CN109374608B

CN109374608B - A kind of spectrophotometric method for detecting amine collectors

Info

Publication number: CN109374608B
Application number: CN201811226293.XA
Authority: CN
Inventors: 刘文刚; 王鑫阳; 彭祥玉; 段浩
Original assignee: Northeastern University China
Current assignee: Northeastern University China
Priority date: 2018-10-18
Filing date: 2018-10-18
Publication date: 2021-05-28
Anticipated expiration: 2038-10-18
Also published as: CN109374608A

Abstract

一种分光光度法检测水质中胺类捕收剂的方法，涉及化学、浮选药剂/环境检验测定技术领域，本发明的方法包括胺类捕收剂标准曲线的制作方法和测定待测样品中胺类捕收剂浓度。相对于溴酚蓝分光光度法、金橙II分光光度法及液(气)相色谱法，本发明方法简化了检测步骤，实验中使用的显色剂大大降低了实验过程中对操作人员和环境的危害以及实验所需成本，同时经过条件优化，使该方法具有良好的可靠性，较宽的检测范围。A spectrophotometric method for detecting amine collectors in water quality relates to the technical field of chemistry, flotation reagents/environmental inspection and determination. Amine collector concentration. Compared with bromophenol blue spectrophotometry, golden orange II spectrophotometry and liquid (gas) chromatography, the method of the invention simplifies the detection steps, and the chromogenic agent used in the experiment greatly reduces the impact on operators and the environment during the experiment. The hazard and the cost of the experiment, and the conditions are optimized, so that the method has good reliability and a wide detection range.

Description

Method for detecting amine collecting agent by spectrophotometry

Technical Field

The invention relates to the technical field of chemistry, flotation reagents and environmental inspection and determination, in particular to a method for detecting an amine collecting agent by a spectrophotometry.

Background

The amine collecting agent is widely applied to the flotation process of silicate, carbonate and soluble salt minerals, but the amine collecting agent is an organic compound which is difficult to biodegrade and high in toxicity, and can cause serious pollution to the water environment. However, at present, the related reports of the concentration determination and the discharge standard of the amine collecting agent in water quality at home and abroad are less, and some problems exist. The common quantitative analysis method is to use a liquid chromatograph or a gas chromatograph in combination with the determination of TOC (total organic carbon), but the TOC detector and the chromatograph are expensive. The document mentions that bromphenol blue or gold orange II complex amine collecting agents are used, and a spectrophotometric method for extracting trichloromethane is used for measuring the concentration of the bromphenol blue or gold orange II complex amine collecting agents, the method is high in sensitivity, but the manual complexing and extracting processes are complicated, the extraction is incomplete, the trichloromethane is sensitive to light, and is decomposed to generate virulent phosgene and hydrogen chloride when being exposed to light, so that the harm to operators and the environment is caused.

Therefore, a new method for measuring the spectrophotometry of the amine collecting agent is needed, which can reduce the harm to human bodies caused by the adoption of trichloromethane and can not reduce the sensitivity and the accuracy in the detection process.

Disclosure of Invention

The invention provides a method for detecting an amine collecting agent by a spectrophotometric method, aiming at solving the technical problems that a new spectrophotometric system for detecting the amine collecting agent is established, a new color-developing agent Congo red is selected to replace bromophenol blue or golden orange II in an old system, the extraction of trichloromethane is omitted, the experimental operation is simplified, and the harm of the trichloromethane to personnel and the environment is reduced. The method can provide a technical foundation for the research on the influence of the water quality/mine environment of the amine collecting agent in the future.

The invention adopts spectrophotometry to measure the concentration of amine collecting agent in water quality, and the idea is that acetic acid buffer solution is added into a sample to be measured to adjust the pH value of the solution to be 5, the solution is shaken up, Congo red is added for complex reaction and color development, and after standing for 10min, a 10mm cuvette is used for color comparison at the position of 497nm wavelength.

