Method for measuring content of chloride ions in production wastewater
The ion-selective electrode method accurately measures chloride ions in copper smelting wastewater, overcoming color interference and environmental hazards, ensuring precise and economical water quality control.
Patent Information
- Application Number
- CN202510458401.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-14
- Publication Date
- 2025-07-15
AI Technical Summary
The existing water quality analysis methods have problems such as difficulty in judging end points, reagents pollute the environment and high analysis costs when determining the chloride ion content in copper smelting wastewater.
The ion selection electrode method was used to prepare standard working curves and sample determination, and the chloride ion concentration was measured using ionic strength regulators and composite electrodes, avoiding color interference and matrix influence, simplifying operation and reducing environmental pollution.
Improve the accuracy and precision of the measurement results, reduce analysis costs, reduce harm to the environment and people's health, and provide fast and reliable guiding data.
Smart Images
Figure CN120314404A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of industrial water analysis in copper smelting enterprises, and particularly relates to a method for determining the chloride ion content in production wastewater. Background Art
[0002] In copper smelting enterprises, if the chloride ion content in industrial water exceeds the standard, it will affect production equipment, pipelines, etc. Chloride ions can accelerate the corrosion rate of metals. In an environment with a high concentration of chloride ions, stainless steels such as 304 and 316L will be rapidly oxidized and corroded. Over time, the service life of industrial equipment will be shortened. According to the "Preliminary Design Report of the Comprehensive Recovery Project for the Annual Treatment of 1.5 million tons (optimized to 0.8 million tons) of copper concentrates by Houma Beitung Copper Industry Co., Ltd.", "The chloride ion concentration is a control factor for the concentration ratio of the open indirect cooling water system". In order to determine whether the chloride ion content in industrial water is effectively controlled, how to accurately measure the chloride ion content in copper smelting production wastewater directly affects the service life of industrial pipelines and equipment and the concentration ratio of production water.
[0003] At present, the methods for determining the chloride ion content in water quality analysis are mainly for domestic water, natural water, circulating cooling water, softened water, and boiler water. There are roughly four analysis methods:
[0004] 1. Silver nitrate titration method. Its principle is based on the reaction between silver nitrate and chloride ions to form silver chloride white precipitate. When all chloride ions react with silver ions, the excess silver nitrate will react with the indicator potassium chromate to form brick-red silver chromate precipitate, thus indicating the arrival of the titration end point. However, due to the color of copper smelting production wastewater itself, it will cause great interference to the judgment of the titration end point, resulting in large analysis errors, and at the same time, chromium elements will be introduced into the production wastewater system.
[0005] 2. Potentiometric titration method. The principle of this method is to use a potentiometric titration instrument to measure the potential change of the solution during titration and calculate the chloride ion concentration. However, in the determination of acidic wastewater, due to the complex composition of the wastewater and large matrix interference, the accuracy and precision are poor when using this method, and the chloride ion content in the wastewater cannot be accurately determined.
[0006] 3. Coprecipitation enrichment spectrophotometry. The principle of this method is to use a spectrophotometer to measure the absorbance of the sample at a specific wavelength and calculate the chloride ion concentration. The determination cost of spectrophotometry is relatively high, and the reagents used will cause great pollution to the environment, and it is applicable to trace chloride ions in water.
[0007] 4. Ion chromatography. The principle of this method is that according to the different affinities of the separation column for various anions, various anions to be measured in the sample are separated after entering the ion exchange system with the eluent. The separated chloride ions flow through the suppressor system and are converted into strong acids with high conductivity, while the eluent is converted into carbonic acid with low conductivity. After the conductivity detector measures the conductivity, the chloride ions are quantitatively analyzed by the peak area. This method is applicable to the water quality analysis of groundwater, surface water, domestic sewage, etc. with low heavy metal content, and the analysis time is long and the cost is high. For the copper smelting production wastewater with complex components and difficult to distinguish, it is impossible to specifically remove the elements that damage the chromatographic column. Once it enters the ion chromatograph, it will cause unpredictable damage to the chromatographic column. Summary of the Invention
[0008] The purpose of the present invention is to overcome the disadvantages of existing water quality analysis methods in the determination of chloride ions in copper smelting production wastewater, such as difficult endpoint judgment, reagent pollution of the environment, high analysis cost, etc., and to provide a method for determining the chloride ion content in production wastewater.
