Uranium photometric analysis with the development of uranium geology career and national attention to environmental protection, the rapid development of nuclear power has been widely used in recent years has made great progress.

First, conventional photometry

(a) azo III method

Azo III is a common color developer for the analysis of uranium. Bai Yun, et al., using benzotrimethane (DBM)-TBP plasticized polyurethane foam, rapidly quantitatively adsorb uranium in aqueous solution (saturated adsorption capacity 120μg/g) at pH=6.5, and then use 0.6mol/ 20 mL of L HCl solution was used to quantitatively elute uranium from the chromatography column, and then a trace amount of uranium was measured with azo-III uranium reagent. Zheng Jie et al. introduced that U and Th complexes can be extracted from HNO ₃ solution simultaneously with tri-n-octylamine in the presence of aluminum nitrate. Other elements are not extracted, and Th can not form stable network in HCl solution. The nature of the compound, back-extracting Th, U nitrate mixture with 8 mol / L HCl solution into a chlorine complex and remaining in the organic phase, back extraction of uranium with 0.2mol / L HNO ₃ solution, in the presence of a masking agent U and Th in the aqueous phase were determined by azo-III uranium reagent spectrophotometry. Li Fangqing the like introduced in 8mol / LHCl solution, arsenazo -â…¢ with uranium reagent color, absorbance only stable, but less interference ions, the direct determination of uranium and thorium may not isolated.

(B) arsenazo M method

Zhou Jingxia et al. studied the determination of trace uranium and plutonium by CL-TBP leaching resin separation-continuous spectrophotometry. At low temperature, the ore is melted with mixed ammonium salt, the ore sample is dissolved with 1 mol/L nitric acid solution, and the uranium is selectively adsorbed by CL-TBP leaching resin in 1 mol/L HNO ₃ ^- 1.25 mol/L NH ₄ NO ₃ system. And oh. For uranium and plutonium adsorbed on the resin, the ruthenium is first rinsed with 4mol/L hydrochloric acid, then the uranium is rinsed with water, and then the azo and the uranium in the eluent are continuously spectrophotometrically treated with azo sm. Method determination. In the buffer solution of monochloroacetic acid-ammonium acetate with pH=2.0, uranium forms a purple-red complex with azo M. The complex has maximum absorption at 645 nm, and the apparent molar absorptivity is ε645nm=4.8×104. Uranium The mass concentration is linear in the range of 0.01-1.5 mg/L, the precision is ±6.7%, and the standard addition recovery is 97.4%-110.3%. It is used to determine uranium in ore and solution with satisfactory results.

(3) 5-Br-PADAP method

In the triethanolamine solution with pH 8.2, uranium can form red complex with 5-Br-PADAP in the presence of OP, λ=535nm, ε=1×10 ⁵ , and uranium mass concentration in the range of 0-7μg/25mL. There is a linear relationship inside. Zn, Cu, Fe, Al, Ga, and Th all interfere with the measurement, and can be separated by TBP extraction resin. A method for measuring ash coal trace uranium, with satisfactory results.

(iv) chlorophosphonazo III method

Li Boping precipitated with sodium carbonate and other studies, P350 Determination of iron levextrel resin column chromatography combination Determination of Uranium Ore. First, a large amount of iron in the sample solution was precipitated with sodium carbonate, and then trace uranium was enriched by a P350 microcolumn column, and then eluted with 4 g/L NaF solution to determine the color. The iron separation efficiency can reach 99.9%.

(5) Phenylfluorone method

Zhou Xiulin and other research results show that in the presence of CTMAB in the ammonia medium with pH=1, uranium can react with PF to form a colored complex; complex λ=560nm, ε=1.07×10 ⁵ , composition It is n(U):n(PF)=1:3, stable for more than 24h; the mass concentration of uranium is in the range of 0-20μg/25mL according to Beer's law; the interference elements are Cu ^{2 +} , Cd ^{2 +} , Mn ^{2 +} , Fe ^{2 +} , A1 ^{3 +} , V ^{5 +,} etc., can be separated and removed by trioctylamine-xylene extraction. The method is applied to the determination of trace uranium in coal ash, and the results are good. A new developer, p-carboxyphenylfluorone (PC-PF), has also been used. In the ammonia-acetate buffer solution with pH=6.5, in the presence of CTMAB, PC-PF reacted with uranium to form a 1:1 complex, and the complex was stable for 24 h, and its λ was 570 nm. The uranium concentration was linear in the range of 0-100μg/25mL. It was used for the determination of trace uranium in water samples with good results.

