CN111208075A - Phosphorus-containing water treatment agent total phosphorus detection method based on continuous flow analyzer - Google Patents
Phosphorus-containing water treatment agent total phosphorus detection method based on continuous flow analyzer Download PDFInfo
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- 239000011574 phosphorus Substances 0.000 title claims abstract description 94
- 229910052698 phosphorus Inorganic materials 0.000 title claims abstract description 94
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title claims abstract description 93
- 238000001514 detection method Methods 0.000 title claims abstract description 54
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 239000003795 chemical substances by application Substances 0.000 title claims abstract description 51
- 239000000243 solution Substances 0.000 claims abstract description 148
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 80
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims abstract description 74
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 69
- 229960005070 ascorbic acid Drugs 0.000 claims abstract description 37
- 235000010323 ascorbic acid Nutrition 0.000 claims abstract description 37
- 239000011668 ascorbic acid Substances 0.000 claims abstract description 37
- WYWFMUBFNXLFJK-UHFFFAOYSA-N [Mo].[Sb] Chemical compound [Mo].[Sb] WYWFMUBFNXLFJK-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000011259 mixed solution Substances 0.000 claims abstract description 24
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 claims abstract description 23
- 238000002835 absorbance Methods 0.000 claims abstract description 20
- 230000029087 digestion Effects 0.000 claims description 49
- 238000010438 heat treatment Methods 0.000 claims description 40
- 238000002156 mixing Methods 0.000 claims description 39
- 238000006243 chemical reaction Methods 0.000 claims description 33
- 230000002378 acidificating effect Effects 0.000 claims description 19
- 239000012086 standard solution Substances 0.000 claims description 19
- 239000007788 liquid Substances 0.000 claims description 16
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 claims description 13
- 235000018660 ammonium molybdate Nutrition 0.000 claims description 13
- 239000011609 ammonium molybdate Substances 0.000 claims description 13
- 229940010552 ammonium molybdate Drugs 0.000 claims description 13
- 238000005259 measurement Methods 0.000 claims description 9
- 229940026189 antimony potassium tartrate Drugs 0.000 claims description 8
- WBTCZEPSIIFINA-MSFWTACDSA-J dipotassium;antimony(3+);(2r,3r)-2,3-dioxidobutanedioate;trihydrate Chemical compound O.O.O.[K+].[K+].[Sb+3].[Sb+3].[O-]C(=O)[C@H]([O-])[C@@H]([O-])C([O-])=O.[O-]C(=O)[C@H]([O-])[C@@H]([O-])C([O-])=O WBTCZEPSIIFINA-MSFWTACDSA-J 0.000 claims description 8
- 230000003472 neutralizing effect Effects 0.000 claims description 6
- 229940032330 sulfuric acid Drugs 0.000 claims description 5
- 229910000402 monopotassium phosphate Inorganic materials 0.000 claims description 4
- 235000019796 monopotassium phosphate Nutrition 0.000 claims description 4
- PJNZPQUBCPKICU-UHFFFAOYSA-N phosphoric acid;potassium Chemical compound [K].OP(O)(O)=O PJNZPQUBCPKICU-UHFFFAOYSA-N 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 2
- IIQJBVZYLIIMND-UHFFFAOYSA-J potassium;antimony(3+);2,3-dihydroxybutanedioate Chemical compound [K+].[Sb+3].[O-]C(=O)C(O)C(O)C([O-])=O.[O-]C(=O)C(O)C(O)C([O-])=O IIQJBVZYLIIMND-UHFFFAOYSA-J 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 16
- 238000004458 analytical method Methods 0.000 abstract description 8
- 239000000126 substance Substances 0.000 abstract description 7
- 238000012360 testing method Methods 0.000 description 7
- 229910021642 ultra pure water Inorganic materials 0.000 description 7
- 239000012498 ultrapure water Substances 0.000 description 7
- 238000005303 weighing Methods 0.000 description 7
- 239000012153 distilled water Substances 0.000 description 6
- 238000011084 recovery Methods 0.000 description 6
- 239000004698 Polyethylene Substances 0.000 description 5
- 239000003153 chemical reaction reagent Substances 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 5
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 5
- -1 polyethylene Polymers 0.000 description 5
- 229920000573 polyethylene Polymers 0.000 description 5
- 239000002455 scale inhibitor Substances 0.000 description 5
- 229910019142 PO4 Inorganic materials 0.000 description 4
- 239000010452 phosphate Substances 0.000 description 4
- 238000010561 standard procedure Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 230000003442 weekly effect Effects 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- 239000008367 deionised water Substances 0.000 description 3
- 229910021641 deionized water Inorganic materials 0.000 description 3
- 238000005206 flow analysis Methods 0.000 description 3
- 239000003112 inhibitor Substances 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 2
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 229910017053 inorganic salt Inorganic materials 0.000 description 2