[0009] To achieve the above purpose, the technical solution adopted by the present invention is:
[0010] A method for determining the chloride ion content in production wastewater, comprising the following steps:
[0011] The first step, sample treatment
[0012] The production wastewater is subjected to dry filtration to remove suspended impurities therein, and then 5.00 mL of the dry-filtered sample is accurately pipetted into a 100 mL volumetric flask, 5.00 mL of an ionic strength regulator is added, and the volume is made up to the mark with pure water and shaken well for standby; at the same time, a blank test is carried out with pure water instead of the sample.
[0013] The second step, preparation of the standard working curve solution
[0014] 0.50, 1.00, 5.00, and 10.00 mL of a chloride ion standard solution with a concentration of 1000 mg / L are respectively pipetted into 100 mL volumetric flasks, 5.00 mL of an ionic strength regulator is added respectively, and the volume is made up to the mark with distilled water and shaken well to obtain the standard working curve solution for standby.
[0015] The third step, drawing of the standard working curve
[0016] Select the chloride ion determination method on the operation interface of the Leici ion meter, click to recalibrate the electrode, pour the standard working curve solution into the beaker respectively and add a stir bar, insert the chloride ion composite electrode into the standard solution to be measured in turn to start the measurement, and end the measurement after the potential value is stable. After all the standard working curve solutions are measured, the ion meter draws the standard working curve online. The abscissa is the negative logarithm of the concentration, and the ordinate is the potential value. Draw the standard working curve to obtain the equation: y = kx + b, where y is the potential value and x is the negative logarithm of the chloride ion concentration;
[0017] Step 4, sample determination
[0018] Pour the blank and the sample into the beaker in turn, add a stir bar and place it on the stirrer. Insert the composite electrode into the solution to be measured and click to start the measurement. End the measurement and read the value after the concentration value is stable;
[0019] Step 5, result calculation
[0020] The sample result is calculated according to the following formula:
[0021] Where C is the content of chloride ions in the water sample, in mg / L; C1 is the measured value of the chloride ion concentration in the water sample, in mg / L; C0 is the chloride ion concentration in the blank, in mg / L; V1 is the volume of the sample taken, in mL; V is the total volume of the sample, in mL; f is the dilution factor.
[0022] In a further preferred solution, the ionic strength regulator is a 100 g / L potassium nitrate solution, and nitric acid is adjusted to a pH value of 2 - 3.
[0023] The ion selective electrode method of the present invention, compared with the silver nitrate titration method commonly used in the Houma Beitong Metrology and Inspection Center, the color and complex matrix of the production wastewater will not affect the analysis result. It has high accuracy and repeatability, fast analysis speed, simple operation, uses fewer reagents, and will not cause environmental pollution. The analysis cost is low, and it can provide accurate and reliable guiding data in actual production.
[0024] The beneficial effects of the present invention are:
[0025] 1. The ion selective electrode method for determining production wastewater has higher accuracy and precision, less interference, and faster analysis speed than the silver nitrate titration method.
[0026] 2. Avoid using toxic and harmful reagents to endanger the health of workers and the environment, and can provide accurate and reliable guiding data in actual production. Brief description of the drawings
[0027] Figure 1 It is the chloride ion standard working curve graph. Detailed implementation manners
[0028] A method for measuring the chloride ion content in production wastewater according to this embodiment includes the following steps:
[0029] First step, sample treatment
[0030] Dry-filter the production wastewater to remove suspended impurities therein. Then accurately transfer 5.00 mL of the dry-filtered sample into a 100 mL volumetric flask, add 5.00 mL of an ionic strength regulator, and make up the volume to the mark with pure water and shake well for standby; at the same time, use pure water instead of the sample to conduct a blank test;
[0031] Second step, preparation of standard working curve solutions
[0032] Respectively transfer 0.50, 1.00, 5.00, 10.00 mL of a chloride ion standard solution with a concentration of 1000 mg / L into 100 mL volumetric flasks. Then add 5.00 mL of the ionic strength regulator to each flask, make up the volume to the mark with distilled water and shake well to obtain standard working curve solutions for standby; the ionic strength regulator is a 100 g / L potassium nitrate solution, and nitric acid is used to adjust the pH value to 2 - 3.
