Method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in environment based on color developing agent

Abstract

The invention discloses a method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developing agent, and belongs to heavy metal ion detection.The method comprises the following steps that a sample to be detected is taken, and acid liquor is added to adjust the pH value of the sample to be detected; adding a color developing agent and a surfactant into the to-be-detected solution, mixing, and standing; after full reaction, the absorbance is measured through a spectrophotometric method, the measured absorbance value of the trivalent antimony ions / hexavalent chromium ions corresponds to the standard curve, and the concentration of the trivalent antimony ions or hexavalent chromium ions in the to-be-measured sample is obtained. Sb < 3 + > / Cr < 6 + > reacts with a color developing agent to generate a stable orange complex, and the stable orange complex has the characteristics of low detection limit and high sensitivity to trivalent antimony ions and hexavalent chromium ions. In addition, the method does not depend on large instruments and equipment, and is simple, efficient and convenient to operate.

Description

Technical Field

[0001] The invention belongs to heavy metal detection, and in particular relates to a detection method of heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer. Background Art

[0002] Antimony and chromium are toxic metals that can accumulate in organisms. Long-term exposure to an environment containing antimony / chromium may lead to health problems such as heart disease, respiratory problems, liver and kidney damage, and skin lesions. Antimony / chromium can also pollute the soil and affect crop growth. Therefore, monitoring and controlling the trace content of antimony / chromium in the environment is extremely important for protecting the environment and human health. Effective, rapid, and sensitive detection and analysis methods are necessary conditions for studying the distribution status of antimony and chromium in the environment and the prevention and control of heavy metal pollution. At present, the detection methods of heavy metals include atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), inductively coupled plasma emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence spectrometry (XRF), ultraviolet-visible spectrophotometry, flame atomic absorption spectrometry (FAAS), graphite furnace atomic absorption spectrometry (GFAAS), etc. These methods have their own advantages and applicable scenarios. Appropriate detection technology can be selected according to specific detection needs and conditions, but some methods involve large instruments, which are costly, complex to operate, and difficult to popularize.

[0003] Spectrophotometry is widely used due to its advantages of simplicity, rapidity, high sensitivity, low cost, and easy promotion. The original spectrophotometric method for detecting antimony is to prepare antimony hydrogen and detect it through 5-Br-PADAP color development. The process of preparing antimony hydrogen is complicated, with large errors and potential safety hazards. There are also literature reports on the use of benzophenone to detect heavy metal antimony, but the sensitivity can only reach 0.1 mg / L, which cannot meet the maximum emission limit standard of 0.05 mg / L required by industries such as textiles. Summary of the invention

[0004] Purpose of the invention: In order to solve the above technical problems, the present invention aims to provide a method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in the environment based on a color developer. The color developer used in the detection method of the present invention contains Sb 3+ and Cr 6+ Highly affinity coordination site, high sensitivity and selectivity, high stability, simple operation, can effectively detect Sb in water such as industrial wastewater at the same time 3+ and Cr 6+ The detection method is simple and highly sensitive, and can fully meet the existing maximum limit requirements. It is a new method for detecting heavy metal antimony and chromium in water that is easy to promote and use. It has strong innovative significance and practical value.

[0005] Technical solution: In order to achieve the above-mentioned purpose, the present invention discloses a method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer, comprising the following steps: (1) Take the sample to be tested and add acid to adjust the pH value of the sample to be tested; (2) Add a color developer and a surfactant to the test solution, mix and let stand; (3) After sufficient reaction, the absorbance is measured by spectrophotometry, and the measured absorbance value of trivalent antimony ion / hexavalent chromium ion is matched to the standard curve to obtain the concentration of trivalent antimony ion or hexavalent chromium ion in the sample to be tested; The developer structural formula is as follows: ;

[0006] Wherein, the R is selected from , , , or .

[0007] Wherein, the environment includes a water environment or a soil environment.

[0008] Wherein, the acid solution in step (1) is hydrochloric acid or sulfuric acid, and the pH is adjusted to 2-7.

[0009] Furthermore, the acid solution in step (1) is a 20% hydrochloric acid solution, and the pH value of the reaction system is adjusted to 3.

[0010] Wherein, the surfactant in step (2) is any one or a combination of Tween-80, CTMAB, OP-100, OP-CTMAB, with a concentration of no more than 5% and an addition amount of 0.2-1.0 mL.