- 238000012417 linear regression Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 229940083575 sodium dodecyl sulfate Drugs 0.000 description 2
- 235000019333 sodium laurylsulphate Nutrition 0.000 description 2
- 238000002798 spectrophotometry method Methods 0.000 description 2
- 239000012085 test solution Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- 238000003556 assay Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000011964 heteropoly acid Substances 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 description 1
- LWIHDJKSTIGBAC-UHFFFAOYSA-K potassium phosphate Substances [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- ZMRUPTIKESYGQW-UHFFFAOYSA-N propranolol hydrochloride Chemical compound [H+].[Cl-].C1=CC=C2C(OCC(O)CNC(C)C)=CC=CC2=C1 ZMRUPTIKESYGQW-UHFFFAOYSA-N 0.000 description 1
- 229920002545 silicone oil Polymers 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/38—Diluting, dispersing or mixing samples
Abstract
The invention belongs to the field of chemical analysis, and particularly relates to a phosphorus-containing water treatment agent total phosphorus detection method based on a continuous flow analyzer, which comprises the following steps: a) sequentially introducing air, a potassium persulfate solution, a sample to be detected and a sulfuric acid solution into the continuous flow analyzer; b) sequentially introducing air and a sodium hydroxide solution into the continuous flow analyzer; c) sequentially introducing a molybdenum-antimony mixed solution and an ascorbic acid solution into the continuous flow analyzer; d) and (3) taking ascorbic acid as a color developing agent to carry out absorbance determination, and calculating according to the measured absorbance value and a pre-established standard curve to obtain the total phosphorus content in the sample to be measured. The method adopts the continuous flow analyzer to measure the total phosphorus content in the water treatment agent, has the advantages of high precision, low detection limit, high accuracy and the like, can completely digest the sample automatically by the analyzer, can realize continuous automatic analysis, can treat a large amount of samples at one time, improves the analysis efficiency, and has strong universal applicability in the high-efficiency automatic chemical industry.
Description
Technical Field
The invention belongs to the field of chemical analysis, and particularly relates to a method for detecting total phosphorus in a phosphorus-containing water treatment agent based on a continuous flow analyzer.
Background
The pipeline scaling phenomenon caused by industrial circulating cooling water is serious, the heat exchange efficiency of a system is influenced, and the generated scale corrosion is easy to cause safety accidents. The phosphorus-containing water treatment agent is a medicament which has the functions of dispersing insoluble inorganic salt in water, preventing or interfering the precipitation and scaling of the insoluble inorganic salt on the metal surface and maintaining good heat transfer effect of metal equipment. It mainly comprises inorganic phosphorus-containing polymer water treatment agent, composite phosphate, organic phosphate and other low-phosphorus or phosphorus-free medicaments. The phosphorus-containing water treatment agent has good chemical stability and high temperature and pH resistance, and can be used in combination with other water treatment agents, so that the phosphorus-containing water treatment agent is widely applied to circulating cooling water systems. The total phosphate content is one of the important indexes for evaluating the performance of the phosphorus-containing water treatment agent.
The current industry standard for determining total phosphorus in phosphorus-containing water treatment agents is ammonium molybdate spectrophotometry water treatment agent scale and corrosion inhibitor II (HG/T2430-. Under the acidic condition, orthophosphate reacts with ammonium molybdate to generate phosphomolybdic heteropoly acid, which is reduced into blue complex by ascorbic acid and measured at 710nm under the normal temperature. The method comprises the following specific steps: weighing about 1.5g (plus or minus 0.2mg) of sample, diluting the sample into a 500mL volumetric flask, fixing the volume by using distilled water, and shaking up; transferring 10.00mL of the sample, placing the sample in a 500mL volumetric flask, fixing the volume with distilled water, and shaking up to obtain a test solution A; transferring 20.00mL of the test solution A, 1mL of the sulfuric acid solution and 5mL of the ammonium persulfate solution into a 50mL conical flask, heating to boil, and boiling for 10-15 min (until the volume of the solution is 1/2 of the initial volume). And cooling to room temperature, transferring into a 50mL volumetric flask, adding 5mL ammonium molybdate solution and 3mL ascorbic acid solution, fixing the volume with distilled water, shaking up, standing for 10min at 25-30 ℃, and measuring the absorbance at 710nm by using a 1cm absorption cell and taking a blank reagent as a reference.
