Ti-Pure TITANIUM DIOXIDE DETERMINATION OF PARTICLE SIZE DISTRIBUTION OF RPS ( Horiba (LA-900) Procedure) METHOD: T4400.274.03WP 1
TITANIUM DIOXIDE (Ti-Pure ) Determination of Particle Size Distribution of RPS ('Horiba' (LA-900) Procedure) I. Principle The particle size of titanium dioxide is measured in dilute aqueous dispersions with a HORIBA LA-900. The `Horiba' uses Mie scattering theory to measure `equivalent spherical diameter' as a function of % Transmission and scattered light. The size of the particle determines where the light is scattered. Therefore, by measuring the % Transmission, Front Scatter, Side Scatter, and Back Scatter the size of the particle can be calculated. The refractive index of the buffer and the particle and primary constants relating to particle size. These constants are supplied and are called Relative Refractive Index. II. Applicability A. General This method is used to measure the particle size of insoluble materials in the range of 0.04 to 1000 microns. B. Specific This method will measure several quantities used to characterize titanium dioxide pigment. The instrument records the cumulative % of the total mass in each size increment. The particle size is usually represented as calculated quantities: D50 - the median diameter in microns GSD - the geometric standard deviation is defined as the square root of Coarse Tail (D) divided by Fine Tail D. Use method T4400.274.02.WP to determine PSD parameters for RPD Vantage. (Dry Finished Product) III. Limitations The material must be dispersed in the liquid medium, but not soluble in it. It measures the diameters as `equivalent spherical diameter', i.e., 2
the diameter the particles would be if they were spheres. In fact, titanium dioxide particles are somewhat acicular (needle like crystals). The refractive index of the material must be known. IV. Sensitivity Precision and Accuracy A. Sensitivity No data is available. B. Precision 1. Single Operator _ The average analysis (X), standard deviation (s) and 95% confidence limits (95% CL) established for the single operator precision of the method were as follows: _ X s 95% CL RPS Vantage D50,um 0.379 0.0013 ± 0.0026 RPS Vantage GSD 1.50 0.0062 ± 0.012 The above data were calculated from 10 replicate analyses of one sample performed by one technician over a period of 7 days. 2. Multiple Operator _ The average analysis (X), standard deviation (s) and 95% confidence limits (95% CL) established for the multiple operator precision of the method were as follows: _ X s 95% CL RPS Vantage D50, um 0.384 0.0029 ± 0.0059 RPS Vantage GSD 1.51 0.017 ± 0.033 The above data were calculated from 40 replicate analyses of one sample performed by 4 technicians in Edge Moor Control laboratory over a period of 30 days. 3
C. Accuracy No study has been made; however, results have been satisfactory based upon experience. V. Special Apparatus (Equivalent apparatus may be substituted) 1. Balance capable of weighing 100 ± 0.01 g. 2. HORIBA LA-900, Horiba Instruments Inc., 17671 Armstrong, Irvine, CA 92714, (714) 250-4811. 3. Horiba Reservoir Unit. 4. Horiba Auto Sampler. 5. Diskette (3½"), Pre-formatted for IBM PC, XT, Double-Sided (DS), High Density (HD). 6. Tubing, Masterflex Silicone, Cat. No. G-96410-15 or equivalent. 7. Sonicator tip, titanium, Cat No. 027 (pack of 5) or standard Heat Systems tip with Heat Systems unit. 8. IBM PC or equivalent. 9. Oxford Benchmater Pipette, 1001-10001, Fisher Scientific or other adjustable pipetter with comparable precision. VI. Reagents (Reagent grade except as noted) 1. Tetrapotassium Pyrophosphate (TKPP), reagent grade. 2. Kodak, Photo-Flo 200, wetting agent. VII. Special Safety Considerations A. Product Hazards 1. There are no unusual product hazards. 4
