CN105628770A - Low concentration soluble metal thallium on-line detection apparatus and method - Google Patents

Abstract

The present invention discloses a low concentration soluble metal thallium on-line detection apparatus and method, wherein the apparatus comprises an electrolysis cup, a blender, an electrochemical workstation, a microcomputer PC and an electrode group, the method is based on an anodic voltammetric stripping method for establishment of the online heavy metal thallium online apparatus, the method has high sensitivity and low detection limit, does not require large amounts of organic solvents, has no secondary pollution to operating personnel and environment, and can achieve rapid online detection. The on-line detection apparatus can be widely used in water source detection, drinking water security assurance and other fields.

Description

A kind of device and method of on-line checking low concentration deliquescent metal thallium

Technical field

The present invention relates to the detection method of thallium, particularly relate to the device and method of a kind of on-line checking low concentration deliquescent metal thallium.

Background technology

1) thallium fundamental property, distribution:

Thallium (T1) is the rare heavy metal element of a kind of high degree of dispersion, and thallium is in blueness to silvery white, and property is soft and has ductility, very unstable in atmosphere, water insoluble is soluble in acid. Thallium has isotope (203T129.5%, 205T170.5%) two kinds stable and 26 kinds of induced radioisotopes. Thallium is widely used in the fields such as high-energy physics, superconductor, medical and health, space flight, electronics, communication, military project and chemical industry catalysis material.

Thallium is distributed widely in the water body of nature, and content is generally relatively low, and regional differences is bigger. In the snow water of the arctic, content is only 0.3��0.9pg/L; Content respectively 0.006��0.715/��g/L and 0.001��0.036/��g/L in river, lake water; Subsoil water is 0.001��1.264/��g/L; The surface water of Britain's sulfide mixing mining area tailings is 110/��g/L; T1 is 1��80/��g/L in the river flowing through certain river, mining area of Canada; Shen Tuo ore deposit, Nanhua pit water is 2.9��13.0/��g/L; Xingren County, Guizhou Province Lan Mu factory's hydrargyrum thallium ore deposit pit water is 26.6��26.9/��g/L; Up to 13��1966g/Lc in Southwest Guizhou groundwater in mining area, surface water is 1.9��8.1/��g/L; Yunfu, guangdong Province sulfuric acid plant dust waste water is 15.4��400/��g/L.

Thallium is also a typical murder by poisoning element, its toxicity far super Hg, Cd, Cu, Pb etc.; T1 has extremely strong accumulative, can cause continued damage. Tl is one of main hazard refuse in WHO emphasis restricted list, is listed in the pollutant list of priority acccess control by China. China is the country that thallium resource is enriched very much, substantial amounts of thallium is by mining, metal smelt, commercial production, geothermal exploitation and the approach entered environments such as closely bound up electronic product of living with people, accumulation in the environment has greatly trend seriously out of control, threatens descendants. Therefore the research of the environmental assessment of thallium pollution, monitoring is seemed particularly urgent. In recent years, about the event common reporter of thallium poisoning, but WHO and most countries also do not formulate the safety criterion of Tl in water head site and drinking water so far. Only U.S. Environmental Protection Agency (EPA) (1993) has formulated the safe threshold of Tl in drinking water is 0.002mg/L, and safety value at a specified future date is 0.0005mg/L. The safe threshold of this standard harmful element more many than other is more strict, is 0.05mg/L if As be 0.05mg/L, Cd is 0.005mg/L, Pb. In Russia's drinking water, the safety criterion of Tl is more strict at present, is only 0.0001mg/L. China has started to the concern to Tl toxic, and the Ministry of Construction set up Tl standard in urban water supply water quality in 2006, is also 0.0001mg/L.

2) anode volt-ampere leaching brief introduction

Anodic stripping voltammetry is that a kind of sensitivity is significantly high, electrochemical methods for trace components. If replacing the dropping-mercury electrode in general polarography, the equally possible polarogram obtaining being applicable to quantitative assay with hanging mercury electrode. In a of Fig. 1, mercury electrode is negative electrode, and what electrode rose is reduction reaction:

Cd²⁺+2e+Hg����Cd(Hg)

If the current potential of hanging mercury electrode is fixed on E ' place (about-1 volt), Cd²⁺Just it is reduced on electrode and generates amalgam. After electrolysis a period of time, the Cd in hydrargyrum has reached finite concentration, then the dividing potential drop of 883 type polarographs is taken turns the position pulling " moving back ", allows the current potential of hanging mercury electrode move to the direction of zero potential from-1 volt, just obtain the oxidation wave of Cd in the b of Fig. 1. At this moment electrode reaction is:

Cd(Hg)����Cd²⁺+2e+Hg

Cadmium metal is " dissolution " from electrode, is again oxidized to Cd2+, returns in solution. Owing in process in leaching, the mercury electrode such as hanging mercury electrode is anode, again because the polarizing electrode used not is dropping-mercury electrode but the surface hanging mercury electrode, mercury film electrode or the vitreous carbon mercury electrode that no longer update, therefore claim anodic stripping voltammetry.

