Test method for mixed catalyst solution of cobalt acetate, manganese acetate and hydrobromic acid (7)

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The copper in the sample is oxidized to copper ions by nitric acid.

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Weigh 0.

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2 Preparation of standard colorimetric solution

Accurately pipette appropriate amount of copper (Cu ²⁺ ) standard solution, place it in a 250mL separatory funnel, add 15mL nitric acid, 5mL ammonium citrate solution, 10mL ammonia, add (10±0.
05)mL copper coloring solution, shake vigorously for 5min , Stand for layering, discard the water phase, put the organic phase into a 25mL colorimetric tube, the amount of copper (Cu ²⁺ ) standard solution added should be determined according to the limit value of the copper content of the sample, and the principle of the addition amount is The color of the standard colorimetric solution should be close to or darker than the color of the sample solution
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3 Determination of sample solution

Weigh 1g or an appropriate amount of sample, accurate to 0.
1g, place it in a 100mL beaker, add 10mL water, add 15mL nitric acid solution, stir for 5min, add 5mL ammonium citrate melt, 10mL ammonia, and transfer to another 250mL separatory funnel , Add (10±0.
05) mL of copper colorimetric solution, process it in the same way as the preparation of standard colorimetric solution, and visually compare the color with white background
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13 Determination method of determination limit value of nickel (Ni ²⁺ ) content

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1 Method summary

The nickel (Ni ²⁺ ) in the sample is complexed with the ethanol solution of dimethylglyoxime (nickel reagent), and then extracted with chloroform and hydrochloric acid solutions.
In a strong alkaline solution, the nickel (Ni ²⁺ ) and The nickel reagent showed a brown-red color, and it was compared with the nickel (Ni2+) standard colorimetric solution horizontally
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The detection range is nickel (Ni ²⁺ ) 3mg/L~30mg/L
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2 Reagents

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1 Ammonium persulfate
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2 Sodium citrate solution: 100g/L
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3 Hydrochloric acid solution: 1+50
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4 Dimethylglyoxime (nickel reagent) ethanol solution, 10g/L: Weigh 1g of dimethylglyoxime (nickel reagent) to the nearest 0.
1g, place it in a 50mL beaker, and dissolve it with ethanol , Transfer to a 100mL volumetric flask, dilute to the mark with ethanol , mix well, the reagent becomes invalid when it changes color
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5 Sodium hydroxide solution: 100g/L
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6 Nickel (Ni ²⁺ ) standard solution: 0.
1mg/mL
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3 Analysis steps

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1 Preparation of standard colorimetric solution

Add 20mL hydrochloric acid solution to a 250mL separatory funnel, add an accurate amount of nickel (Ni ²⁺ ) standard solution, add 5mL sodium citrate solution, dilute to about 50mL, add 5mL ammonia water, add 20mL nickel reagent ethanol solution, shake well, and place 3min
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Extract 3 times with 15mL, 10mL, 5mL dichloromethane respectively, combine the lower methylene chloride phase, extract 2 times with 10mL hydrochloric acid solution respectively, combine the upper hydrochloric acid solution in a 50mL colorimetric tube, add ammonia to about 30mL, add 0.
5g Ammonium persulfate , let stand for 20 minutes
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The amount of nickel (N ^{_i 2+} ) standard solution added should be determined according to the limit value of the nickel content of the sample.
The principle of the amount added is that the color of the standard colorimetric solution should be close to or darker than the color of the sample solution
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2 Determination of sample solution

Weigh 1g or an appropriate amount of sample, accurate to 0.
1g, and place it in a 50mL beaker.
Use 25mL of water to transfer to a 250mL separatory funnel.
Except for the nickel standard solution, the following is the same as the preparation method of the standard colorimetric solution.
Visual color comparison
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Related links: Test method of mixed catalyst solution of cobalt acetate, manganese acetate and hydrobromic acid (6)