[0011] Wherein, the surfactant is Tween-80 microemulsion.

[0012] Preferably, the surfactant is 4% Tween-80 microemulsion, the dosage is 0.5 mL Wherein, the concentration of the color developer in step (2) is 1-5 g / L, and the amount added is 0.1-1 mL.

[0013] Preferably, the concentration of the developer is 1 g / L and the amount added is 0.1 mL.

[0014] The standing time after mixing in step (2) is 1-20 min.

[0015] Wherein, the structural formula of the developer in step (2) is as follows: .

[0016] The preparation method of the color developer is as follows: adding an organic solvent and concentrated sulfuric acid to 1,2,4-triacetoxybenzene, stirring and heating under reflux to obtain a clear solution, adding 4-aminobenzaldehyde, 4-formylbenzoic acid, 4-nitrobenzaldehyde, 2-hydroxybenzaldehyde or 4-formylbenzenesulfonic acid to the mixture, keeping the stirred mixture under reflux, and then adding K2S2O8, the mixture changes from a brown solution to a viscous dark suspension, continuing to reflux, and then pouring into ice water, stirring, filtering to obtain a product, and vacuum drying to obtain a color developer.

[0017] Preferably, the preparation method of the developer is as follows: 1,2,4-triacetoxybenzene is added to a round-bottom flask equipped with a heater and a mechanical stirrer, 50% EtOH is added as a solution and a small amount of concentrated sulfuric acid, and heated to reflux until a clear solution is obtained. Half the amount of 1,2,4-triacetoxybenzene is added dropwise to the boiling mixture within 2 minutes. The stirred mixture is kept under reflux and stirred for another 1.5 h. Subsequently, under reflux conditions at 80°C, half the amount of K2S2O8 of 1,2,4-triacetoxybenzene is added within 50 minutes, and the mixture changes from a brown solution to a viscous dark suspension, and the contents are refluxed for another 20 minutes. Then pour into ice water twice the volume of the solution, stir for 30 minutes, filter to obtain the product, and dry in a vacuum oven at 60°C to obtain 9-(4-aminophenyl)-2,6,7-trihydroxyxanthene-3-one as the developer.

[0018] The maximum absorption wavelength of the trivalent antimony ion in step (3) is 560 nm, and the maximum absorption wavelength of the hexavalent chromium ion is 500 nm.

[0019] The detection method provided by the present invention provides a specific color developer which can show specific recognition and color development of trivalent antimony ions / hexavalent chromium ions in the detection of twelve metal ion recognitions.

[0020] The detection method and the colorimetric analysis of the present invention mainly include the following steps: Optimization of measurement conditions: By finely controlling the pH value, selecting the appropriate acid type and its concentration, optimizing the type and amount of microemulsion, determining the optimal maximum absorption wavelength, and reasonably setting the measurement parameters, the sensitivity, stability, and specific selectivity can be maximized.

[0021] Anti-interference ability investigation: The interference of other heavy metal ions on the detection results when detecting antimony / chromium in the present invention is studied, and detection conditions with specific selectivity are established to improve the detection accuracy of antimony / chromium.

[0022] Repeatability study: The same sample is tested multiple times to examine the repeatability of the test results under the same conditions in order to evaluate the stability of the detection method and reagents.

[0023] Method reliability investigation: The detection results of the present invention are compared with the standard solution to verify its accuracy and precision and ensure the reliability of the detection method.

[0024] By using spectrophotometry, a standard curve is drawn according to the antimony / chromium concentration of each antimony / chromium standard solution and the absorbance value obtained by the corresponding standard solution to be tested as the ordinate, and the concentration of trivalent antimony ions / hexavalent chromium ions as the abscissa; Obtain the test solution, add acid solution after pretreatment to adjust the pH value of the test standard solution; Adding a color developer and a homogenizing agent to the test solution, mixing and then allowing to stand; The liquid to be tested was tested for Sb by spectrophotometry 3+ / Cr 6+ Detection of Sb 3+ The measurement wavelength is 560nm, Cr 6+ The measurement wavelength is 500 nm; After sufficient reaction, the absorbance is measured by spectrophotometry, and the measured absorbance value is matched to the standard curve to obtain the trivalent antimony ion / hexavalent chromium ion concentration of the sample to be tested.