A method for detecting an amine collecting agent by spectrophotometry is carried out according to the following steps:

establishing a standard curve equation by taking the absorbance as a vertical coordinate y and the concentration of the amine collecting agent as a horizontal coordinate x, wherein the absorbance is a value obtained by subtracting the absorbance of reference deionized water from the absorbance of a mixed solution of the amine collecting agent, an acetic acid buffer solution and a Congo red solution;

② adding acetic acid buffer solution into the sample to be measured to adjust the pH of the solution to 5, adding the solution with the concentration of 5 multiplied by 10^-4Fixing the volume of mol/L Congo red solution with deionized water, uniformly mixing, standing for 10 minutes to obtain a mixed solution to be detected, wherein the volume ratio of the sample to be detected, the Congo red solution and the mixed solution to be detected is 5:2:25, and placing the mixed solution to be detected in an ultraviolet spectrophotometer with the wavelength of 490-497 nm to measure the absorbance;

and thirdly, substituting the value obtained by subtracting the absorbance of the deionized water used as the reference from the absorbance of the mixed solution to be detected as the y value of the ordinate into the standard curve equation in the step I, and calculating to obtain the concentration of the amine collecting agent in the sample to be detected.

Preferably, the volume ratio of the sample to be detected, the acetic acid buffer solution, the Congo red solution and the mixed solution to be detected is 5:1:2: 25.

Preferably, the standard curve equation is established as follows:

preparing at least 5 amine collecting agent solutions with different concentrations, wherein the selected concentration is within the range of 0.00-20.00 mg/L; adding acetic acid buffer solution to make pH 5, and adding at 5 × 10^-4Uniformly mixing the Congo red solution serving as a color developing agent in mol/L, and standing for 10 minutes to obtain a mixed solution; the volume ratio of the amine collecting agent solution to the Congo red solution to the mixed solution to be detected is 5:2: 25; and (3) placing the mixed solution to be measured in an ultraviolet spectrophotometer at the wavelength of 490-497 nm for absorbance measurement, taking deionized water as reference for absorbance measurement, taking the absorbance of the mixed solution to be measured minus the absorbance of the deionized water as reference as ordinate y, taking the concentration of the amine collecting agent as abscissa x, and drawing a curve to obtain a standard curve equation.

Preferably, the standard curve equation is established as follows:

preparing at least 5 amine collecting agent solutions with different concentrations, wherein the selected concentration is in the range of 0.00-20.00 mg/L; adding acetic acid buffer solution to make pH 5, and adding at 5 × 10^-4Uniformly mixing the Congo red solution serving as a color developing agent in mol/L, and standing for 10 minutes to obtain a mixed solution; the volume ratio of the amine collecting agent solution to the Congo red solution to the mixed solution to be detected is 5:2: 25; and (3) placing the mixed solution to be measured at the position of an ultraviolet spectrophotometer with the wavelength of 497nm for measuring absorbance, taking deionized water as reference for measuring absorbance, taking the absorbance of the mixed solution to be measured minus the absorbance of the deionized water as reference as a vertical coordinate y, taking the concentration of the amine collecting agent as a horizontal coordinate x, and drawing a curve to obtain a standard curve equation.

Preferably, the volume ratio of the amine collector solution, the acetic acid buffer solution, the congo red solution and the mixed solution to be detected is 5:1:2: 25.

Preferably, the concentration of the amine collecting agent solution is selected within the range of 0.00-20.00 mg/L, and the selected concentration value is uniformly dispersed.

Further, the concentration of the selected amine collecting agent solution is within the range of 0.00-20.00 mg/L, preferably, the selected concentration is changed in a gradient manner, and the selected points are not suitable for concentration.

Preferably, the standard curve equation is established as follows:

adding 1mL of acetic acid buffer solution into 0.00, 4.00, 8.00, 10.00, 14.00 and 20.00mg/L of amine collector solution respectively, and adjusting the pH value of 6 solution samples to be 5;

② adding 2mL of 5X 10 solution into each solution obtained in the step I^-4Adding mol/L Congo red solution and deionized water to a constant volume of 25mL, uniformly mixing, and standing for 10 minutes to obtain a mixed solution;

standing the solution obtained in the step two in a 10mm cuvette, and measuring absorbance at the wavelength of 497nm of an ultraviolet spectrophotometer by taking deionized water as a reference;

fourthly, subtracting the absorbance A of the deionized water reference from the measured absorbance A of the mixed solution₀And (3) drawing a curve by taking the concentration of the amine collecting agent as an abscissa x and taking the ordinate y as an ordinate, so as to obtain a standard curve equation.

Preferably, the standard curve equation is-0.01577 x +0.72964, R²＝0.9906。

Preferably, the curve has a linear relationship, R²>0.99, and the concentration range of the amine collecting agent is 0.8-20 mg/L.

Preferably, the amine collector adopts a primary amine cationic collector or a quaternary ammonium salt cationic collector.

