A method for detecting total phosphorus content in nonferrous metal extraction wastewater

Abstract

The detection method described in the present invention is specifically studied for the problem of detecting the total phosphorus content in non-ferrous metal extraction waste liquid. The key lies in the use of ferrate solution for digestion. On the one hand, since the standard redox potential of ferrate is much higher than that of other inorganic oxidants, it can fully digest the organic phosphorus in the test sample and ensure the accuracy of the total phosphorus content. On the other hand, the product after ferrate reduction is an iron hydroxide suspension with a flocculation effect, which can effectively remove trace heavy metal ions, such as arsenides, sulfides and chromium compounds in the test sample, and can effectively reduce the turbidity and color of the test sample. The test sample with high turbidity can be directly digested without pretreatment, exerting the synergistic effect of oxidation, flocculation, adsorption and precipitation. In addition, the trace cobalt and nickel ions in the non-ferrous metal extraction waste liquid can catalyze the accelerated decomposition of ferrate, and the addition of excess ferrate solution will not affect subsequent detection.

Description

Technical Field

[0001] The present invention relates to the technical field of water body detection, specifically to the technical field of total phosphorus content detection in water bodies, and in particular to a method for detecting the total phosphorus content of non-ferrous metal extraction waste liquid. Background Art

[0002] Total phosphorus includes dissolved, particulate, organic, and inorganic phosphorus. Non-ferrous metal extractants are generally phosphorus-containing, resulting in high levels of organic phosphorus in the wastewater from non-ferrous metal extraction. Phosphorus is a key water quality monitoring parameter for controlling eutrophication. It is a water quality parameter that must be effectively monitored to ensure the development value of water resources for drinking, tourism, aquaculture, and other purposes. It is a mandatory measurement item in water environment monitoring.

[0003] At present, the pre-treatment of the determination method of total phosphorus in water quality is relatively cumbersome and time-consuming, and there is also a certain degree of pollution to the reagents and tools used for determination, which brings inconvenience to the analysis work. The digestion of organic phosphorus according to the existing conventional method is very complicated and inefficient, and requires a high level of operator experience in using the equipment, which increases the difficulty of subsequent testing of total phosphorus content. For the detection of total phosphorus in wastewater, digestion is the most critical. In order to meet the requirements of emergency monitoring of sudden water pollution and modern water quality monitoring Internet of Things technology for low-power detection instruments, an analytical experimental method for efficient digestion and rapid detection of total phosphorus in water quality under normal temperature and pressure conditions is developed. This not only has important scientific significance for the development of water quality total phosphorus analysis and detection technology, but also lays an important theoretical, methodological and technical foundation for the development of low-power, portable or online monitoring instruments.

[0004] Currently, the primary method for determining total phosphorus in water both domestically and internationally is spectrophotometry. The main domestic method for total phosphorus testing is the ammonium molybdate spectrophotometric method, as specified in GB / T 11893-1989, Determination of Total Phosphorus in Water Quality—Ammonium Molybdate Spectrophotometry, which includes potassium persulfate high-temperature, high-pressure digestion and the nitric acid-perchloric acid hot plate digestion. Internationally, total phosphorus determination is mostly performed using ICP-AES. The potassium persulfate high-temperature, high-pressure digestion method requires heating in a high-pressure steam sterilizer equipped with a pressure gauge for approximately 30 minutes to an hour. This is not only time-consuming and labor-intensive, but can also result in incomplete digestion for unusual water samples. Incomplete potassium persulfate decomposition can affect absorbance measurements, leading to experimental error or even failure. The nitric acid-perchloric acid hot plate digestion method requires digestion on an electric furnace. Due to limitations of the furnace, digestion can typically only be performed on six test solutions at a time, taking approximately one hour. Each additional test solution requires an additional 10 minutes, and the results are also subject to poor reproducibility. The method of the present invention is simple, simple and convenient, and has the advantages of simple structure, convenient operation and convenient maintenance.In addition, because nitric acid and perchloric acid are all strong oxidants, in the process of clearing up the test solution, easily cause sample to splash loss and digestion process out of control, serious time also can cause explosion incident, therefore, need always wait by electric furnace in the digestion process, waste time and energy.In addition, this method needs to manually add phenolphthalein indicator, sodium hydroxide solution and sulfuric acid solution to regulate the mensuration state of solution in cooling sample solution after clearing up, but the addition of each solution needs strict control in this process, if add less, can not reach the requirement of mensuration, if add more color deepens, can affect the color development below, finally can make testing result higher, error is larger, therefore, the precision requirement of reagent is high. The ICP-AES method adopted abroad, i.e. inductively coupled plasma emission spectrometry, although this method does not need to be cleared up to test sample, can directly utilize ICP instrument to detect, but ICP instrument cost is high, expensive, operation must be fine, when phosphorus content is higher in test sample, accuracy is poor, and need consume a large amount of argon gas during work, so running cost height.

[0005] CN202110252360.0 discloses a method for detecting total phosphorus in sludge from a municipal sewage treatment plant. For sludge samples with a high solid content, although the detection method uses ultraviolet light and ultrasonic crushing to pre-treat the sludge samples, it is subsequently heated in a high-pressure steam sterilizer and needs to be digested under high temperature and high pressure conditions, which increases the detection time. CN202010180425.0 discloses a method for detecting total phosphorus in iron-containing pickling wastewater, which includes adding dilute sulfuric acid solution and potassium persulfate to the pretreated iron-containing pickling wastewater to dissolve it, mixing it evenly and then sealing it for digestion. However, the detection method uses phosphorus vanadium molybdenum yellow spectrophotometry, which is mainly suitable for wastewater with high phosphorus concentration, especially for the detection of total phosphorus content in high-phosphorus and high-iron samples. For the detection of low-concentration total phosphorus, there is a problem of large error. CN201310112751.8 discloses a method for efficient digestion and rapid detection of total phosphorus in water quality. The detection method mainly uses ultrasound-assisted Fenton reagent digestion, which is very easy to introduce iron ions, affecting the accuracy of spectrophotometric detection of total phosphorus content. CN201510050021.9 discloses a method for detecting total nitrogen and total phosphorus in a watershed. This method uses microwave-assisted potassium persulfate digestion of the sample and spectrophotometric detection of total phosphorus and total nitrogen. However, the digestion process is performed in a colorimetric tube and requires heating to 125°C and maintaining it for 30 minutes, significantly reducing detection efficiency. Current methods for detecting total phosphorus in water often require digestion under high-temperature and high-pressure conditions, which is time-consuming and energy-intensive.