Preelectrolysis: this is first step operation, by determined metal ion under certain current potential (being equivalent to produce on the cathodic wave of this ion the current potential of carrying current), partly it is reduced to metal, this metal or be dissolved in mercury electrode, or precipitate out at electrode surface. In order to accelerate electrolytic process, solution to be stirred. Preelectrolysis is an enrichment process, and the time of preelectrolysis is longer, and the time of dissolution is shorter, then sensitivity is higher, the sensitivity of existing polarography can be improved 2��4 orders of magnitude. If the time of preelectrolysis is ��, preelectrolysis electric current is I, and dissolution time is t, and the peak current of dissolution is ip, then:

�� I=tip

If �� > > t, then ip > > I. Carry out anodic stripping on Singe-sweep polarography instrument and pulse polarograph, then the time of dissolution is very short, and sensitivity is significantly high, and the concentration that Differential Pulse Polarography anodic stripping voltammetry can measure can be low to 10-12mol/L. The peak current of anodic stripping voltammetry is partly decided by preelectrolysis, is partly decided by dissolving-out technology. For hanging mercury electrode, if the preelectrolysis time is not long, the volume of sample solution is sufficiently large again, then preelectrolysis electric current actually remains unchanged, if the metal molar number precipitated out on electrode is ��, then:

$M=\frac{\mathrm{I\τ}}{\mathrm{nF}}$

In formula, n is the electron transfer number of electrode reaction; F is Faraday constant. If V is the volume of hanging mercury electrode,(r0 is the radius hanging hydrargyrum), then in hanging mercury electrode, metal concentration in hydrargyrum is:

$C_{\mathrm{Hg}}=\frac{M}{V}=\frac{3}{4}\frac{\mathrm{I\τ}}{{\mathrm{\πr}}_0^3\mathrm{nF}}$

For stirring the hanging mercury electrode in solution, preelectrolysis electric current is:

$I=4\mathrm{\π}{r}_0\mathrm{nFDC}+{\mathrm{knr}}_0^2{D}^{2/3}\mathrm{Cf}$

In formula, C is by measured ion concentration in sample solution; D is the diffusion coefficient of ion; F is mixing speed; K is experiment value.

Anodic stripping is that the current potential making microelectrode in some way is moved by the direction that negative sense is positive, makes the metal in electrode again aoxidize and produces the process of oxidation current. If carrying out anodic stripping on Singe-sweep polarography instrument, then the dissolution peak current obtained on hanging mercury electrode is:

$i_p={\mathrm{kn}}^{3/2}{\mathrm{AD}}_{\mathrm{Hg}}^{1/2}{C}_{\mathrm{Hg}}{v}^{1/2}$

In formula, A is electrode area; DHg is metal diffusion coefficient in hydrargyrum; The speed that when v is dissolution, electrode potential changes.

By above formula it can be seen that the dissolution peak current finally obtained not only is decided by the concentration of tested metal, the speed that when being also dependent upon the time of preelectrolysis, mixing speed, the radius hanging hydrargyrum and dissolution, electrode potential changes. Therefore, for the favorable reproducibility of experimental result, it is necessary to strict Control release condition.

The advantage of hanging mercury electrode is favorable reproducibility, and shortcoming is: 1. electrode area is little with the ratio of volume, makes sensitivity low, dissolution peak width; 2. in order to prevent hydrargyrum from dripping, mixing speed wants slow; 3. need to provide hydrargyrum to drip with dropping-mercury electrode.

Having the advantages of of mercury film electrode (platinum ball is silver-plated being stained with hydrargyrum): 1. area is big with the ratio of volume, and highly sensitive, dissolution peak is narrow; 2. the speed of rotation electrode or agitating solution is fast; 3. easy to use. The shortcoming of mercury film electrode has: 1. poor reproducibility; 2. needing other metals and make substrate, the supervoltage of Qi Zhongyin, nickel, platinum etc. is low, and is slightly soluble in hydrargyrum, substrate metal and be likely between lining metal generate intermetallic compound, make dissolution peak poor reproducibility.

Vitreous carbon mercury electrode, with vitreous carbon for substrate, overcomes the shortcoming that mercury film electrode can form intermetallic compound.

Shown in Fig. 2, the unit of available anode and Cathodic Stripping Voltammetry have about 40 kinds.

