CN109142618B

CN109142618B - Method for rapidly determining trivalent arsenic in acidic arsenic-containing liquid

Info

Publication number: CN109142618B
Application number: CN201811052324.4A
Authority: CN
Inventors: 朱国荣; 代君; 魏海彬; 王勇; 江洋; 邓力能; 江红卫
Original assignee: Jiangxi Copper Corp
Current assignee: Jiangxi Copper Corp
Priority date: 2018-09-10
Filing date: 2018-09-10
Publication date: 2021-07-16
Anticipated expiration: 2038-09-10
Also published as: CN109142618A

Abstract

The invention relates to a method related to the detection of trivalent arsenic in acid arsenic-containing liquid generated in the process of producing arsenic trioxide by a wet method, in particular to a method for rapidly determining trivalent arsenic in the acid arsenic-containing liquid, which comprises the steps of sampling, sample measurement, calculation and the like, wherein the used medicaments mainly comprise sodium hydroxide standard solution, iodine solution, saturated sodium thiosulfate solution, methyl red solution and other medicaments; the iodine solution oxidizes trivalent arsenic into arsenic acid; the methyl red is used as an indicator; and (3) titrating hydrogen ions of the first-order ionization of arsenic acid by the sodium hydroxide standard solution to calculate the content of trivalent arsenic. The method can stably and reliably measure the content of trivalent arsenic in the acidic arsenic-containing liquid, and has the characteristics of rapidness, economy and the like.

Description

Method for rapidly determining trivalent arsenic in acidic arsenic-containing liquid

Technical Field

The invention relates to a method for detecting trivalent arsenic in acid arsenic-containing liquid generated in the process of producing arsenic trioxide by a wet method, in particular to a method for rapidly determining trivalent arsenic in the acid arsenic-containing liquid.

Background

At present, the determination of the content of trivalent arsenic in acidic arsenic-containing liquid generated in the process of producing arsenic trioxide by the existing wet method has guiding significance on the redox effect in the production process, because the production continuity needs to know the result immediately, a large-scale instrument has low analysis speed, the process is complicated, and no guiding significance exists, so that a detection method which can be used on site and is simple and easy to learn in operation is needed.

Disclosure of Invention

The invention aims to provide a method for rapidly measuring trivalent arsenic in acid arsenic-containing liquid, which can be rapidly and stably implemented and provides reliable data.

The technical scheme of the invention is as follows: a method for rapidly measuring trivalent arsenic in acidic arsenic-containing liquid specifically comprises the following steps:

measuring the volume of the solution to be measured by using a pipette, firstly titrating total acid by using NaOH standard solution A, and then I₂Oxidizing trivalent arsenic in solution into arsenic acid by using methyl red and phenolphthalein as referencesAnd (4) using NaOH standard solution B to titrate the total arsenic content of the trivalent arsenic.

Further, the method comprises the following specific steps:

step 1: transferring 2-5 ml of solution to be detected into a 500ml triangular beaker by using a pipette, adding 50ml of pure water, and titrating total acid by using NaOH standard solution A for later use;

step 2: dripping NaOH standard solution B into the solution after titrating the total acid, and then adding I₂Shaking the solution while adding, keeping the dropping speed consistent with the dropping speed of the sodium hydroxide standard solution until the solution is red, dropping the solution with NaOH standard solution B until the solution is red, slowly fading, continuously adding the I2 solution, and if the solution is red, dropping the solution with NaOH standard solution B until the solution is I added₂After the solution is not obviously red, continuously adding excessive I₂Liquid of formula I₂After the natural color, adding a certain amount of saturated sodium thiosulfate solution, using methyl red as an indicator, using NaOH standard solution B to drip to a bright yellow end point, and recording the volume V of the consumed NaOH standard solution B₁I.e. the amount of trivalent arsenic;

and step 3: the content of trivalent arsenic and total arsenic is determined according to the following formula:

，

in the formula: c is the concentration, mol/L and V of NaOH standard solution B₁The volume of NaOH standard solution B consumed for titration of trivalent arsenic, ml, V the amount of the sample removed, ml, 74.92g/mol is the atomic weight of As.

Further, the concentration of the NaOH standard solution B is 0.05-1 mol/L.

Further, the concentration of the NaOH standard solution A in the step 1 is 0.1-0.5 mol/L.

Further, the amount of the saturated sodium thiosulfate solution added in the step 2 is 10 ml.

The invention has the beneficial effects that: by adopting the technical scheme, the method can stably and reliably measure the contents of trivalent arsenic and total arsenic in the acidic arsenic-containing liquid, and has the characteristics of simple operation, quick detection and the like.

Detailed Description

The technical solution of the present invention is further described with reference to the following specific embodiments.

The invention relates to a method for rapidly measuring trivalent arsenic in an acidic arsenic-containing liquid, which comprises the following steps:

measuring the volume of the solution to be measured by using a pipette, firstly titrating total acid by using NaOH standard solution A, and then I₂Oxidizing trivalent arsenic in the solution into arsenic acid, and titrating the content of the trivalent arsenic by using NaOH standard solution B by using methyl red as an indicator.

