by the surfactant-of-choice in some end-use systems. The presence of other surfactants may cause the dispersed pigment particles to associate (floe or bridge) because of interactions of the residual strongly adsorbed surfactant. SDG material was treated with caustic to improve the stability of the resulting R-950 slurries. The results are Shown in Table IV. DUP050059357 R-950 PERFORMANCE DESOTO 7811AGHTG AT lU0P -7- P5 O 00 Q Ht o oo o CM . 00 -4 O .4A O.A CMA GOA VOA ONA O OJ CM CM H H H H PJ O O O O O O O O O O O -4A HfA CO a O OA CMA CMA O o CO op VP VO c*~ pH H 8 8 8o o covi NO On Lf\ CM IA VO a cvi HA Hn >8 8o o AA O 8 O 0O0 OO -4A OO COA On t~ IA LA 8o o OO o Soo CM CO o VP H CM On On 3: o O VO 8 8 O 8 8 CM A COA VOA COA IA 00 00 00 V0O0 a O00 0000 vooo I0A0 aCO .C4O HOO -4 oo oo I0A0 CM 8 St V0O0 0000 5! 5 HH gg 3% 88 o oo oo VO Wg g Sr 3B -C4O -O4 L1A -P4 IA1 O vo L1A P VO L1A t-- o -I4A IOAO O931N VO Vr0orHDi 5 C oO o O IA IA IA IA IA On ON ON On ON ON (k Pt? pej PCi pc# CDP-ES-80-1 DUP050059358 -8 - CDP-ES-80-1 Treatment of SDG material by either caustic at pH 8.5 produces R-950 slurry with lower viscosity and reduced-loss-of-gloss upon aging at 140P. NH^OH treatment seems to give a higher gloss and lower viscos ity than the corresponding NaOH-treated SDG. Heating the SDG at 60C, pH=8.5, showed no improvement in slurry stability. Two other experiments should be run: R-900 used instead of SDG to make up R-950. If the gloss instability approaches that obtained with SDG, then the surfactant package is probably responsible. Glass containers are currently used in the aging test. We have found considerable silica migration at room temperature (in one day) from glass to pigment surfaces in our zeta potential studies. To eliminate this possible testing artifact, plastic containers should be used. One additional point should be noted: the viscosity of all the slurries, including R-940 made from R-900, increased markedly during the three week aging test. If replacement of the glass con tainers by plastic does not eliminate this increase, then it may be caused by either alumina or the surfactant system. If it is alumina, then ways will have to be found to stabilize the surface. On the other hand, the surfactant system could either degrade or bridge particles; both mechanisms would increase viscosity. The experiments performed, therefore, seem to show that control of the alumina surface has a desirable effect by reducing initial viscosities. However, the % increase in viscosity on aging at 140F was the same for the caustic treated and non-treated SDG samples. The viscosity of R-940 increases similarly upon aging and therefore strongly indicates that aluminum gels of same sort may be forming in the liquid. This problem should be studied in conjunction with restructuring the alumina surface. E. Particle Size Measurements of pigment Dispersions The transient turbidity apparatus of Dr. C. M. Paulson (Engg) was successfully evaluated and setup in R. E. Johnson's laboratory (4). Transient turbidity is a size measuring technique complementary to the sedigraph. Listed in Table V is a comparison of the two techniques. - DUP050059359 - 9 CDP-ES-80-1 Table V COMPARISON OF SEDIGRAPH VS TRANSIENT TURBIDITY System Sedigraph Transient Turbidity Time/Run 30-90 min. 10 sec. 1 min + prep, time Suspension Stability Stable Stable and unstable TiOg Level 2% 0.005% Limits particle size must be >0.3 ym solution conductivity must be <100 ym The sedigraph is extremely useful in obtaining particle size distributions of pigments. Its main drawbacks are the long times (30-90 min) required per analysis and that distributions for particles below 0.3 urn will be in error because of Brownian motion. It can readily handle slurries with 1-2% pigment concentration in the pre sence of surfactants, etc. The transient turbidity apparatus uses light transmission as a monitor and therefore requires very dilute Ti02 pigment suspensions. Furthermore, because it uses