[0033] Third step, plotting of the standard working curve
[0034] Select the chloride ion determination method in the operation interface of the Leici ion meter, click to recalibrate the electrode. Pour the standard working curve solutions into beakers respectively and add magnetic stirrers. Insert the chloride ion composite electrode into the standard solutions to be measured in turn to start measurement. End the measurement after the potential value stabilizes. After all the standard working curve solutions are measured, the ion meter plots the standard working curve online. The abscissa is the negative logarithm of the concentration, and the ordinate is the potential value. Plot the standard working curve to obtain the equation: y = kx + b, where y is the potential value and x is the negative logarithm of the chloride ion concentration; as Figure 1 shown in the chloride ion standard working curve graph;
[0035] Table 1 Parameters for plotting the standard working curve
[0036] Serial number 1 2 3 4 Concentration μg / mL 5.00 10.00 50.00 100.00 Negative logarithm of concentration -0.69897 -1 -1.698970004 -2 Potential value mV 113.26 96.54 60.05 42.31
[0037] Fourth step, sample determination
[0038] Pour the blank and the sample into beakers in turn, add magnetic stirrers and place them on the stirrer. Insert the composite electrode into the solution to be measured and click to start measurement. End the measurement and read the value after the concentration value stabilizes;
[0039] Fifth step, result calculation
[0040] The sample result is calculated according to the following formula:
[0041] Where C is the chloride ion content in the water sample, with the unit of mg / L; C1 is the measured value of the chloride ion concentration in the water sample, with the unit of mg / L; C0 is the chloride ion concentration in the blank, with the unit of mg / L; V1 is the volume of the sample aliquot, with the unit of mL; V is the total volume of the sample, with the unit of mL; f is the dilution factor.
[0042] Example 1
[0043] Randomly select 2 production wastewaters, and parallelly determine the chloride ion content seven times respectively by the ion selective electrode method and the silver nitrate titration method.
[0044] 1. Sample treatment:
[0045] Dry filter the two water samples respectively to remove suspended solids and other impurities.
[0046] After diluting Sample 1 by 100 times step by step, accurately pipette 5.00 mL of the diluted sample into a 100 mL volumetric flask, add 5.00 mL of the ion strength regulator (100 g / L potassium nitrate solution), and then make up the volume to the mark with distilled water and shake well for standby.
[0047] After diluting Sample 2 by 10 times, accurately pipette 5.00 mL of the diluted sample into a 100 mL volumetric flask, add 5.00 mL of the ion strength regulator (100 g / L potassium nitrate solution), and then make up the volume to the mark with pure water and shake well for standby.
[0048] At the same time, use pure water instead of the sample to do a blank test.
[0049] 2. Sample determination:
[0050] On the operation interface of the ion meter, select the corresponding determination method, select the latest calibration record, pour the blank and the sample into the beaker in turn, add a magnetic stir bar and place it on the stirrer, insert the combined electrode into the solution to be measured, click Start Measurement, and end the measurement and read the value after the concentration value is stable.
[0051] 3. Result calculation
[0052] The sample result is calculated according to the following formula:
[0053] Where C is the chloride ion content in the water sample, with the unit of mg / L; C1 is the measured value of the chloride ion concentration in the water sample, with the unit of mg / L; C0 is the chloride ion concentration in the blank, with the unit of mg / L; V1 is the volume of the sample aliquot, with the unit of mL; V is the total volume of the sample, with the unit of mL; f is the dilution factor.
[0054] As can be seen from Table 2, the average values of the results of measuring the water sample by the two methods do not differ much. For the silver nitrate titration method, when parallelly determining two production wastewaters, the relative standard deviations are 11.6% and 9.6% respectively, and the measurement results are unstable. This is because during the titration process, it is often difficult for manual operation to grasp the moment when the brick red color appears, and the color of the production wastewater will affect the end point, resulting in poor precision. While using the ion selective electrode method to parallelly determine two production wastewaters, the relative standard deviations are 5.3% and 4.0% respectively, and the measurement results are relatively stable.
[0055] Table 2 Results of Sample Determination
[0056]
[0057]
[0058] Example 2
[0059] Use two methods to conduct spiked determination on the same water sample. Accurately pipette 50.00 mL of the water sample into a 100 mL volumetric flask, add 10.00 mL of the chloride ion standard solution (1000 mg / L), and make up the volume to the mark with distilled water and shake well for standby.
[0060] 1. Sample treatment:
[0061] Dry filter the water sample to remove suspended solids and other impurities.