[0006] In summary, digestion is the most critical factor in the detection of total phosphorus content in non-ferrous metal extraction wastewater. At present, there is an urgent need to develop a detection method for the total phosphorus content in non-ferrous metal extraction wastewater, which is not only simple to operate, has a short detection cycle, economical and practical equipment, and high detection accuracy, but also can reduce the consumption of reagents and can be directly digested without pretreatment, thereby minimizing the analysis time. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention relates to a method for detecting the total phosphorus content of non-ferrous metal extraction waste liquid. The detection method is specifically studied for the problem of detecting the total phosphorus content in non-ferrous metal extraction waste liquid. The key lies in using a ferrate solution for digestion. On the one hand, since the standard redox potential of ferrate is much higher than that of other inorganic oxidants, it can fully digest the organic phosphorus in the test sample and ensure the accuracy of the total phosphorus content. On the other hand, the product after ferrate reduction is an iron hydroxide suspension with a flocculating effect, which can effectively remove trace heavy metal ions, such as arsenides, sulfides and chromium compounds in the test sample, and can effectively reduce the turbidity and color of the test sample. The test sample with high turbidity can be directly digested without pretreatment, and the synergistic effect of oxidation, flocculation, adsorption and precipitation is exerted. In addition, the trace cobalt and nickel ions in the non-ferrous metal extraction waste liquid can catalyze the accelerated decomposition of ferrate, and the addition of excess ferrate solution will not affect subsequent detection.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The object of the present invention is to provide a method for detecting the total phosphorus content of non-ferrous metal extraction wastewater, the detection method comprising the following steps:

[0010] (1) Collecting non-ferrous metal extraction waste liquid as test samples;

[0011] The cobalt content in the non-ferrous metal extraction wastewater is 1-5 mg / L, and the nickel content is 1-5 mg / L;

[0012] (2) placing the test sample described in step (1) into a sample jar, adding ferrate solution and sealing the jar so that the pH of the digestion system is greater than 9, and obtaining a digestion solution after digestion;

[0013] (3) adding sulfuric acid solution, ascorbic acid solution and molybdate solution to the digestion solution obtained in step (2) in sequence and constant volume to obtain a reaction solution;

[0014] (4) The absorbance of the reaction solution in step (3) is measured by spectrophotometry, and the total phosphorus content in the non-ferrous metal extraction waste liquid is calculated with reference to a total phosphorus standard curve.

[0015] The detection method described in the present invention is specifically studied for the problem of detecting the total phosphorus content in non-ferrous metal extraction waste liquid. The key lies in the use of ferrate solution for digestion. On the one hand, because the standard redox potential of ferrate is much higher than that of other inorganic oxidants, it can fully digest the organic phosphorus in the test sample and ensure the accuracy of the total phosphorus content. On the other hand, the product after ferrate reduction is an iron hydroxide suspension with a flocculating effect, which can effectively remove trace heavy metal ions, such as arsenides, sulfides and chromium compounds in the test sample, and can effectively reduce the turbidity and color of the test sample. The test sample with high turbidity can be directly digested without pretreatment, exerting the synergistic effect of oxidation, flocculation, adsorption and precipitation. In addition, trace cobalt and nickel ions in the non-ferrous metal extraction waste liquid can catalyze the accelerated decomposition of ferrate, and the addition of excess ferrate solution will not affect subsequent detection. In addition, the detection method described in the present invention has the advantages of simple operation, short detection cycle, economical and practical equipment, high detection accuracy, and low reagent consumption.

[0016] As a preferred technical solution of the present invention, after step (1) and before placing the sample into the sample jar in step (2), the method further includes diluting the test sample and placing the diluted test sample into the sample jar.

[0017] It is worth noting that the dilution in the present invention is selected based on the total phosphorus content of the non-ferrous metal extraction waste liquid, and those skilled in the art can make a reasonable selection based on actual conditions.

[0018] As a preferred technical solution of the present invention, the ferrate in the ferrate solution in step (2) is sodium ferrate and / or potassium ferrate.

[0019] Preferably, the pH of the ferrate solution in step (2) is 9.4 to 9.7, such as 9.4, 9.5, 9.6 or 9.7, but is not limited to the listed values. Other values ​​not listed within the above range are also applicable.

[0020] Preferably, the concentration of the ferrate solution in step (2) is 0.8 to 1.2 g / L, for example, 0.8 g / L, 0.85 g / L, 0.9 g / L, 0.95 g / L, 1 g / L, 1.05 g / L, 1.1 g / L, 1.15 g / L or 1.2 g / L, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0021] It is worth noting that the preparation method of the ferrate solution described in the present invention includes the following content, which is introduced using a sodium ferrate solution with a concentration of 1g / L as an example. 1g of sodium ferrate solid is weighed and dissolved in 900mL of pure water. The pH is adjusted to 9.4-9.7 with a 1mol / L sodium hydroxide solution (pH 14), and finally the volume is fixed to 1000mL. Moreover, the inventors have experimentally confirmed that ferrate solutions with lower concentrations are more easily stored stably and less prone to decomposition at a pH between 9.4 and 9.7.

[0022] Preferably, in step (2), the volume ratio of the test sample to the ferrate solution is controlled to be 1:(0.5-1.5), for example, 1:0.5, 1:0.6, 1:0.8, 1:1, 1:1.1, 1:1.3, 1:1.4 or 1:1.5, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0023] As a preferred technical solution of the present invention, the sample tank in step (2) is a polytetrafluoroethylene tank.

[0024] Preferably, the digestion in step (2) is carried out in a COD digester.