In the operation process, the pretreatment process of the traditional manual method is complicated, the test result is influenced by improper operation, and the accuracy is low; the consistency of each detection operation cannot be ensured, and the detection repeatability is poor; the problems of small sample measurement amount, time consumption and the like exist, and the rapid and large-scale detection of samples cannot be realized.
Disclosure of Invention
In view of the above, the invention aims to provide a method for detecting total phosphorus in a phosphorus-containing water treatment agent based on a continuous flow analyzer, and the method provided by the invention has the advantages of high precision, low detection limit, high accuracy and the like, can realize accurate, large-amount and rapid determination of the content of the total phosphorus in the phosphorus-containing water treatment agent, and has strong general applicability in the efficient and automatic chemical industry.
The invention provides a phosphorus-containing water treatment agent total phosphorus detection method based on a continuous flow analyzer, which comprises the following steps:
a) sequentially introducing air, a potassium persulfate solution, a phosphorus-containing water treatment agent sample to be detected and a sulfuric acid solution into a continuous flow analyzer; mixing a phosphorus-containing water treatment agent sample to be detected introduced into the continuous flow analyzer with a potassium persulfate solution, carrying out ultraviolet digestion in an ultraviolet digestion device of the continuous flow analyzer after mixing, mixing a digestion product with a sulfuric acid solution introduced into the continuous flow analyzer, and flowing through a first heating reaction tank of the continuous flow analyzer after mixing to obtain an acidic digestion solution;
b) sequentially introducing air and a sodium hydroxide solution into the continuous flow analyzer; mixing the acidic digestion solution flowing out of the first heating reaction tank with a sodium hydroxide solution introduced into the continuous flow analyzer, and neutralizing residual sulfuric acid in the acidic digestion solution to obtain a neutralized digestion solution;
c) sequentially introducing a molybdenum-antimony mixed solution and an ascorbic acid solution into the continuous flow analyzer, wherein the molybdenum-antimony mixed solution contains ammonium molybdate, sulfuric acid and antimony potassium tartrate; mixing the neutralized digestion solution with a molybdenum-antimony mixed solution and an ascorbic acid solution which are introduced into the continuous flow analyzer, flowing through a second heating reaction tank of the continuous flow analyzer after mixing, and heating in the second heating reaction tank to generate an antimony-phosphate-molybdate complex solution;
d) and (3) allowing the antimony-phosphate-molybdate complex solution and the ascorbic acid solution to flow into a detection pool of the continuous flow analyzer, taking ascorbic acid as a color developing agent to perform absorbance determination, and calculating according to the measured absorbance value and a pre-established standard curve to obtain the total phosphorus content in the phosphorus-containing water treatment agent sample to be detected.
Preferably, in step a), the concentration of the potassium persulfate solution is 0.5 wt%; the liquid inlet speed of the potassium persulfate solution is 0.23 mL/min;
and the liquid inlet speed of the phosphorus-containing water treatment agent sample to be detected is 0.42 mL/min.
Preferably, in step a), the concentration of the sulfuric acid solution is 13.5 vol%; the liquid inlet speed of the sulfuric acid solution is 0.32 mL/min.
Preferably, in the step a), the operating temperature of the first heating reaction tank is 100-120 ℃.
Preferably, in the step b), the concentration of the sodium hydroxide solution is 1.3 mol/L; the liquid inlet speed of the sodium hydroxide solution is 0.32 mL/min.
Preferably, in the step c), the concentration of ammonium molybdate in the molybdenum-antimony mixed solution is 6g/L, the concentration of sulfuric acid is 3 vol%, and the concentration of antimony potassium tartrate is 0.225 g/L; the liquid inlet speed of the molybdenum-antimony mixed solution is 0.23 mL/min.
Preferably, in step c), the concentration of the ascorbic acid solution is 1.5 wt%; the feed rate of the ascorbic acid solution was 0.23 mL/min.
Preferably, in the step c), the operating temperature of the second heating reaction tank is 30-50 ℃.
