This method is included in NEMI for informational purposes as it is approved by EPA for regulatory use. Detailed information on this method is not currently. eropoly acid. This is reduced to silicomolybdenum blue that is determined pho- tometrically. The method is analogous to APHA SiO2 D+E, ASTM D, . Find the most up-to-date version of ASTM D at Engineering
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NOTE 4—Batch to batch variations in ammonium molybdate have been found to affect results at low concentrations below 0. Current edition approved Feb. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters. Due to the complexity of silica chemistry, the form of silica measured is defined by the analytical method as molybdate-reactive silica.
Standard – Standard Test Method for Silica in Water ASTM D –
The collecting apparatus and storage containers for the reagent water must be polyethylene or other suitable plastic. It is particularly applicable to treated industrial waters. Precision and Bias 5 In contrast, silica may be added as a treatment chemical in some systems, for example, in corrosion control. Refer d8599 Appendix X1 for historical information. For standards in the 0.
Standard Test Method for Silica in Water
Due to the complexity of silica chemistry, the form of silica measured is de? Quality Control QC Unless otherwise indicated, it is intended that all reagents shall conform to the speci? ASTM D95 – Silica removal is commonly accomplished by ion exchange, distillation, reverse osmosis, or by precipitation, usually with magnesium compounds in a hot or cold lime softening process.
Spike a portion of a water or other sample from each batch with the method analytes at the level of the IDP solution. The CVS is a solution of the method analyte of known concentration mid-calibration range used to fortify reagent water.
Since the method includes an evaporation step, the applicable concentration range depends upon the volume of sample used in the determination. Prepare a blank using a Historical Version s – view previous versions of standard Translated Version s: Summary of Test Method 4. For seawater or brines, this test method is applicable only if matched matrix standards or standard addition techniques are employed.
The LCS is a solution of method analytes of known concentration added to a matrix that sufficiently challenges the Test Method.
A blank d59 also be run with each sample batch maximum of 20 samples to check for sample or system contamination. Calibration and Standardization Link to Active This link will always route to the current Active version sstm the standard.
ASTM D859 – 16
The presence of most silica in natural waters comes from the gradual degradation of silica-containing minerals. It may be applied to natural waters and wastewaters following filtration or dilution, or both. This is acceptable when, as frequently occurs, the molybdate-reactive silica is in the milligram per litre concentration range while the nonmolybdate-reactive silica, if present at all, is in the microgram per litre concentration range.
Complex silicate residues that do not yield to this treatment are dissolved by alkali fusion and dehydrated with HCl. No other units of measurement are included in this standard. In cooling water systems, silica forms deposits when solubility limits are exceeded. Such waste waters may also contain organic compounds that may interfere in the color formation. It is particularly applicable to treated industrial waters.
It is found as the oxide in crystalline forms, as in quartz; combined with other oxides and metals in a variety of silicates; and in amorphous forms. The upper limit for acceptable precision and the range of acceptable recoveries are detailed below: Refer to Appendix X1 for historical information. For measurements made at nm, silica concentration may be read directly in milligrams SiO2 per litre from the calibration curve prepared in No other units of measurement are included in this standard.
Under certain conditions, silica forms troublesome silica and silicate scales, particularly on highpressure steam turbine blades. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below.
It is applicable to most waters, but some waters may require filtration and dilution to remove interferences from color and turbidity. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every?
Shelf life of this reagent may be extended by refrigeration. Type II water was speci? Wstm solution it can exist as silicic acid or silicate ion, depending upon pH. Reagents and Materials NOTE 3—Store all reagents to be used in this test method in polyethylene or other suitable plastic bottles.
It is the skeletal material of diatoms but is not known to play a significant role in the structure of processes of higher life forms. If non-detects are expected in all the samples to be analyzed, a Matrix Spike Duplicate should be run instead. It is applicable to most waters, but some waters may require filtration and dilution to remove interferences from color and turbidity. Note 1—For many natural waters, a measurement of molybdate-reactive silica by this test method provides astk close approximation of total silica, and, in practice, the colorimetric method is frequently substituted for other more time-consuming techniques.
The lower limit of this method is 5 mg of silica. The mean and standard deviation of the seven values should then be calculated and compared, according to Practice Dto the single operator precision and recovery established for this Test Method. Precision and bias information on this test method see Section 13 is aastm on data obtained at nm.
This is acceptable when, as frequently occurs, the molybdate-reactive silica is in the milligram per litre concentration range while the nonmolybdate-reactive silica, if present at all, is in the microgram per litre concentration range. Spectrophotometers shall conform to Practice E Each operator made six determinations at each level, for a total of 72 determinations at each level.