GB/T 15555.10-1995 Determination of nickel in solid wastes - Dimethylglyoxime spectrophotometric method
Some standard content:
National Standard of the People's Republic of China
Determination of nickel in solid waste
Dimethylglyoxime spectrophotometric method
Solid waste-Determination of nickel--Dimethylglyoxime spectrophotometric method1 Subject content and scope of application
1.1 Subject content
GB/T15555.10—1995
This standard specifies the dimethylglyoxime (dimethylglyoxal) spectrophotometric method for the determination of nickel in solid waste leachate. 1.2 Scope of application
1.2.1 This standard is applicable to the determination of nickel in nickel-containing waste residue overflow liquid. 1.2.2 The detection concentration of this standard is 0.1mg/L, and the upper limit of determination is 4mg/L. 1.2.3 Iron, cobalt and copper ions interfere with the determination. Adding Na2-EDTA solution can eliminate the interference of 300 mg/L iron, 100 mg/L cobalt and 50 mg/L copper on the determination of 5 mg/L nickel. If the content of iron, cobalt and copper exceeds the above concentration, they can be separated and removed by diacetyl-n-butanol extraction (see Appendix A).
Cyanide also interferes with the determination. Before the determination, 2 mL of sodium hypochlorite solution and 0.5 mL of nitric acid can be added to the sample and heated to decompose the nickel cyanide complex.
2 Principle
In the ammonium citrate-ammonia water medium, in the presence of iodine as an oxidant, nickel reacts with diacetyl to form a wine-red complex with a composition ratio of 1:4, which can be measured spectrophotometrically at a wavelength of 530 nm. 3 Reagents
Unless otherwise specified, analytical reagents and distilled water or water of equivalent purity that meet national or professional standards are used in the analysis. 3.1 Nitric acid (HNO,), p=1.40 g/mL. 3.2 Ammonia (NH,·H,O), p=0.90 g/mL. 3.3 Perchloric acid (HClO,), p=1.68 g/mL. 3.4 Ethanol (C,H,OH), 95% (V/V). 3.5 Sodium hypochlorite (NaOCI) solution, active chlorine content not less than 52 g/L. 3.6 n-Butanol [CH:(CH2),CH,OH], Pza=0.81 g/mL. 3.7 Nitric acid solution, 1+1 (V/V). bZxz.net
3.8 Sodium hydroxide solution, c (NaOH)=2 mol/L. 3.9 Ammonium citrate (NH,);CHsO,] solution, 500 g/L. 3.10 Ammonium citrate [(NH,);CH,C, solution, 200 g/L. 3.17 Iodine solution, c(12) = 0.05 mol/L: Weigh 12.7 g of iodine tablets (I2), add to a small amount of water containing 25 g of potassium iodide (KI), grind and dissolve, then dilute with water to 1000 mL.
GB/T15555.10--1995
3.12 Butanedione [(CH3)2C2(NOH)2] solution, 5 g/L: Weigh 0.5 g of butanedione and dissolve in 50 mL of nitrogen water (3.2), dilute with water to 100 mL.
3.13 Butanedione ethanol solution, 10 g/L: Weigh 1 g of butanedione and dissolve in 100 mL of ethanol (3.4). 3.14 Naz-EDTA[C1oHiN,O.Na2·2H,O solution, 50 g/L. 3.15 Ammonia solution, 1+1 (V/V).
3.16 Ammonia solution, c(NH3·H,0)0.5 mol/L3.17 Hydrochloric acid solution, c(HCl)0.5 mol/L. 3.18 Ammonia-ammonium chloride buffer solution, pH=10±0.2: Weigh 16.9 g ammonium chloride (NH.C1), add to 143 mL ammonia solution (3.2), dilute with water to 250 mL. Store in a polyethylene plastic bottle at 4°C. 3.19 Nickel standard stock solution 100 mg/L: Accurately weigh 0.1000 g of nickel metal (content above 99.9%) and dissolve it in 10 mL of nitric acid solution (3.7). Heat and evaporate until almost dry. After cooling, add nitric acid solution (3.7) to dissolve, transfer to a 100 mL volumetric flask, and dilute with water to the mark. 3.20 Nickel standard working solution, 20.0 mg/L: Take 10.0 mL of nickel standard stock solution (3.19) in a 500 mL volumetric flask and dilute with water to the mark.
3.21 Phenolic acid ethanol solution, 1 g/L: Weigh 0.1 g of phenolic acid and dissolve it in 100 mL of ethanol (3.4). 4 Instruments
Common laboratory instruments and spectrophotometers. 5 Steps
5.1 Sample storage
After the leachate is prepared, it should be acidified by adding concentrated nitric acid (3.1) to a pH value of 1 to 2. The storage time should not exceed one week. 5.2 Blank test:
A blank test is carried out at the same time as the determination. The reagents and amounts used are the same as those used in the determination (5.4, 5.5). The determination steps are also the same, but 10.0mL of water is used instead of the sample.