Preferably, in step d), the determination of the absorbance is performed at 880 nm.
Preferably, in step d), the standard solution used for establishing the standard curve is an aqueous potassium dihydrogen phosphate solution.
Compared with the prior art, the invention provides a method for detecting total phosphorus in a phosphorus-containing water treatment agent based on a continuous flow analyzer, which comprises the following steps: a) sequentially introducing air, a potassium persulfate solution, a phosphorus-containing water treatment agent sample to be detected and a sulfuric acid solution into a continuous flow analyzer; mixing a phosphorus-containing water treatment agent sample to be detected introduced into the continuous flow analyzer with a potassium persulfate solution, carrying out ultraviolet digestion in an ultraviolet digestion device of the continuous flow analyzer after mixing, mixing a digestion product with a sulfuric acid solution introduced into the continuous flow analyzer, and flowing through a first heating reaction tank of the continuous flow analyzer after mixing to obtain an acidic digestion solution; b) sequentially introducing air and a sodium hydroxide solution into the continuous flow analyzer; mixing the acidic digestion solution flowing out of the first heating reaction tank with a sodium hydroxide solution introduced into the continuous flow analyzer, and neutralizing residual sulfuric acid in the acidic digestion solution to obtain a neutralized digestion solution; c) sequentially introducing a molybdenum-antimony mixed solution and an ascorbic acid solution into the continuous flow analyzer, wherein the molybdenum-antimony mixed solution contains ammonium molybdate, sulfuric acid and antimony potassium tartrate; mixing the neutralized digestion solution with a molybdenum-antimony mixed solution and an ascorbic acid solution which are introduced into the continuous flow analyzer, flowing through a second heating reaction tank of the continuous flow analyzer after mixing, and heating in the second heating reaction tank to generate an antimony-phosphate-molybdate complex solution; d) and (3) allowing the antimony-phosphate-molybdate complex solution and the ascorbic acid solution to flow into a detection pool of the continuous flow analyzer, taking ascorbic acid as a color developing agent to perform absorbance determination, and calculating according to the measured absorbance value and a pre-established standard curve to obtain the total phosphorus content in the phosphorus-containing water treatment agent sample to be detected. The method adopts the continuous flow analyzer to measure the total phosphorus content in the water treatment agent, has the advantages of high precision, low detection limit, high accuracy and the like, can completely digest the sample automatically by the analyzer, can realize continuous automatic analysis, can treat a large amount of samples at one time, and improves the analysis efficiency, so the method has stronger universal applicability in the high-efficiency automatic chemical industry. The experimental results show that: the out limit of the detection method provided by the invention is 0.048mg/L, the lower limit of the determination is 0.16mg/L, the precision is less than 1.3%, and the standard recovery rate is within the range of 95-105%, so that the requirement of a standard method can be met.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a flow chart of total phosphorus detection provided by an embodiment of the present invention;
FIG. 2 is a standard curve diagram of a phosphorus solution provided by an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a phosphorus-containing water treatment agent total phosphorus detection method based on a continuous flow analyzer, which comprises the following steps:
a) sequentially introducing air, a potassium persulfate solution, a phosphorus-containing water treatment agent sample to be detected and a sulfuric acid solution into a continuous flow analyzer; mixing a phosphorus-containing water treatment agent sample to be detected introduced into the continuous flow analyzer with a potassium persulfate solution, carrying out ultraviolet digestion in an ultraviolet digestion device of the continuous flow analyzer after mixing, mixing a digestion product with a sulfuric acid solution introduced into the continuous flow analyzer, and flowing through a first heating reaction tank of the continuous flow analyzer after mixing to obtain an acidic digestion solution;
b) sequentially introducing air and a sodium hydroxide solution into the continuous flow analyzer; mixing the acidic digestion solution flowing out of the first heating reaction tank with a sodium hydroxide solution introduced into the continuous flow analyzer, and neutralizing residual sulfuric acid in the acidic digestion solution to obtain a neutralized digestion solution;
c) sequentially introducing a molybdenum-antimony mixed solution and an ascorbic acid solution into the continuous flow analyzer, wherein the molybdenum-antimony mixed solution contains ammonium molybdate, sulfuric acid and antimony potassium tartrate; mixing the neutralized digestion solution with a molybdenum-antimony mixed solution and an ascorbic acid solution which are introduced into the continuous flow analyzer, flowing through a second heating reaction tank of the continuous flow analyzer after mixing, and heating in the second heating reaction tank to generate an antimony-phosphate-molybdate complex solution;
d) and (3) allowing the antimony-phosphate-molybdate complex solution and the ascorbic acid solution to flow into a detection pool of the continuous flow analyzer, taking ascorbic acid as a color developing agent to perform absorbance determination, and calculating according to the measured absorbance value and a pre-established standard curve to obtain the total phosphorus content in the phosphorus-containing water treatment agent sample to be detected.