an electrical voltage to align the particles' rotation, the conductivity of the pigment dispersion is limited to lOOy mho to prevent thermal currents, etc. The electrical measurement takes a few seconds and its conversion has been cali brated for a log-normal distribution in diameter (weight) and its standard deviation. Shown in Figures 8 and .9 are particle size measurements for R-900 and R-960 aqueous Tamo! 731 suspensions @ pH 10, using the transient turbidity and sedigraph techniques, respectively. By measuring particle size as a function of time, we observed that R-960 agglomerates from 0.42 ym at 2 minutes to 0.50 ym at 30 minutes, even though the zeta potential of the particles is highly negative. After ~ 30 minutes, the agglomerate size of R-960 is reasonably stable. Corresponding sedigraph measurements give sizes of 0.51 for R-960 and 0.41 for the R-900. The agglomerate size changes for R-900 and R-960 could not be monitored by the sedigraph which requires at least 30 minutes for a measurement. The size instability and agglomerate growth of R-960 in an aqueous Tamol suspension may be responsible for its low gloss in some paint formulations. Furthermore, the transient turbidity size measurement for R-960 extrapolates to the same size as R-960, DUP050059360 10 - CDP-ES-80-1 *0.38 ym, at zero suspension time or when these pigments came out of the micronizer. Thus the micronizer is able to grind R-960 down to the same aggregate size as R-900 but the R-960 surface is prob ably not as well-stabilized as R-900's. for: Figure 10 shows the transient turbidity size measurements Commercial R-900 Laboratory prepared 'boehmite'-coated-R-900' Laboratory prepared 'bayerite-coated-R-900 * in Aqueous/Tamol 731 suspensions. The commercial grade of R-900 and the lab prep are similar as expected. The bayerite-coated pigment keeps On agglomerating under the same conditions in which the boehmite surface is stable. Thus, transient turbidity size measurements might provide a rapid method of predicting a pigment's gloss and stability in end-use systems. Shown in Table VI are transient turbidity size measurements for various pigment grades. DUP050059361 11 - CDP-ES-80-1 Table VI TRANSIENT TURBIDITY SIZE MEASUREMENTS OF AQUEOUS . ____PIGMENT SUSPENSIONS NO SURFACTANTS (1) Material R-900 c d (3) R-900 CD (SM)(4) R-900 DD(5) R-900 pH 6.3 4.6 6.2 10.4 Size, ym^ 0,97 0.40 0.62 0.415 3% A1 o a O RPS CD 6.3 R-960 DD R-960 R-902-08 (Lot 9256) R-931-01 (Lot 6639) R-933-01 (Lot 7230) 6.8 4.8 10.2 8.2 10.3 1.03 0.49 0.46 0,62 0.67 6% Si, 2% A1 % Si % A1 l 1/2 3 87 10 7 R-994 (Lot 9749) 9.5 0.54 LW (Lot 5250) 4.1 0.63 Notes: (1) HC1, NaOH used to ;adjust pH; suspensions were sonicated (2) Stable, smallest agglomerate size (3) CD; cyclone discharge, unground (4) SM; steam micronized (5) DD; dryer discharge DUP050059362 - 12 - CDP-ES-80-1 Within experimental error, the size of CD materials, r -900 CD and RPS CD (EM base), was measured at 0.9 ym. Under extended sonication and high pH conditions, the size of the CD materials was some what reduced to 0.6-0.7 ym. Steam micronization at 3:1 S/P ratio, of the R-900 CD reduced the agglomerate size down to 0.40' ym. The agglom erate sizes for R-900 DD and R-960 DD were 0.62 ym and 1.03 ym, respectively. This size difference may relate to the tendency of R-960 to agglomerate and therefore may provide a good measure of the effectiveness of the alumina hydrate coating. The agglomerate sizes of R-900 (3% hydrated oxide), R-902 (4 1/2%), R-960 (8%), R-931 (15%) and R-933 (17%) are directly depend ent on the amount of their hydrous oxide coatings as shown in Figure 11. One of the functions of these coatings seems to be to stabilize the 'primary aggregates' of 0.4 ym into larger sized agglomerates. The extrapolated value of 0.36 ym for uncoated particles is within the accepted size range for the 'primary aggregate'. From this size and the measured sizes of the various coated products, the number of pri mary aggregates