[0025] Preferably, the digestion in step (2) is performed under microwave assistance.

[0026] It is worth noting that common COD digesters in the prior art often have a microwave-assisted function. Those skilled in the art can determine whether the microwave-assisted function is turned on based on the actual COD digester model used, and further determine the digestion time based on the actual COD digester model used.

[0027] As a preferred technical solution of the present invention, after the digestion in step (2), cooling and filtering are carried out in sequence to obtain the digestion solution.

[0028] Preferably, the cooling comprises placing the sample jar in a water bath to cool to room temperature.

[0029] As a preferred technical solution of the present invention, in step (3), sulfuric acid solution is added to make the pH of the system 3-4, and then ascorbic acid solution is added and mixed, and then molybdate solution is added after 30-60 seconds.

[0030] The addition of sulfuric acid solution in the present invention makes the pH of the system 3 to 4, for example, pH 3, pH 3.1, pH 3.3, pH 3.5, pH 3.7, pH 3.9 or pH 4, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0031] The interval between adding the ascorbic acid solution and adding the molybdate solution in the present invention is 30 to 60 seconds, for example, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, 55 seconds or 60 seconds, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0032] As a preferred technical solution of the present invention, the concentration of the sulfuric acid solution in step (3) is 0.8 to 1.2 mol / L, for example, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L or 1.2 mol / L, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0033] It is worth noting that the preparation method of the sulfuric acid solution of the present invention includes the following contents, which are introduced by taking a sulfuric acid solution with a concentration of 1 mol / L as an example: 27 mL of concentrated sulfuric acid is measured and slowly added to 973 mL of pure water and stirred evenly.

[0034] Preferably, the concentration of the ascorbic acid solution in step (3) is 95-105 g / L, and the amount of the ascorbic acid solution added satisfies: 1-3 mL of the ascorbic acid solution is added to every 10 mL of the test sample.

[0035] It is worth noting that the preparation method of the ascorbic acid solution of the present invention includes the following contents, which are introduced by taking an ascorbic acid solution with a concentration of 100 g / L as an example: 10 g of ascorbic acid solid is weighed, dissolved in 100 mL of pure water, and stirred evenly.

[0036] Preferably, the amount of the molybdate solution added in step (3) satisfies: the molybdate solution is added so that the pH of the system is 2 to 3, for example, pH 2, pH 2.1, pH 2.3, pH 2.5, pH 2.7, pH 2.9 or pH 3, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0037] Preferably, the preparation method of the molybdate solution in step (3) comprises: dissolving ammonium molybdate and potassium antimony tartrate in pure water to obtain an ammonium molybdate aqueous solution and an antimony potassium tartrate aqueous solution, respectively; adding the ammonium molybdate aqueous solution to a 1+1 sulfuric acid solution under continuous stirring; and finally adding the solution to the potassium antimony tartrate aqueous solution and mixing to obtain the molybdate solution.

[0038] As a preferred technical solution of the present invention, the volume determination in step (3) is carried out in a colorimetric tube.

[0039] As a preferred technical solution of the present invention, the spectrophotometry in step (4) is performed using an ultraviolet spectrophotometer, using a quartz cuvette with an optical path of 10 mm, and measuring the absorbance at a wavelength of 700 nm with water as a reference.

[0040] As a preferred technical solution of the present invention, the detection method comprises the following steps:

[0041] (1) Collecting non-ferrous metal extraction waste liquid as test samples;

[0042] The cobalt content in the non-ferrous metal extraction wastewater is 1-5 mg / L, and the nickel content is 1-5 mg / L;

[0043] (2) placing the test sample described in step (1) into a polytetrafluoroethylene can, adding ferrate solution and sealing the can to make the pH of the digestion system greater than 9, and then placing the whole can into a COD digestion instrument. After microwave-assisted digestion, the polytetrafluoroethylene can is placed in a water bath and cooled to room temperature, and the digestion solution is obtained by filtration;

[0044] The ferrate in the ferrate solution is sodium ferrate and / or potassium ferrate; the pH of the ferrate solution is 9.4-9.7; the concentration of the ferrate solution is 0.8-1.2 g / L; and the volume ratio of the test sample to the ferrate solution is controlled to be 1:(0.5-1.5);

[0045] (3) In a colorimetric tube, the digestion solution obtained in step (2) is added with a sulfuric acid solution having a concentration of 0.8 to 1.2 mol / L so that the pH of the system is 3 to 4, and then an ascorbic acid solution having a concentration of 95 to 105 g / L is added and mixed. After 30 to 60 seconds, a molybdate solution is added to make the pH of the system 2 to 3 and the volume is constant to obtain a reaction solution;

[0046] The amount of the ascorbic acid solution added satisfies the following conditions: 1 to 3 mL of the ascorbic acid solution is added to every 10 mL of the test sample; the method for preparing the molybdate solution in step (3) comprises: dissolving ammonium molybdate and potassium antimony tartrate in pure water to obtain an ammonium molybdate aqueous solution and an antimony potassium tartrate aqueous solution, adding the ammonium molybdate aqueous solution to a 1+1 sulfuric acid solution under continuous stirring, and finally adding the solution to the antimony potassium tartrate aqueous solution and mixing to obtain the molybdate solution;

[0047] (4) The absorbance of the reaction solution in step (3) is determined by spectrophotometry. The spectrophotometry is performed using an ultraviolet spectrophotometer, a quartz cuvette with an optical path of 10 mm, and water as a reference at a wavelength of 700 nm. The total phosphorus content in the non-ferrous metal extraction waste liquid is calculated by referring to a total phosphorus standard curve.

[0048] The detection method described in the present invention is specifically designed to detect the total phosphorus content in non-ferrous metal extraction wastewater. The key lies in using a ferrate solution for digestion, which can achieve the purpose of rapid digestion at room temperature and pressure. Then, ammonium molybdate spectrophotometry is used to achieve rapid colorimetry of the total phosphorus content, thereby minimizing analysis time.

