Method for determining concentrations of various dissolved phosphorus forms in industrial sewage

Abstract

The invention discloses a method for measuring the concentration of various dissolved phosphorus forms in industrial sewage. The method comprises the following steps: S1, preparing a plurality of mixed solutions with different concentrations and containing various phosphorus forms in a dissolved state, and respectively carrying out ion chromatographic analysis on the mixed solution with each concentration; establishing a standard curve of each phosphorus form according to the concentration of each phosphorus form and the chromatographic peak of each phosphorus form in the ion chromatogram corresponding to the concentration; the multiple phosphorus forms comprise orthophosphate radicals, pyrophosphate radicals, trimetaphosphate radicals and tripolyphosphate radicals; s2, adjusting the pH value of a to-be-detected industrial sewage sample to be neutral, enabling the to-be-detected industrial sewage sample to sequentially pass through the column 1, the column 2 and the column 3, and then performing ion chromatographic analysis on the water sample passing through the columns to obtain an ion chromatogram of the water sample; and obtaining the concentration of each phosphorus form in the water sample according to the ion chromatogram of the water sample and the standard curve of each phosphorus form. The purpose of automatically analyzing the concentrations of various phosphates in the industrial sewage is achieved, operation is easy, and accuracy is high.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial wastewater detection, and specifically relates to a method for determining the concentrations of multiple dissolved phosphorus forms in industrial wastewater. Background Art

[0002] Phosphates in sewage can cause eutrophication of water bodies. They are widely present in sewage and improper treatment will have serious negative effects on the environment. Phosphates are widely used in industrial production. The discharge of industrial sewage is large and may impact the activated sludge in the sewage treatment unit. Accurate detection of phosphate concentration in industrial sewage can be used as an influencing factor in analyzing the changes in the activated sludge microbial community and determining the types of phosphates that impact the activated sludge in industrial sewage treatment plants, thereby providing a basis for improving the efficiency of phosphorus treatment.

[0003] Based on the above purpose, accurately determining the content of various phosphates in industrial wastewater is very important for sewage treatment plants to cope with the impact of various forms of phosphates. Ammonium molybdate spectrophotometry is a commonly used method for determining total phosphorus in water. Its basic principle is to use potassium persulfate (or nitric acid-perchloric acid) to digest the sample under neutral conditions and oxidize all the contained phosphorus into orthophosphate. In an acidic medium, orthophosphate reacts with ammonium molybdate to generate phosphomolybdic heteropolyacid in the presence of antimony salt, and is immediately reduced by ascorbic acid to generate a blue complex. Under visible light 700nm, the absorbance is determined by spectrophotometry to obtain the total phosphorus content. CN102998266A discloses a method for analyzing total phosphorus in industrial wastewater samples, which uses the principle of ammonium molybdate spectrophotometry for total phosphorus determination to determine the total phosphorus content under normal pressure by ultraviolet visible spectrophotometer equipment. CN109406426A discloses a reagent for rapid determination of total phosphorus in sewage, and its preparation method and application. After the water sample is digested, it is taken out, and after cooling, molybdate solution and ascorbic acid solution are added respectively and mixed. At a wavelength of 700nm, the concentration of the sample is measured with a zero concentration solution as a reference. CN109632662A discloses a reagent for rapid determination of orthophosphate in sewage, and its preparation method and application. After adding molybdate solution to the water sample to be tested, it is mixed. At a wavelength of 700nm, the concentration of orthophosphate in the water sample to be tested is measured with a zero concentration solution as a reference. At present, the detection of phosphorus forms in industrial sewage focuses on total phosphorus concentration and orthophosphate concentration, and lacks the detection of pyrophosphate, trimetaphosphate and tripolyphosphate in industrial sewage. In addition, the chloride ion concentration in industrial sewage is relatively high, which will interfere with the determination of various phosphates. Summary of the invention