In the detection method provided by the invention, firstly, air, potassium persulfate solution, phosphorus-containing water treatment agent sample to be detected and sulfuric acid solution are sequentially introduced into a continuous flow analyzer. Wherein the continuous flow analyzer is preferably a SAN + + model continuous flow analyzer manufactured by Skalar analytical instruments, Netherlands; the concentration of the potassium persulfate solution is preferably 0.5 wt%; the liquid inlet speed of the potassium persulfate solution is preferably 0.23 mL/min; the liquid inlet speed of the phosphorus-containing water treatment agent sample to be detected is preferably 0.42 mL/min; the concentration of the sulfuric acid solution is preferably 13.5 vol%; the feed rate of the sulfuric acid solution is preferably 0.32 mL/min. And then mixing the phosphorus-containing water treatment agent sample to be detected introduced into the continuous flow analyzer with a potassium persulfate solution, carrying out ultraviolet digestion in an ultraviolet digestion device of the continuous flow analyzer after mixing, mixing a digestion product with a sulfuric acid solution introduced into the continuous flow analyzer, and flowing through a first heating reaction tank of the continuous flow analyzer after mixing to obtain an acidic digestion solution. The ultraviolet digestion device is made of corrosion-resistant stainless steel, uses less heating medium (silicone oil), can quickly heat up and cool down, does not need stirring, is totally closed, and is free from maintenance; the operating temperature of the first heating reaction tank is preferably 100-120 ℃, and more preferably 110 ℃.
In the detection method provided by the invention, after air, potassium persulfate solution, phosphorus-containing water treatment agent sample to be detected and sulfuric acid solution are sequentially introduced, air and sodium hydroxide solution are sequentially introduced into the continuous flow analyzer. Wherein the concentration of the sodium hydroxide solution is preferably 1.3 mol/L; the liquid inlet speed of the sodium hydroxide solution is 0.32 mL/min. And then, mixing the acidic digestion solution flowing out of the first heating reaction tank with a sodium hydroxide solution introduced into the continuous flow analyzer, and neutralizing residual sulfuric acid in the acidic digestion solution to obtain a neutralized digestion solution.
In the detection method provided by the invention, after air and sodium hydroxide solution are sequentially introduced, molybdenum-antimony mixed solution (containing ammonium molybdate, sulfuric acid and antimony potassium tartrate) and ascorbic acid solution are sequentially introduced into the continuous flow analyzer. Wherein the concentration of ammonium molybdate in the molybdenum-antimony mixed solution is preferably 6g/L, the concentration of sulfuric acid is preferably 3 vol%, and the concentration of antimony potassium tartrate is preferably 0.225 g/L; the liquid inlet speed of the molybdenum-antimony mixed solution is preferably 0.23 mL/min; the concentration of the ascorbic acid solution is preferably 1.5 wt%; the feed rate of the ascorbic acid solution is preferably 0.23 mL/min. And then, mixing the neutralized digestion solution with a molybdenum-antimony mixed solution and an ascorbic acid solution which are introduced into the continuous flow analyzer, flowing through a second heating reaction tank of the continuous flow analyzer after mixing, and heating in the second heating reaction tank to generate an antimony-phosphate-molybdate complex solution. The operating temperature of the second heating reaction tank is preferably 30-50 ℃, and more preferably 40 ℃.
In the detection method provided by the invention, the antimony-phosphate-molybdate complex solution generated in the second heating reaction tank and the ascorbic acid solution flow into the detection tank of the continuous flow analyzer together, the ascorbic acid is used as a color developing agent to carry out absorbance determination, and then the total phosphorus content in the phosphorus-containing water treatment agent sample to be detected is calculated according to the measured absorbance value and a pre-established standard curve. In the present invention, the measurement of the absorbance is preferably performed at 880 nm; the standard solution used to establish the standard curve is preferably an aqueous solution of potassium dihydrogen phosphate.