per agglomerate may be calculated and Table VII sum marizes the results. Table VII ESTIMATED NUMBER OF 'PRIMARY AGGREGATES' PER STABLE AGGLOMERATE CALCULATED FROM TRANSIENT TURBIDITY MEASUREMENTS Material ____________ Number of Primaries (5%) R-900 R-902 R-960 R-931 R-933 1.50 2.0 2.5 5.0 6.0 If these numbers are significant, then the coatings may well function as size adjusters (controlled clumping). DUP050059363 13 CDP-ES-80-1 P. Competitive Pigments There is a lack of physical and chemical information on compet itive pigments (other than standard pigments data). fit present, we cannot relate a pigment's end-use performance to its physical and chemical properties, Therefore we do not know what those properties should be to maximize a pigment's performance. Our efforts in product improvement would be better spent in defining the end-use performance of pigments in terms of their readily measurable physical and chemical properties. If, for example, we could define and make a specific type of hydrated alumina surface for R-900 that would be acceptable by most of our customers, we could reduce costs by eliminating many of the package codes presently required. Another example of cost reduction might be definition of the target hydrated alumina surface required for the reactor discharge slurry product and its counterpart dry grade. Therefore, if we learn what pigment properties are important and how they control end-use performance, this information will then be used to guide our product improvement and cost reduction programs. As a first step to providing these relationships, we have started to catalog those properties which appear to control perform ance in specific end-uses. To accomplish this we are compiling property performance data of competitives as well as our pigments according to their chief end-uses. Table VIII is a partial list of pigments col lected and some of their properties measured-to-date. Grade Titanox 2090 Titanox 2131 Unitane OR580 Tronox CR800 Tronox CR820 Tronox CR822 Titanox 2020 Tioxide RHD6U Table VIII COMPETITIVE PIGMENT ANALYSIS TC# 9089 % SiO,, nil .%.A1 f,,it0on 2.7 S.A., M2/G 13.9 9090 9.5 4.9 41,7 9091 0.1 2.4 17.3 9092 0.1 1.9 11.1 9082 2,1 2,4 11.7 9088 3.3 3.1 14.1 9104 nil 3,1 13.9 9086 0.1 2.9 18.6 Size, urn 0,42 0,58 ' 0.40 0.38 0.38 0,45 0.38 0.35 DUP050059364 - 14 CDP-ES-80-1 The % SiOj and AI2O3 were measured by X-ray fluorescence using an Exam-6. The surface area measurements were done by CR&DD using BET N2 adsorption-desorption data. The pigment particle sizes were calcu lated using transient turbidity measurements on stable aqueous pigment suspensions (sonicated). Using the relationship shown in Figure 11, which was developed for Du Pont Ti-Pure pigments, and the total % of hydrous oxides noted in Table VIII, the expected aggregate size (from Figure 11) is, within error, the size that was measured. Beta potential vs pH measurements (IEP curves) were performed on CR&DD's new system 3000 instrument and are shown plotted in Figures 12-18. The iso-electric point (IEP) curves for some Du Pont pigments are shown in Figure 12. The transition in IEP of 4.5 to 9.0 for the grades shows the effect of an alumina coating (IEP 9) vs a silica coating with an IEP of 2. Shown in Figure 13 are the IEP curves of some chalk-resistant paint grades. Except for the R-902 curve, the IEP curves are very similar and indicate that they probably have similar alumina-silica coatings. Furthermore, particle Size measurements indicate that the competitives are all about 0.45 urn in size. Therefore, any differ ences in end-use performance such as gloss, dispersion and hiding power are probably caused by surface chemical factors. By using adsorption, ESCA and other measurements, we hope to isolate and define these factors for each end-use and establish standards for that end-use Shown in Figures 14 & 15 are the IEP Curves of some enamel grades. The competitives have similar compositions, 0.1% Si02 and 2% Al203, and