[0004] The purpose of the present invention is to provide a method for determining the concentrations of various dissolved phosphorus forms in industrial wastewater. By a series of treatments of industrial wastewater samples and direct detection thereof using an ion chromatograph, the purpose of automatic analysis of the concentrations of various phosphates in industrial wastewater is achieved. The method has the advantages of simple operation and high accuracy.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for determining the concentration of multiple dissolved phosphorus forms in industrial wastewater, comprising the following steps: S1. preparing a plurality of mixed solutions containing various forms of dissolved phosphorus of different concentrations, and performing ion chromatography analysis on the mixed solution of each concentration to obtain an ion chromatogram of the mixed solution of each concentration; A standard curve for each phosphorus form is established based on the concentration of each phosphorus form and the chromatographic peak of each phosphorus form in the ion chromatogram corresponding to the concentration; The multiple phosphorus forms include orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate; S2, adjusting the pH value of the industrial wastewater sample to be tested to neutral, and then passing it through columns 1, 2 and 3 in sequence, and then performing ion chromatography analysis on the water sample passing through the columns to obtain an ion chromatogram of the water sample; The column 1 is a porous divinylbenzene resin column; The column 2 is an Ag-type sulfonate column; The column 3 is a sodium type cross-linked styrene sulfonic acid resin column; The concentration of each phosphorus form in the water sample is obtained according to the ion chromatogram of the water sample and the standard curve of each phosphorus form.

[0006] Based on the above technical solution, due to the presence of hydrophobic substances in industrial water samples, higher concentrations of chloride ions and higher concentrations of Ca 2+ Etc., by sequentially passing through three separation columns, impurities can be removed while retaining orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate, thereby reducing the interference of impurity ions on the determination of orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate. Specifically, the present invention sequentially passes the water sample of the industrial wastewater to be tested through an Rp-type porous divinylbenzene resin column to remove hydrophobic substances in the sample matrix, an Ag-type sulfonate column to remove halogen ions such as chloride ions, and a Na-type cross-linked styrene sulfonic acid resin column to remove Ca in the water sample. 2+ and Mg 2+ Ion chromatography was further used to simultaneously determine orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate in industrial wastewater samples.

[0007] In the above method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater, as an example, the column 1 is a Dionex OnGuard II RP column; The column 2 is a Dionex OnGuard II Ag column; The column 3 is a Dionex OnGuard II Na column.

[0008] In the above-mentioned method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater, further, the sequentially passing through column 1, column 2 and column 3 includes any of the following: 1) The three columns are connected in sequence and then the water sample is passed through; 2) After passing through column 1, collect the water sample in a container, then pass through column 2, collect the water sample in a container, and then pass through column 3; 3) After passing through column 1, collect the water sample in a container and then pass it through columns 2 and 3 connected in sequence; 4) After passing through columns 1 and 2 connected in sequence, use a container to collect the water sample after passing through the columns, and then pass through column 3.

[0009] In the above method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater, further, in step S1 and step S2, the detection parameters of the ion chromatography analysis are as follows: Injection volume: 20-30 μL, such as 25 μL; Chromatographic column: Dionex IonPac AS11-HC column; Guard column: Dionex IonPac AG11 guard column; Flow rate: 1.2 mL / min; Column temperature: 30°C; Detection mode: external circulation suppression conductivity; Suppressor: Dionex AERS 500 anion suppressor; Eluent generator: Thermo Fisher KOH eluent tank-EGC500 eluent generator; The eluent gradient program is as follows: 00.0~20.0 min 20 mM KOH eluent; 12.1~20.0 min 50 mM KOH eluent; 20.1~26.0 min 80 mM KOH eluent; 26.1~30.0 min 20 mM KOH eluent.

[0010] Based on the above detection parameters, the present invention further realizes the determination of four target ions by adjusting different concentrations of potassium hydroxide eluents and different potassium hydroxide eluent flow rates. When the eluent gradient program is not suitable or the eluent flow rate is not good, it may not be possible to elute all five phosphates that need to be detected, or there may be an abnormally large number of peaks, or the tripolyphosphate peaks may not be completely separated, or there may be interference from unknown miscellaneous peaks, or the peak times of various phosphates may differ greatly. The present invention obtains an ion chromatogram with six completely separable peaks and a relatively flat baseline by optimizing the eluent gradient program and the eluent flow rate.

[0011] In the above-mentioned method for determining the concentrations of multiple dissolved phosphorus forms in industrial wastewater, as an example, the several mixed solutions of different concentrations are respectively recorded as solution 1, solution 2, solution 3, solution 4 and solution 5, the concentration of each phosphorus form in solution 1 is 0.25 mg / L, the concentration of each phosphorus form in solution 2 is 1.0 mg / L, the concentration of each phosphorus form in solution 3 is 2.5 mg / L, the concentration of each phosphorus form in solution 4 is 5.0 mg / L, and the concentration of each phosphorus form in solution 5 is 10 mg / L.