The method adopts the continuous flow analyzer to measure the total phosphorus content in the water treatment agent, has the advantages of high precision, low detection limit, high accuracy and the like, can completely digest the sample automatically by the analyzer, can realize continuous automatic analysis, can treat a large amount of samples at one time, and improves the analysis efficiency, so the method has stronger universal applicability in the high-efficiency automatic chemical industry. The experimental results show that: the out limit of the detection method provided by the invention is 0.048mg/L, the lower limit of the determination is 0.16mg/L, the precision is less than 1.3%, and the standard recovery rate is within the range of 95-105%, so that the requirement of a standard method can be met.
For the sake of clarity, the following examples are given in detail.
Example 1
1) Reagent preparation
Potassium persulfate solution (0.5 wt%): 5g of potassium persulfate was dissolved in 1000mL of distilled water, sulfuric acid (guaranteed reagent, 97% strength) was added with careful stirring, the pH of the solution was adjusted to 1.1-1.2, and the solution was stored in a polyethylene bottle and refreshed weekly.
Sulfuric acid solution (13.5 vol%): 135mL of sulfuric acid was carefully added while stirring 865mL of distilled water, cooled, and then 0.5mL of sodium dodecylsulfate diphenoxy was added and mixed well, stored in a polyethylene bottle and refreshed weekly.
Sodium hydroxide solution (1.3 mol/L): dissolve 52g NaOH in 1000mL distilled water, add 1mL sodium dodecyl sulfate and mix well, store in polyethylene bottle, refresh weekly.
Molybdenum-antimony mixed solution: 0.225g of antimony potassium tartrate was weighed, dissolved in 970mL of deionized water, and then 30mL of sulfuric acid was added thereto with careful stirring and cooled. 6g of ammonium molybdate was added, mixed well, filtered, stored in polyethylene bottles, refreshed weekly, stored at 4 ℃ when not in use.
Ascorbic acid solution (1.5 wt%): weighing 11g ascorbic acid, dissolving with 940mL deionized water, adding 60mL acetone, mixing, filtering, storing in polyethylene bottle, refreshing every 3 days, and storing at 4 deg.C when not in use.
2) Total phosphorus detection operation
The total phosphorus detection is carried out according to the flow shown in figure 1, and comprises the following steps:
a) sequentially introducing air, a potassium persulfate solution, a phosphorus-containing water treatment agent sample to be detected and a sulfuric acid solution into a continuous flow analyzer; mixing the phosphorus-containing water treatment agent sample to be detected with a potassium persulfate solution, performing ultraviolet digestion in an ultraviolet digestion device of a continuous flow analyzer, mixing a digestion product with a sulfuric acid solution, and allowing the mixture to flow through a first heating reaction tank of the continuous flow analyzer to obtain an acidic digestion solution;
b) sequentially introducing air and a sodium hydroxide solution into the continuous flow analyzer; mixing the acidic digestion solution flowing out of the first heating reaction tank with the sodium hydroxide solution, and neutralizing residual sulfuric acid in the acidic digestion solution to obtain a neutralized digestion solution;
c) sequentially introducing a molybdenum-antimony mixed solution and an ascorbic acid solution into the continuous flow analyzer; the neutralized digestion solution, the molybdenum-antimony mixed solution and the ascorbic acid solution are mixed, then flow through a second heating reaction tank of the continuous flow analyzer and are heated in the second heating reaction tank to generate an antimony-phosphate-molybdate complex solution;
d) the antimony-phosphate-molybdate complex solution and the ascorbic acid solution flow into a detection pool of the continuous flow analyzer, absorbance determination is carried out at 880nm by taking ascorbic acid as a color developing agent, and the total phosphorus content in the phosphorus-containing water treatment agent sample to be detected is obtained through calculation according to the measured absorbance value and a pre-established standard curve;
e) before and after each sample detection, cleaning a sample injector of the continuous flow analyzer by using cleaning solution (deionized water);
wherein the continuous flow analyzer is a SAN + + model continuous flow analyzer manufactured by Skalar analytical instruments of the Netherlands; the flow rate of a pump pipe of the potassium persulfate is 0.23 mL/min; the flow rate of a pump pipe of the sample is 0.42 mL/min; the flow rate of a pump pipe of the sulfuric acid solution is 0.32 mL/min; the flow rate of a pump pipe of the sodium hydroxide solution is 0.32 mL/min; the flow rate of a pump pipe of the ammonium molybdate solution is 0.23 mL/min; the pump tube flow rate of the ascorbic acid is 0.23 mL/min; the flow rate of the sample injector cleaning liquid is 2 mL/min; the operating temperature of the first heating reaction tank is 110 ℃; the operating temperature of the second heating reaction tank is 40 ℃.