IEP curves. Most of the enamel grades'have sizes in the 0.38-0.42 ym range with the notable exception of Tioxide1s RHD6U which is 0.35 ym as measured by transient turbidity. IEP curves for competitives are very similar for other enduses as shown in Figures 16, 17 & 18. Again, specific performance differences are probably caused by surface chemical factors which have not, as yet, been defined. Dispersion appears to be an end-use parameter with the widest range of values achieved using commercially 'good performing' pigments. Differences in dispersion quality are probably caused by pigment sur face composition. By using adsorption, ESCA and other techniques, we hope to identify those factors which control performance in each end-use and optimize the surface composition to establish new perform ance standards and product recipes for each end-use* DUP050059365 15 CDP-ES-80-1 G.- Tamol Adsorption Studies Surfactants are widely used in pigment end-uses to improve dispersibility, gloss and stability. In order to understand how these properties depend on surfactant/surface interaction, adsorption measurements of an anionic surfactant, Tamol 731, were obtained for a variety of materials under differing suspension conditions. When pigment particles are dispersed into water, the instan taneous pH of their electrical double layers is probably close to the pigment's equilibrium pH value.* The seta potential of a powder when first put into water is probably close to the value asso ciated with the equilibrium pH. As the powder surface equilibrates in pH with its surroundings, its zeta potential changes. If the particles are forced to go through zero zeta potential, flocculation (agglomeration) may occur. Flocculation will occur if the adsorption of surfactant or other species is slow such that the rate of zeta potential change is also slower than the rate of flocculation. Fur thermore, if the powder is heterogeneous, different rates of zeta potential modification by adsorption can occur; again leading to flocculation if both positive and negative or near zero zeta poten tial particles are present. The discussion of the results for R-900 can serve as a general model. At its equilibrium pH of 7.4, R-900 particles have a zeta potential of 37 mv; designated as point E in Figure 19. When IS R-900 is put into pH 4 water, the final suspension pH becomes 5.2 and the zeta potential of the particles moves from 37 mv @ point E to 54 mv @ point A. In this case, the zeta potential of the particles was always >+30 mv, signifying that they should be stable with respect to flocculation. Size measurement of R-900 by transient turbidity confirms this. When R-900 is dispersed in pH 10.5 water (NaOH used to adjust pH), the zeta potential of the particles shifts from +37 mv @ point E to -35 mv @ point B. Flocculation should occur if this change in zeta potential is slow (on the order of 10-20 seconds), Transient turbidity shows that flocculation has occurred with about 2 aggre gates per floe. Thus flocculation occurs rapidly (<1 sec) and the system is quite stable by the time the transient turbidity measure ment is made. The change in floe size as measured by transient turbid ity can provide an estimate of the order of magnitude of the rates of zeta potential modification and of the adsorption process. Curve CD&P in Figure 19 represents the zeta potential-pH for an R-900 suspension containing Tamol 731. By considering only the final zeta potential values, which are highly negative, one would expect that the resulting suspensions would be very stable and not flocculate. If we assume, however, that the instantaneous pH of the *Equilibrium pH is measured by titrating a powder into water. The pH at which no further change occurs upon addition of more powder is defined as the equilibrium pH (Prof. E. L. Hench), DUP050059366 16 CDP-ES-i80-l R-900 powder particles when first put into suspension is near their equilibrium pH, 7.4 (point E, with an associated zeta