This standard specifies the method for determining the acid-insoluble lignin content of papermaking raw materials. This standard is applicable to various wood and non-wood plant fiber papermaking raw materials. GB/T 2677.8-1994 Determination of acid-insoluble lignin content of papermaking raw materials GB/T2677.8-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of Chinabzxz.net
Fibrous raw material-Determinationof acid-insoluble lignin
Subject content and scope of application
This standard specifies the method for determining the acid-insoluble lignin content of papermaking raw materials. This standard is applicable to various wood and non-wood plant fiber papermaking raw materials. 2 Reference standards
GB/T2677.1 Sample collection for papermaking raw material analysisGB/T2677.2 Determination of moisture content of papermaking raw materialGB/T2677.3 Determination of ash content of papermaking raw materialGB/T2677.6 Determination of organic solvent extract content of papermaking raw material3 Principle
GB/T 2677.8-94
Replaces GB2677.8-81
Use (72±0.1)% (m/m) sulfuric acid to hydrolyze the sample extracted with a benzene-alcohol mixture, and then quantitatively determine the mass of the hydrolysis residue (i.e., acid-insoluble lignin).
4 Instruments
Laboratory-general instruments.
4.2 Temperature-controlled porous water bath.
4.3 Soxhlet extractor: 150mL.
4.4 Conical flask with stopper: 100mL.
4.5 Conical flask: 1000mL.
4.6 Measuring cylinder: 500mL.
Controllable temperature electric heating plate.
Precision density meter.
5 Reagents
5.12: 1 (V/V) Benzene-alcohol mixture: Mix 2 volumes of benzene and 1 volume of 95% ethanol and shake well. 5.2 (72±0.1)% (m/m) sulfuric acid solution [density of this solution is P20= (1.6338±0.0012) g/mL]: Pour 665mL (95~98)% sulfuric acid into 300mL distilled water slowly under constant stirring. After cooling, add distilled water to a total volume of 1000mL. Shake well, adjust the temperature to 20℃, pour part of the solution into a 500mL measuring cylinder, and use a precision density meter (4.8) to measure the density of the acid solution. If it is not within the range of (1.6338±0.0012)g/mL, add appropriate amount of sulfuric acid or distilled water to adjust until it meets the above density requirements. 5.3 10% barium chloride solution.
Approved by the State Administration of Technical Supervision on September 24, 1994 and implemented on March 1, 1995
5.4 Quantitative filter paper and qualitative filter paper.
5.5 Wide range pH test paper.
6 Sampling and processing
GB/T 2677.8—94
Sampling and processing shall be carried out in accordance with the provisions of GB/T2677.1. 7 Test steps
7.1 Sample weighing and treatment
Weigh 1g (accurate to 0.0001g) of sample (at the same time determine the moisture content according to GB/T2677.2), wrap it with qualitative filter paper and tie it with cotton thread, extract it with benzene alcohol according to GB/T2677.6, and finally air-dry the sample package. 7.2 Hydrolysis of sample
7.2.1 Hydrolysis with (72±0.1)% sulfuric acid
Open the air-dried filter paper package, transfer the sample extracted with benzene alcohol into a 100mL stoppered conical flask (4.4), and add 15mL of (72±0.1)% sulfuric acid (5.2) cooled to 12-15℃, so that the sample is completely permeated with the acid solution, and cover the bottle stopper. Then place the conical flask in a water bath (or sink) (4.2) at 18-20℃, keep it warm for a certain period of time (2h for wood raw materials and 2.5h for non-wood raw materials), and shake the conical flask from time to time to ensure that the reaction in the flask is evenly carried out. 7.2.23% sulfuric acid hydrolysis
After reaching the specified time, transfer all the contents of the conical flask into a 1000mL conical flask (4.5) while rinsing with distilled water, and add distilled water (including rinsing) to a total volume of 560mL. Place this conical flask on an electric hot plate (4.7) and boil for 4h. During this period, water should be added continuously to maintain the total volume of 560mL, and then let it stand to allow the acid-insoluble lignin to settle. 7.3 Filtration and constant weight of acid-insoluble lignin
Use quantitative filter paper that has been constant weight in a weighing bottle (or aluminum box) (the filter paper should be washed three or four times with 3% sulfuric acid solution in advance, then washed with hot distilled water until the washing liquid is no longer acidic, and dried to constant weight), filter the above acid-insoluble lignin, and wash with hot distilled water until the washing liquid is no longer turbid after adding a few drops of 10% barium chloride solution (5.3), and use pH test paper (5.5) to check that the edge of the filter paper is no longer acidic. Then move the filter paper into the weighing bottle (or aluminum box) used for constant weight and dry it in an oven at 105±2℃ to constant weight. If it is non-wood raw material, the ash content in the acid-insoluble lignin should be determined according to GB/T2677.3.
8 Calculation of results
The acid-insoluble lignin content X(%) in wood raw materials is calculated according to formula (1): m×100
Wherein: mi-
The mass of acid-insoluble lignin after drying, g;
The mass of the absolutely dry sample, g.
The acid-insoluble lignin content X2(%) in non-wood raw materials is calculated according to formula (2): Xz = ml= m2 × 100
Wherein: m1—The mass of acid-insoluble lignin after drying, g; The mass of ash in acid-insoluble lignin, g;
m-The mass of the absolutely dry sample, g.
GB/T 2677.894
Carry out two determinations at the same time, take the arithmetic mean to the second decimal place, and the difference between the calculated values ​​of the two determinations should not exceed 0.20%.
9 Test report
Number of this national standard;
Test results and necessary explanations;
Any abnormal phenomena observed during the test, any operations that are not specified in this national standard or referenced standards and may affect the results. Additional notes:
This standard is proposed by the China Light Industry General Association.
This standard is under the jurisdiction of the National Technical Committee for Standardization of Paper Industry. This standard was drafted by the Paper Industry Scientific Research Institute of the Ministry of Light Industry. The main drafters of this standard are Chen Qizhao, Zhu, and Zhang Guilan. This standard was first published in 1961 and revised for the first time in 1981. This standard refers to the American Pulp and Paper Association standard TAPPIT222om-88 "Acid-insoluble lignin in wood and pulp". 215
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