B. Procedure Hazards 1. Observe all appropriate procedures, including general safety rules. 2. Do not place anything, including fingers, in the path of the laser beam while it is operating. Do not bypass any interlocks. Do not open the cell door or any panel while it is operating. 3. Because of the possibility of electrical shock, turn the instrument off and unplug it before removing any of the cover panels. 4. The auto-sampler lid is heavy. Be sure the lid hinge prop is properly locked to insure the lid does not fall and pinch hand and fingers. VIII. Procedure A. Operating Conditions a. Dispensing Solution Make-up Make a 20 liter container of 0.4 ± 0.01 g/l solution of TKPP (Tetrapotassium Pyrophosphate) by weighing 8.0 ± 0.1 g of TKPP into a labeled container. Add 30.0 ± 0.1 ml of photo-flo (wetting agent), fill to the 20 liter mark with distilled water. Mix well. (Mixing method to be determined by individual sites). b. Instrument Turn On & Set-UP 1. Turn on solvent reservoir, main instrument, computer monitor, computer and printer. The computer will come on and after starting DOS and windows will go into the Program Manager Screen. 2. Double click on the HORIBA LA-900 icon. This will put you into the Horiba Icon Screen. 3. Double click on the SWITCH icon. This will put the SWITCH button at the top left. Move the button to the upper right portion of the screen out of the way. 5
4. Double click on the MEASURE icon. This will put you into the measuring program and the run graph screen. The last sample run will be displayed. 5. Press the SWITCH button. This puts you back into the HORIBA LA-900 icon screen. 6. Double click on the DISPLAY 1.81 icon. This puts you into DISPLAY screen. Press the SWITCH button. This puts you into the MEASURE screen. You will now be able to move back and forth between the MEASURE screens and the DISPLAY 1.18 Module by pressing the SWITCH button. 7. Allow the instrument to warm up for approximately 15 minutes before running a sample. 8. While the instrument is warming-up, click on the word CONDITION in the upper left corner. This will put you into the Measure Condition Screen. 9. Check and insure that all of the parameters are as shown below for MEASURE CONDITION. If the conditions match go to Step A; if they do not match, input the settings below. c. Measure Condition 1. Agitation Speed: ON 3 2. Circulation Speed: ON 4 3. Ultrasonic working time: ON 1 4. Ultrasonic works during meas. NO 5. Waiting time after ultrasonic: 5 (sec) 6. Number of data sampling: 10 7. Shape of distribution: 1 8. Dispersant vol.: 200 (ml) 9. Dispersant vol for step: 10 (ml) 10. Rinsing solution vol.: 150 (ml) 11. Automatic print: NO 12. Relative refractive index: 1.88-0.001 13. Auto conc adjustment: NO 1. If the conditions match figure #1, click on the box marked D-CONDITION. 6
2. Check and insure that all of the parameters are as shown below for DISPLAY CONDITION. d. Display Condition 1. Cumulative distribution graph: ON 2. Type of cumulative distribution: OVER 3. Histogram scale: AUTO 4. Fixed graph scale: 5 5. Diameter on % [1]: ON 10.0 (%) [2]: ON 20.0 (%) [3]: ON 30.0 (%) [4]: ON 40.0 (%) [5]: ON 50.0 (%) 6. % on Diameter: 0.60 (micro meters) 7. Distribution Base: Volume 8. Sample Name 3. If they match, click on OK. This will put you back into the graph screen. If they do not match, input the above settings. e. Sample Operation 1. Find out the percent solids of the sample. 2. Weigh the slurry so that you have the equivalent amount of 5 grams of dry pigment: 5.0 gms x 100 % Solids 3. Pour into a beaker. Bring up level to 200 ml with deionized water. 4. Mix with magnetic stirrer for 30 minutes. 5. Pour through a 325 mesh screen into a labeled sample container. Entire operations should last about 45 minutes. 6. If the sample will not be run immediately, place in a beaker and stir on a magnetic stirrer. 7
f. Operating Procedure 1. Click on the word MEASURE in the upper left corner of the screen. This will put you into the Measure screen. If already in this screen, go to the next Step. 2. Click on the SET circle in the FEED box. This feeds 200 ml of buffer to the instrument reservoir. At the first of the shift and at any time the machine has been left idle with distilled water in the sample chamber, the chamber must be drained and rinsed before filling. This is done by clicking ON DRAIN ALL and then RINSE. The feed portion of this operation is timed. It is supposed to feed 150 ml of "RINSE" and 200 ml of "FEED SET". If it does not, adjust the rotameter on the reservoir, rinse or fill again. Keep doing this until the correct amount is pumped over. 3. When FEED is completed, click on the blue box for AGITATION (the reservoir stirrer will come on) then click on the blue CIRCULATION Box (the circulation pump will come on). 