[0025] Preferably, the preparation method of various reagents in the trivalent antimony ion / hexavalent chromium ion detection is: (1) Preparation of color developer solution: Weigh 0.1-0.5 g of a color developer such as 9-(4-aminophenyl)-2,6,7-trihydroxyxanthene-3-one and dissolve it in DMF to prepare 100 mL of solution with a concentration of 1-5 g / L.

[0026] (2) Preparation of 20% hydrochloric acid solution: Take 100 g of concentrated hydrochloric acid (mass fraction 36.5%) and add 82.5 g of water to prepare a 20% hydrochloric acid solution.

[0027] (3) Preparation of 20% sulfuric acid solution: First, add 70 mL of water to a beaker, measure 12.3 mL of 98% concentrated sulfuric acid, and slowly pour it into the water along the wall of the beaker, stirring with a glass rod while pouring to ensure uniform mixing and prevent splashing. After the solution cools to room temperature, add water to 100 mL and make up to volume.

[0028] (4) Preparation of Tween-80 microemulsion: The mass ratio of Tween-80 microemulsion is Tween-80: n-heptane: n-butanol: deionized water = 1~10: 1~10: 1~5: 10~100.

[0029] Among them, other coexisting ions when determining trivalent antimony ions / hexavalent chromium ions include: Ag + 、Al 3+ , Ba 2+ 、Cd 2+ 、Co 2 + , Cu 2+ , Fe 3+ , K + Mg 2+ 、Ni 2+ , at concentrations with Sb 3+ / Cr 6+ When appropriate, they do not interfere with the determination.

[0030] Furthermore, the detection of trivalent antimony ions / hexavalent chromium ions has a concentration of 0.05-1 mg / L.

[0031] Among them, Sb 3+ The linear equation of the standard curve is y = 0.52323x + 0.13275 (R 2 =0.99673), the detection range of trivalent antimony ion concentration is 0.05-1 mg / L, and the detection limit of trivalent antimony ion concentration is 0.005 mg / L. Cr 6+ The linear equation of the standard curve is y=0.347x+0.0146 (R 2 =0.99506), and the detection limit of hexavalent chromium ion is 5×10 -2 mg / L, detection range is 0.08-1 mg / L.

[0032] The present invention uses a solution with a pH value of 2 to 7 as an acid solution, such as a 9-(4-aminophenyl)-2,6,7-trihydroxyxanthene-3-one solution as a color developer, and a Tween-80 microemulsion as a surfactant. The spectrophotometric method can be used to detect trivalent antimony ions / hexavalent chromium ions in the aqueous phase, wherein the detection range of trivalent antimony ions is 0.05 to 1 mg / L, and the apparent molar absorption coefficient is 1.368×10 4 L / (mol·cm), the detection limit is about 5×10 -3 mg / L. The detection range of hexavalent chromium ions is 0.08~1 mg / L, and the apparent molar absorption coefficient is 6.136×10 3 L / (mol·cm), the detection limit is about 5×10 -2 mg / L.

[0033] The color developer provided by the present invention has a detection limit of 0.005 mg / L for antimony under the best experimental conditions, a detection range of 0.05-1 mg / L, and an apparent molar absorption coefficient of 1.368×10 4L / (mol·cm), the detection limit of chromium is 0.05 mg / L, the detection range is 0.08-1 mg / L, and the apparent molar absorption coefficient is 6.136×10 3 L / (mol·cm), with low detection limit and high sensitivity, no environmental pollution will be caused during the detection process, no reliance on large-scale instruments and equipment is required, and the operation is simple, efficient and convenient.

[0034] The color developer used in the detection method of the present invention has a structure containing a plurality of hydroxyl groups, which are combined with Sb 3+ / Cr 6+ The present invention has a well-designed molecular structure to make the color developer have good chemical stability and light stability, which ensures that the color developer can maintain stable color development characteristics under different environmental conditions (such as different temperatures and light conditions), avoids the influence of environmental factors on the test results, and improves the accuracy and repeatability of the test results.