[0049] It is worth noting that the total phosphorus standard curve in step (4) of the detection method of the present invention generally requires 6 to 8 sets of standard solution tests. The specific experiment includes the following contents:

[0050] (a) Prepare a 50 μg / mL standard solution using a phosphorus standard solution;

[0051] (b) Pipette 0.1 mL, 0.5 mL, 1.0 mL, 2.0 mL, and 4.0 mL of the standard solution obtained in step (a) into five stoppered colorimetric tubes, remove one stoppered colorimetric tube without adding the standard solution obtained in step (a), and add pure water to each of the six stoppered colorimetric tubes to half the colorimetric tube scale;

[0052] (c) adding 1 mL of ascorbic acid solution to each of the six stoppered colorimetric tubes described in step (b), and then adding 2 mL of molybdate solution after 30 seconds, and finally making up to volume with pure water for later use;

[0053] (d) pouring the six colorimetric solutions obtained in step (c) into a quartz cuvette with an optical path of 10 mm, measuring the absorbance using an ultraviolet spectrophotometer at a wavelength of 700 nm with water as a reference, and plotting the total phosphorus standard curve.

[0054] Compared with the existing technical solutions, the present invention has at least the following beneficial effects:

[0055] (1) The detection method of the present invention is specifically studied for the detection of total phosphorus content in non-ferrous metal extraction wastewater. The key lies in the use of ferrate solution for digestion. On the one hand, since the standard redox potential of ferrate is much higher than that of other inorganic oxidants, it can fully digest the organic phosphorus in the test sample and ensure the accuracy of the total phosphorus content. On the other hand, the product of ferrate reduction is a ferric hydroxide suspension with a flocculating effect, which can effectively remove trace heavy metal ions, such as arsenide, sulfide and chromium compounds in the test sample, and can effectively reduce the turbidity and color of the test sample. The test sample with high turbidity can be directly digested without pretreatment, and the synergistic effect of oxidation, flocculation, adsorption and precipitation is exerted;

[0056] (2) The detection method of the present invention is based on the fact that trace amounts of cobalt and nickel ions in the non-ferrous metal extraction wastewater can catalyze the accelerated decomposition of ferrate, so that the addition of excess ferrate solution will not affect subsequent detection, thereby ensuring the accuracy of the total phosphorus content;

[0057] (3) The detection method of the present invention preferably uses a ferrate solution for digestion under microwave assistance. For non-ferrous metal extraction wastewater, digestion can be performed directly without pretreatment, which can achieve the purpose of rapid digestion at room temperature and pressure. Then, ammonium molybdate spectrophotometry is used to achieve rapid colorimetry of total phosphorus content, which minimizes analysis time.

[0058] (4) The detection method of the present invention uses ferrate solution for digestion, which can effectively remove arsenide, sulfide and chromium compounds in the test sample and flocculate and precipitate them, effectively reducing the turbidity and color of the test sample and preventing them from interfering with the subsequent color development reaction;

[0059] (5) The detection method of the present invention has the advantages of simple operation, short detection cycle, economical and practical equipment, high detection accuracy, and low drug consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a bar chart comparing four detection methods based on the anti-magnesium solution described in Example 1. DETAILED DESCRIPTION

[0061] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0062] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0063] The method for detecting the total phosphorus content of non-ferrous metal extraction waste liquid of the present invention comprises the following steps:

[0064] (1) Collect nonferrous metal extraction waste liquid as a test sample and dilute it b times with pure water;

[0065] The cobalt content in the non-ferrous metal extraction wastewater is 1-5 mg / L, and the nickel content is 1-5 mg / L;

[0066] (2) The diluted test sample obtained in step (1) is placed in a polytetrafluoroethylene jar with a sampling volume of 1 ml (<40 mL), and then a / 2 mL of ferrate solution is added and sealed to make the pH of the digestion system greater than 9. The whole is then placed in a COD digestion instrument. After microwave-assisted digestion, the polytetrafluoroethylene jar is placed in a water bath and cooled to room temperature, and the digestion solution is obtained by filtration;

[0067] (3) In a 50 mL colorimetric tube, the digestion solution obtained in step (2) was added with sulfuric acid solution, ascorbic acid solution, and molybdate solution in sequence and the volume was constant to obtain a reaction solution;

[0068] (4) The absorbance of the reaction solution in step (3) is determined by spectrophotometry. The spectrophotometry is performed using an ultraviolet spectrophotometer, a quartz cuvette with an optical path of 10 mm, and water as a reference at a wavelength of 700 nm to determine the absorbance. The phosphorus content M (mg / L) in the reaction solution is obtained by referring to the total phosphorus standard curve. Then, the total phosphorus content C (TP) (mg / L) in the non-ferrous metal extraction waste liquid can be calculated according to the following calculation formula: C (TP) = 50 × bM / a.

[0069] The COD digestion instrument parameters used in the detection method of the present invention are as follows:

[0070] Instrument model: WD-1;

[0071] Microwave power: 700W, 2450MHZ;

[0072] Rated current and voltage: 5.6A, 220V, 50HZ;

[0073] In addition, the gear position and digestion time of the COD digester were adjusted according to the gear adjustment table shown in Table 1.

[0074] Table 1

[0075] Number of test samples Digestion instrument gear Digestion time (minutes) 0～2 Low 5 3～5 middle 10 5 or more high 10

[0076] (1) For different non-ferrous metal extraction wastewater

[0077] Example 1

[0078] This embodiment provides a method for detecting the total phosphorus content of non-ferrous metal extraction wastewater, the detection method comprising the following steps:

[0079] (1) Collecting the anti-magnesium solution from the non-ferrous metal extraction workshop as the test sample;

[0080] The cobalt content in the anti-magnesium solution is 2.45 mg / L, and the nickel content is 4.36 mg / L;

[0081] (2) 5 groups of test samples described in step (1) were respectively placed in 5 polytetrafluoroethylene cans, each with a sampling volume of 10 mL, and 5 mL of sodium ferrate solution with a concentration of 1 g / L and a pH of 9.4-9.7 was added to each can and sealed, so that the pH of the digestion system was greater than 9. Then the whole was placed in a COD digestion instrument, and the COD gear was adjusted to the middle gear according to Table 1 above. The digestion time was 10 minutes. After microwave-assisted digestion, the 5 polytetrafluoroethylene cans were placed in a water bath and cooled to room temperature. Five groups of digestion solutions were obtained by filtration;