In water by Spectrophotometry body, Tl is a kind of widely used method, and owing to the sensitivity of method itself is relatively low, general many employing organic solvents carry out pretreatment, and wherein the research of color development system is particularly important. Current developer is mainly basic stain class developer, azo dye developer, ketone stain and amine stain etc., and is maximum with above two kinds of application.

Basic stain developer system mainly includes crystal violet, iodide one ethyl violet one arabic gum system, viride nitens, malachite green oxalate, rhodamine, and potassium iodide one basic triphenylmethane dyes system etc. Azo dye color development system mainly includes the amine colour reagents such as the azo dyes such as 1 one (4 one antipyrinylazo)-2-amino naphthalenes, 2,3 one dicarboxyl 1 semi-annular jade pendant base phenvlazo diphenyl diimides, Biozobenzenediazoamiwithobene withobene sulfonic acid, 2,6 one dichloro 1 amino-sulfonic group phenyldiazonium aminoazabenzols, quinolyl or thiazolyl, o Hydroxybenzenediazoaminoazobenzene n, 1 one (2 one pyridylazo)-2 one naphthols and 1-(2-[4-morpholinodithio azo) one 2 one naphthols, and chlorpromazine hydrochloride. The �� of this type of method is all more than the 1O4 order of magnitude. Cao little An etc. have studied in the chromogenic reaction that have studied cadion 2B and thallium (III), establishes the determination of trace new method with polyaminoresin foam plastic adherence Tl (III). The mensuration of useless underwater trace Tl is easier, and the Tl determination step in sample ore is cumbersome; Li Jinwen etc. utilize in Aug. 1st hydroxyquinoline water by Spectrophotometry sample and point out after the content of Tl, and heavy metal ion has certain interference to measuring.

Prior art has the drawback that: the ambient condition of spectrophotometry Tl requires stricter, sensitivity is relatively low, need a large amount of organic reagents to extract when trace semimicrodetermination, thus have impact on the response rate, and the application of a large amount of organic solvent can endanger operator and environment, be not suitable for on-line instrument and use.

Summary of the invention

In view of this, it is an object of the invention to provide the device and method of a kind of on-line checking low concentration deliquescent metal thallium, to solve deficiency of the prior art.

In order to achieve the above object, it is an object of the invention to be achieved through the following technical solutions:

The device of a kind of on-line checking low concentration deliquescent metal thallium is provided, wherein, including electrolysis cup, agitator, electrochemical workstation, microcomputer PC and electrode group, described electrode group includes working electrode, reference electrode and auxiliary electrode, described agitator is placed on described electrolysis cup, described working electrode, described reference electrode and described auxiliary electrode are inserted in described electrolysis cup, described electrochemical workstation is connected with described working electrode, described reference electrode and described auxiliary electrode respectively by standard cable, and described electrochemical workstation is connected with described microcomputer PC.

The device of above-mentioned on-line checking low concentration deliquescent metal thallium, wherein, described working electrode is hanging mercury electrode, and described reference electrode is the Ag/AgCl electrode of saturated potassium chloride, and described auxiliary electrode is platinum filament.

On the other hand, it is provided that a kind of method of on-line checking low concentration deliquescent metal thallium realized based on device described above, it is characterised in that comprise the following steps:

Taking 1mL testing sample and be placed in electrolysis cup, concentration is designated as C_Sample, add 1mL electrolyte, 7mL screening agent A, 1mL screening agent B, turn on agitator, mixing speed is 2000r min, opens electrochemical workstation, is enriched with 3min under-0.80V current potential, stand 10s, with the scanning speed of 2.44mV/s, anodic stripping between-0.80��-0.20V;

The dissolution peak of thallium is around-0.5V, and the data of electrochemical workstation collection are transferred to microcomputer PC and carry out later data process, obtains treating to be designated as h by the dissolution peak height of test sample_Sample, the dissolution peak height of a concentration known standard specimen is measured by same process, dissolution peak is designated as h_{Standard specimen}, concentration is designated as C_{Standard specimen}, then the concentration of unknown sample can be calculated by following equation:

Wherein, screening agent A is: 0.35mol/LEATA and 0.015%PEG20000; Electrolyte is: 1.50mol/LKCl and 0.50mol/LNaAc and 0.25mol/LHAc; Screening agent B is: dissolves 4g ascorbic acid in water, is dissolved to 100mL.

Compared with the prior art, the beneficial effects of the present invention is:

The present invention sets up the online equipment of online heavy metal thallium based on anode volt-ampere leaching, method has highly sensitive, detection limit is low, do not need a large amount of organic solvents, operator and environment do not had secondary pollution, being capable of quick online detection, online detection instrument can be widely used in the fields such as water source detection, drinking water safety guarantee.

