1、TAPPI/ANSI T 692 om-13 PROVISIONAL METHOD 1980 OFFICIAL TEST METHOD 1985 REVISED 1993 REVISED 2000 REVISED 2004 REVISED 2008 REAFFIRMED 2013 2013 TAPPI The information and data contained in this document were prepared by a technical committee of the Association. The committee and the Association ass
2、ume no liability or responsibility in connection with the use of such information or data, including but not limited to any liability under patent, copyright, or trade secret laws. The user is responsible for determining that this document is the most recent edition published. Approved by the Standa
3、rd Specific Interest Group for this Test Method TAPPI CAUTION: This Test Method may include safety precautions which are believed to be appropriate at the time of publication of the method. The intent of these is to alert the user of the method to safety issues related to such use. The user is respo
4、nsible for determining that the safety precautions are complete and are appropriate to their use of the method, and for ensuring that suitable safety practices have not changed since publication of the method. This method may require the use, disposal, or both, of chemicals which may present serious
5、 health hazards to humans. Procedures for the handling of such substances are set forth on Material Safety Data Sheets which must be developed by all manufacturers and importers of potentially hazardous chemicals and maintained by all distributors of potentially hazardous chemicals. Prior to the use
6、 of this method, the user must determine whether any of the chemicals to be used or disposed of are potentially hazardous and, if so, must follow strictly the procedures specified by both the manufacturer, as well as local, state, and federal authorities for safe use and disposal of these chemicals.
7、 Determination of suspended solids in kraft green and white liquors 1. Scope This method provides a means of determining the level of suspended solids in kraft green liquor and kraft white liquor. 2. Significance A procedure for determining suspended solids is needed to establish the efficiency of f
8、iltering equipment or of chemical additives used to reduce the level of suspended solids in these liquors. 3. Summary The method given is based upon a filtration through glass fiber filter discs, with hot water wash to remove the dissolved solids. It is similar to the method used by the U.S. Public
9、Health Service, called the “Gooch Crucible-Asbestos Fiber Method.” The use of the glass fiber filter disc is recommended since the caliper of the glass fiber media is uniform, and insures reproducible results. 4. Apparatus 4.1 Filter discs1, glass fiber, pore diameter less than 2.5 micron, 47 mm ove
10、rall outer diameter. (If other diameter filter disc is used, report diameter used). 4.2 Gooch crucibles1(or alternative - see note 2). 4.3 Gooch crucible filter adapter1 (or alternative see note 2). 4.4 Filter flask, 1-L. 1Names of suppliers of testing equipment and materials for this method may be
11、found on the Test Equipment Suppliers list in the set of TAPPI Test Methods, or may be available from the TAPPI Technical Operations Department. T 692 om-13 Determination of suspended solids / 2 in kraft green and white liquors 4.5 Vacuum (aspirator satisfactory). 4.6 Distilled water. 4.7 Drying ove
12、n (105C 3C). 4.8 Analytical balance. 4.9 Desiccator. NOTE 1: The pore size in the glass fiber discs specified in this method is less than 2.5 micron. Other inert filtering media with a comparable pore size may be employed if glass fiber discs are not available. Filter paper should yield comparable r
13、esults. However, no data are available comparing other media with the glass fiber disc. Whatever medium is employed, it still remains important to filter the sample at the temperature specified, and to rinse with hot distilled water to remove the dissolved solids prior to weighing. NOTE 2: Membrane
14、or Buchner filter apparatus are acceptable alternative equipment selections, providing that the pore size of the filter material is less than 2.5 microns. Report type of equipment used (if other than Gooch) and the diameter of filter disc used. 5. Procedure 5.1 Collect a representative sample of the
15、 liquor to be tested. A minimum of 2 L is required. Record temperature. If possible, maintain at that temperature for testing by using an insulated type container. If not possible, reheat the liquor to its original temperature prior to testing (see Note 3). NOTE 3: Temperature of sample is critical.