Further, a pipette is used to transfer 2-5 ml of the solution to be detected into a 500ml triangular beaker, 50ml of pure water is added, and NaOH standard solution A is used to titrate the total acid. Adding NaOH standard solution B (added according to the content of As3+ (As appropriate) in advance) dropwise into the solution after titration of total acid, and adding I₂Shaking the solution while adding until the solution is red, dripping NaOH standard solution B until the red color is removed, and continuously adding I₂The solution, if red, is dropped with NaOH standard solution B until I is added₂No obvious red color is generated after the solution is added, and the excessive I is continuously added₂Liquid to solution is I₂Adding 10ml of saturated sodium thiosulfate solution into the solution, dropwise adding 2 drops of methyl red, continuously dropwise adding NaOH standard solution B until the solution is bright yellow, and recording the total amount of the consumed NaOH standard solution B;

，

The concentration of the NaOH standard solution B is 0.05-1 mol/L.

The concentration of the NaOH standard solution A in the step 1 is 0.1-0.5 mol/L.

The addition amount of the saturated sodium thiosulfate solution in the step 2 is 10 ml.

Example one:

and (4) taking the production liquid of the oxidation tank, and measuring the content of trivalent arsenic in the oxidation tank. Since the oxidation tank oxidizes all trivalent arsenic into pentavalent arsenic, and the content of trivalent arsenic is low, a small amount of trivalent arsenic is added when sodium hydroxide standard solution is added in advance.

Step 1: 2 ml of the production solution of the oxidation tank is taken and put into a 500ml triangular beaker, 50ml of pure water is added, and 0.2mol/l NaOH standard solution is used for titrating the total acid;

step 2: adding 0.05mol/l NaOH standard solution into the solution after the total acid is titrated in advance until the solution is yellow-green (the addition amount is about 3-5 ml), and then using I₂Continuously oxidizing until the solution is not red and is I₂10ml of saturated sodium thiosulfate and 2 drops of methyl red are added, and the solution is continuously dropped by 0.05mol/l of NaOH standard solution until the solution is bright yellow, and then 15ml of 0.05mol/l of NaOH standard solution is consumed.

And step 3: as iii (g/L) =0.05 × 74.92 × 15/2 × 3=9.37 g/L

Example two:

taking the production liquid of the reduction tank, and measuring the content of trivalent arsenic in the reduction tank. Since the reduction tank is used for reducing all pentavalent arsenic into trivalent arsenic, the trivalent arsenic content is high, so when the sodium hydroxide standard solution is added in advance, the adding amount is more than that of the oxidation tank.

Step 1: 2 ml of reduction tank production liquid is taken and put into a 500ml triangular beaker, 50ml of pure water is added, and 0.2mol/l NaOH standard solution is used for titrating total acid;

step 2: adding 0.05mol/l NaOH standard solution into the solution after the total acid is titrated in advance until the solution is yellow-green (the addition amount is about 8-10 ml), and then using I₂Continuously oxidizing until the solution is not red and is I₂10ml of saturated sodium thiosulfate and 2 drops of methyl red are added, and the solution is continuously dropped by 0.05mol/l of NaOH standard solution until the solution is bright yellow, and then 36ml of 0.05mol/l of NaOH standard solution is consumed.

And step 3: as iii (g/L) =0.05 × 74.92 × 36/2 × 3=22.48 g/L.

While the best mode for carrying out the invention has been described in detail, it is to be understood that the invention is merely illustrative of the presently preferred embodiments and that no limitation of the scope of the invention is thereby intended. All equivalent changes and modifications made within the scope of the present invention should be covered by the claims of the present invention.

Claims

1. A method for rapidly measuring trivalent arsenic in acidic arsenic-containing liquid specifically comprises the following steps:

using methyl orange as indicator, firstly titrating sulfuric acid in production liquid by using sodium hydroxide standard solution A to obtain total acid amount, and adding I into the solution after titrating the total acid₂By means of I₂Oxidizing arsenous acid into arsenic acid, using methyl red as an indicator, titrating hydrogen ions of arsenic acid first-order ionization by using a sodium hydroxide standard solution B, and calculating the content of trivalent arsenic, wherein the method comprises the following specific steps:

step 1: transferring a certain amount of solution to be measured into a 500ml triangular beaker by using a pipette, adding 50ml of pure water, and titrating total acid by using NaOH standard solution A for later use;

step 2: dripping NaOH standard solution B into the solution after titrating the total acid, and then adding I₂Shaking the solution while adding until the solution is red, dripping NaOH standard solution B until the solution is red, slowly removing, and continuously adding I₂The solution, if red, is dropped with NaOH standard solution B until I is added₂After the solution is not obviously red, continuously adding excessive I₂Liquid of formula I₂After the natural color, adding saturated sodium thiosulfate solution, using methyl red as an indicator, then titrating with NaOH standard solution B to a bright yellow color as an end point, and recording the total volume V of the NaOH standard solution B used during titration₁I.e. the amount of trivalent arsenic;

and step 3: the content of trivalent arsenic is determined according to the following formula:

，

in the formula: c is the concentration, mol/L and V of NaOH standard solution B₁In the titration, the total volume of the NaOH-removed standard solution B is calculated, ml and V are the amount of the solution to be measured, ml and 74.92 are the atomic weight of As, g/mol, and As III is the content of trivalent arsenic.

2. The method of claim 1, wherein the concentration of the NaOH standard solution B is 0.05-1 mol/L.

3. The method of claim 1, wherein the concentration of the NaOH standard solution A in the step 1 is 0.1-0.5 mol/L.

4. The method of claim 1, wherein the saturated sodium thiosulfate solution is added in an amount of 10ml in the step 2.