CN114509529A - Method for measuring iron content without mercury - Google Patents
Method for measuring iron content without mercury Download PDFInfo
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- CN114509529A CN114509529A CN202210076323.3A CN202210076323A CN114509529A CN 114509529 A CN114509529 A CN 114509529A CN 202210076323 A CN202210076323 A CN 202210076323A CN 114509529 A CN114509529 A CN 114509529A
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 151
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims abstract description 50
- 229910052753 mercury Inorganic materials 0.000 title claims description 12
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 title claims description 10
- 239000000243 solution Substances 0.000 claims abstract description 109
- KMUONIBRACKNSN-UHFFFAOYSA-N potassium dichromate Chemical compound [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O KMUONIBRACKNSN-UHFFFAOYSA-N 0.000 claims abstract description 41
- 239000012086 standard solution Substances 0.000 claims abstract description 22
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Inorganic materials [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 11
- 239000000203 mixture Substances 0.000 claims abstract description 10
- 239000011780 sodium chloride Substances 0.000 claims abstract description 10
- DGXTZMPQSMIFEC-UHFFFAOYSA-M sodium;4-anilinobenzenesulfonate Chemical compound [Na+].C1=CC(S(=O)(=O)[O-])=CC=C1NC1=CC=CC=C1 DGXTZMPQSMIFEC-UHFFFAOYSA-M 0.000 claims abstract description 10
- 229910021626 Tin(II) chloride Inorganic materials 0.000 claims abstract description 9
- 239000002253 acid Substances 0.000 claims abstract description 9
- 238000010438 heat treatment Methods 0.000 claims abstract description 8
- QCJQWJKKTGJDCM-UHFFFAOYSA-N [P].[S] Chemical compound [P].[S] QCJQWJKKTGJDCM-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims abstract description 5
- IMBKASBLAKCLEM-UHFFFAOYSA-L ferrous ammonium sulfate (anhydrous) Chemical compound [NH4+].[NH4+].[Fe+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O IMBKASBLAKCLEM-UHFFFAOYSA-L 0.000 claims abstract description 5
- 239000012286 potassium permanganate Substances 0.000 claims abstract description 5
- 229940010514 ammonium ferrous sulfate Drugs 0.000 claims abstract description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N phosphoric acid Substances OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 18
- 238000004448 titration Methods 0.000 claims description 18
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 14
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 239000007788 liquid Substances 0.000 claims description 9
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 8
- 229910021607 Silver chloride Inorganic materials 0.000 claims description 7
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 claims description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 6
- 239000012362 glacial acetic acid Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 4
- 229960000583 acetic acid Drugs 0.000 claims description 4
- JSABTPDNEXHNOQ-UHFFFAOYSA-N n-phenylaniline;sodium Chemical compound [Na].C=1C=CC=CC=1NC1=CC=CC=C1 JSABTPDNEXHNOQ-UHFFFAOYSA-N 0.000 claims description 4
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 claims description 3
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 11
- 229960002523 mercuric chloride Drugs 0.000 abstract description 2
- LWJROJCJINYWOX-UHFFFAOYSA-L mercury dichloride Chemical compound Cl[Hg]Cl LWJROJCJINYWOX-UHFFFAOYSA-L 0.000 abstract description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 17
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 14
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000006722 reduction reaction Methods 0.000 description 8
- YONPGGFAJWQGJC-UHFFFAOYSA-K titanium(iii) chloride Chemical compound Cl[Ti](Cl)Cl YONPGGFAJWQGJC-UHFFFAOYSA-K 0.000 description 8
- 238000009835 boiling Methods 0.000 description 5
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 5
- PGSADBUBUOPOJS-UHFFFAOYSA-N neutral red Chemical compound Cl.C1=C(C)C(N)=CC2=NC3=CC(N(C)C)=CC=C3N=C21 PGSADBUBUOPOJS-UHFFFAOYSA-N 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- TXUICONDJPYNPY-UHFFFAOYSA-N (1,10,13-trimethyl-3-oxo-4,5,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-17-yl) heptanoate Chemical compound C1CC2CC(=O)C=C(C)C2(C)C2C1C1CCC(OC(=O)CCCCCC)C1(C)CC2 TXUICONDJPYNPY-UHFFFAOYSA-N 0.000 description 3
- 229910010062 TiCl3 Inorganic materials 0.000 description 3