[0035] The color developer used in the detection method of the present invention has a coordination site with high affinity to the trivalent antimony ion / hexavalent chromium ion, and can form a stable complex with the trivalent antimony ion / hexavalent chromium ion. This specific structural design significantly improves the sensitivity of the color developer to the trivalent antimony ion / hexavalent chromium ion. When the concentration of the trivalent antimony ion / hexavalent chromium ion changes, the change amplitude of the absorbance is large, thereby realizing high-sensitivity detection of low-concentration trivalent antimony ions / hexavalent chromium ions. The method not only has high sensitivity and high selectivity, but also is easy to operate and has good stability. The method can effectively detect the content of the trivalent antimony ion / hexavalent chromium ion in water, and provides a new solution for environmental monitoring.

[0036] Among the existing methods, flame atomic absorption spectrophotometry and graphite furnace atomic absorption spectrophotometry have low detection limits, and involve large instruments, and are costly, complicated to operate, and difficult to popularize. Currently, many industries require the maximum emission limit of antimony to be less than 0.05 mg / L. Therefore, researching and developing new non-toxic, highly sensitive spectrophotometric detection methods for antimony / chromium is a task of great significance. The method of the present invention can achieve high-sensitivity detection of low-concentration trivalent antimony ions / hexavalent chromium ions. In addition, the method is simple to operate, has strong stability, can effectively determine the content of trivalent antimony ions / hexavalent chromium ions in water, and is significantly better than the detection limit of existing methods. The color developer is an environmentally friendly material and will not cause environmental pollution during the detection process.

[0037] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The detection limit of the detection method of the present invention is low, because the color developer and Sb 3+ / Cr 6+It can form a stable complex and cause obvious absorbance changes even at extremely low concentrations. The detection method of the present invention realizes the detection of Sb 3+ As low as 5 × 10 -3 mg / L and Cr 6+ As low as 5 × 10 -2 The detection limit of mg / L is used to simultaneously detect trace amounts of Sb in environmental and industrial wastewater 3 + / Cr 6+ , which is of great significance for environmental protection and human health monitoring.

[0038] 2. The color developer in the detection method of the present invention has high sensitivity, and the new color developer has the same 3+ / Cr 6+ High affinity coordination site, able to bind Sb 3+ / Cr 6+ The specific structural design significantly improves the color development agent to form a stable complex. 3 + / Cr 6+ sensitivity.

[0039] 3. The selectivity of the color developer in the detection method of the present invention is enhanced. By introducing a functional group with specific recognition ability, it can specifically bind to Sb 3+ / Cr 6+ The reaction combination has good selectivity and is less interfered by other metal ions, such as copper, iron, cadmium, nickel and other metal ions. When this method is used to detect trivalent antimony ions / hexavalent chromium ions, the interference of other metal ions in the sample can be eliminated, and the results are more reliable.

[0040] 4. The present invention is based on a specific detection method of a specific color developer, and the detection operation is simple, does not rely on large-scale equipment and instruments, is simple to operate, takes a short time, is efficient and convenient, and has no strict requirements on the detection environment and time, thereby ensuring rapid determination. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The ultraviolet absorption spectrum of the complex of the developer and trivalent antimony ion of the present invention; Figure 2 is the ultraviolet absorption spectrum of the developer of the present invention; Figure 3 It is the ultraviolet absorption spectrum of the complex of the developer of the present invention and hexavalent chromium ion; Figure 4 Effect of surfactant and dosage on BWT-Sb 3+ / Cr 6+ Absorbance influence diagram of the complex; Figure 5 The effect of different pH on BWT-Sb3+ / Cr 6+ Absorbance influence diagram of the complex, the developer does not complex with the metal ion under alkaline conditions, where pH = 2, 3, 4, 5, 6, 7; Figure 6 Effect of Tween-80 surfactant and its dosage on BWT-Sb 3+ / Cr 6+ Absorbance influence diagram of the complex; Figure 7 This is the effect of the amount of developer on absorbance; Figure 8 For the present invention Sb 3+ Concentration (0.05-1 mg / L) absorbance standard curve fitting diagram; Fig. 9 Cr 6+ Concentration (0.1-1 mg / L) absorbance standard curve fitting diagram; Fig.10 The ultraviolet absorption spectra of the color developer selectivity for metal ions in the presence of different metal ions. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0043] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources. Experimental methods without specific conditions specified in the examples are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0044] The specific configuration of each reagent in the embodiment: Preparation method of color developer solution: weigh 0.1 g of color developer 9-(4-aminophenyl)-2,6,7-trihydroxyxanthene-3-one, dissolve it in DMF, and prepare 100 mL solution with a concentration of 1 g / L.