16、 If the temperature of the sample, or sample aliquot, is allowed to drop before testing, or during the filtration step, the sample should be reheated to the original sampling temperature and stirred for a period of time sufficient to re-dissolve any salts (crystals), which may have precipitated as t
17、he sample cooled. The sample should be kept hot, using a water or steam bath if necessary, during the filtration step. 5.2 Insert a glass fiber filter pad, felt side up, into a Gooch crucible. The felt side is easily recognized by its smoother surface as compared with the wire side (which is charact
18、erized by a wire mark). Place filter unit in adapter in the filtering flask and turn on medium vacuum. Use about 50 mL of distilled water and seat the filter. 5.3 Place the prepared filter unit in an oven at 105C and dry to constant weight (about 60 min). Cool filter unit in a desiccator and obtain
19、tare weight. Weigh to nearest 0.1 mg. 5.4 Place the filter unit in the filter adapter in the filtering flask. Wet filter with 10-15 mL distilled water; pull down slightly with vacuum to seat filter in bottom of crucible. Hold small amount of vacuum to keep filter in place. 5.5 Stir sample vigorously
20、, and measure out desired volume into a graduated cylinder. Usual sample size is 200 mL, and duplicate determinations should be made. When liquor suspended solids are low, i.e. after a pressure filter, the sample size should be increased. 5.6 Pour sample into filter unit and adjust vacuum to optimum
21、 conditions for each sample. The vacuum should be held to a minimum. Excessive vacuum will pull the suspended solids into the pores of the filter media and prolong the filtering time. If the suspended solids are high and the filtration rate is slow, repeat the test transferring only 30-50 mL aliquot
22、s of the sample into the filter unit at any one time. Keep the rest of the sample hot using a hot plate, water bath or steam bath (see Note 3). CAUTION: Excessive vacuum may also cause flashing of the hot filtrate & unseat the filter disc, thus voiding the test result. 5.7 Rinse the graduated cylind
23、er used in 5.5 onto the filter media with 100-200 mL of hot distilled water. After sample is entirely filtered, rinse the filter with 100-200 mL of hot distilled water to remove dissolved or precipitated solids. Repeat for a total of three or more rinses. Phenolphthalein can be used to check the alk
24、alinity of the filtrate after the third wash to determine if more rinses are needed. The phenolphthalein should not be put on the filtered solids or filter paper. To check the filtrate, you must empty the filtration flask after the filtration step and first two washes, prior to the last wash, or use
25、 a second filter flask to capture the filtrate from the third wash. More washes are needed if the phenolphthalein turns pink or moive when added to the filtrate from the third wash. 5.8 Dry filter unit in oven at 105C to constant weight (2 h is usually sufficient). Cool in a desiccator and weigh. 5.
26、9 The difference in the two weighings is calculated as suspended solids in milligrams per liter: Suspended solids, mg/L = (Wc- WT)1000/V 3 / Determination of suspended solids T 692 om-13 in kraft green and white liquors where Wc= weight of crucible + solids, g WT = tare weight, g V = sample volume,
27、L Examples: Sample size: 1.0 L of white liquor Temperature: 82C Weight of crucible plus solids: 76.9083 g Tare weight: 76.8005 g 0.1078 g Report: 108 mg of suspended solids/L 6. Report 6.1 Report the difference in the two weighings as suspended solids in milligrams per liter. Test results should be
28、based upon the average of duplicate determinations. 6.2 Report the temperature of the liquor sample at time of testing. 7. Precision Repeatability (within a laboratory) is about 2 to 7%, based upon duplicate determinations. Reproducibility (between laboratories) is 2 to 10%, based again on duplicate
29、 determinations. 8. Caution Kraft liquors are hazardous. Safety precautions should be followed when obtaining samples and when handling these liquors. As a minimum precaution when obtaining samples of these liquors, face and eye protection should be required and rubber gloves worn. 9. Keywords Kraft
30、 liquors, Green liquors, White liquors, Suspended solids, Solids content 10. Additional information 10.1 Effective date of issue: April 30, 2013. 10.2 The filter pore size range was determined through research performed at Paprican on lime mud particulate size. See Figure 1. Based on this research,
31、a filter disc with less than a 2.5 micron pore diameter is considered acceptable for particulate retention. 10.3 In response to the comments received in this 2008 revision, in section 4.1, the word “outer” was added before “diameter” to avoid confusion on the size of the filter discs. In section 5.7
32、, a sentence was added to clarify when more washing was necessary. T 692 om-13 Determination of suspended solids / 4 in kraft green and white liquors Fig. 1. Cumulative distributions by number for hydrated lime Ca(OH)2 and by number and weight for CaCO3. Your comments and suggestions on this procedure are earnestly requested and should be sent to the TAPPI Standards Department.