(6) 2-(2-Quinolinylazo)-5-dimethylchlorophenol (QAD-MAP) method

In the triethanolol-hydrochloric acid buffer solution with pH=7.8, in the presence of TritonX-100, the new reagent Q can react with uranium to form a binary complex. If 10mL/L NaCl solution is added, 1mL is controlled. In the color liquid [F ^- ] / [UO ₂ ^{2 +} ] in the range of 400 ~ 1000, the binary complex can be converted into a more sensitive ternary complex, composed of n (F): n ( UO ₂ ^{2 +} ) at n(QADMAP) = 1:1:1, λ = 590 nm, ε = 1.12 × l0 ⁵ . The uranium concentration was linear in the range of 0-50 ug/25 mL, and the detection limit was 0.05 μg/mL. Common elements Fe, Zn, Co, Ni, Cu, Mn2+ have serious interference, which can be eliminated by TBP leaching resin color separation. The method was applied to the determination of uranium in ore and satisfactory results were obtained.

(7) 5-(H-acid azo)-phenyl-3-methylpyridinone (HAPMPP) method

The new reagent HAPMPP reacts with uranium to form a 1:1 pink complex in HAc-NaAc solution at pH=4, λ=540 nm, ε=6.31 ×10 ⁴ . The uranium mass concentration is linear in the range of 0-35μg/25mL, which is used for the determination of uranium in synthetic samples with satisfactory results.

(VIII) 5-(p-sulfonylazo)-8-hydroxyquinolinyl (SPHQ) method

Dong Xuechang et al. established a new reagent SPHQ spectrophotometric method for the determination of uranium. The absorbance was measured at a wavelength of 550 nm in a HAC-NaAc buffer solution at pH=5.5. The red color of the developer and uranium was 2:1. The sensitivity was high, ε=5.95×10 ⁴ , and the uranium mass concentration was 0. Beer's law is obeyed in the range of ~30μg/25mL. The method was applied to the determination of uranium in environmental water samples, and the results were satisfactory, but Zn and Th had positive interference and should be separated and removed.

Further, according to other Liaoli Fu uranium, thorium, lanthanum and other metal ions having a different stability constants with different time arsenazo Ⅲ action, different metal ions and different hydrolysis constants, and metallic complexes thereof with acidity and absorbance wavelength The change has different characteristics. The acidity-spectral bilinear data matrix rank disappearance factor analysis method of the metal complex is obtained through experiments to quantitatively analyze the uranium in the mixture. The results showed that the detection limit was 0.085μg/L and the uranium range was 1.19~4.76mg/L under the conditions of pH 0.3~4.8 and λ=600～680nm.

Second, solid phase extraction spectrophotometry

(a) 2-(2-quinoline azo)-5-dimethylaminophenol (QAD-MAP) method

The new synthetic reagent QADMAP ethanol solution reacts with uranium in the presence of Triton X-100 in a triethanolamine-hydrochloric acid buffer solution of pH=7.8. At a wavelength of 590 nm, ε can reach 1.05×10 ⁵ , uranium The linear range is 0-20 μg/10 mL. The uranium in the environmental water sample can be determined by separation and enrichment with a TBP leaching resin solid phase extraction column.

(2) 2-(2-Quinolinylazo)-4-methyl1,3-hydroxybenzene (QAM-DHB) method

In the triethanolamine-HCl buffer solution with pH=7.8, in the presence of TritonX-100 and F-, QAMDHB reacted with U and F to form a 1:1:1 purple ternary complex with a absorbance measurement wavelength of 562 nm. ε = 8 × 10 ⁴ , and the uranium mass concentration is in accordance with Beer's law in the range of 0-20 μg/10 mL. For uranium in environmental water samples, it can be determined by separation and enrichment with TBP leaching resin solid phase extraction column.

Third, catalytic kinetic spectrophotometry

In the dilute HNO ₃ solution, uranium can catalyze the fading reaction of rhodamine B oxidized by H ₂ O ₂ . According to this, Yang Jing et al. established a catalytic kinetic fading spectrophotometry. The measurement wavelength was 556 nm, ε = 2.47 × 10 ⁵ , and the linear range of uranium was 1.7 to 12 μg / 25 mL. When measuring uranium in wastewater, the interference with Cr, Mo, W can be extracted by CHCl ₃ ^- n-butanol extraction or eliminated by CL-TBP leaching resin.