[0012] In the above-mentioned method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater, as an example, the standard curve is a concentration-peak area standard curve.

[0013] Furthermore, the establishment of a standard curve for each phosphorus form comprises: According to the concentration of orthophosphate and the peak area of ​​orthophosphate corresponding to each concentration, a standard curve of orthophosphate is established; A pyrophosphate standard curve is established according to the concentration of pyrophosphate and the peak area of ​​pyrophosphate corresponding to each concentration; A trimetaphosphate standard curve is established according to the concentration of trimetaphosphate and the peak area of ​​trimetaphosphate corresponding to each concentration; A standard curve of tripolyphosphate was established based on the concentration of tripolyphosphate and the peak area of ​​tripolyphosphate corresponding to each concentration.

[0014] In the above-mentioned method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater, further, the industrial wastewater is wastewater generated in the production process of an industrial park, and the pH value is 1 to 14; The neutral pH value is 6 to 8, such as 7.

[0015] In the above-mentioned method for determining the concentrations of various dissolved phosphorus forms in industrial wastewater, the method further includes the following steps: before the industrial wastewater sample passes through the column, removing impurities with a particle diameter ≥ 0.45 μm in the water sample, preferably passing the water sample through a 0.45 μm filter membrane.

[0016] In the above-mentioned method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater, further, the OnGuardⅡ RP column is an activated purification column, the activation reagents are methanol and deionized water, and the standing time after activation is 30 to 50 minutes; The OnGuard II Ag column is an activated purification column, the activation reagent is deionized water, and the standing time after activation is 30 to 50 minutes; The OnGuard II Na column is an activated purification column, the activation reagent is deionized water, and the standing time after activation is 30 to 50 minutes.

[0017] The present invention has the following beneficial effects: The present invention treats industrial wastewater by adjusting pH, filtering and purifying, and then uses an ion chromatograph to detect the content of various phosphates, and finally calculates the content of various phosphates in the industrial wastewater in terms of total phosphorus. The method has the following advantages: 1. The detection method provided by the present invention realizes direct detection of industrial wastewater, and the detection results are more intuitive and accurate.

[0018] 2. The detection method provided by the present invention has a simple operation process, a short detection time, and a small sample requirement.

[0019] 3. The detection method provided by the present invention provides for detecting the concentration of various phosphates in industrial wastewater; moreover, through a series of combined treatments of industrial wastewater, the interference of various organic matter, chloride ions and various cations in the water sample is avoided, further improving the accuracy of the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention provides a process flow chart for determining the concentrations of various dissolved phosphorus forms in industrial wastewater.

[0021] Figure 2 This is an ion chromatogram of a mixed standard solution containing four phosphate groups, namely orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate, in Example 1 of the present invention, wherein the concentration of each ion is 0.25 mg / L.

[0022] Figure 3 This is an ion chromatogram of a mixed standard solution containing four phosphate groups, namely orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate, in Example 1 of the present invention, wherein the concentration of each ion is 1.0 mg / L.

[0023] Figure 4 This is an ion chromatogram of a mixed standard solution containing four phosphate groups, namely orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate, in Example 1 of the present invention, wherein the concentration of each ion is 2.5 mg / L.

[0024] Figure 5 This is an ion chromatogram of a mixed standard solution containing four phosphate groups, namely orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate, in Example 1 of the present invention, wherein the concentration of each ion is 5.0 mg / L.

[0025] Figure 6 This is an ion chromatogram of a mixed standard solution containing four phosphate groups, namely orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate, in Example 1 of the present invention, wherein the concentration of each ion is 10.0 mg / L.

[0026] Figure 7 This is the concentration-peak area standard curve of orthophosphate in Example 1 of the present invention.

[0027] Figure 8 This is the concentration-peak area standard curve of pyrophosphate in Example 1 of the present invention.

[0028] Fig. 9 This is the concentration-peak area standard curve of trimetaphosphate in Example 1 of the present invention.

[0029] Fig.10 This is the concentration-peak area standard curve of tripolyphosphate in Example 1 of the present invention.

[0030] Fig.11 This is the ion chromatogram of water sample 1 in Example 4 of the present invention that has not been pretreated by three small columns.

