1. This standard specifies the test method for the iodine adsorption value of wood activated carbon.
This standard applies to wood activated carbon.
2, the reference standard
The provisions contained in the following standards constitute provisions of this standard by reference in this standard. At the time of publication, the editions indicated were valid. All standards will be revised and parties using this standard should explore the possibility of using the latest version of the following standards.
3. Method summary
After a certain amount of the sample and the iodine solution are sufficiently oscillated and adsorbed, the mixture is filtered and taken, and the amount of iodine remaining in the filtrate is titrated with a sodium thiosulfate solution. The amount of iodine (in milligrams) per gram of carbon adsorbed by the remaining iodine concentration of 0.02 mol/L (1/2I2) was determined as the iodine value.
4, instruments and reagents
The water used in this standard shall comply with the third-grade water regulation in GB/T6682; the listed reagents shall be analytically pure reagents unless otherwise specified.
4.1 Balance, the sensitivity is 0.1mg.
4.2 Electric constant temperature drying oven.
4.3 Oscillator, frequency 240-275 times / min.
4.4 Test sieve, sieve hole 71μm.
4.5 Iodine (GB/T 675).
4.6 Potassium iodide (GB/T 1272).
4.7 sodium thiosulfate (Na2S2O3? 5H2O) (GB/T637).
4.8 Soluble starch (HGB 3095).
4.9 Potassium dichromate (GB 1259), reference reagent.
The State Bureau of Quality and Technical Supervision approved the implementation of 2000-04-01
GB/T12496.8 - 1999
5, the solution
5.1 0.1mol/L iodine (1/2I2) standard solution
Take 26g of potassium iodide dissolved in about 30mL of water, add 13g of iodine, make iodine fully soluble in potassium iodide solution, then dilute to 1000mL with water, adjust the iodine concentration in the range of (0.1?0.002) mol/L, shake well and stand still for 2 days. After being calibrated, it is stored in a brown glass bottle.
Calibration: Pipette 20mL of iodine solution accurately into 500mL iodine volumetric flask, add water 200mL. Titrate with 0.1mol/L sodium thiosulfate standard solution, gently shake the iodine volume bottle. When titrating until the solution is light yellow, add 2mL of starch indicator solution, then carefully drop to colorless, which is the end point.
The concentration of iodine solution is calculated according to formula (1)
C2 ?V2c2 ?V2
C1 = = ............... (1)
V1 20
Where: c1 ---- concentration of iodine (1/2I2) standard solution, mol / L;
C2 - concentration of sodium thiosulfate (Na2S2O3? 5H2O) standard solution, mol / L;
V2---- volume of mL of sodium thiosulfate standard solution consumed by titration;
V1----Check the amount of iodine solution, 20mL.
5.2 starch indicator solution
Weigh 1.0g soluble starch, add 10mL water, inject 190mL boiling water under stirring, place it for 2min, then place it, take the supernatant solution, and prepare this solution before use.
5.3 0.1 mol/L sodium thiosulfate standard solution
Weigh 26g sodium thiosulfate (Na2S2O3? 5H2O) dissolved in 1000mL water, slowly boil for 10min, cool, set for two weeks and then filter in brown glass bottle for use.
Calibration: Weigh 0.150g (weighed to 0.1mg) at 120 ° C to constant weight of potassium dichromate (4.9), placed in a 250mL iodine bottle, add 25mL water to dissolve, add 2g potassium iodide and 20mL " 1+8" sulfuric acid, shake well, place in the dark for 10min. Add 100mL water, titrate with 0.1mol/L sodium thiosulfate standard solution, add 3mL starch indicator solution near the end point, continue titration until the solution changes from blue For bright green. Also do a blank test, see equation (2):
m
c = ............... (2)
(V1 -V2) ? 0.04903
Where: c----concentration of sodium thiosulfate, mol / L;
m ---- potassium dichromate quality, g;
V1----sodium thiosulfate solution, mL;
V2---- Blank test sodium thiosulfate solution, g/mol.
49.03----potassium dichromate (1/6K2Cr2O7) molar mass, g/mol.
6, activated carbon detection steps
6.1 Weigh 0.5g of dry sample pulverized to 71μm (weighed to 0.4mg), powdered charcoal should be supplemented and ground to meet the requirements of 71μm, put into a dry 100mL iodine volumetric flask, accurately added (1+9 10.0mL hydrochloric acid, the sample is wet, placed on an electric furnace to heat to boiling, slightly boiling (30 ~ 2) s, after cooling to room temperature, add 50.0mL of 0.1mol / L iodine standard solution. Immediately sieve the cap, Shake for 15 min on a shaker and quickly filter into a dry beaker.
6.2 Pipette 10.0mL of the filtrate into a 250mL iodine volumetric flask, add 100mL of water, titrate with 0.1mol / L sodium thiosulfate standard solution, add 2mL starch indicator solution when the solution is light yellow, Continue titration to make the solution colorless, recording the volume of sodium thiosulfate used.
7. Calculation of activated carbon test results
5(10c1-1.2c2V2)? 127
A = ( )? D ......... (3)
m
Where: A--- iodine adsorption value of the sample, mg / g;
C1--- concentration of iodine standard solution, mol / L;
C2----concentration of sodium thiosulfate standard solution, mol/L
V2----the amount of sodium thiosulfate solution consumed, moL
m---sample quality, g;
127---Iodine (1/2) I2 molar mass, g/mol;
D---correction coefficient, according to the remaining rich c3 check table 1.
C3= c2?V2/10 ----------(4)
Note: If the remaining concentration exceeds the correction factor table, reduce the amount of carbon or increase the amount of carbon and then test and calculate the iodine adsorption value.
8, the accuracy and error of activated carbon detection
The iodine value of two parallel samples (in the same laboratory) shall not exceed 5.6% when the iodine value is between 600 and 1450 mg/g.
When the iodine value between the two laboratories is 600-1450mg/g, it shall not be greater than 10.2%.
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