3) Establishing a standard curve
3.1) preparation of Standard solutions
Phosphorus standard solution 1000 mg/L: 4.394g of monopotassium phosphate (Kemi Europe, analytical purity) is weighed, and the volume is fixed to 1000mL by ultrapure water;
phosphorus standard solution 100 mg/L: weighing 10mL of 1000mg/L phosphorus standard solution, and metering the volume to 100mL by using ultrapure water;
phosphorus standard solution 1 mg/L: weighing 1mL of 100mg/L phosphorus standard solution, and metering the volume to 100mL by using ultrapure water;
phosphorus standard solution 2 mg/L: weighing 2mL of 100mg/L phosphorus standard solution, and metering the volume to 100mL by using ultrapure water;
phosphorus standard solution 3 mg/L: weighing 3mL of 100mg/L phosphorus standard solution, and using ultrapure water to fix the volume to 100 mL;
phosphorus standard solution 4 mg/L: weighing 4mL of 100mg/L phosphorus standard solution, and using ultrapure water to fix the volume to 100 mL;
phosphorus standard solution 5 mg/L: 5mL of 100mg/L phosphorus standard solution was weighed and made to 100mL with ultrapure water.
3.2) Total phosphorus detection and establishment of a Standard Curve
According to the detection method provided in step 2), absorbance detection is performed on the phosphorus standard solutions with the concentrations of 1mg/L, 2mg/L, 3mg/L, 4mg/L and 5mg/L, and standard curves are drawn by taking the phosphorus concentrations and the absorbances as horizontal and vertical coordinates respectively, and the results are shown in fig. 2, wherein fig. 2 is a standard curve chart of the phosphorus solution provided by the embodiment of the invention.
Obtaining a linear regression equation according to standard curve fitting, wherein the linear regression equation specifically comprises the following steps: y is-0.0165 +0.7236x, and the linear correlation coefficient r is 0.9998, the linear fit is good.
Example 2
Limit of detection test
According to the detection method provided in step 2) of example 1, 11 blank reagents were measured by a continuous flow analyzer, and the mean value and standard deviation of the measured values were calculated, with the total phosphorus content corresponding to 3 times the standard deviation as the detection limit and the total phosphorus content corresponding to 10 times the standard deviation as the lower measurement limit. The results are shown in Table 1:
TABLE 111 blank reagent solutions phosphorus concentration and statistics
The detection limit and the lower measurement limit were calculated from the results in table 1, detection limit: 3S ═ 0.048(mg/L phosphorus), assay lower limit: 10S-0.16 (mg/L phosphorus). It can be seen that the detection limit and the lower measurement limit meet the requirements of the standard method.
Example 3
Precision test
According to the detection method provided by the step 2) in the embodiment 1, the total phosphorus content in three different phosphorus-containing scale inhibitors of the same manufacturer is determined: taking 1mL of samples, respectively placing the samples in 1000mL volumetric flasks to be diluted to a scale, and shaking up; then 2mL, 1mL and 1mL are transferred and diluted to the scale in a 100mL volumetric flask to be used as the liquid to be tested for testing, meanwhile, a blank test is carried out, and the detection results of the samples are shown in Table 2:
TABLE 2 results of the precision test
As can be seen from Table 2, the relative standard deviation RSD of the three phosphorus-containing scale inhibitors is less than 1.2% in the precision confirmation experiment result, which indicates that the total phosphorus detection precision is good, and the measurement average value is within the reference value range, thereby meeting the requirements of the standard method.
Example 4
Standard recovery test
In order to verify the reliability of the continuous flow analysis method, the three phosphorus-containing scale inhibitors were subjected to a standard recovery experiment, and samples to be tested were measured with different concentrations of standard solutions according to the detection method provided in step 2) of example 1, with the results shown in table 3:
table 3 results of recovery normalized (n ═ 5)
As can be seen from Table 3, the recovery rates of the samples with the standard addition are all within the range of 95-105%.
