Ⅰ、Blue absorption test

Ⅱ、Inpection theory

Add trial sample into Dilute solution of sodium pyrophosphate,Micro-boiling heat to disperse,then filter as indicator,Drop with methylene blue standard solution.

Ⅲ、Reagents：

3.1 Sodium pyrophosphate solution ρ(Na4P2O7·10H2O)＝10g／L: measured 10.00g Pyrophosphate(Na4P2O7·10H2O ),put it into beaker 250ml,Micro-boiling heat to dissolve,move it to 1000ml flask, Diluted with water to the mark,shake well ,place after 24h use

3.2 methylene blue standard solution c(C16H18N3SCl)一0.0050mol／L

3.2.1　General preparation method: Weigh 10.0000g commercially available methylene blue bake 4h in oven at 93 ℃ ± 3 ℃ ,Cooled to room temperature inside a desiccator, weigh it, calculate content of Methylene blue crystal water and free water,then calculate the purity of Methylene blue commercially available . By pure methylene blue (C16H18N3SCl) 1.599 g converted into the commercially available amount of methylene blue, put it into 250ml beaker,completely dissolved with water(if methylene bule is difficult to dissolve, it can micro heat, temperate can not be too high to change its property of methylene blue),move it to 1000ml brown flask, Diluted with water to the mark,shake well.

3.2.2 Arbitration preparation method

3.2.2.1 Determination of methylene blue content:

weigh 0.4000g methylene blue(C16H18N3SCl·3H2O), put it into 250ml beaker, add 100ml water to dissolve. Heat solution to 75 degree, add 50ml Potassium dichromate solution[c(1／2 K2Cr2O7)＝0.1mol／L],put the beaker into 75 degree water to heat preservation 5-10 min.After cooled, filter with known mass on the 4th glass frit funnel,use Potassium dichromate solution[c(1／2 K2Cr2O7)＝0.1mol／L] to wash beaker,then wash precipitate three to four times, then use Potassium dichromate solution[c(1／2 K2Cr2O7)＝0.02mol／L] to wash six to seven times, last use water to wash one time.Put glass frit funnel and precipitate into oven to bake 1h at 120 degree, remove and place in a desiccator to cool, weigh it. Bake 0.5h, weigh it, until constant.

　Calculate methylene blue content by Formula (1)

(1) In formula:m1--After drying, the precipitate numerical quality, unit is g;

m--number of methylene blue quality, unit is g;

0.8147--Conversion factor, Molecular mass ratio2(C16H18N3SCl)／(C16H18N3S)2Cr2O7

3.2.2.2 According to Formula (2) to calculate the preparation 1000mL of methylene blue standard solution required amount of methylene blue

（2）Weigh dosage of methylene blue(C16H18N3SCl·3H2O ，With accuracy of ±0.0001g) by Formula (2),put it into 250ml beaker, completely dissolved with water, move it to 1000ml brown flask, Diluted with water to the mark,shake well ,place after 24h use

Ⅳ 、Test Procedure：

4.1 sample：weigh dry sample 0.2000g with grain size less than 0.074mm

4.2 Calibration test：along with sample to test the same type sample

4.3 test：

4.3.1 Put sample(5.1)into 250ml Erlenmeyer flask with 50ml water,shake sample to make it dispersed. Then add 20ml Sodium pyrophosphate solution(4.1), shake well.

4.3.2 Put Erlenmeyer flask with sample solution on the oven, Micro-boiling heat 5min,remove and cool it to room temperature.

4.3.3 Drop Methylene blue standard solution(4.2),at the beginning, drop 5ml step by step, Successively reduced to 2 ~ 3mL, Near the end, each dropping 0.5 ~ 1mL. After each dropping, shake it 15~30s,use 1ml pipette drop one test solution on middle speed quantitative filter paper,observe whether appear light green halo around central deep blue spot.IF not appear, continue dropping, until appear light green halo around deep blue spot, shake 30s again,drop one test solution on filter paper again,if the halo disappear, that is the endpoint of titration. Count down titration consumed ml of methylene blue standard solution.

4.3.4 after end,continue dropping 1~2ml methylene blue standard solution(4.2),if the light green halo width increases,it proves the end of the judgment is correct.

V. Calculation of test result 

5.1 Calculation blue adsorption by formula (3) x 0.3199x100

V.Calculation of test result 

5.1 Calculate blue absorption by Formula(3)×0.442 ×100 　 

(3) In Formula: Ab--numerical quality of blue absorption, the unit is (g/100g);

C--Value of methylene blue standard solution concentration, unit is mo1／L

V--Consumed value of methylene blue standard solution volume, unit is ml

M--Value of sample quality, unit is g.

Use Blue absorption to converse montmorillonite content in bentonite

Formula     M=Ab/0.442

In formula: M--value of montmorillonite content in sample, that is quality rate(%)

Ab——Value of blue absorption, unit is (g／100g)；

　　KM——Conversion factor,For montmorillonite is 0.442.