4. Insure that the door to the optical cell is tightly closed. 5. After the baseline (blue horizontal line at bottom) in the CHANNEL Box has settled down, and there are no red lines in the box on the right, click on the box named BLANK. The instrument will then blank the baseline. Do not add sample until the Blank routine is complete and the instrument has settled down. When this is complete, the T% He-Ne: (just above the CHANNEL Box) should read 100%. NOTE: If it reads anything other than 100%, repeat Steps 2-5 until the T% He-Ne reads 100%. 6. Remove ~85 µl of sample from the beaker and adjust the %TRANSMISSION to 85% ± 1%. 8
NOTE: The amount of sample will vary some with the type of pipette, calibration of the pipette and the grade of material being run. Since the % Transmission will be adjusted for each individual sample, the amount of sample being drawn into the pipette is not critical. If you have a %Transmission of less than 84%, dump the sample by performing steps 20-22. Then start with Step 6 again. 7. Add sample to the reservoir until the T% He-Ne: reads 85% ± 1%. The green bar down the left side on the CHANNEL Box will move down, the Baseline will change and the aim Box will show red lines. 8. Click on the box named MEASURE. The instrument will now measure the sample. 9. When MEASURE is completed, the agitation and circulation will stop and the screen will change back to the Graph screen with the sample graph on the screen. 10. Click on CONDITION, then on the D-CONDITION Box. Move the arrow to the sample Name Box and click once. Type the sample name into the Sample Name Box. 11. Click on OK. You will return to the Measure/Display Screen. 12. Click on FILE. The Measure File Dialogue Box will appear. Make sure the ASCii FILE SAVE Box is checked. 13. Place the mouse arrow in the FILE: Box and click once, then press the BACKSPACE Key. The FILE: Box should now be completely blank. 14. Type in the file name (no more than eight (8) characters). 15. Click on the SAVE Box. The file will be saved and the SAMPLE INFORMATION Dialogue Box will appear. 16. Fill in the appropriate sample information and click on OK (It is not necessary to add any information. You can simply leave everything blank and click on OK). The file name will appear, highlighted, in the lower left hand box. 9
17. Click on the CANCEL Box. The File Dialogue Box will disappear. 18. To print the standard Distribution Graph and Particle Size Distribution Data Table, click on PRINT. When the hourglass disappears you can continue with Step 20. If you wish to print graphs and data other than the one that appears on the screen, click on FILE, then click on the file name, then click on OPEN. The file will open and the graph will appear on the screen. Click to PRINT. 19. Click on MEASURE. The Measure screen will appear. 20. Click on the ALL circle in the DRAIN Box. The reservoir will be drained. 21. When the instrument stops, Click on the RINSE circle of the FEED Box. The instrument will now rinse itself and drain the rinse. 22. When RINSE is complete, the instrument will stop, leaving you in the Measure Screen. 23. If there are other samples to run, start over with Step 2. 24. After completing the last sample, if the machine is to be left idle for a while, after the rinse, manually fill the sample chamber with 200 ml of distilled water. Click on agitate and circulate, leave on for 1 minute, then turn off. B. Calibration Instrument calibration will be done according to manufacturer specifications (Operators Manual for Horiba LA-900) and site requirements. C. Sampling Samples are normally supplied by production. D. Sample Analysis Refer to section VIII. 10
E. Calculations Refer to section VIII. IX. Quality Control A TiO 2 sample or monodisperse beads (Duke Scientific or equivalent) is used as a reference standard to monitor the quality of the Horiba LA-900 instrument. Samples should be run at least once/shift. X. Comments A. General None B. Specific None XI. References A. General Operators Manual for the Horiba LA-900. B. Specific None XII. Appendix 1. Revision Sheet. XIII. Approval/Certification Origin: Edge Moor Control Laboratory, March 29, 1996 Prepared by: B. Pericles and R. G. Puder 11