potential of +37 mv), then flocculation might occur if: * the rate of zeta potential change is slow when passing through or near zero * the particles are heterogeneous, providing different adsorption rates and resulting in a suspension with both (+) and (-) charged particles. When R-900 is put into an aqueous Tamol solution at pH 4, the zeta potential of the particles shifts from +37 mv at point E to -50 mv at point C (Figure 19), Transient turbidity shows that some flocculation, about 40%, occurred. The amount of flocculation for this case is ~l/2 as large as for the aqueous pH 10 suspension. The adsorption of Tamol on the alumina coating and attendant zeta potential change at pH 4 is faster than the OH" sorption process at pH 10, No measurable flocculation occurs when R-900 is dispersed in a pH 10/Tamol solution. The adsorption/zeta potential modification process is much more rapid than flocculation. The alumina coating, therefore, provides a homogeneous, uniform surface that rapidly adsorbs anions to allow particles to migrate quickly through large zeta potential changes together, thereby minimizing flocculation. A similar rationale explains most of the data for R-960 shown in Figure 20. When R-960 is added to pH 4 water, the pH of the result ing 1% suspension is 7.5, point A, because of the high basic titer of the pigment. This pH is close to the IEP of R-960 and massive flocculation occurs. When placed in pH 10 water, the OH- sorption/ zeta potential modification is somewhat rapid and little floccula tion occurs. On the other hand, when R-960 is dispersed in aqueous/Tamol suspensions, flocculation is observed throughout the entire pH range studied. Tamol does adsorb On the R-960 as indicated by the shift of zeta potential-pH curves in Figure 20. However, flocculation is more extensive for R-960 than for R-900 for the same water/Tamol system. The difference in degree of flocculation suggests that the hydrated alumina surface of R-900 adsorbs Tamol more rapidly and uniformly than the silica-alumina surface of R-960. Furthermore, the addition of alumina in the R-960 coating process does not produce a surface with the reactivity of R-900. The combination of techniques (trans ient turbidity, zeta potential/pH, equilibium pH) can provide a qualitative definition of the desired surface chemistry and reactivity for a specific end-use surfactant system. DUP050059367 - 17 CDP-ES-80-1 The adsorption of Tamol 731, an anionic surfactant, was meas ured for a variety of pigments and powders because it is widely used by our customers and is the basis of our aqueous emulsion gloss test. Instead of using ion chromatography as previously done (4) to follow Tamol adsorption, UV absorbance measurements were used. A plot of UV absorbance vs ppm Tamol in aqueous solution was developed, as shown in Figure 21, by monitoring the absorbance of a peak @ ~205 nm. Association of the Tamol at concentrations above 250 ppm is evident from this calibration curve. For this reason, only the linear por tion of the curve in the 0-200 ppm range was used. More concentrated solutions were diluted to this range. The calibration curve is shown in Figure 22. Shown in Figures 23-26 are the Tamol adsorption data, shown as langmuir isotherms, as functions of pH for R-900, R-960, R-900 CD and R-900 CD (steam micronized), All of these materials adsorb much more Tamol at pH 3 than they .do at higher pH's. Figure 27 shows the R-900/Tamo1 adsorption-pH profile whose drop-off is typical for the materials. The adsorption drop-off is probably caused by the dis placement of Tamol by OH" at high pH or by a decrease in the number of adsorption sites. The data were replotted as the amount adsorbed in a monolayer as a function of pH in Figure 28, The data were fitted with a least squares straight line. The drop-off in Tamol adsorption is similar for the alumina-only powders, R-900, R-900 CD and R-900 CD (steam micronized). R-960 behaves quite differently and has a much faster