[0082] (3) In five 50 mL colorimetric tubes, the five groups of digestion solutions obtained in step (2) were added with 5 mL of 1 mol / L sulfuric acid solution to adjust the pH of the system to 3-4, and then 2 mL of 100 g / L ascorbic acid solution was added and mixed. After 30 seconds, molybdate solution was added to adjust the pH of the system to 2-3 and the volume was fixed to obtain five groups of reaction solutions;

[0083] The amount of the ascorbic acid solution added satisfies the following conditions: 2 mL of the ascorbic acid solution is added to every 10 mL of the test sample; the preparation method of the molybdate solution in step (3) comprises: dissolving 13 g of ammonium molybdate and 0.35 g of potassium antimony tartrate in 100 mL of pure water to obtain an ammonium molybdate aqueous solution and an antimony potassium tartrate aqueous solution, adding the ammonium molybdate aqueous solution to 300 mL of a 1+1 sulfuric acid solution under constant stirring, and finally adding the solution to the potassium antimony tartrate aqueous solution and mixing to obtain the molybdate solution;

[0084] (4) The absorbance of the five groups of reaction solutions in step (3) was determined by spectrophotometry. The spectrophotometry was performed using an ultraviolet spectrophotometer. A quartz cuvette with an optical path of 10 mm was used. The absorbance was determined at a wavelength of 700 nm with water as a reference. The phosphorus content in the five groups of reaction solutions was obtained by referring to the total phosphorus standard curve, and the average value was taken as the phosphorus content M in the reaction solution. As shown in Table 2, the measured values ​​of the five groups of parallel samples were relatively close, with a deviation of less than 5% and good consistency. The total phosphorus content in the non-ferrous metal extraction waste liquid was obtained as 5.70 mg / L according to the calculation formula C(TP)=50×bM / a.

[0085] Table 2

[0086]

[0087] Example 2

[0088] This embodiment provides a method for detecting the total phosphorus content of non-ferrous metal extraction wastewater, the detection method comprising the following steps:

[0089] (1) Collect chloride wastewater from the non-ferrous metal extraction workshop as test samples;

[0090] The cobalt content in the chloride wastewater is 1.25 mg / L, and the nickel content is 2.18 mg / L;

[0091] (2) 5 groups of test samples described in step (1) were respectively placed in 5 polytetrafluoroethylene cans, with a sampling volume of 20 mL each, and 10 mL of sodium ferrate solution with a concentration of 1 g / L and a pH of 9.4-9.7 was added to each can and sealed, so that the pH of the digestion system was greater than 9. Then the whole was placed in a COD digestion instrument, and the COD gear was adjusted to the middle gear according to Table 1 above. The digestion time was 10 minutes. After microwave-assisted digestion, the 5 polytetrafluoroethylene cans were placed in a water bath and cooled to room temperature. Five groups of digestion solutions were obtained by filtration;

[0092] (3) In five 50 mL colorimetric tubes, the five groups of digestion solutions obtained in step (2) were added with 5 mL of 1 mol / L sulfuric acid solution to adjust the pH of the system to 3-4, and then 4 mL of 100 g / L ascorbic acid solution was added and mixed. After 30 seconds, molybdate solution was added to adjust the pH of the system to 2-3 and the volume was fixed to obtain five groups of reaction solutions;

[0093] The amount of the ascorbic acid solution added satisfies the following conditions: 2 mL of the ascorbic acid solution is added to every 10 mL of the test sample; the preparation method of the molybdate solution in step (3) comprises: dissolving 13 g of ammonium molybdate and 0.35 g of potassium antimony tartrate in 100 mL of pure water to obtain an ammonium molybdate aqueous solution and an antimony potassium tartrate aqueous solution, adding the ammonium molybdate aqueous solution to 300 mL of a 1+1 sulfuric acid solution under constant stirring, and finally adding the solution to the potassium antimony tartrate aqueous solution and mixing to obtain the molybdate solution;

[0094] (4) The absorbance of the five groups of reaction solutions in step (3) was determined by spectrophotometry. The spectrophotometry was performed using an ultraviolet spectrophotometer. A quartz cuvette with an optical path of 10 mm was used. The absorbance was determined at a wavelength of 700 nm with water as a reference. The phosphorus content in the five groups of reaction solutions was obtained by referring to the total phosphorus standard curve, and the average value was taken as the phosphorus content M in the reaction solution. As shown in Table 3, the measured values ​​of the five groups of parallel samples were relatively close, with a deviation of less than 5% and good consistency. The total phosphorus content in the non-ferrous metal extraction waste liquid was obtained as 4.28 mg / L according to the calculation formula C(TP)=50×bM / a.

[0095] Table 3

[0096]

[0097] Example 3

[0098] This embodiment provides a method for detecting the total phosphorus content of non-ferrous metal extraction wastewater, the detection method comprising the following steps:

[0099] (1) Collect lithium wastewater from the nonferrous metal extraction workshop as a test sample and dilute it twice with pure water;

[0100] The cobalt content in the lithium wastewater is 3.21 mg / L, and the nickel content is 1.84 mg / L;

[0101] (2) 5 groups of diluted test samples obtained in step (1) were respectively placed in 5 polytetrafluoroethylene cans, with a sampling volume of 10 mL. 5 mL of sodium ferrate solution with a concentration of 1 g / L and a pH of 9.4 to 9.7 was added to each can and sealed, so that the pH of the digestion system was greater than 9. Then the whole can was placed in a COD digestion instrument, and the COD gear was adjusted to the middle gear according to Table 1. The digestion time was 10 minutes. After microwave-assisted digestion, the 5 polytetrafluoroethylene cans were placed in a water bath and cooled to room temperature. Five groups of digestion solutions were obtained by filtration.

