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BS ISO 5073:2013 pdf free

BS ISO 5073:2013 pdf free.Brown coals and lignites – Determination of humic acids
Weigh about 10 g of analysis sample of brown coals and lignites into three or four conical flasks separately depending on the humic acid content of the sample (can yield 3 g or 4 g of humic acid sample).Pipette an appropriate amount of the alkaline sodium pyrophosphate extraction (5.1) into each conical flask equivalent to 150 ml per gram of the analysis sample and mix until the sample is thoroughly wetted.Place a small funnel on the flask and heat in the billing water bath (6.1) for 2 h, shaking frequently to ensure precipitation of insoluble material.
Remove the flask from the water bath, cool to room temperature, centrifuge the contents of flasks for 5 min. Collect the solution in the beakers. Add (1 + 1) HCl to the solution until the humic acid is precipitated fully (pH 1 to pH 3 for the solution).
Centrifuge the suspension. Decant and discard the solution. Separate the residue through a medium-textured paper, wash the residue with water until peptization of the humic acids begins, which is indicated by the formation of a gel or colloid (pH 6 to pH 7 for the filtered solution).
Transfer the residue to the clear beakers or vessels and dry it at 105°C to 110 °C. The dried residue is the humic acid sample.
Weigh 0,1 g, to the nearest 0,2 mg, of the humic acid sample (see A.4) into a conical flask. Add 150 ml of the alkaline sodium pyrophosphate extraction solution (5.1). Shake to enable it to be dissolved fully.Transfer the contents of the flask to a 200 ml volumetric flask and dilute to the mark with water. Shake to ensure thorough mixing, then dry-filter through a medium-textured paper into a flask. Accurately pipette 5 ml of filtered solution into a 250 ml conical flask. Determine the carbon content of the humic acid sample as specified in 8.3.BS ISO 5073 pdf download.

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