5.3 Sample pretreatment
Unless it is proved that the digestion treatment of the sample is unnecessary, the color development can be carried out directly. Otherwise, the treatment is carried out according to the following steps. Take an appropriate amount of sample (containing no more than 100μg of nickel) in a beaker, add 0.5mL of nitric acid (3.1), place it on a hot plate, evaporate it to near dryness under near boiling state, cool it, add 0.5mL of nitric acid (3.1) and 0.5mL of perchloric acid (3.3) to continue heating and digestion, and evaporate it to near dryness. Dissolve it with nitric acid solution (3.7). If the solution is still not clear, repeat the above steps until the solution is clear. Transfer the solution to a 25mL volumetric flask, rinse the beaker with a small amount of distilled water, and develop the color according to (5.4). 5.4 Color Development
Take an appropriate amount of sample (containing no more than 100μg nickel), place it in a 25mL volumetric flask and dilute it with water to about 10mL, use about 1mL of sodium hydroxide solution (3.8) to neutralize it, add 2mL of ammonium citrate solution (3.9), 1mL of iodine solution (3.11), add water to about 20mL, shake well, add 2mL of diacetyl solution (3.12) and shake well. Add 2mL of Na2-EDTA solution (3.14), add water to the mark, and spread evenly. Let it stand for 5min. Note: Add ammonium citrate to complex iron and manganese, prevent the formation of hydroxide precipitation in ammonia alkalinity, and make the color developing solution reach stability faster. It does not interfere with the determination, but slightly reduces the sensitivity.
5.5 Measurement
Use a 10mm cuvette and water as the reference solution to measure the absorbance of the color solution (5.4) at a wavelength of 530nm and deduct the absorbance measured by the blank (5.2).
Note: When color is developed at room temperature below 20°C, the absorbance of the complex should remain unchanged for at least 1 hour, otherwise the absorbance stability of the complex will decrease with increasing temperature. Therefore, in this case, the color development measurement must be carried out in a shorter time (15min), and the color development time of the sample measurement and the calibration curve should be as consistent as possible. 5.6 Drawing of calibration curve
GB/T15555.10—1995
Add 0, 1.00, 2.00, 3.00, 4.00 and 5.00 mL of nickel standard working solution (3.20) to 6 25 mL volumetric flasks respectively, add water to 10 mL, add 2 mL of ammonium citrate solution (3.9), and perform color development and measurement as described in (5.4) and (5.5). Draw a calibration curve with the absorbance of each standard solution minus the absorbance of the blank (zero concentration) and the nickel content of the corresponding standard solution.
Representation of results
The nickel concentration c (mg/L) in the leachate is calculated by the regression equation or the following formula: Where: m—nickel content found on the calibration curve, μg; V-volume of the sample, mL.
7 Precision and accuracy
7.1 Refer to GB11910 "Determination of nickel in water - diacetyl spectrophotometry". 7.2 Add 10-20μg of nickel slag overflow liquid (containing 12.5μg nickel) and the recovery rate is between 95% and 103%. 563
A1 Extraction and separation
GB/T15555.10-1995
Appendix A
Diacetyl-n-butanol extraction and separation operation steps (supplement)
A1.1 Place the sample in a 100mL separatory funnel, add 2mL of ammonium citrate solution (3.10) and 2mL of diacetyl ethanol solution (3.13), and shake well. Add a drop of phenolic acid solution (3.21), add ammonia solution (3.15) until the solution turns red, then add 1 mL of chlorine water-ammonium chloride buffer (3.18), add water to about 30 mL, and shake well. A1.2 is extracted with 10 mL of n-butanol (3.6) for 1-2 min, and after standing and stratification, the aqueous phase is discarded. A1.3 is extracted with 5 mL of ammonia solution (3.16) Shake for 30 seconds, wash the organic phase once, and discard the aqueous phase. A1.4 Add 5 mL of hydrochloric acid solution (3.17) and shake for 1 to 2 minutes to extract nickel. After stratification, transfer the aqueous phase completely to a 25 mL volumetric flask, wash the organic phase once with 5 mL of water, and combine the aqueous phases. A2 Color development and measurement
Add about 1 mL of sodium hydroxide solution (3.8) to a 25 mL volumetric flask to make it neutral, add 0.5 mL of ammonium citrate solution (3.10), and perform color development and measurement according to steps 5.4) and (5.5). A3 Drawing of the calibration curve
Add 0, 0.50, 1.00, 2.00 and 2.50 mL of nickel standard working solution (3.20) to 6 100 mL separatory funnels, respectively. The following steps A1 and A2 are used for extraction, separation, color development and measurement. The absorbance of each standard solution is measured to deduct the absorbance of the blank, and a calibration curve is drawn with the nickel content of the corresponding standard solution. Note: For the preparation method of the leaching solution, refer to Appendix B of GB/T15555.1-1995 "Determination of the total product of solid waste by cold atomic absorption spectrophotometry". Additional notes:
This standard was proposed by the Science and Technology Standards Department of the State Environmental Protection Administration. This standard was drafted by the China National Environmental Monitoring Center. The main drafter of this standard is Chen Fuxing.
This standard is entrusted to the China National Environmental Monitoring Center for interpretation. 564
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