- RCTYPNKXASFOBE-UHFFFAOYSA-M chloromercury Chemical compound [Hg]Cl RCTYPNKXASFOBE-UHFFFAOYSA-M 0.000 description 3
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 3
- 239000001119 stannous chloride Substances 0.000 description 3
- 235000011150 stannous chloride Nutrition 0.000 description 3
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 229910001448 ferrous ion Inorganic materials 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229940012189 methyl orange Drugs 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- UYDPQDSKEDUNKV-UHFFFAOYSA-N phosphanylidynetungsten Chemical compound [W]#P UYDPQDSKEDUNKV-UHFFFAOYSA-N 0.000 description 2
- YXANNIUJXVGEJX-UHFFFAOYSA-K potassium hydroxy-(hydroxy(dioxo)chromio)oxy-dioxochromium chloride Chemical compound [Cl-].[K+].O[Cr](=O)(=O)O[Cr](O)(=O)=O YXANNIUJXVGEJX-UHFFFAOYSA-K 0.000 description 2
- ZNNZYHKDIALBAK-UHFFFAOYSA-M potassium thiocyanate Chemical compound [K+].[S-]C#N ZNNZYHKDIALBAK-UHFFFAOYSA-M 0.000 description 2
- 229940116357 potassium thiocyanate Drugs 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 231100000331 toxic Toxicity 0.000 description 2
- 230000002588 toxic effect Effects 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910010710 LiFePO Inorganic materials 0.000 description 1
- 229910052493 LiFePO4 Inorganic materials 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 239000012445 acidic reagent Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000010425 asbestos Substances 0.000 description 1
- 238000003556 assay Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 238000004737 colorimetric analysis Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- PNDPGZBMCMUPRI-UHFFFAOYSA-N iodine Chemical compound II PNDPGZBMCMUPRI-UHFFFAOYSA-N 0.000 description 1
- -1 iron ions Chemical class 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 150000002730 mercury Chemical class 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- STZCRXQWRGQSJD-GEEYTBSJSA-M methyl orange Chemical compound [Na+].C1=CC(N(C)C)=CC=C1\N=N\C1=CC=C(S([O-])(=O)=O)C=C1 STZCRXQWRGQSJD-GEEYTBSJSA-M 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- KAQHZJVQFBJKCK-UHFFFAOYSA-L potassium pyrosulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OS([O-])(=O)=O KAQHZJVQFBJKCK-UHFFFAOYSA-L 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 229910052895 riebeckite Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 229910000367 silver sulfate Inorganic materials 0.000 description 1
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 1
- 235000019345 sodium thiosulphate Nutrition 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- AXZWODMDQAVCJE-UHFFFAOYSA-L tin(II) chloride (anhydrous) Chemical compound [Cl-].[Cl-].[Sn+2] AXZWODMDQAVCJE-UHFFFAOYSA-L 0.000 description 1
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 1
- SWGJCIMEBVHMTA-UHFFFAOYSA-K trisodium;6-oxido-4-sulfo-5-[(4-sulfonatonaphthalen-1-yl)diazenyl]naphthalene-2-sulfonate Chemical compound [Na+].[Na+].[Na+].C1=CC=C2C(N=NC3=C4C(=CC(=CC4=CC=C3O)S([O-])(=O)=O)S([O-])(=O)=O)=CC=C(S([O-])(=O)=O)C2=C1 SWGJCIMEBVHMTA-UHFFFAOYSA-K 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/16—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using titration
-
- 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
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
Abstract
A method for mercury-free determination of iron content, comprising the steps of: (1) dissolving the iron-containing sample to obtain iron-containing solution to be detected; (2) heating the iron-containing solution to be detected, and dropwise adding SnCl2The solution is dissolved until the light yellow of the solution containing iron to be detected disappears to obtain solution A; (3) cooling the solution A, and then dropwise adding a solution I2Until the solution A is light yellow, obtaining a solution B; (4) adding AgCl-NaCl mixture or Ag to the solution B2SO4Obtaining a solution C; (5) adding a sulfur-phosphorus mixed acid solution into the solution C, then adding a sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution, and recording the volume of the consumed potassium dichromate standard solution; (6) replacing the iron-containing sample in the step (1) with an ammonium ferrous sulfate standard solution which is oxidized by a potassium permanganate solution and accurately quantified, and measuring a blank value according to the steps (1) - (5); (7) the iron content of the iron-containing sample was calculated. The invention does not use mercuric chloride reagent and has simple operationAnd the accuracy is high.