drop-off than the alumina-only powders. The presence of silica seems to interfere with anion adsorption processes. The adsorption-pH curves for Tamol and simple anions (F", SO4", Cl") on R-900 CD are shown in Figure 29, The slopes of the two curves are parallel and suggest that the same adsorption mech anism is operating. The R-960 data is shown for reference and its different fall-off is apparent. The effect of Tamol adsorption on zeta potential was measured for R-900, R-900 CD, R-900 CD (sm) and R-960 for the pH range 3-11. Shown in Figure 30 is the data for R-960 at pH 3. This information is useful in predicting if flocculation should occur. As more Tamol is added, >40 ppm, the zeta potential drops below +30 mv and floccula tion occur. In the region 40-250 ppm Tamol, the zeta potentials are in the flocculation range. Above 300 ppm Tamol adsorbed, the zeta potential is sufficiently negative to inhibit flocculation if adsorp tion rates are first. Shown in Figure 31 are the corresponding size measurements for the samples used to make Figure 30. The adsorption-zeta potentialsize rationale is, qualitatively, as predicted. This rationale operates throughtout the pH range studied and for the other materials. DUP050059368 - 18 - CDP-ES-BO-l Tamol adsorption was measured for Minusil silica, surface area ~3.5 m2/g. Within experimental error, hardly any Tamol was adsorbed; almost 100 times less (per unit area) than R-960. it appears that R-960 does not behave like silica with respect to Tamol adsorp tion. Future experiments should provide definition of the desired surface coating(s) for various grades by comparing Tamol or ion adsorp tion of corapetitives that disperse well in a wide range of end-uses. H. Miscellaneous Studies * Florida Humate settling. We showed that FeClj added to a humate suspension at pH 5 raised the zeta potential from -21 mv to ~0 mv and caused flocculation. PeCl3 might be added directly in the dredge pond, eliminating the need for settling and finishing ponds. Lab experiments are needed to show that floe rates and volumes are better and smaller than corresponding ones for, H2SO4. * Began ion adsorption study of PO45. Since we are co oxidizing PCI3 with TiCl4 to make RPS, the resulting chemical state of phosphorous on the surface has had pronounced effects on viscosity. A program was just initiated to study phosphate adsorption to provide insights into JV-EM base differences, etc. Phosphate contents of RPS suspensions were obtained by ion chromatography for A. Baidins to aid his rheology studies. * An analytical technique using ion chromatography was developed for E. W. Gillow and s. A. Hallock to measure the sulfate content of sales grade FeCl3 (5). Mixed acid analysis (HNO3/H2SO4) was also demonstrated for R. W. Craft (Repauno).* * With K. Kirksey, developed an alternative route to 'wet' R-100 & R-101 using F- as a flocculating agent instead of hydrous alumina. DUP050059369 - 19 - CDP-ES-80-1 XI. REFERENCES 1. Interim Report: L. Abrams, CDP-EX-78-15, "Surface Chemistry of TiC^-II". 2. Ti02 Product Development Report, L. Abrams, PTD-SA-78-18, "Chemical Characterization of TiC>2 Pigment - I", 3. 6. Bardossy & J. L. White, Science 203, 355-6 (1979). 4. Memo to F. J. Darnell from R. E. Johnson & L. Abrams, May 8, 1978, 5. Notebook E17895-39, 1978 DUP050059370 XII. APPENDIX - 20 - CDP-ES-80-1 DETERMINATION OF Al Ions PYROCATECHOL VIOLET COLORIMETRIC METHOD I. APPLICABILITY This method is applicable to sample solutions containing 0**10 ppm. II, PRINCIPLE The sample is dissolved by heating with HCl. Hydroxylamine hydrochloride and 1,10-phenanthroline are added to reduce and complex iron and prevent its interfering. .Pyrocatechol violet is added to form a colored Al complex. After pH adjustment, absorbance at 585nm is measured to determine A1 concentration. III. UNUSUAL SAFETY CONSIDERATIONS Handle glacial acetic acid with care. Conduct all work in a hood . Wear rubber gloves and an apron, avoiding all contact . with the skin and inhalation of vapor. MAC in air is 10 ppm. IV. SENSITIVITY/ PRECISION AND ACCURACY The smallest amount of A1 detectable by the method is approximately 0.5 jig. Precision and accuracy have not been measured. V. APPARATUS AND REAGENTS (Equivalent apparatus may be substituted. Reagents are reagent grade.) Use deionized water throughout procedure, 1. Visible spectrophotometer capable of measuring absorbance at 585nm through a 10mm cell path (20 or 50mm cells preferred for samples containing less than 0.lppm A1). 