[0031] Fig.12 This is the ion chromatogram of water sample 1 pretreated with three small columns in Example 4 of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0033] The methods used in the following examples, unless otherwise specified, are all conventional methods, carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources.

[0034] Ion chromatograph used in the following examples: Thermofish Dionex 5000+, ThermoFisher Scientific, USA.

[0035] The industrial wastewater used in the following examples comes from Hebei Yuehai Water Group Co., Ltd., and the industrial wastewater is taken from the Zhongzhan Wastewater Treatment Plant in Jiaozuo, Henan.

[0036] The OnGuard Ⅱ RP column used in the following examples is the Thermo Fisher Dionex™ OnGuard™ II RP pretreatment column, 1 mL; OnGuard II Ag column is Thermo Fisher Dionex™ OnGuard™ II Ag pretreatment column, 1mL; OnGuard II Na column is a Thermo Fisher Dionex™ OnGuard™ II Na pretreatment column, 1mL.

[0037] Example 1: Establishment of standard curves for determination of various phosphate contents and feasibility verification of detection methods 1. Establish a standard curve Prepare standard samples and establish a standard curve as follows: (1) Weigh a certain amount of sodium orthophosphate, sodium pyrophosphate, sodium trimetaphosphate, and sodium tripolyphosphate, respectively, and finally prepare a mixed solution. The mixed solution contains orthophosphate, pyrophosphate, trimetaphosphate, and tripolyphosphate in concentration gradients of 0.25 mg / L, 1.0 mg / L, 2.5 mg / L, 5.0 mg / L, and 10 mg / L, respectively. Transfer them to five 1000 mL volumetric flasks, mix them thoroughly, and set aside; (2) Transfer the mixed standard solution in each volumetric flask into the quantitative vial for testing; (3) Use ion chromatography to detect mixed standard samples and establish a standard curve; The detection parameters of the ion chromatograph are as follows: Injection volume: 25 μL; Chromatographic column: Dionex IonPac AS11-HC column (4×250 mm); Guard column: Dionex IonPac AG11 guard column (4×50 mm); Flow rate: 1.2 mL / min; Column temperature: 30°C; Detection mode: external circulation suppression conductivity; Suppressor: Dionex AERS 500 anion suppressor, suppression current 279 mA; Eluent: EGC 500 KOH Cartridge, Analytical, HPIC; Eluent generator: Thermo Fisher KOH eluent tank-EGC500 eluent generator; The eluent gradient program is as follows: 00.0-20.0 min 20 mM KOH eluent; 12.1-20.0 min 50 mM KOH eluent; 20.1-26.0 min 80 mM KOH eluent; 26.1-30.0 min 20 mMKOH eluent.

[0038] The ion chromatogram of the mixed standard solution with each ion concentration of 0.25 mg / L is shown in Figure 2 .

[0039] The ion chromatogram of the mixed standard solution with each ion concentration of 1.0 mg / L is shown in Figure 3 .

[0040] The ion chromatogram of the mixed standard solution with each ion concentration of 2.5 mg / L is shown in Figure 4 .

[0041] The ion chromatogram of the mixed standard solution with each ion concentration of 5.0 mg / L is shown in Figure 5 .

[0042] The ion chromatogram of the mixed standard solution with each ion concentration of 10.0 mg / L is shown in Figure 6 .

[0043] The obtained standard curve formula is as follows: Orthophosphate: Y=0.1044x-0.0252, R 2 =0.9956( Figure 7 ); Pyrophosphate: Y=0.1302x-0.0233, R 2 =0.9964( Figure 8 ); Trimetaphosphate: Y=0.1172x-0.0256, R 2 =0.9959( Fig. 9 ); Tripolyphosphate: Y=0.1538x-0.0218, R 2 =0.9977( Fig.10 ); Where: Y: peak area; x: concentration of various phosphates in the water sample.

[0044] The above curves show that each phosphate has a linear relationship in the range of 0.25 mg / L-10.0 mg / L.