Example 5
Method comparison
Three different phosphorus-containing scale inhibitors from the same manufacturer are selected, and the 3 phosphorus-containing scale inhibitors are respectively tested by the detection method provided by the step 2) in the example 1 and the detection method of the total phosphate content in the water treatment agent scale and corrosion inhibitor II according to the industrial standard HG/T2430-:
TABLE 4 comparison of the results of spectrophotometry and continuous flow analysis
As can be seen from Table 4, the comparison of the results of the two detection methods shows that the absolute difference values are less than 0.2%, the allowable difference of the measurement results in accordance with the industrial standards is met, the measurement results are basically consistent, and the continuous flow analysis method is proved to be suitable for detecting the content of total phosphorus in the scale and corrosion inhibitor.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A phosphorus-containing water treatment agent total phosphorus detection method based on a continuous flow analyzer comprises the following steps:
a) sequentially introducing air, a potassium persulfate solution, a phosphorus-containing water treatment agent sample to be detected and a sulfuric acid solution into a continuous flow analyzer; mixing a phosphorus-containing water treatment agent sample to be detected introduced into the continuous flow analyzer with a potassium persulfate solution, carrying out ultraviolet digestion in an ultraviolet digestion device of the continuous flow analyzer after mixing, mixing a digestion product with a sulfuric acid solution introduced into the continuous flow analyzer, and flowing through a first heating reaction tank of the continuous flow analyzer after mixing to obtain an acidic digestion solution;
b) sequentially introducing air and a sodium hydroxide solution into the continuous flow analyzer; mixing the acidic digestion solution flowing out of the first heating reaction tank with a sodium hydroxide solution introduced into the continuous flow analyzer, and neutralizing residual sulfuric acid in the acidic digestion solution to obtain a neutralized digestion solution;
c) sequentially introducing a molybdenum-antimony mixed solution and an ascorbic acid solution into the continuous flow analyzer, wherein the molybdenum-antimony mixed solution contains ammonium molybdate, sulfuric acid and antimony potassium tartrate; mixing the neutralized digestion solution with a molybdenum-antimony mixed solution and an ascorbic acid solution which are introduced into the continuous flow analyzer, flowing through a second heating reaction tank of the continuous flow analyzer after mixing, and heating in the second heating reaction tank to generate an antimony-phosphate-molybdate complex solution;
d) and (3) allowing the antimony-phosphate-molybdate complex solution and the ascorbic acid solution to flow into a detection pool of the continuous flow analyzer, taking ascorbic acid as a color developing agent to perform absorbance determination, and calculating according to the measured absorbance value and a pre-established standard curve to obtain the total phosphorus content in the phosphorus-containing water treatment agent sample to be detected.
2. The detection method according to claim 1, wherein in the step a), the concentration of the potassium persulfate solution is 0.5 wt%; the liquid inlet speed of the potassium persulfate solution is 0.23 mL/min;
and the liquid inlet speed of the phosphorus-containing water treatment agent sample to be detected is 0.42 mL/min.
3. The detection method according to claim 1, wherein in step a), the concentration of the sulfuric acid solution is 13.5 vol%; the liquid inlet speed of the sulfuric acid solution is 0.32 mL/min.
4. The detection method according to claim 1, wherein in the step a), the operating temperature of the first heating reaction tank is 100-120 ℃.
5. The detection method according to claim 1, wherein in step b), the concentration of the sodium hydroxide solution is 1.3 mol/L; the liquid inlet speed of the sodium hydroxide solution is 0.32 mL/min.
6. The detection method according to claim 1, wherein in step c), the concentration of ammonium molybdate in the molybdenum-antimony mixed solution is 6g/L, the concentration of sulfuric acid is 3 vol%, and the concentration of potassium antimony tartrate is 0.225 g/L; the liquid inlet speed of the molybdenum-antimony mixed solution is 0.23 mL/min.
7. The detection method according to claim 1, wherein in step c), the concentration of the ascorbic acid solution is 1.5 wt%; the feed rate of the ascorbic acid solution was 0.23 mL/min.
8. The detection method according to claim 1, wherein in the step c), the operating temperature of the second heating reaction tank is 30-50 ℃.
9. The detection method according to claim 1, wherein in step d), the measurement of the absorbance is performed at 880 nm.
10. The detection method according to claim 1, wherein in step d), the standard solution used for establishing the standard curve is an aqueous solution of potassium dihydrogen phosphate.
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