2. pH meter 3. Acetic acid; dilute cone, acid 50% by weight 4. Aluminum standard solution, 1 ml 1 mg. Al. Fisher Scientific Co., No. So-A-442 or make up 1000 ppm standard Al+3 at pH - 3. 5. Aluminum Working Standard; 10 ppm Al. To 1.000 g of 1000 ppm standard solution, add 1.00 g cone. HCl and dilute total to 100.0 g with distilled (deionized water). PREPARE FRESH FOR EACH CALIBRATION PROCEDURE. DUP050059371 * 21 - CDP-ES^-80-1 6. Ammonium acetate solution; 10% (by weight) in H2O. 7. Ammonium hydroxide solution; dilute cone, base 50% with H2O. 8. Hydroxylamine hydrochloride solution, 20% (by weight) in H2O. 9. 1,10 phenanthroline solution; 0.30 gm/100 g H2O solution, 10. Pyrocatechol violet solution; " * *" Also known as catechol violet, pyrocatechol sulfone phthalein. VI. STANDARDIZATION 1. Take 7-250 ml beakers (preferably Teflon) with stirring bars. Weigh out 1.000, 2.000, 4, 6, 8 and 10.000 g of 10 ppm Al working standard into six beakers (1 beaker is a control for absorbance measurement). 2. Add 1 ml cone, HC1 to each beaker (7) (stir). 3. Add H2O to bring solution weight to 50.00 g for each beaker. 4. Add 30.0 g of 10% ammonium acetate solution (stir). . 5. Add 1.00 g of hydroxylamine hydrochloridesolution (stir). 6. Add " " 1,10-phenanthroline " (stir). 7. Add " " pyrocatechol * (stir). 8. Standardize pH meter in 6 to 7 range, 9. Adjust pH of standardization solutions to 6.15 0.05 using either 50% NH4OH or acetic acid solutions. IF pH goes above 7 during Adjustment, discard solution. 10. Add H2O to bring total solution Weight to 100.0 g for each beaker. Stir 15-25 minutes. 11. Measure absorbances at 585 nm in 10 mm cells. Use control as blank (reference), 12. Plot absorbance vs ppm (linear), VII. SAMPLE ANALYSIS 1. Tare 250 ml beakers with stirring bars (leave one beaker as a control). 2. Add 10.00 g sample solution into beaker. If the aluminum content is known to exceed 10 ppm, dilute 10X or 100X as needed. If the Al content is below 0.2 ppm, use 50.00 g of sample Or longer cells (20, 50 or 100 mm). DUP050059372 22 CDP-ES-80-1 3. Add 1 xnl cone. HC1 to each beaker. 4. Heat sample beakers to 60C and stir for 1 hour or until solution is complete. 5* Cool to room temperature. 6. Perform steps VI-3 to VI*11. 7* Using calibration chart prepared in step VI-12, read ppm in sample solution. VIII. REFERENCE CD&P Method W200.015 LA/kkg DUP050059373 - 23 - CDP-ES-80-1 XIII. INDEXING TEEMS Surface alumina on. Ti02 pigments Restructuring of surface alumina on TiC>2 pigments Ti02 pigment colloidal properties Aluminum adsorption/desorption by Ti02 pigments Measurement of soluble aluminum Flocculation behavior of Ti02 pigments Tamol 731 adsorption by Ti02 pigments Effect of pH on Tamol 731 adsorption Reactor discharge slurry Pigment surface chemistry Adsorption measurements on TiC>2 pigments Zeta potential measurements of TiC>2 pigment suspensions Size measurements of Ti(>2 pigment suspensions Humate flocculation Competitive Ti02 pigments DUP050059374 F ig u re 1. S h ift in Z .P . o f R-900 C yclone D ischarge DUP050059375 -c335.3013 IS : 28 13 SEP-76 <Ql M |N ]> F ig u re 2 . Z eta P o te n tia l H isto g ra m fo r R-900 C yclo n e D isch a rg e in pH 5 SUSPENSION CONC. ,0 0 0 1 s R900 CD CC024 (AUl/IDd ) ADN3n03dd Q3ZnVWaON DUP050059376 ZETA POTENTIAL CMV) (AW/IDd ) ADN3fl03dd CBZIlVUdON DUP050059377 c335.301] 16:30 13-SEP-76 F ig u re 3. Z e ta P o te n tia l H is to g ra m Show ing E ffe c t o f A1 A d s o rp