Description
Technical Field
The invention relates to a method for measuring iron content, in particular to a method for measuring iron content without using a mercury-containing reagent.
Background
There are three main standard methods for determining the total iron content in iron-containing samples: EDTA photometric titration method, titanium trichloride reduction-potassium dichromate titration method and stannous chloride reduction-mercury chloride-potassium dichromate dropsAnd (4) determining. The EDTA photometric titration method for determining the iron content has large interference influence with metal ions coexisting with iron, needs to accurately control the acidity, needs to use a photometric electrode to indicate a terminal point and control a titration process through computer software, and is not easy to popularize. The titanium trichloride reagent used in the titanium trichloride reduction-potassium dichromate titration method is unstable, is easy to oxidize and deteriorate, is not easy to control the amount of the titanium trichloride in the reduction process, when the amount of the titanium trichloride is excessive, the color of the generated phosphorus tungsten blue is too dark, the blue color of the phosphorus tungsten blue is difficult to completely fade when the excessive titanium trichloride is removed by using the dilute potassium dichromate, experimental errors are easy to cause, and a large amount of white TiO is easy to generate2Precipitation, affecting the observation of the end point color, with less accuracy. Stannous chloride reduction-mercury chloride-potassium dichromate titration is the most common method for measuring the iron content, and has good accuracy and precision, however, toxic mercury chloride solution is used in pretreatment, and the waste liquid after measurement needs special recovery treatment, so that the operation is complex and the method is not environment-friendly.
In addition, a mercury-free iron measurement method of stannous chloride-titanium trichloride combined reduction or stannous chloride-methyl orange combined reduction is also a commonly used method at present, although the method avoids the use of a mercury reagent, the control of the acidity of the solution has an important influence on the reduction sequence of the methyl orange and the Fe (III), strict condition control is required, the operation is complex, and the precision and the accuracy are poor.
CN 102608112A discloses a new method for measuring iron without mercury, which uses mixed acid of hydrochloric acid, sulfuric acid and phosphoric acid to decompose a sample, uses neutral red and sodium diphenylamine sulfonate as indicators, and uses SnCl2-TiCl3-K2Cr2O7Volumetric determination of iron by phi Sn4+/Sn 2+Reduction of phi Fe with 0.16V stannous dichloride3+/Fe2+0.76V Fe ═3+When the solution is light yellow, a small amount of Fe still exists in the solution3+When the neutral red reagent is added, the neutral red reagent is added into Fe3+Blue in solution when Fe3+When the iron oxide is completely reduced, the neutral red is reduced to be colorless, and the color change of the neutral red is changed into Fe3+Is completely reduced into Fe2+Is added dropwise toφTi4+/Ti3+Titanium trichloride (0.1V) disappears in blue, and excess titanium trichloride is added at 5.000 g.L-1Oxidizing and removing the diphenylamine sodium sulfonate-potassium dichromate by a standard solution method, and finally calculating the iron grade of the sample. The method adds phosphoric acid when decomposing the sample, reduces the concentration of hydrochloric acid and theoretically reduces phi Fe3+/Fe2+Stannous dichloride may be more easily overdosed during pretreatment where the TiCl is3The oxygen in the air more readily oxidizes the reduced ferrous ions, TiCl, before further processing and titration3Is not easy to store in use, needs to be prepared for use, and has TiCl3Excessive problem, and subsequent oxidation with potassium dichromate is not only required to remove excessive TiCl3The procedure is complicated, and when TiCl is used3When the excessive amount is too large, a large amount of precipitate is generated by hydrolysis, and the accuracy of the result is seriously affected.