Fourth, flow injection spectrophotometry

(a) 2-(3-Hydroxyphenylazo)-7-(4-chloro-2-phosphonophenylazo)-1,8-dihydroxy-3,6-naphthalenedisulfonic acid (CPA-mK) )law

In the HNO ₃ medium, uranium reacts rapidly with CPA-mK to form a 1:2 blue complex. The reaction conditions are: HNO ₃ concentration 0.36mol/L, solution flow rate 6mL/min, color developer concentration 0.2g/L, masking agent diethylenetriamine pentaacetic acid mass concentration 10g/L, injection volume 150μL, λ=650nm . Measurement of uranium in water, can be used to remove Fe, Al, Ca, Mg, Ga, Th interference cellulose phosphate.

(B) azo III method

The FS-4 flow injection analyzer was used to establish a continuous flow injection analysis method using TBP-xylene as the extractant, azo III as the stripping agent, NaNO ₃ as the salting-out agent, EDTA as the masking agent, and turbidity. Rapid determination of trace uranium in wastewater. The pH of the acid was measured to be about 2.5, and the detection limit of the method was 5.7 μg/L.

5. Chemiluminescence analysis

Yang Lingjuan et al. used potentiostatic electrolysis technology to reduce the luminescence-free uranium (VI) to uranium (III) and uranium (III) at a potential of 0.70 V (vs. Ag/NaCI) after passing through a self-made circulating carbon cell. It can produce chemical fluorescence with luminol under alkaline conditions. The linear range of the method is 1×10 ^-6 to 1×10 ^-2g/L , and the detection limit is 2×10 ^-7g/L . 1 time of Fe ^{2 +} interference, 732 type cation exchange column ((5mm × 20cm) can be installed in the flow path. This method is used for the determination of uranium in seawater, the results are satisfactory; the determination of trace uranium in coal ash The sensitivity is higher than that of uranium in seawater. The detection limit is 2×10 ^-10g/mL , and the linear range is 1×10 ^-9 ～1×10 ^{-5 g/mL} .

Sixth, fluorescence spectrophotometry

(1) Liquid fluorescence method

Liu Jinqi, etc., leaching and separating with 10mL of 50g / L Na ₂ CO ₃ solution, stir the bottom residue, heat at 105 ° C for 30min, then transfer all into a 10mL colorimetric tube, water rushed to the mark, mix, rest ,clarify. Take 5mL of fluorescence enhancer in the quartz cuvette to measure the fluorescence intensity; then use a micro-injector to separate 20~100μL of the sample supernatant into the colorimetric tube, shake it to measure the fluorescence intensity; then use the micro-injector Add 50 μL of uranium standard solution (0.1 mg/L), measure the fluorescence intensity after shaking, and calculate the mass concentration of uranium according to the formula. Fe, Zn, Ca, Co, Ni, Cu, Mn, etc. remain in the residue without interference measurement. The linear range of uranium measurement is 0-0.5 mg/L, and the detection limit is 0.009 μg/g (injection amount is 100 μL). Wang Yahong et al. studied the determination of trace uranium in geological samples by four-acid leaching and additional iron interference-laser uranium meter. It is important to note that due to the different iron content in the sample, the interference is also inconsistent. Therefore, the iron interfering agent is added in sections to the sample. The detection limit of this method is 1 ng/mL, and the precision is <10%.

(2) Solid fluorescence method

Solid fluorescence is a common method for determining uranium. Under the action of HNO ₃ ^- Al(NO ₃ ) ₃ salting-out agent with pH=2.5, uranyl nitrate can be quantitatively extracted by TBP-xylene in HNO ₃ system, and the organic phase can directly fire fluorescent beads. Fluorometric method for the determination of trace uranium in human urine, the minimum detection limit is 1 × 10 ^{-7g / L.}

Seven, the conclusion

In recent years, uranium analysis methods have been active, some new chromogens have been developed, and the sensitivity is relatively high (ε = 5.95 × 10 ⁴ ~ 1.12 × 10 ⁵ ), applied to the determination of uranium in actual samples, The effect is better.

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