[0102] (3) In five 50 mL colorimetric tubes, the five groups of digestion solutions obtained in step (2) were added with 5 mL of 1 mol / L sulfuric acid solution to adjust the pH of the system to 3-4, and then 2 mL of 100 g / L ascorbic acid solution was added and mixed. After 30 seconds, molybdate solution was added to adjust the pH of the system to 2-3 and the volume was fixed to obtain five groups of reaction solutions;

[0103] The amount of the ascorbic acid solution added satisfies the following conditions: 2 mL of the ascorbic acid solution is added to every 10 mL of the test sample; the preparation method of the molybdate solution in step (3) comprises: dissolving 13 g of ammonium molybdate and 0.35 g of potassium antimony tartrate in 100 mL of pure water to obtain an ammonium molybdate aqueous solution and an antimony potassium tartrate aqueous solution, adding the ammonium molybdate aqueous solution to 300 mL of a 1+1 sulfuric acid solution under constant stirring, and finally adding the solution to the potassium antimony tartrate aqueous solution and mixing to obtain the molybdate solution;

[0104] (4) The absorbance of the five groups of reaction solutions in step (3) was determined by spectrophotometry. The spectrophotometry was performed using an ultraviolet spectrophotometer. A quartz cuvette with an optical path of 10 mm was used. The absorbance was determined at a wavelength of 700 nm with water as a reference. The phosphorus content in the five groups of reaction solutions was obtained by referring to the total phosphorus standard curve, and the average value was taken as the phosphorus content M in the reaction solution. As shown in Table 4, the measured values ​​of the five groups of parallel samples were relatively close, with a deviation of less than 5% and good consistency. The total phosphorus content in the non-ferrous metal extraction waste liquid was obtained as 8.20 mg / L according to the calculation formula C(TP)=50×bM / a.

[0105] Table 4

[0106]

[0107] Example 4

[0108] This embodiment provides a method for detecting the total phosphorus content of non-ferrous metal extraction waste liquid. Compared with Example 1, the only difference is that the amount of sodium ferrate solution added in step (2) is adjusted to 10 mL, 15 mL, 20 mL, and 25 mL, respectively, and 5 groups of parallel samples are measured. That is, the phosphorus content in 5 groups of reaction solutions corresponding to different amounts of sodium ferrate solution added are obtained by referring to the total phosphorus standard curve, and the average value is taken as the phosphorus content in the reaction solution. The specific measurement results are shown in Table 5.

[0109] Table 5

[0110]

[0111] As can be seen from Table 5, for different addition amounts of sodium ferrate solution, the average phosphorus content in the reaction solution obtained by the test is not significantly affected when the addition of sodium ferrate solution is within 15 mL. However, when more than 15 mL of sodium ferrate solution is added, the test result will be lower. Therefore, the detection method of the present invention sets the volume ratio of the test sample to the ferrate solution to 1: (0.5-1.5).

[0112] Comparative Example 1

[0113] This comparative example provides a method for detecting the total phosphorus content of non-ferrous metal extraction waste liquid. Compared with Example 1, the only difference is that the amount of sodium ferrate solution added in step (2) is adjusted to 3 mL, resulting in the pH of the digestion system being only 8.3, which does not meet the requirement of pH>9. In addition, 5 groups of parallel samples are also measured, that is, the phosphorus content in 5 groups of reaction solutions is obtained by referring to the total phosphorus standard curve and the average value is taken as the phosphorus content in the reaction solution. The specific measurement results are shown in Table 6.

[0114] Table 6

[0115]

[0116] As can be seen from Table 6, the pH value when adding ferrate solution for digestion has a great influence on the subsequent spectrophotometric detection of total phosphorus content, and the pH value of the digestion system needs to be strictly controlled to be above 9.

[0117] Comparative Example 2

[0118] This comparative example provides a method for detecting the total phosphorus content of non-ferrous metal extraction waste liquid. Compared with Example 1, the only difference is that: the cobalt ions and nickel ions in the reverse magnesium solution in step (1) are effectively removed, so that the cobalt content in the reverse magnesium solution is less than 1 mg / L, and the nickel content is less than 1 mg / L. In addition, 5 groups of parallel samples are also measured, that is, the phosphorus content in 5 groups of reaction solutions is obtained by referring to the total phosphorus standard curve and the average value is taken as the phosphorus content in the reaction solution. The specific measurement results are shown in Table 7.

[0119] Table 7

[0120]

[0121]

[0122] As can be seen from Table 7, the presence of cobalt and nickel ions in the non-ferrous metal extraction waste liquid has a great influence on the subsequent spectrophotometric detection of total phosphorus content. The reason is that trace cobalt and nickel ions have a catalytic decomposition effect on the added sodium ferrate, so that the addition of excessive sodium ferrate does not affect the subsequent detection of total phosphorus content; however, if the content of cobalt and nickel ions in the non-ferrous metal extraction waste liquid is too low, excessive sodium ferrate will affect the detection of total phosphorus content, and the amount of sodium ferrate added needs to be further adjusted.

[0123] (2) Spike recovery test

[0124] Taking the anti-magnesium solution described in Example 1 as an example, the spike recovery test is introduced. The specific operation is as follows:

[0125] (1') Collecting the reverse magnesium solution from the nonferrous metal extraction workshop as a test sample;

[0126] The cobalt content in the anti-magnesium solution is 2.45 mg / L, and the nickel content is 4.36 mg / L;

[0127] (2') Take two groups of test samples described in step (1') and place them in two polytetrafluoroethylene cans with a sampling volume of 10 mL each. Add a spike to one of the polytetrafluoroethylene cans and control the spike amount to 1.00 mg / L. The cans are defined as spiked samples, and the other is defined as original samples. Add 5 mL of a sodium ferrate solution with a concentration of 1 g / L and a pH of 9.4 to 9.7 to the original samples and seal the cans. Add 10 mL of a sodium ferrate solution with a concentration of 1 g / L and a pH of 9.4 to 9.7 to the spiked samples and seal the cans so that the pH of the two digestion systems is greater than 9. Then place the whole cans in a COD digester. Adjust the COD gear to a low gear according to Table 1 above. The digestion time is 5 minutes. After microwave-assisted digestion, place the two polytetrafluoroethylene cans in a water bath and cool to room temperature. Filter to obtain two groups of digestion solutions.