[0045] 2. Feasibility Verification of the Method 1. Precision A mixed solution containing orthophosphate, pyrophosphate, trimetaphosphate, and tripolyphosphate at a concentration of 4.65 mg / L was prepared. A batch of water samples with calibrated concentrations were selected and sequentially passed through an Rp-type porous divinylbenzene resin column to remove hydrophobic substances in the sample matrix, an Ag-type sulfonate column to remove halogen ions such as chloride ions, and a Na-type cross-linked styrene sulfonic acid resin column to remove Ca in the water sample. 2+ and Mg 2+ The precision test was then carried out and the test results were as follows: the orthophosphate concentrations in the mixed solutions were 4.63 mg / L, 4.63 mg / L and 4.62 mg / L, respectively, with an RSD of 0.07%; the pyrophosphate concentrations were 4.63 mg / L, 4.63 mg / L and 4.62 mg / L, respectively, with an RSD of 0.07%; the trimetaphosphate concentrations were 4.64 mg / L, 4.63 mg / L and 4.63 mg / L, respectively, with an RSD of 0.12%; the tripolyphosphate concentrations were 4.71 mg / L, 4.71 mg / L and 4.71 mg / L, respectively, with an RSD of 0.07%. It can be seen that the relative standard deviations (RSD) of various phosphate concentrations meet the precision requirement of 10% for conventional chemical tests.

[0046] 2. Accuracy Three samples with known phosphate concentrations of 0.5 mg / L, 3.5 mg / L and 8.0 mg / L were tested in a random order with seven industrial wastewater samples. The final test results showed that the concentrations of orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate in the samples with a phosphate concentration of 0.5 mg / L were 0.52 mg / L, 0.50 mg / L, 0.54 mg / L and 0.52 mg / L, respectively. The concentrations of orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate in the samples with a phosphate concentration of 3.5 mg / L were 3.63 mg / L, 3.44 mg / L, 3.45 mg / L and 3.44 mg / L, respectively. The concentrations of orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate in the samples with a phosphate concentration of 8.0 mg / L were 7.82 mg / L, 7.82 mg / L, 8.20 mg / L and 7.96 mg / L, respectively. The recovery rates of orthophosphate were between 97.73% and 103.67%, pyrophosphate between 97.70% and 99.16%, trimetaphosphate between 98.63% and 108.83%, and tripolyphosphate between 98.29% and 103.69%. It can be seen that the detection results of the sample content of this detection method are accurate and the method has good accuracy.

[0047] 3. Fitting degree R of four phosphate standard curves 2>0.99, indicating that it has feasibility and linear relationship.

[0048] 4. The detection limit range is: the phosphate concentration in the sample is between 0.25 mg and 10.00 mg.

[0049] Example 2: Detection of various phosphate concentrations in industrial wastewater according to Figure 1 The flow chart shown is used to detect various phosphate concentrations in industrial wastewater. The specific steps are as follows: The OnGuard II RP column, OnGuard II Ag column and OnGuard II Na column were activated in sequence. The activation method was as follows: Before use, the OnGuard II RP column (1.0 mL) was passed with 10 mL of methanol and 15 mL of water in sequence, and allowed to stand for activation for 30 min; the OnGuard II Ag column (1.0 mL) was passed with 10 mL of water and allowed to stand for activation for 30 min; the OnGuard II Na column (1.0 mL) was passed with 10 mL of water and allowed to stand for activation for 30 min. The pH of the water sample to be tested is adjusted to neutral, and then the industrial wastewater sample is passed through a 0.45 μm aqueous filter membrane syringe filter to obtain an industrial wastewater sample containing multiple dissolved phosphates. The industrial wastewater sample is passed through an OnGuardⅡ RP column, an OnGuard II Ag column, and an OnGuard II Na column in sequence (the column operation method and conditions are shown in the product manual), and the water sample after the column is transferred to a quantitative vial, and the content of various phosphates in the sample is detected by an ion chromatograph (the detection parameters of the ion chromatograph are the same as those in Example 1), and finally the concentrations of orthophosphate, pyrophosphate, trimetaphosphate, and tripolyphosphate calculated in terms of P are nd, nd, nd, and 0.20 mg / L, respectively. The calculation method for the content of various phosphates in terms of P is to multiply the concentration of each phosphate by the percentage content of the element P in the corresponding phosphate molecular weight.