The invention discloses CN 104678050A, and relates to a method for determining ferric iron content in lithium iron phosphate by an iodometry method. The method dissolves LiFePO in hydrochloric acid medium4In this case, a substance capable of generating a gas which does not react with the divalent/trivalent iron ions is added, and the generated gas drives oxygen to thereby obtain LiFePO4Oxidation-reduction reaction does not occur in the sample dissolving process and the cooling process after complete dissolution; then, measuring the content of ferric iron in the lithium iron phosphate by an iodometry method, namely, under the acidic condition, the ferric iron reacts with I-Quantitative oxidation to I2And then titrated with sodium thiosulfate to determine the content of the trivalent iron. The method has the disadvantages that the method can only measure the content of the ferric iron in a sample with a single composition, can not accurately measure the content of the constant component total iron in a complex sample, and simultaneously Cu2+Can seriously affect the accuracy of the assay.
CN 102590202a discloses a method for measuring iron, comprising the following steps: preparing a plurality of Fe with different concentrations3+A standard solution; to the plurality of Fe respectively3+Adding a first nitric acid solution and a first potassium thiocyanate solution into the standard solution to perform a color reaction; preparing a solution of a to-be-detected product from a lithium iron phosphate sample; adding a second nitric acid solution into the solution of the sample to be detectedPerforming color development reaction on the second potassium thiocyanate solution; the solution of the sample to be detected after the color reaction and the plurality of Fe after the color reaction are subjected to the color reaction3+And carrying out color comparison on the standard solution, and obtaining the iron content in the solution to be detected according to a color comparison result. The method is used for measuring the content of ferric iron in a solution to be measured by a semi-quantitative colorimetric method, the measuring principle does not belong to a potassium dichromate titration method with good selectivity and high accuracy, and the content of a major component, namely total iron, cannot be accurately measured.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects in the prior art and provide the method for measuring the iron content without using a mercury-containing reagent, and the method is simple to operate and high in precision and accuracy.
The invention solves the technical problem by adopting the technical scheme that the method for measuring the content of the iron without mercury comprises the following steps:
(1) dissolving the iron-containing sample to obtain iron-containing solution to be detected;
(2) heating the iron-containing liquid to be detected obtained in the step (1), and dropwise adding SnCl in a near-boiling state2The solution is dissolved until the light yellow of the liquid containing iron to be detected disappears to obtain solution A;
(3) cooling the solution A obtained in the step (2) to room temperature, and dropwise adding the solution A containing I2Until the solution A is light yellow, obtaining a solution B;
(4) adding AgCl-NaCl mixture or Ag into the solution B obtained in the step (3)2SO4Fully shaking the solution to obtain a solution C;
(5) adding a sulfur-phosphorus mixed acid solution into the solution C obtained in the step (4), then adding a sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution, and recording the volume of the consumed potassium dichromate standard solution;
(6) and (3) mixing an ammonium ferrous sulfate solution and a potassium permanganate solution to replace the iron-containing sample in the step (1), then carrying out titration according to the steps (1) to (5), recording the volume of the consumed potassium dichromate standard solution, and calculating to obtain the iron content in the iron-containing sample.
Further, in the step (2), the SnCl2The concentration of the solution is 80-110 g/L, preferably 100g/L。
Further, in the step (2), the heating is carried out until the temperature is 85-100 ℃, and then SnCl is dripped under the temperature of 85-100 ℃ (near boiling state)2And (3) solution.
Further, in the step (3), the compound contains I2In a solution of2Glacial acetic acid, I2-ethanol solution, I2KI solution and I2-one or more of acetone solutions.