[0128] (3') In two 50 mL colorimetric tubes, add 5 mL of 1 mol / L sulfuric acid solution to the digestion solution obtained from the original sample to adjust the pH of the system to 3-4. Add 10 mL of 1 mol / L sulfuric acid solution to the digestion solution obtained from the spiked sample to adjust the pH of the system to 3-4. Then, add 100 g / L ascorbic acid solution to each of the two tubes and mix thoroughly. After 30 s, add molybdate solution to each of the two tubes to adjust the pH of the system to 2-3 and adjust the volume to obtain two sets of reaction solutions.

[0129] Wherein, the amount of the ascorbic acid solution added satisfies: 2 mL of the ascorbic acid solution is added to every 10 mL of the test sample; the preparation method of the molybdate solution in step (3') comprises: dissolving 13 g of ammonium molybdate and 0.35 g of potassium antimony tartrate in 100 mL of pure water to obtain an ammonium molybdate aqueous solution and an antimony potassium tartrate aqueous solution, adding the ammonium molybdate aqueous solution to 300 mL of 1+1 sulfuric acid solution under constant stirring, and finally adding the antimony potassium tartrate aqueous solution to mix to obtain the molybdate solution;

[0130] (4') The absorbance of the two groups of reaction solutions in step (3') is determined by spectrophotometry. The spectrophotometry is performed using an ultraviolet spectrophotometer, a quartz cuvette with an optical path of 10 mm, and water as a reference at a wavelength of 700 nm. The phosphorus content in the two groups of reaction solutions is obtained by referring to a total phosphorus standard curve, and the spiked recovery rate is then calculated.

[0131] Similarly, the chloride wastewater described in Example 2 was spiked and treated according to the detection method described in Example 2, and the lithium wastewater described in Example 3 was spiked and treated according to the detection method described in Example 3. Specific experimental data are shown in Table 8.

[0132] Table 8

[0133]

[0134] As can be seen from Table 8, the detection method of the present invention can accurately determine the total phosphorus content in non-ferrous metal extraction wastewater, and the spiked recovery rate is between 98% and 102%, and the measured value is basically the same as the theoretical value.

[0135] (3) Comparison of the four detection methods

[0136] The reverse magnesium solution described in Example 1 was used as the detection object, and the total phosphorus content was detected using the method for detecting the total phosphorus content of non-ferrous metal extraction waste liquid according to the present invention (referred to as the sodium ferrate digestion method), the potassium persulfate high-temperature and high-pressure digestion method described in GB / T 11893-1989 (referred to as the potassium persulfate digestion method) and optimized to microwave-assisted digestion, the ICP direct detection method, and the nitric acid-perchloric acid hot plate digestion method described in GB / T 11893-1989 (referred to as the nitric acid-perchloric acid digestion method) for detecting the total phosphorus content.

[0137] Take 5mL, 10mL, 15mL, 20mL, 25mL of the anti-magnesium solution of Example 1 in each group, that is, use the above four detection methods to detect the total phosphorus content, and measure the phosphorus content in the reaction solution obtained after digestion. The specific results are summarized in Table 9, and the relevant data in Table 9 are plotted as shown in the figure. Figure 1 The bar graph is shown.

[0138] Table 9

[0139]

[0140] From Table 9 and Figure 1 It can be seen that:

[0141] (i) Compared with the ICP direct test method and the nitric acid-perchloric acid digestion method, the total phosphorus content measured by the detection method of the present invention is higher, and is about 10-19% higher. This shows that the detection method of the present invention can make the organic phosphorus in the reverse magnesium solution digested more fully, reduce the loss of total phosphorus in the reverse magnesium solution, and is more representative. In addition, the detection method of the present invention is simpler and more convenient, and can directly digest the test sample and then perform rapid colorimetric detection, which has obvious advantages.

[0142] (ii) Compared with the potassium persulfate digestion method, the potassium persulfate digestion method generates a large amount of gas during the digestion process, causing the polytetrafluoroethylene can to expand and increase the loss of the polytetrafluoroethylene can. In contrast, the detection method of the present invention uses a sodium ferrate solution for digestion under microwave assistance. The reduction product is a suspended iron hydroxide, which generates less gas and does not affect the subsequent use of the polytetrafluoroethylene can. In addition, the total phosphorus content measured by the detection method of the present invention is more than 5% higher than the total phosphorus content measured by the potassium persulfate digestion method.

[0143] (iii) The detection method of the present invention is specifically designed for the detection of total phosphorus content in non-ferrous metal extraction wastewater. The key lies in the use of ferrate solution for digestion under microwave-assisted temperature regulation. It has the advantages of high detection accuracy, small error, and strong stability, and can better reflect the actual total phosphorus content in non-ferrous metal extraction wastewater.

[0144] In summary, the detection method of the present invention is specifically studied for the problem of detecting the total phosphorus content in non-ferrous metal extraction waste liquid. The key lies in the use of ferrate solution for digestion. On the one hand, since the standard redox potential of ferrate is much higher than that of other inorganic oxidants, it can fully digest the organic phosphorus in the test sample and ensure the accuracy of the total phosphorus content. On the other hand, the product after ferrate reduction is a ferric hydroxide suspension with a flocculating effect, which can effectively remove trace heavy metal ions, such as arsenides, sulfides and chromium compounds in the test sample, and can effectively reduce the turbidity and color of the test sample. The test sample with high turbidity can be directly digested without pretreatment, and the synergistic effect of oxidation, flocculation, adsorption and precipitation is exerted. In addition, the trace cobalt and nickel ions in the non-ferrous metal extraction waste liquid can catalyze the accelerated decomposition of ferrate, and the addition of excess ferrate solution will not affect subsequent detection. In addition, the detection method of the present invention has the advantages of simple operation, short detection cycle, economical and practical equipment, high detection accuracy, and low reagent consumption.