tio n on Sample Sh SUSPENSION CONC. .000156 R900 CD ( C02- ZETA POTENTIAL CflV) F ig u re 4 . Z e ta P o te n tia l M easurem ents fo r 'C le a n e d ' R-900 C.D DUP050059378 EFFECT OF pH ON ZETA POTENTIAL HISTOGRAM OF CLEAN R-900 (CD) DUP050059379 ^ uG A l- C^o ipf ilgo xu r e 6. C a lib r a t io n C u rv e f o r IIe a s .' ir in g S o lu b le A lu iu in m a C a lib ra tio n C u rvi 3 IS DUP050059380 - 30 - CDP~ES-80-i o in os T IQ 2 RECOVERY FROM R - 9 5 0 t0o) <UD l PH4 DUP050059381 F ig u re 8 . T ra n s ie n t T u r b id ity S izes fo r R-900 and R-960 Aqueous/Tam ol Suspe TIME (MINUTES) DUP050059382 - 32 - CDP-ES-80-1 (M icron*) DUP050059383 F ig u re 10. T ra n s ie n t T u r b id ity S ize s f o r R-900 and Two Lab A lum ina-C oated DUP050059384 DUP050059385 35 CDP-ES-80-1 ZETA POTENTIAL Figure 12 DUP050059386 2ETA p o t e n t ia l Figure 13 DUP050059387 - 37 CDP-ES-80-1 Figure 14 ZETA POTENTIAL W IBP CURVES OF ENAMEL GRADES DUP050059388 Figure 15 ZETA POTENTIAL IEP CURUES OF ENAMEL GRAPES DUP050059389 39 CDP-ES-80-X Figure 16 ZETA POTENTIAL M IEP CURUES FOR HIGH PVC FLAT PAINT GRADES DUP050059390 40 - CDP-ES-80-1 Figure 17 PH DUP050059391 - 41 - CDP-ES-80-1 Figure 18 2ETA POTENTIAL . Ml. ZETA POTENTIAL CURUE8 FOR INK GRADES 75. *-- I--t- 1 1 i- I. .. -I - I --> I y i 25.- 0. -25.- -75. GRADE IEP N TRONOX CR-800 X TKOXIOE RHD6U 6.4 7.4 T UNITANE 0R-588 6.4 X TITANQX OAOA 7.7 * TI-PURE R-900 9.0 k * 1' V k ' V F` r k' A.' A.' ik PH DUP050059392 - 42 ~ CPP-ES-80-1 F i g . 19 R - 9 0 0 I N .0 0 1 N N o C l a n d 1 g / l T A M O L 7 3 1 (AW) nVIlN310d VX3Z DUP050059393 F ig , 20 R -960 IN .001 N NoCl ond 1 g / t TAMOL (AUI) nvilN310d V13Z DUP050059394 - 44 CDP-ES-80-1 PPM Xt0 3 Figure 21 UU ABSORBANCE CALIBRATION OF TAMOL 731 SOLUTIONS DUP050059395 45 CDP-ES-80-1 PPM Figure 22 UM ABSORBAHCE CALIBRATION OF TAMOL 731 SOLUTIONS muu 11111u n t.i it>> i f m i t n mn11111 11 lu DUP050059396 M n ^ n ih m lim lu n tu n ilm iln n V tv M im Figure 23 PPM ADSORBED / GPf rmsL 73s ad s o r pt io n o n R-f^a <cie$c> DUP050059397 47 - CDP-ES-80-1 Figure 24 PPM ADSORBED / CM TMOL 73i ADSORPTION ON R-S59 <C104> DUP050059398 CDP-ES-80-1 Figure 25 PPM ADSORBED / GH TAMOL 731 ADSORPTION ON R-990 CO DUP050059399 PPrl ADSORBED / GM 49 Figure 26 CDP-ES-80-1 i i t h it i t in t l i i ii, | u u ! i ml EGUIL. COHC. TAHOL <PPM> DUP050059400 - 56 - Figure 27 c d p -e s -80-i PPM ftOSQPBEO / CM TAMO. 731 ADSORPTION ON R-990 <C104C> (v >. DUP050059401 -- 51 CDP-ES-80-1 LOG PPM APSORBQJ <MONOLAYFR> m 3.0 TANOC 731 ADSORPTION US. PH i iiliu i litnlu Li > fi t Lu txl-t jul PH . w DUP050059402 - 52 - Figure 29 LOG MONOLAYER ADSORBED AMOUNT ADSCRPTIOM-FH CURVES CDP-ES-80-1 DUP050059403 53 Figure 30. R-960 @ pH 3 CDP-ES-80-1 2ETA POTENTIAL# MM ZETA POTENTIAL AS A FUNCTION OF SURFACE COVERAGE DUP050059404 t . . I . . . . I H I I . I I t I j i i l I u - 54 - CDP-ES-80-1 Figure 31. Agglomerate Size Measurement of Suspensions Used to Generate Figure 30 MICROMETERS 2.90 *. <, 1.75- PARTICLE SIZE AS A FUNCTION OF COVERAGE l 1 U l.l.l | , | I 1.50- 1.251.00-f 0.750.50- o Iu 0.25- 0.00 rriTf n ri-T i t ~t 't -e i ri r ,,ui i11 ri'TiTi "gii,'"""-r,ii > i t 0. 50. 100. 150. 208. 250. 300. PPM TAMQL ADSORBED -- 350. *4 DUP050059405 55 - CDP-ES-80-1 DISTRIBUTION Copy No. 1. L. Abrams, 356 2. K. K, Bhatia 3. W. J. Marshall, EM 4. H. B. Clark/R. W. Hess 5. R. A. Darby/A, S. Bjornson/L. T, Frick/J. 6. Ishikawa 6. E. C. Broge/J* Blackwell/J. A, Blumberg 7> J. M. Hustler 8. L. N. Fisher/G. A. Hapka 9-10. Central Report Index, ISD, C-2311 11-12. L. A. Wierzbowski, EM 13-17. CD&P Information Center, 336 R. B* Johnson, CR&DD 19, J. P, Jesson/H. S. Jarrett/R. V. Kasowski/W 20. W, D. Ross/S. V. Mastrangelo/H. R. Linton/D 21. J. H. Boughton 22. W. L. Kremer/G. H. Senkler, EM \ 23. G. E Lynskey/D. U. Gwost/M. Baloga, JV 24. D. H. Eastham/T. B. Scarfe/D. P. Schussler, 25. J. G. Dickinson/W. J. McGinnis, CR 26. CR&DD Tech. Records, E301 27. R. J. Bouchard, CR&DD CO rH DUP050059406