Further, in the step (3), the I2The concentration of glacial acetic acid is 0.01-0.1 mol.L-1(ii) a Said I2-ethanol solution, I2KI solution and I2The concentration of the acetone solution is 0.01-0.10 mol.L-1。
Further, in the step (4), the mass content of AgCl in the AgCl-NaCl mixture is 5-50%.
Further, in the step (4), the addition amount of the AgCl-NaCl mixture is 0.01-0.30 g.
Further, in the step (5), the sulfur-phosphorus mixed acid solution is a mixed acid formed by mixing sulfuric acid, phosphoric acid and water, and the volume ratio of the sulfuric acid to the phosphoric acid to the water is (10-30): (40-80), preferably 15:15: 70.
Further, in the step (5), the addition amount of the mixed sulfuric-phosphoric acid solution is 10-20 mL, preferably 13-17 mL, and more preferably 15 mL.
Further, in the step (5), the mass concentration of the sodium diphenylamine sulfonate indicator is 0.1-0.3%, and preferably 0.2%.
Further, in the step (5), the amount of the sodium diphenylamine sulfonate indicator is 2-6 drops.
Further, in the step (5), the concentration of the potassium dichromate standard solution is 0.008-0.020 mol.L-1Preferably 0.01667mol · L-1。
Further, in the step (6), the amount of the ferrous ammonium sulfate solution is 1.00mL, and the concentration is 0.1000 mol/L; the amount of the potassium permanganate solution is 1mL, and the concentration is 0.02 mol/L.
Because the iron-containing sample usually contains Fe3+And Fe2+Ions, therefore, the reducing agent must be used first to determine the total ironAll Fe is mixed3+Pre-reduction to Fe2+Then use K2Cr2O7The standard solution was titrated. SnCl is commonly used in the prior art2Reduction of Fe3+Then using HgCl2Solution oxidation to remove excess SnCl2Finally by using K in an acidic medium2Cr2O7Solution titration of generated Fe2+Ionic, but HgCl used in the process2The solution is extremely toxic and requires very strict protective measures, otherwise it can cause harm to human body and environment. The invention uses a compound containing I2Replacing HgCl with the solution of (1)2Solution with AgCl or Ag2SO4Masking generated I-And the pollution of mercury salt to the environment is avoided.
The principle of the invention is as follows: firstly, the decomposition of the iron-containing sample is carried out according to the decomposition method in GBT6730.70-2013 by adopting different methods according to the properties of the sample: dissolving a sample with vanadium content of less than or equal to 0.05 wt%, molybdenum content of less than or equal to 00.1 wt% or copper content of less than or equal to 00.1 wt% in hydrochloric acid, filtering residues, burning, treating with hydrofluoric acid and sulfuric acid, removing silicon dioxide, melting with potassium pyrosulfate, dissolving a melt in hydrochloric acid, adding ammonia water to precipitate iron, adding hydrochloric acid to dissolve the precipitate again, and merging the solution into a main liquid to obtain a liquid to be detected and containing iron; or, melting the sample with vanadium content more than 0.05 wt% with alkali, leaching the melt with water, filtering, discarding the filtrate, and acidifying with hydrochloric acid to obtain iron-containing solution to be detected; then, SnCl is used for the obtained iron-containing solution to be detected2Mixing Fe3+Reduction of the ion to disappearance of the yellow colour and subsequent use of I2By oxidation of excess SnCl2Until the solution appeared stable light yellow, and the generated I was masked by adding AgCl-The corresponding reaction formula is as follows:
Sn2++I2＝2I-+Sn4+
I-+AgCl＝AgI+Cl-
finally, sodium diphenylamine sulfonate is usedIndicator, with K2Cr2O7The standard solution titrates ferrous ions, and the titration reaction formula is as follows:
6Fe2++Cr2O7 2-+14H+＝6Fe3++2Cr3++7H2O
the titration jump range is 0.93-1.34V; since the condition potential of the diphenylamine sodium sulfonate is 0.85V, which is lower than the jump range of titration, when the diphenylamine sodium sulfonate is used as an indicator, a sulfur-phosphorus mixed acid reagent (containing H) is added3PO4) Fe produced by titration3+Conversion to colourless Fe (HPO)4)2 -Complex ions, thus reducing free Fe on the one hand3+Concentration of ions, lowering Fe3+/Fe2+The condition potential of the electric pair expands the jump range to 0.71-1.34V, the indicator can change color in the range, the titration end point error is reduced, and the reaction is more complete; on the other hand, FeCl capable of eliminating yellow generated in the titration process4 -Interference with endpoint observation.
