ไปหามาให้ ครับ
2720 B. Volumetric Method
เจอที่นี่ครับ
http://www.scribd.com/doc/44520215/Stan ... 9#download แล้ว search หา 2720B ครับผมวิธีละเอียดดีครับ
Standard Methods for the Examination of Water and Wastewater
© Copyright 1999 by American Public Health Association, American Water Works Association, Water EnvironmentFederation
to water. After each of the above steps, the volume of gas remaining is measured; the decreasethat results is a measure of the relative percentage of volume of each component in themixture. Finally, CH
4
is determined by conversion to CO
2
and H
2
O in a slow-combustionpipet or a catalytic oxidation assembly. The volume of CO
2
formed during combustion ismeasured to determine the fraction of methane originally present. Nitrogen is estimated byassuming that it represents the only gas remaining and equals the difference between 100%and the sum of the measured percentages of the other components.When only CO
2
is measured, report only CO
2
. No valid assumptions may be made aboutthe remaining gases present without making a complete analysis.Follow the equipment manufacturers’ recommendations with respect to oxidationprocedures.C
AUTION
:
Do not attempt any slow-combustion procedure on digester gas because of thehigh probability of exceeding the explosive 5% by volume concentration of CH
4
.
2. Apparatus
Orsat-type gas-analysis apparatus,
consisting of at least: (1) a water-jacketed gas buretwith leveling bulb; (2) a CO
2
-absorption pipet; (3) an O
2
-absorption pipet; (4) a cupricoxide-hydrogen oxidation assembly; (5) a shielded catalytic CH
4
-oxidation assembly orslow-combustion pipet assembly; and (6) a leveling bulb. With the slow-combustion pipet usea controlled source of current to heat the platinum filament electrically. Preferably use mercuryas the displacement fluid; alternatively use aqueous Na
2
SO
4
-H
2
SO
4
solution for samplecollection. Use any commercially available gas analyzer having these units.
3. Reagents
a. Potassium hydroxide solution:
Dissolve 500 g KOH in distilled water and dilute to 1 L.
b. Alkaline pyrogallol reagent:
Dissolve 30 g pyrogallol (also called pyrogallic acid) indistilled water and make up to 100 mL. Add 500 mL KOH solution.
c. Oxygen gas:
Use approximately 100 mL for each gas sample analyzed.
d. Displacement liquid (acidic salt solution):
Dissolve 200 g Na
2
SO
4
in 800 mL distilledwater; add 30 mL conc H
2
SO
4
. Add a few drops of methyl orange indicator. When colorfades, replace solution.
4. Procedure
a. Sample introduction:
Transfer 5 to 10 mL gas sample into gas buret through acapillary-tube connection to the collector. Expel this sample to the atmosphere to purge thesystem. Transfer up to 100 mL gas sample to buret. Bring sample in buret to atmospheric orreference pressure by adjusting leveling bulb. Measure volume accurately and record as
V
1
.
b. Carbon dioxide absorption:
Remove CO
2
from sample by passing it through theCO
2
-absorption pipet charged with the KOH solution. Pass gas back and forth until samplevolume remains constant. Before opening stopcocks between buret and any absorption pipet,