[0050] Example 3: Detection of various phosphate concentrations in industrial wastewater according to Figure 1 The flow chart shown is used to detect various phosphate concentrations in industrial wastewater. The specific steps are as follows: The OnGuard II RP column, OnGuard II Ag column and OnGuard II Na column were activated in sequence. The activation method was as follows: Before use, the OnGuard II RP column (1.0 mL) was passed with 10 mL of methanol and 15 mL of water in sequence, and allowed to stand for activation for 30 min; the OnGuard II Ag column (1.0 mL) was passed with 10 mL of water and allowed to stand for activation for 30 min; the OnGuard II Na column (1.0 mL) was passed with 10 mL of water and allowed to stand for activation for 30 min. The pH of the water sample to be tested was adjusted to neutral, and then the industrial wastewater sample was passed through a 0.45 μm aqueous filter membrane syringe filter to obtain an industrial wastewater sample containing multiple dissolved phosphates. The industrial wastewater sample was passed through an OnGuard Ⅱ RP column, an OnGuard II Ag column, and an OnGuard II Na column in sequence. The water sample after passing through the column was transferred to a quantitative vial, and the content of various phosphates in the sample was detected by an ion chromatograph (the detection parameters of the ion chromatograph were the same as those in Example 1). Finally, the concentrations of orthophosphate, pyrophosphate, trimetaphosphate, and tripolyphosphate in terms of P were calculated to be nd, nd, nd, and 0.09 mg / L, respectively. The calculation method for the content of various phosphates in terms of P is to multiply the concentration of each phosphate by the percentage content of the element P in the corresponding phosphate molecular weight.

[0051] Example 4: Comparison of ion chromatograms of water samples from the same batch after pretreatment and without pretreatment The industrial wastewater sample 1 without pretreatment by three small columns was directly tested by ion chromatography. The results showed that a large number of water-soluble ions remained in the sample 1, suspected to be chloride ions, nitrate ions, and sulfate ions. Fig.11 , which is the full-size spectrum of sample 1. It can be seen from the figure that there are excessive impurity ions in the interval of 3.0min to 7.0min. It can be seen that the water sample that has not been pretreated by three small columns cannot obtain clear four phosphate concentrations due to the influence of impurity ions (the detection parameters of the ion chromatograph are the same as those in Example 1).

[0052] The OnGuard Ⅱ RP column, OnGuard II Ag column and OnGuard II Na column were activated in sequence. The activation method was as follows: Before use, the OnGuard Ⅱ RP column (1.0mL) was passed with 10mL methanol and 15mL water in sequence, and then left to activate for 30min; the OnGuard Ⅱ Ag column (1.0mL) was passed with 10mL water, and then left to activate for 30min; the OnGuard Ⅱ Na column (1.0mL) was passed with 10mL water, and then left to activate for 30min. The pH of the water sample to be tested was adjusted to neutral, and then the industrial wastewater sample 1 was passed through a 0.45 μm aqueous filter membrane syringe filter to obtain a water sample 1 containing multiple dissolved phosphates. The industrial wastewater sample 1 was passed through the OnGuard Ⅱ RP column, OnGuard II Ag column and OnGuard II Na column in sequence. The water sample after passing through the column was transferred to a quantitative vial. The ion chromatogram of the water sample 1 pretreated by the three columns is shown in Fig.12 (The detection parameters of the ion chromatograph are the same as those in Example 1).

[0053] Depend on Figure 11-Figure 12 The comparison results show that the pretreatment of the three small columns avoids the interference of various organic matter, chloride ions and various cations in the water sample, and realizes the direct determination of the concentration of various dissolved phosphorus forms. The present invention analyzes the components in the water and the ions that may affect the test results, and uses the fillers in the three columns to purify in a targeted manner, ultimately achieving an ideal detection effect.

[0054] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, can implement the present invention in a wider range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principle of the present invention, the application is intended to include any changes, uses or improvements to the present invention, including departing from the disclosed scope in the application and the changes made with conventional techniques known in the art.

Claims

1. A method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater, comprising the following steps: S1. preparing a plurality of mixed solutions containing various forms of dissolved phosphorus of different concentrations, and performing ion chromatography analysis on the mixed solution of each concentration to obtain an ion chromatogram of the mixed solution of each concentration; A standard curve for each phosphorus form is established based on the concentration of each phosphorus form and the chromatographic peak of each phosphorus form in the ion chromatogram corresponding to the concentration; The multiple phosphorus forms include orthophosphate, pyrophosphate, trimetaphosphate and tripolyphosphate; S2, adjusting the pH value of the industrial wastewater sample to be tested to neutral, and then passing it through columns 1, 2 and 3 in sequence, and then performing ion chromatography analysis on the water sample passing through the columns to obtain an ion chromatogram of the water sample; The column 1 is a porous divinylbenzene resin column; The column 2 is an Ag-type sulfonate column; The column 3 is a sodium type cross-linked styrene sulfonic acid resin column; The concentration of each phosphorus form in the water sample is obtained according to the ion chromatogram of the water sample and the standard curve of each phosphorus form.