Compared with the prior art, the invention has the following beneficial effects: (1) the method does not need a mercuric chloride reagent in the determination process, and is safe and environment-friendly; (2) with SnCl2–TiCl3Compared with the combined reduction method, the invention is easy to control the dropwise adding SnCl during pretreatment2Amount of solution, further appropriate excess of I2The judgment of the titration end point is not influenced, and the precision and the accuracy are high; (3) the reagent used in the invention has more stable property and simpler and more convenient operation.
Detailed Description
The present invention will be further described with reference to the following specific examples.
Sulfuric acid, phosphoric acid, hydrochloric acid, stannous chloride, iodine, glacial acetic acid, NaCl and sodium diphenylamine sulfonate used in the embodiment of the invention are obtained through conventional commercial approaches, and AgCl is a silver chloride solid obtained by recovering waste liquid from a chlorine content test by a Mohr method.
Example 1
The method for measuring the content of iron without mercury comprises the following steps:
(1) weighing a proper amount of sample (the sample weighed in the three parallel experiments is slightly different in mass, and the specific mass is shown in table 1) in a conical flask, adding 10mL of concentrated HCl, placing a short-necked small funnel on the mouth of the conical flask, heating and dissolving the short-necked small funnel in a boiling water bath, washing the small funnel and the inner wall of the flask by using a small amount of water after complete dissolution, and controlling the water consumption during washing to be 10mL to obtain a liquid to be tested containing iron;
(2) heating the iron-containing solution to be detected obtained in the step (1) to 90 ℃, and dripping 100 g.L into the solution under the near-boiling state (heating the solution on an asbestos gauze electric furnace in a boiling water bath)-1SnCl2The solution is stirred for 30 seconds until the light yellow of the liquid to be detected containing iron disappears and 2 drops of the solution are excessive, and the solution is cooled to room temperature under running water to obtain solution A;
(3) cooling the solution A obtained in the step (2) to room temperature, and dropwise adding 0.05 mol.L-1I2-glacial acetic acid until solution a is in a stable pale yellow colour to obtain solution B;
(4) adding 0.1g of AgCl-NaCl mixture (wherein the mass content of AgCl is 20%) into the solution B obtained in the step (3), and fully shaking up to obtain a solution C;
(5) adding 80mL of water and 15mL of sulfur-phosphorus mixed acid (the volume ratio of sulfuric acid to phosphoric acid to water is 15:15:70) into the solution C obtained in the step (4), then adding 6 drops of 0.2% sodium diphenylamine sulfonate indicator, and then adding 0.01667 mol.L-1Titrating the potassium dichromate standard solution, and consuming the potassium dichromate standard solution V when the solution color is changed from green to blue-green and then mutated to purple red, namely the end point1.
(6) Determination of blank value
Taking 1.00mL of 0.1000mol/L ammonium ferrous sulfate solution and 1mL of 0.02mol/L potassium permanganate solution to replace the step (1) of weighing a proper amount of sample, and performing the rest steps and the used reagents and dosage according to the steps (1) - (5), wherein the volume of the potassium dichromate standard solution consumed in the step (5) is V0To obtain a blank value V2(V2＝V0-1.00)；
(7) Calculating the mass fraction of iron in the detected sample according to the following formula, wherein the specific data of the steps (1) to (6) are shown in table 1:
in the formula:
concentration of standard solution of potassium dichromate, mol. L-1
V1Volume of sample consumed Potassium dichromate Standard solution, mL
V2Blank value, mL
m-mass of iron ore sample, g
MFeMolar mass of iron element, g.mol-1
6-coefficient ratio of potassium dichromate to iron
Table 1 test data and results of the method for determining the iron content in example 1
Example 2
The procedure for measuring the iron content without mercury in this example was the same as in example 1, except that 2mL of 0.1mol/L Ag reagent containing silver was used2SO4Solution (0.1 g AgCl-NaCl mixture for example 1). The method for calculating the mass fraction of iron in the test sample in this example is also the same as in example 1. Specific test data and results are shown in table 2.
