AS NZS 1301.011:2018 pdf free.Methods of test for pulp and paper Method 011: Klason lignin in wood and pulp.
6 PREPARATION OF TEST SPECIMEN
The test specimen shall be prepared as follows:
(a) Collect a representative sample of wood chips according to AS/NZS 1301.Ol3rp or a representative sample of pulp according to AS/NZS ISO 7213.
(b) For wood, prepare the sample according to the method prescribed in AS/NZS 1301.002s. For pulp, disintegrate the sample in the high-speed blender as defined in Clause 4.6; however, pulps which do not contain coarse fibres or shives, and which can be dispersed readily in sulphuric acid, could be used without prior disintegration. Mechanical pulp and high yield pulps containing a significant amount of resin shall be extracted with a solvent, in accordance with AS/NZS 1301.012s.
(c) Determine the moisture content of the sample by drying a specimen to constant mass at (105 ±2)°C and calculating loss of mass as a percentage of the air dry mass.
(d) Prepare a specimen by weighing to within 0.1 mg into a 100 mL beaker an amount of sample calculated to contain (1.0 ±0.1) g of oven dry wood or (2.0 ±0.1) g of oven dry pulp. Consider mechanical pulp and very high yield puips as wood. Prepare a duplicate specimen in the same manner using a separate beaker.
7 PROCEDURE
The procedure shall be carried out in duplicate as follows:
(a) Add to the beaker containing a test specimen cold (10°C to 15°C) 72 per cent sulphuric acid; 15 mL for wood and 40 mL for pulp. Add the acid slowly while stirring and macerating the material with a glass rod. Keep the beaker in a water bath at (20 ±1)°C during dispersion. If the material does not absorb the acid and disperse readily, place the beaker in a vacuum desiccator under vacuum for a few minutes to assist the wetting process (5).
(b) After dispersion cover the beaker with a watch glass and keep it in the water bath for 2 h. Stir frequently during this time to ensure the maximum opportunity for solubilization.
(c) Add 300 mL to 400 mL of water to a flask of the appropriate capacity and transfer the contents of the beaker to the flask. Rinse the beaker with water, add the rinsings to the flask and add sufficient additional water to dilute to the mark on the flask.
(d) Boil the mixture for 4 h, maintaining constant volume by fitting a reflux condenser.
(e) Allow the flask to stand to settle the insoluble material. This may require up to one day.
(f) Without stirring the mixture, decant or siphon as much as possible of the supernatant solution through a filtering crucible that has previously been dried in the oven for about 2 h, cooled and tared.
(g) Rinse the siphon with hot water and pass the rinsings through the filter.
NOTE: Acid-soluble lignin in the filtrate can be determined by a spectrophotometric method based on absorption of ultra-violet radiation at a wavelength of 205 nm (3) (4).
(h) Finally using hot water, transfer the residue to the filter crucible, and wash the residue on the filter with hot water.
NOTE: Although small amounts of sulphuric acid which remain at this stage are not sufficient to cause serious error in the lignin yield, they may lower the methoxyl content by as much as half if the sample is dried while they are present.AS NZS 1301.011 pdf download.