[0045] Preparation of 20% hydrochloric acid solution: Take 100 g of concentrated hydrochloric acid (mass fraction 36.5%) and add 82.5 g of water to prepare a 20% hydrochloric acid solution.

[0046] Preparation of 20% sulfuric acid solution: first add 70 mL of water to a beaker, measure 12.3 mL of 98% concentrated sulfuric acid, slowly pour it into the water along the wall of the beaker, stirring with a glass rod while pouring to ensure uniform mixing and prevent splashing. After the solution cools to room temperature, add water to 100 mL and make up to volume.

[0047] Preparation of 4% Tween-80 microemulsion: weigh 4 g Tween-80, 3 g n-heptane, 0.8 g n-butanol, and 92.2 g deionized water, mix them and stir them at room temperature for 30 min.

[0048] Preparation of CTMAB microemulsion: Weigh 2 g of CTMAB, 1 g of n-heptane, 0.5 g of n-butanol, and 96.5 g of deionized water, mix them, and stir them at room temperature for 30 min.

[0049] Preparation of OP-100 microemulsion: Weigh 4.5 g of OP-100, 3 g of n-heptane, 1 g of n-butanol, and 91.5 g of deionized water, mix them, and stir them at room temperature for 30 min.

[0050] Preparation of CTMAB-OP microemulsion: weigh 2.5 g OP-100, 2 g CTMAB, 0.5 g n-heptane, 2 g n-butanol, and 93 g deionized water, mix and stir at room temperature for 30 min.

[0051] Antimony / chromium standard solution: Weigh 1.0000 g of metallic antimony / chromium (99.99%) and dilute it to 1L. The concentration of the resulting solution is 1 mg / mL. When used, dilute it to a solution of 1~5 mg / L.

[0052] Preparation of other coexisting ion solutions: Take high-grade pure nitrates or hydrochlorides of various metals, dissolve them with acid, and prepare aqueous solutions with a concentration of 10 mg / L.

[0053] Chromium metal: analytical grade, Nanjing Wanqing Chemical Glass Instrument Co., Ltd., C915977-100G; Antimony metal: analytical grade, Shanghai MacLean Biochemical Technology Co., Ltd., A875370-5G; Tween-80: chemically pure, Shanghai BiDe Pharmaceutical Technology Co., Ltd., BD148605; CTMAB: chemically pure, Shanghai BiDe Pharmaceutical Technology Co., Ltd., BD21539; OP-100: chemically pure, Shanghai BiDe Pharmaceutical Technology Co., Ltd., BD146108.

[0054] Example 1

[0055] Add 1 g of 1,2,4-triacetoxybenzene to a round-bottom flask equipped with a heater and a mechanical stirrer, add 25 ml of 50% EtOH as a solution and 1 ml of concentrated sulfuric acid, and heat to reflux until a clear solution is obtained. Add 4-aminobenzaldehyde in an amount of half the substance of 1,2,4-triacetoxybenzene to the boiling mixture within 2 minutes, and keep the stirred mixture under reflux for another 1.5 hours. Subsequently, under reflux at 80°C, add K2S2O8 in an amount of half the substance of 1,2,4-triacetoxybenzene within 50 minutes, and the mixture changes from a brown solution to a viscous dark suspension. After the addition is completed, continue to reflux for 20 minutes. Then pour 2 times the volume of the solution into ice water, stir for 30 minutes, filter and obtain the product, and dry it in a vacuum oven at 60°C to obtain 9-(4-aminophenyl)-2,6,7-trihydroxyxanthene-3-one as the color developer. 9-(4-aminophenyl)-2,6,7-trihydroxyxanthene-3-one solid (BWT), purity 90%, yield 66%. NMR report is 1 H NMR (400 MHz, DMSO- d 6) δ 7.32(d, J = 8.5 Hz, 2H), 7.16 (s, 2H), 7.04 (s, 2H), 6.98 (d, J = 8.2 Hz, 2H).ESI-ESI (m / z) Anal. Calcd for C 19 H 13 NO5 (335.08), found: 336.05 [M + H] + . The structure is as follows:

[0056] .