Table 2 test data and results of the method for determining iron content in example 2
Claims (10)
1. A method for measuring the content of iron without mercury is characterized by comprising the following steps:
(1) dissolving the iron-containing sample to obtain iron-containing solution to be detected;
(2) heating the iron-containing solution to be detected obtained in the step (1), and dropwise adding SnCl2The solution is dissolved until the light yellow of the liquid containing iron to be detected disappears to obtain solution A;
(3) cooling the solution A obtained in the step (2) to room temperature, and then dropwise adding the solution A containing I2Until the solution A is light yellow, obtaining a solution B;
(4) adding AgCl-NaCl mixture or Ag into the solution B obtained in the step (3)2SO4 Shaking the solution evenly to obtain a solution C;
(5) adding a sulfur-phosphorus mixed acid solution into the solution C obtained in the step (4), then adding a sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution, and recording the volume of the consumed potassium dichromate standard solution;
(6) and (3) mixing an ammonium ferrous sulfate solution and a potassium permanganate solution to replace the iron-containing sample in the step (1), then carrying out titration according to the steps (1) to (5), recording the volume of the consumed potassium dichromate standard solution, and calculating the iron content in the iron-containing sample.
2. The method for mercury-free determination of iron content according to claim 1, wherein in step (2), the SnCl is2The concentration of the solution is 80-110 g/L.
3. The method for measuring the content of iron in the mercury-free manner according to claim 1 or 2, wherein in the step (2), the heating is carried out until the temperature is 85-100 ℃, and then SnCl is dropwise added at the temperature of 85-100 DEG C2And (3) solution.
4. The method for mercury-free determination of iron content according to any one of claims 1 to 3, wherein in step (3), the content of I is determined2In a solution of I2Glacial acetic acid, I2-ethanol solution, I2KI solution and I2-one or more of acetone solutions.
5. The method for mercury-free determination of iron content according to claim 4, wherein I is2The concentration of glacial acetic acid is 0.01-0.1 mol.L-1(ii) a Said I2-ethanol solution, I2KI solution and I2The concentration of the acetone solution is 0.01-0.10 mol.L-1。
6. The method for measuring the content of iron in the mercury-free manner according to any one of claims 1 to 5, wherein in the step (4), the mass content of AgCl in the AgCl-NaCl mixture is 5 to 50%.
7. The method for measuring the content of iron in the mercury-free manner according to any one of claims 1 to 6, wherein in the step (4), the AgCl-NaCl mixture is added in an amount of 0.01 to 0.30 g.
8. The mercury-free method for measuring iron content according to any one of claims 1 to 7, wherein in the step (5), the mixed sulfuric-phosphoric acid solution is a mixed acid formed by mixing sulfuric acid, phosphoric acid and water, and the volume ratio of the mixed sulfuric-phosphoric acid solution to the mixed acid is 10-30: 40-80; the addition amount of the mixed sulfuric-phosphoric acid solution is 10-20 mL.
9. The method for measuring the content of iron in the mercury-free manner according to any one of claims 1 to 8, wherein in the step (5), the mass concentration of the sodium diphenylamine sulfonate indicator is 0.10-0.30%; the adding amount of the diphenylamine sodium sulfonate indicator is 2-6 drops.
10. The method for mercury-free determination of iron content according to any one of claims 1 to 9, wherein in the step (5), the concentration of the potassium dichromate standard solution is 0.008 to 0.020 mol-L-1。
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| 张冶: "铁矿石中全铁量(有汞法)测定条件的研究", 《中国高新技术企业》 * |
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