BS ISO 6588-2:2012 pdf free.Paper, board and pulps – Determination of pH of aqueous extracts Part 2: Hot extraction.
This part of ISO 6588 specifies a method for the determination of the pH-value defined by the electrolytes extractable by hot water from a sample of paper, board or pulp.
This part of ISO 6588 is applicable to all kinds of paper, board and pulp.
As the quantity of extractable ionic material approaches zero, as in the case of highly puritied pulps, the precision of the method becomes poor because of the difficulties encountered in making p1-I measurements on water containing little electrolytic material.
Since the extraction in this part of ISO 6588 is performed with distilled or deionised water, the p1-I-value measured will sometimes be different (e.g. fully bleached pulp) from the pH-value measured under mill process conditions in which various types of process waters, e.g. chemically treated river water containing electrolytes, are used.
It is necessary to be aware that the results will not be the same when measuring pH according to this part of ISO 6588 when compared to ISO 29681. The differences can be significant especially when measuring pulps having a low ionic strength.
ISO 6588-1 differs from this part of 1506588 only as regards the extraction conditions. No general guidance can be given as to which of the two procedures (hot or cold) is best suited in a particular situation.
For cellulosic papers used for electrical purposes, the method used should be that given in IEC 60554-2 (see 141 in the Bibliography).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 186, Paper and board-—Sampling to determine average quality
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 7213, Pulps — Sampling for testing
3 Principle
Extraction of a sample of 2 g for 1 h with 100 ml of boiling water of high purity. Filtration of the extract and addition of a salt solution. Measurement of the p11-value of the extract at a temperature between 20 °C and 25 °C.
4 Reagents
4.1 Water, distilled or deionised water shall be used throughout the test. The conductivity of the water shall not exceed 0,1 mS/rn after boiling for 1 h and cooling in an acid-free atmosphere (e.g. free of C02, SOz, H2S) to a temperature between 20 °C and 25 °C. The pH of the water should be in the range of 6,8 to 7,3. Instructions for the determination of conductivity are specified in ISO 3696.
4.2 Standard buffer solutions, with known pH-values of about 4, 7 and 9. Such buffer solutions are commercially available. Some examples of suitable buffer solutions are given, and their preparation is described, in Annex A.
4.3 Potassium chloride solution, I M. Dissolve 7,4 g of KCI, analytical grade, in 100 ml of freshly boiled, distilled water. Prepare a fresh solution every week.
5 Apparatus and equipment
Use the following, in addition to ordinary laboratory apparatus and equipment.
5.1 Glassware of chemically resistant glass, flasks with ground-glass joints, stoppers, beakers, reflux condenser and fritted glass filter. All glassware shall be cleaned with an acid cleaning solution, without the use of soap or detergent, and they shall be carefully rinsed with water (4.1) and allowed to dry before use.
5.2 pH-meter, fitted with glass and calomel electrodes or with a combined electrode, capable of being read to at least 0,05 pH-unit.
6 Sampling and preparation of sample
6.1 Sampling
The sampling procedure to be followed depends on the particular circumstances in each case. If the analysis is being made to evaluate a lot or a consignment of pulp, paper or board, the sample shall be taken in accordance with ISO 7213 or ISO 186, as relevant. If the analysis is made on another type of sample, report the origin of the sample and, if possible, the sampling procedure, and ensure that the specimen taken in 7.1 is representative of the sample received.
Wear clean protective gloves when handling the sample.BS ISO 6588-2 pdf free download.