Preferably, the primary amine cationic collector is a dodecylamine or hexadecylamine collector.

Preferably, the quaternary ammonium salt cationic collector is dodecyl trimethyl ammonium chloride or dodecyl trimethyl ammonium bromide.

Compared with the method mentioned in the technical background, the method has the advantages that: a new color developing agent Congo red is selected to replace bromophenol blue or golden orange II in an old system, extraction of trichloromethane is omitted, experimental operation is simplified, and meanwhile harm of the trichloromethane to personnel and environment is reduced. The method can provide a technical foundation for the research on the influence of the water quality/mine environment of the amine collecting agent in the future.

Drawings

FIG. 1 is a graph of a dodecylamine standard curve determined in the present invention.

FIG. 2 is a graph showing a standard curve of dodecyltrimethylammonium chloride measured in the present invention.

FIG. 3 is a graph showing the effect of different pH values on the absorbance of the color reaction in the present invention.

FIG. 4 is a graph showing the effect of wavelength on the absorbance of a Congo red developer in the present invention.

Detailed Description

The following non-limiting examples are presented to enable those of ordinary skill in the art to more fully understand the present invention and are not intended to limit the invention in any way.

The test methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.

The reagents used in the test are analytically pure, and the test water is deionized water.

Example 1

1. Preparing a solution:

the concentration is 5X 10^-4mol/L Congo red solution: weighing 0.3483g Congo red, dissolving in a small amount of water, diluting to 1000mL, and storing in a brown bottle;

lauryl amine solution: accurately weighing 0.0200g of dodecylamine, dripping 3 drops of hydrochloric acid, diluting with water to 1000mL to obtain a dodecylamine solution with the concentration of 20.00mg/L, and diluting with water to prepare a dodecylamine solution with the concentration of 4.00mg/L, 8.00mg/L, 10.00mg/L and 14.00 mg/L.

Acetic acid buffer solution at pH 5: 11.50g of sodium acetate is weighed, 1.4mL of glacial acetic acid is added, the mixture is diluted to 250mL by water, and the pH value of the solution is adjusted to 5 by the glacial acetic acid appropriately, so that the solution is ready for use.

2. Preparation of a dodecylamine standard curve:

adding 5mL of each 0.00, 4.00, 8.00, 10.00, 14.00 and 20.00mL/g of dodecylamine collecting agent solution into 6 colorimetric tubes with plugs, adding 1mL of acetic acid buffer solution with the pH value of 5, and adjusting the pH values of the 6 samples to be 5; 2mL of 5X 10 were added^-4Fixing the volume of the mol/L Congo red solution to 25mL, uniformly mixing, and standing for 10 minutes; placing in a 10mm cuvette, measuring absorbance at 497nm wavelength with deionized water as reference(ii) a The absorbance A of the deionized water reference was subtracted from the measured absorbance A₀And (3) drawing a curve by taking the concentration of the dodecylamine collecting agent in the prepared series of solutions as an abscissa x to obtain a standard curve equation: -0.01577x +0.72964, R²0.9906, as shown in fig. 1.

3. Determining the concentration of a dodecylamine collecting agent in a water sample to be detected:

taking 5mL of a sample to be detected into a 25mL colorimetric tube, determining the absorbance A of the sample according to the steps, wherein the calculation formula of the concentration of the dodecylamine in the sample is as follows:

ρ(mg/L)＝(A-A₀-0.72964)/(-0.01577)；

4. accuracy and precision measurement experiment

The method of example 1 is adopted to carry out 7 times of measurement on the dodecylamine with the concentration of 10.00mg/L and 15.00mg/L, the average value of the 7 times of measurement is 10.25mg/L and 15.10mg/L respectively, the relative error is 2.44 percent and 0.66 percent respectively, and the Relative Standard Deviation (RSD) is 3.69 percent and 4.10 percent respectively, and the method has good accuracy and precision.

TABLE 1 dodecylamine relative standard deviation analysis

Measurement results	1	2	3	4	5	6	7	Mean value of	RSD/％
										10.00mg/L	10.23	10.56	10.83	10.50	10.26	10.06	9.28	10.25	3.69
15.00mg/L	14.34	14.76	14.92	14.57	15.91	15.34	15.86	15.1	4.10

Example 2

Standard curve equations for primary and quaternary amine salt type collectors.