[0145] While the present invention is described through the above-described embodiments to illustrate the detailed structural features of the present invention, the present invention is not limited to these detailed structural features, nor does it necessarily rely on these detailed structural features for implementation. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components, additions of auxiliary components, and selection of specific embodiments, etc., fall within the scope of protection and disclosure of the present invention.

[0146] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0147] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0148] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for detecting the total phosphorus content of non-ferrous metal extraction wastewater, characterized in that: The detection method comprises the following steps: (1) Collecting non-ferrous metal extraction waste liquid as test samples; The cobalt content in the non-ferrous metal extraction wastewater is 1-5 mg / L, and the nickel content is 1-5 mg / L; (2) placing the test sample described in step (1) into a sample jar, adding ferrate solution and sealing the jar so that the pH of the digestion system is greater than 9, and obtaining a digestion solution after digestion; The pH of the ferrate solution is 9.4 to 9.7; the concentration of the ferrate solution is 0.8 to 1.2 g / L; and the volume ratio of the test sample to the ferrate solution is controlled to be 1:(0.5 to 1.5); (3) adding sulfuric acid solution, ascorbic acid solution and molybdate solution to the digestion solution obtained in step (2) in sequence and constant volume to obtain a reaction solution; (4) The absorbance of the reaction solution in step (3) is measured by spectrophotometry, and the total phosphorus content in the non-ferrous metal extraction waste liquid is calculated with reference to a total phosphorus standard curve.

2. The detection method according to claim 1, wherein After step (1) and before placing the sample into the sample jar in step (2), the method further includes diluting the test sample and placing the diluted test sample into the sample jar.

3. The detection method according to claim 1, wherein The ferrate in the ferrate solution in step (2) is sodium ferrate and / or potassium ferrate.

4. The detection method according to claim 1, wherein The sample tank in step (2) is a polytetrafluoroethylene tank.

5. The detection method according to claim 1, wherein The digestion in step (2) is carried out in a COD digester.

6. The detection method according to claim 1, characterized in that The digestion in step (2) is performed under microwave assistance.

7. The detection method according to claim 1, characterized in that After the digestion in step (2), cooling and filtering are performed in sequence to obtain the digestion solution.

8. The detection method according to claim 7, characterized in that The cooling includes placing the sample jar in a water bath to cool to room temperature.

9. The detection method according to claim 1, wherein In step (3), sulfuric acid solution is added to make the pH of the system 3-4, and then ascorbic acid solution is added and mixed. After waiting for 30-60 seconds, molybdate solution is added.

10. The detection method according to claim 9, characterized in that: The concentration of the sulfuric acid solution in step (3) is 0.8 to 1.2 mol / L.

11. The detection method according to claim 9, characterized in that The concentration of the ascorbic acid solution in step (3) is 95-105 g / L, and the amount of the ascorbic acid solution added satisfies the following conditions: 1-3 mL of the ascorbic acid solution is added to every 10 mL of the test sample.

12. The detection method according to claim 9, characterized in that The amount of the molybdate solution added in step (3) satisfies the requirement that the pH of the system is 2 to 3.

13. The detection method according to claim 9, characterized in that The preparation method of the molybdate solution in step (3) comprises: dissolving ammonium molybdate and potassium antimony tartrate in pure water to obtain an ammonium molybdate aqueous solution and an antimony potassium tartrate aqueous solution, respectively; adding the ammonium molybdate aqueous solution to a 1+1 sulfuric acid solution under continuous stirring; and finally adding the solution to the potassium antimony tartrate aqueous solution and mixing to obtain the molybdate solution.

14. The detection method according to claim 1, characterized in that The volume determination in step (3) is carried out in a colorimetric tube.

15. The detection method according to claim 1, characterized in that The spectrophotometry in step (4) is performed using an ultraviolet spectrophotometer, using a quartz cuvette with an optical path of 10 mm, and measuring absorbance at a wavelength of 700 nm with water as a reference.

16. The detection method according to claim 1, characterized in that The detection method comprises the following steps: (1) Collecting non-ferrous metal extraction waste liquid as test samples; The cobalt content in the non-ferrous metal extraction wastewater is 1-5 mg / L, and the nickel content is 1-5 mg / L; (2) placing the test sample described in step (1) into a polytetrafluoroethylene can, adding ferrate solution and sealing the can to make the pH of the digestion system greater than 9, and then placing the whole can into a COD digestion instrument. After microwave-assisted digestion, the polytetrafluoroethylene can is placed in a water bath and cooled to room temperature, and the digestion solution is obtained by filtration; The ferrate in the ferrate solution is sodium ferrate and / or potassium ferrate; the pH of the ferrate solution is 9.4-9.7; the concentration of the ferrate solution is 0.8-1.2 g / L; and the volume ratio of the test sample to the ferrate solution is controlled to be 1:(0.5-1.5); (3) In a colorimetric tube, the digestion solution obtained in step (2) is added with a sulfuric acid solution having a concentration of 0.8 to 1.2 mol / L so that the pH of the system is 3 to 4, and then an ascorbic acid solution having a concentration of 95 to 105 g / L is added and mixed. After 30 to 60 seconds, a molybdate solution is added to make the pH of the system 2 to 3 and the volume is constant to obtain a reaction solution; The amount of the ascorbic acid solution added satisfies the following conditions: 1 to 3 mL of the ascorbic acid solution is added to every 10 mL of the test sample; the method for preparing the molybdate solution in step (3) comprises: dissolving ammonium molybdate and potassium antimony tartrate in pure water to obtain an ammonium molybdate aqueous solution and an antimony potassium tartrate aqueous solution, adding the ammonium molybdate aqueous solution to a 1+1 sulfuric acid solution under continuous stirring, and finally adding the solution to the antimony potassium tartrate aqueous solution and mixing to obtain the molybdate solution; (4) The absorbance of the reaction solution in step (3) is determined by spectrophotometry. The spectrophotometry is performed using an ultraviolet spectrophotometer, a quartz cuvette with an optical path of 10 mm, and water as a reference at a wavelength of 700 nm. The total phosphorus content in the non-ferrous metal extraction waste liquid is calculated by referring to a total phosphorus standard curve.

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