[0057] Example 2

[0058] The synthesis steps were the same as those in Example 1, except that 4-aminobenzaldehyde was replaced with 4-formylbenzoic acid to obtain 4-(2,3,7-trihydroxy-6-xanthene-9-yl)benzoic acid with a purity of 85% and a yield of 50%. The NMR report was 1 H NMR (400 MHz, DMSO- d 6) δ 7.84 (d, J = 8.0 Hz, 2H), 7.23 (d, J = 8.1 Hz, 2H), 6.47 (s, 2H),6.33 (s, 2H).ESI-ESI (m / z) Anal. Calcd for C 20 H12 O7 (364.06), found: 365.00 [M+ H] + . The structure is as follows: .

[0059] Example 3

[0060] The synthesis steps were the same as those in Example 1, except that 4-aminobenzaldehyde was replaced with 4-nitrobenzaldehyde to obtain 2,6,7-trihydroxy-9-(4-nitrophenyl)xanthene-3-one with a purity of 87% and a yield of 58%. The NMR report was 1 H NMR (400 MHz, DMSO- d 6) δ 8.48 (d, J = 8.2 Hz, 2H), 7.76 (d, J = 8.2 Hz, 2H), 6.70 (s, 2H), 6.25(s, 2H).ESI-ESI (m / z) Anal. Calcd for C 19 H 11 NO7 (365.05), found: 366.00 [M + H] + The structure is as follows: .

[0061] Example 4

[0062] The synthesis steps were the same as those in Example 1, except that 4-aminobenzaldehyde was replaced with 2-hydroxybenzaldehyde to obtain 2,6,7-trihydroxy-9-(2-hydroxyphenyl)xanthene-3-one with a purity of 90% and a yield of 64%. The NMR report was 1 H NMR (400 MHz, DMSO- d 6) δ 9.78 (s, 1H), 9.01 (s, 1H), 7.73 – 7.58 (m, 1H), 7.54 – 7.37 (m, 1H), 7.25 (s, 1H), 7.26 – 7.06 (m, 2H), 6.75 (s, 1H), 6.65 – 6.46 (m, 1H), 6.49 –6.35 (m, 1H).ESI-ESI (m / z) Anal. Calcd for C19H 12 O6 (336.06), found: 337.05 [M+ H] + . The structure is as follows: .

[0063] Example 5

[0064] The synthesis steps are the same as those in Example 1, except that 4-aminobenzaldehyde is replaced with 4-formylbenzenesulfonic acid, and the obtained structure is shown below: .

[0065] Example 6

[0066] The use of the developer prepared in Example 1 in detecting trivalent antimony ions comprises the following steps: (1) The 9-(4-aminophenyl)-2,6,7-trihydroxyxanthene-3-one prepared in Example 1 is a yellow liquid. Figure 2 As shown in the UV-visible spectrophotometer, there is an absorption peak at 473 nm. 3+ / Cr 6+ There is an orange-red complex BWT-Sb 3+ / Cr 6+ When 1 ml of 1 g / L color developer solution is added to 5 ml of 5 mg / L antimony / chromium standard solution, an orange-red complex BWT-Sb 3+ / Cr 6+ generated), BWT-Sb 3+ There is an absorption peak at 560 nm, such as Figure 1 BWT-Cr 6+ There is an absorption peak at 500 nm, such as Figure 3 shown.

[0067] (2) Determination of surfactants: Prepare four different types of microemulsions (surfactants), namely Tween-80, CTMAB, OP-100, and CTMAB-OP. Take 0.5 ml of each type of surfactant, add 5 ml of 1 mg / L antimony or chromium standard solution and 100 ul of 1 g / L color developer solution, add 20% hydrochloric acid to adjust the pH of the system to 3 and dilute to 10 mL. After standing at room temperature for 15 min, measure with a UV spectrophotometer. 3+ / Cr 6+ The complex solution was used as the control. Figure 4 As shown, BWT-Sb containing CTMAB, OP-100, and CTMAB-OP surfactants 3+ / Cr 6+ The absorbance of the complex was similar to that of the control BWT-Sb 3+ / Cr 6+The absorbance value of the complex was slightly higher than that of the control, while the absorbance in 4% Tween-80 increased by 2 times compared with the control. Finally, 4% Tween-80 was selected as the surfactant.