[0062] Accurately pipette 5.00 mL of the above sample into a 100 mL volumetric flask, add 5.00 mL of the ionic strength regulator (100 g / L potassium nitrate solution), and then make up the volume to the mark with pure water and shake well for standby.
[0063] At the same time, use pure water instead of the sample to do a blank test.
[0064] 2. Sample determination
[0065] On the operation interface of the ion meter, select the corresponding determination method, select the latest calibration record, pour the blank and the sample into the beaker in sequence, add a magnetic stir bar and place it on the stirrer, insert the composite electrode into the solution to be measured and click start measurement. After the concentration value is stable, end the measurement and read the value.
[0066] 3. Result calculation
[0067] The sample result is calculated according to the following formula:
[0068] Where C is the chloride ion content in the water sample, in mg / L; C1 is the measured value of the chloride ion concentration in the water sample, in mg / L; C0 is the chloride ion concentration in the blank, in mg / L; V1 is the volume of the sample taken, in mL; V is the total volume of the sample, in mL; f is the dilution factor.
[0069] As can be seen from Table 3, the recovery rate of the chloride ion standard solution measured by the ion-selective electrode method is between 91.5% and 105%, and its relative standard deviation is 5.4%; the recovery rate of the standard solution measured by the silver nitrate titration method is between 87.4% and 108%, and its relative standard deviation is 7.6%; the experimental results show that the ion-selective electrode method has higher accuracy and precision than the silver nitrate titration method.
[0070] Table 3 Comparison of the results of measuring chloride ion standard solution by two methods
[0071]
[0072] Through comparison, the present invention has higher accuracy and precision than the silver nitrate titration method, less interference, faster analysis speed, avoids the use of relatively expensive and toxic and harmful reagents such as silver nitrate and potassium chromate, which endanger the health of workers and the environment, has simple steps and low requirements for the operation ability of personnel, and can provide accurate and reliable guiding data in actual production. This method is fast, accurate, simple, economical, safe and environmentally friendly, so it can be popularized and used in the copper smelting industry.
Claims
1. A method for determining the chloride ion content in production wastewater, characterized in that, It includes the following steps: The first step: sample treatment Perform dry filtration on the production wastewater to remove suspended impurities therein. Then accurately transfer 5.00 mL of the dry-filtered sample into a 100 mL volumetric flask, add 5.00 mL of the ionic strength regulator, and make up the volume to the mark with pure water and shake well for standby; at the same time, use pure water instead of the sample to conduct a blank test; The second step: preparation of standard working curve solutions Respectively transfer 0.50, 1.00, 5.00, and 10.00 mL of chloride ion standard solutions with a concentration of 1000 mg / L into 100 mL volumetric flasks, then add 5.00 mL of the ionic strength regulator respectively, make up the volume to the mark with distilled water and shake well to obtain standard working curve solutions for standby; The third step: drawing of the standard working curve Select the chloride ion determination method on the operation interface of the Leici ion meter, click to recalibrate the electrode. Pour the standard working curve solutions into beakers respectively and add magnetic stirrers. Insert the chloride ion composite electrode into the standard solutions to be measured in turn to start the measurement. End the measurement after the potential value is stable. After all the standard working curve solutions are measured, the ion meter draws the standard working curve online. The abscissa is the negative logarithm of the concentration, and the ordinate is the potential value. Draw the standard working curve to obtain the equation: y = kx + b, where y is the potential value and x is the negative logarithm value of the chloride ion concentration; The fourth step: sample determination Pour the blank and the sample into a beaker in turn, add a magnetic stirrer and place it on a stirrer. Insert the composite electrode into the solution to be measured and click to start the measurement. End the measurement and read the value after the concentration value is stable; The fifth step: result calculation The sample results are calculated according to the following formula: Where C is the chloride ion content in the water sample, with the unit of mg / L; C1 is the measured value of the chloride ion concentration in the water sample, with the unit of mg / L; C0 is the chloride ion concentration in the blank, with the unit of mg / L; V1 is the volume of the sample taken, with the unit of mL; V is the total volume of the sample, with the unit of mL; f is the dilution factor.
2. The method for determining the chloride ion content in production wastewater according to claim 1, characterized in that: The ionic strength regulator is a 100 g / L potassium nitrate solution, and nitric acid is adjusted to a pH value of 2 - 3.