Preparation of a collector solution: taking 0.0200g of hexadecylamine collecting agent, adding three drops of concentrated hydrochloric acid dropwise into deionized water at 50 ℃ for dissolving, and placing the solution in an ultrasonic oscillator for diluting to 1000mL by using the deionized water; respectively dissolving 0.0200g of quaternary ammonium salt collecting agent (dodecyl trimethyl ammonium chloride and dodecyl trimethyl ammonium bromide) and deionized water, diluting to 1000mL by using water to obtain collecting agent solution with the concentration of 20.00mg/L, and respectively diluting to required concentration to obtain 4.00, 8.00, 10.00 and 14.00mg/L solutions.

The standard curve equation for other amine collectors (hexadecylamine, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide) was tested according to the method of example 1, listing the standard curve for dodecyltrimethylammonium chloride (quaternary ammonium salt) as shown in figure 2. Correlation coefficient R of standard curve obtained by series of solutions²>0.99, relative deviation of parallel samples<5%, the results are given in the following table. Thus indicating that the test method is suitable for the determination of the concentration of amine collectors.

Table 2 standard curve equation for other amine collectors

EXAMPLE 3

Sampling and analyzing the rivers of tap water and the surface water of the muddy river, carrying out a standard addition recovery experiment, and measuring the concentration of the amine collecting agent in the water body, wherein the results are listed in table 3.

TABLE 3 determination of environmental water samples

Water sample	Addition amount (mg/L)	Total measured value (mg/L)	Percent recovery%
				Tap water
	5	4.83	96.6
				Muddy river water	5	5.21	104.2

The experiment and the data prove that the method for testing the content of.

Claims

1. a method for spectrophotometric detection of amine collector, is characterized in that, described amine collector adopts primary amine cation collector, and carries out according to following steps:

① Take the absorbance as the ordinate y and the concentration of the amine collector as the abscissa x, establish a standard curve equation, and the absorbance is the absorbance of the mixed solution of the amine collector, acetate buffer solution and Congo red solution minus the reference value The value of the absorbance of ionized water;

②Add the sample to be tested into acetic acid buffer solution to adjust the pH of the solution to 5, add Congo red solution with a concentration of 5×10 ^-4 mol/L, dilute to volume with deionized water, mix well, and let stand for 10 minutes to obtain the mixture to be tested solution, the volume ratio of the sample to be tested, the Congo red solution and the mixed solution to be tested is 5:2:25, and the mixed solution to be tested is placed at a wavelength of 490-497 nm with an ultraviolet spectrophotometer to measure the absorbance;

3. Take the value of the absorbance of the mixed solution to be tested minus the absorbance of deionized water as a reference as the y value of the ordinate, and substitute it into the standard curve equation described in step ①, and calculate the concentration of the amine collector in the sample to be tested;

The establishment process of the standard curve equation is as follows:

Prepare at least 5 different concentrations of amine collector solutions, the selected concentration is in the range of 0.00～20.00mg/L; add acetate buffer solution respectively to make the solution pH=5, with 5×10 ^-4 mol/L Congo red The solution is a color developer, mixed evenly, and allowed to stand for 10 minutes to obtain a mixed solution; the volume ratio of the amine collector solution, the Congo red solution and the mixed solution to be tested is 5:2:25; the mixed solution to be tested is Place the UV spectrophotometer at the wavelength of 490-497nm to measure the absorbance, use deionized water as a reference to measure the absorbance, take the absorbance of the mixed solution to be tested minus the absorbance of deionized water as a reference as the ordinate y, and use amines to capture The concentration of the agent is the abscissa x, and the curve is drawn to obtain the standard curve equation.

2. method according to claim 1 is characterized in that, the volume ratio of described sample to be tested, acetate buffer solution, Congo red solution and mixed solution to be tested is 5:1:2:25.

3. method according to claim 1, is characterized in that, the volume ratio of described amine collector solution, acetate buffer solution, Congo red solution and mixed solution to be measured is 5:1:2:25.

4 . The method according to claim 1 , wherein the concentration of the amine collector solution is selected in the range of 0.00-20.00 mg/L, and the selected concentration value is uniformly dispersed. 5 .

5 . The method according to claim 1 , wherein the curve has a linear relationship, R ² >0.99, and the concentration range of the detected amine collector is 0.8-20 mg/L. 6 .

6. The method according to claim 1, wherein the primary amine cationic collector is dodecylamine or hexadecylamine collector.