[0068] (3) Determination of acid solution: Prepare reaction systems with different pH values, add 5 ml of 1 mg / L antimony or chromium standard solution and 1 ml of 1 g / L color developer solution, add 20% hydrochloric acid, adjust the pH value of the system to 2-7, let stand at room temperature for 15 minutes, and then measure with a UV spectrophotometer. Figure 5 As shown, in the acid solution system with pH = 3, BWT-Sb 3+ / Cr 6+ The absorbance value of the complex was the highest, and the acid solution with pH=3 was finally selected.

[0069] (4) Take 0.1 mL, 0.2 mL, 0.3 mL, 0.4 mL, 0.5 mL, 0.6 mL, and 0.7 mL of 4% Tween-80, add 5 mL of 1 mg / L antimony or chromium standard solution and 1 mL of 1 g / L color developer solution, add 20% hydrochloric acid to adjust the pH of the system to 3 and dilute to 10 mL. After standing at room temperature for 15 minutes, measure with a UV spectrophotometer. The results show that: Figure 6 As shown in the figure, when the dosage of 4% Tween-80 is 0.5 mL, the absorbance is the maximum and stable. Therefore, the optimal dosage of 4% Tween-80 is 0.5 mL.

[0070] (5) Determination of the optimal amount of color developer: prepare 0.5 mL of 4% Tween-80, 5 ml of 1 mg / L antimony / chromium standard solution, add 1g / L of color developer to 20 μl, 40 μl, 60 μl, 80 μl, 100 μl, 120 μl, 140 μl, add 20% hydrochloric acid to adjust the pH of the system to 3 and make up to 10 mL, stand at room temperature for 15 minutes, and measure with a UV spectrophotometer. As the amount of color developer increases, the absorbance of the complex gradually increases. When the amount of color developer increases to 100-140 μl, the absorbance of the complex reaches the maximum and remains basically unchanged. As the amount of color developer continues to increase, the absorbance of the complex decreases. Figure 7 As shown, the amount of 1 g / L color developer was selected as 100 μl during the determination.

[0071] Example 7

[0072] The BWT developer solution prepared in Example 1 (concentration of 1 g / L), 20% hydrochloric acid solution, and 4% Tween-80 solution were prepared. At the same time, trivalent antimony ion solutions of different concentrations were prepared for use. Each substance was tested according to the optimal addition amount and detection method in Example 6.

[0073] The absorbance of the mixed solution of trivalent antimony ions and BWT colorimetric reagent of different concentrations was measured by spectrophotometry, and the BWT solution of equal concentration was measured as a blank control. The absorbance difference between the system solution containing different trivalent antimony ion concentrations and the blank control system solution was used as the ordinate, and the concentration of trivalent antimony ions was used as the abscissa to draw a standard curve; Figure 8 As shown, the absorbance of the system solution containing different trivalent antimony ion concentrations is used as the ordinate, and the concentration of trivalent antimony ions is used as the abscissa to draw a standard curve; Figure 8 As shown in Figure 2, the standard curve equation for the concentration of trivalent antimony ions in the range of 0.01 to 0.1 mg / L is y=0.52323x+0.13275 (R 2 =0.99673); apparent molar absorptivity ε = 1.368*10 4 L / (mol·cm), and the detection limit of trivalent antimony ion is 5×10 -3 mg / L, the detection range is 0.05-1 mg / L.

[0074] Example 8

[0075] Prepare BWT color developer solution (concentration of 1 g / L), 20% hydrochloric acid solution, 4% Tween-80 solution, and hexavalent chromium ion solutions of different concentrations for later use. The optimal addition amount of each substance is according to Example 5.

[0076] The absorbance of the mixed solution of hexavalent ions and BWT color developer with different concentrations was measured by spectrophotometry, and the BWT solution with equal concentration was measured as a blank control. The absorbance difference between the system solution containing different hexavalent chromium ion concentrations and the blank control system solution was used as the ordinate, and the concentration of hexavalent chromium ions was used as the abscissa to draw a standard curve; Fig. 9 As shown, the absorbance of the system solution containing different hexavalent chromium ion concentrations is used as the ordinate, and the concentration of hexavalent chromium ions is used as the abscissa to draw a standard curve; Fig. 9 As shown in the figure, the standard curve equation for hexavalent chromium ion concentration in the range of 0.01~0.1 mg / L is y=0.347x+0.0146 (R 2 =0.99506); apparent molar absorptivity ε = 6.136*10 3 L / (mol·cm), the detection limit of hexavalent chromium ion is 5×10 -2mg / L, detection range is 0.08-1 mg / L.