2. The method for determining the concentration of dissolved multiple phosphorus forms in industrial wastewater according to claim 1, characterized in that: The column 1 is a Dionex OnGuard II RP column; The column 2 is a Dionex OnGuard II Ag column; The column 3 is a Dionex OnGuard II Na column.

3. The method for determining the concentration of dissolved multiple phosphorus forms in industrial wastewater according to claim 1 or 2, characterized in that: The sequentially passing through column 1, column 2 and column 3 includes any of the following: 1) The three columns are connected in sequence and then the water sample is passed through; 2) After passing through column 1, collect the water sample in a container, then pass through column 2, collect the water sample in a container, and then pass through column 3; 3) After passing through column 1, collect the water sample in a container and then pass it through columns 2 and 3 connected in sequence; 4) After passing through columns 1 and 2 connected in sequence, use a container to collect the water sample after passing through the columns, and then pass through column 3.

4. The method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater according to any one of claims 1 to 3, characterized in that: In step S1 and step S2, the detection parameters of the ion chromatography analysis are as follows: Injection volume: 20-30 μL; Chromatographic column: Dionex IonPac AS11-HC column; Guard column: Dionex IonPac AG11 guard column; Flow rate: 1.2 mL / min; Column temperature: 30°C; Detection mode: external circulation suppression conductivity; Suppressor: Dionex AERS 500 anion suppressor; Eluent generator: Thermo Fisher KOH eluent tank-EGC500 eluent generator; The eluent gradient program is as follows: 00.0~20.0 min 20 mMKOH eluent; 12.1~20.0 min 50 mM KOH eluent; 20.1~26.0 min 80 mM KOH eluent; 26.1~30.0 min 20 mM KOH eluent.

5. The method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater according to any one of claims 1 to 4, characterized in that: The several mixed solutions of different concentrations are respectively recorded as solution 1, solution 2, solution 3, solution 4 and solution 5. The concentration of each phosphorus form in solution 1 is 0.25 mg / L, the concentration of each phosphorus form in solution 2 is 1.0 mg / L, the concentration of each phosphorus form in solution 3 is 2.5 mg / L, the concentration of each phosphorus form in solution 4 is 5.0 mg / L, and the concentration of each phosphorus form in solution 5 is 10 mg / L.

6. The method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater according to any one of claims 1 to 5, characterized in that: The standard curve is a concentration-peak area standard curve.

7. The method for determining the concentration of dissolved multiple phosphorus forms in industrial wastewater according to claim 6, characterized in that: The standard curve for each phosphorus form is established as follows: Establishing an orthophosphate standard curve according to the concentration of orthophosphate and the peak area of ​​orthophosphate corresponding to each concentration; A pyrophosphate standard curve is established according to the concentration of pyrophosphate and the peak area of ​​pyrophosphate corresponding to each concentration; A trimetaphosphate standard curve is established according to the concentration of trimetaphosphate and the peak area of ​​trimetaphosphate corresponding to each concentration; A standard curve of tripolyphosphate was established based on the concentration of tripolyphosphate and the peak area of ​​tripolyphosphate corresponding to each concentration.

8. The method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater according to any one of claims 1 to 7, characterized in that: The industrial sewage is wastewater generated during the production process of the industrial park, with a pH value of 1 to 14; The neutral pH value is 6-8.

9. The method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater according to any one of claims 1 to 8, characterized in that: The method further comprises the following steps: before the industrial wastewater sample passes through the column, removing impurities with a particle diameter of ≥0.45 μm in the water sample, preferably passing the water sample through a 0.45 μm filter membrane.

10. The method for determining the concentration of various forms of dissolved phosphorus in industrial wastewater according to any one of claims 2 to 9, characterized in that: The OnGuard Ⅱ RP column is an activated purification column, the activation reagents are methanol and deionized water, and the static activation time is 30 to 50 minutes; The OnGuard II Ag column is an activated purification column, the activation reagent is deionized water, and the static activation time is 30 to 50 minutes; The OnGuard II Na column is an activated purification column, the activation reagent is deionized water, and the static activation time is 30 to 50 minutes.

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