[0077] Further, the color developers prepared in Examples 1-4 of the present invention were compared to carry out experiments in Examples 6 and 7, and the results are shown in Table 1.

[0078] Table 1 Detection results of different color developers

[0079] Example 9

[0080] Prepare 12 test solutions, each containing only 5 ml Ag. + 、Al 3+ , Ba 2+ 、Cd 2+ 、Co 2+ Cr 6+ , Cu 2+ , Fe 3+ , K + Mg 2+ 、Ni 2+ , Sb 3+ , and the concentration of each metal ion is 5 mg / L, 100 μl of 1g / L color developer solution prepared in Example 1 and 0.5 ml of 4% Tween-80 solution were added respectively, 20% hydrochloric acid was added to adjust the pH of the system to 3 and the volume was fixed to 10 ml with deionized water, and a color developer solution of equal concentration and without any metal ions was used as a blank solution. After standing at room temperature for 15 minutes, it was measured using a UV spectrophotometer. The results showed that: Fig.10 As shown, the color developer showed good sensitivity to Sb in all the detections of twelve metal ions. 3+ / Cr 6+ Specific detection.

[0081] In summary, the detection method of the present invention has higher sensitivity than existing methods and meets the maximum limit requirements of the industry. The method of the present invention is simple, rapid and easy to promote and use.

Claims

1. A method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer, characterized in that: The steps include: (1) Take the sample to be tested and add acid to adjust the pH value of the sample to be tested; (2) Add a color developer and a surfactant to the test solution, mix and let stand; (3) After sufficient reaction, the absorbance is measured by spectrophotometry, and the measured absorbance value of trivalent antimony ion / hexavalent chromium ion is matched to the standard curve to obtain the concentration of trivalent antimony ion or hexavalent chromium ion in the sample to be tested; The developer structural formula is as follows: ; Wherein, the R is selected from , , , or .

2. The method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer according to claim 1, characterized in that: The environment includes a water environment or a soil environment.

3. The method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer according to claim 1, characterized in that: The acid solution in step (1) is hydrochloric acid or sulfuric acid, and the pH is adjusted to 2-7.

4. The method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer according to claim 1, characterized in that: The surfactant in step (2) is any one or a combination of Tween-80, CTMAB, OP-100, and OP-CTMAB, with a concentration of no more than 5% and an addition amount of 0.2-1.0 mL.

5. The method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer according to claim 1, characterized in that: The surfactant is Tween-80 microemulsion.

6. The method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer according to claim 1, characterized in that: The concentration of the color developer in step (2) is 1-5 g / L, and the amount added is 0.1-1 mL.

7. The method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer according to claim 1, characterized in that: The standing time after mixing in step (2) is 1-20 min.

8. The method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer according to claim 1, characterized in that: The structural formula of the developer in step (2) is as follows: 。 9. The method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer according to claim 1, characterized in that: The preparation method of the color developer is as follows: adding an organic solvent and concentrated sulfuric acid to 1,2,4-triacetoxybenzene, stirring, heating and refluxing to obtain a clear solution, adding 4-aminobenzaldehyde, 4-formylbenzoic acid, 4-nitrobenzaldehyde, 2-hydroxybenzaldehyde or 4-formylbenzenesulfonic acid to the mixture, keeping the stirred mixture under reflux, and then adding K2S2O8, the mixture changes from a brown solution to a viscous dark suspension, continuing to reflux, and then pouring into ice water, stirring, filtering to obtain a product, and vacuum drying to obtain a color developer.

10. The method for detecting heavy metal trivalent antimony ions / hexavalent chromium ions in an environment based on a color developer according to claim 1, characterized in that: The maximum absorption wavelength of the trivalent antimony ion in step (3) is 560 nm, and the maximum absorption wavelength of the hexavalent chromium ion is 500 nm.

Images