Accompanying drawing explanation

The accompanying drawing constituting the part of the present invention is used for providing a further understanding of the present invention, and the schematic description and description of the present invention is used for explaining the present invention, is not intended that inappropriate limitation of the present invention. In the accompanying drawings:

Fig. 1 illustrates Cd in prior art²⁺The oxidation wave (b) of the reduction wave (a) in end liquefied ammonia and Cd (Hg);

Fig. 2 illustrates the element of available anode and Cathodic Stripping Voltammetry in prior art;

Fig. 3 illustrates the schematic diagram of the device of on-line checking low concentration deliquescent metal thallium of the present invention;

The sample that Fig. 4 illustrates in the method for on-line checking low concentration deliquescent metal thallium of the present invention goes out peak figure.

Detailed description of the invention

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is only a part of embodiment of the present invention, rather than whole embodiments. Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under not making creative work premise, broadly fall into the scope of protection of the invention.

It should be noted that when not conflicting, the embodiment in the present invention and the feature in embodiment can be mutually combined.

With reference to Fig. 3, the device of on-line checking low concentration deliquescent metal thallium of the present invention, wherein, including electrolysis cup 1, agitator 2, electrochemical workstation 3, microcomputer PC4 and electrode group, electrode group includes working electrode 5, reference electrode 6 and auxiliary electrode 7, agitator 2 is placed on electrolysis cup 1, working electrode 5, reference electrode 6 and auxiliary electrode 7 are inserted in electrolysis cup 1, electrochemical workstation 3 is connected with working electrode 5, reference electrode 6 and auxiliary electrode 7 respectively by standard cable, and electrochemical workstation 3 is connected with microcomputer PC4.

In presently most preferred embodiment of the invention, working electrode 5 is hanging mercury electrode (glass-carbon electrode), and reference electrode 6 is the Ag/AgCl electrode of saturated potassium chloride, and auxiliary electrode 7 is platinum filament.

The method of the on-line checking low concentration deliquescent metal thallium that the present invention realizes based on device described above, comprises the following steps:

Taking 1mL testing sample to be placed in electrolysis cup 1, concentration is designated as C_Sample, add 1mL electrolyte, 7mL screening agent A, 1mL screening agent B, turn on agitator 2, mixing speed is 2000r min, opens electrochemical workstation 3, is enriched with 3min under-0.80V current potential, stand 10s, with the scanning speed of 2.44mV/s, anodic stripping between-0.80��-0.20V;

The dissolution peak of thallium is around-0.5V, and the data of electrochemical workstation collection are transferred to microcomputer PC4 and carry out later data process, obtains treating to be designated as h by the dissolution peak height of test sample_Sample, the dissolution peak height of a concentration known standard specimen is measured by same process, dissolution peak is designated as h_{Standard specimen}, concentration is designated as C_{Standard specimen}, then the concentration of unknown sample can be calculated by following equation:

Wherein, screening agent A is: 0.35mol/LEATA and 0.015%PEG20000; Electrolyte is: 1.50mol/LKCl and 0.50mol/LNaAc and 0.25mol/LHAc; Screening agent B is: dissolves 4g ascorbic acid in water, is dissolved to 100mL.

Now with the solution example of the thallium solution that this measuring apparatus concentration known is 0.1500ppb, participating in measuring using the thallium standard solution of 0.1000ppb as standard specimen, process is method introduction such as. Measurement obtains initial data about 500 (see following table) altogether;

Table: raw data acquisition table

With reference to shown in Fig. 4, through the calculating of microcomputer PC4, obtain sample and go out peak figure, and obtain peak height h sample=61.93. The peak height obtaining standard specimen with procedure is h standard=39.96, is calculated by above-mentioned formula A and obtains C sample=0.1550ppb, and measurement deviation is+3.33%.

The inventive method has highly sensitive, and detection limit is low, it is not necessary to a large amount of organic solvents, operator and environment is not had secondary pollution, it is possible to realize quick online detection, and this online detection instrument can be widely used in the fields such as water source detection, drinking water safety guarantee.

Above specific embodiments of the invention being described in detail, but the present invention is not restricted to particular embodiments described above, it is intended only as example. To those skilled in the art, any equivalent modifications and replacement are also all among scope of the invention. Therefore, equalization done without departing from the spirit and scope of the invention converts and amendment, all should contain within the scope of the invention.

Claims (3)

1. the device of an on-line checking low concentration deliquescent metal thallium, it is characterized in that, including electrolysis cup (1), agitator (2), electrochemical workstation (3), microcomputer PC (4) and electrode group, described electrode group includes working electrode (5), reference electrode (6) and auxiliary electrode (7), described agitator (2) is placed on described electrolysis cup (1), by described working electrode (5), described reference electrode (6) and described auxiliary electrode (7) insert in described electrolysis cup (1), described electrochemical workstation (3) by standard cable respectively with described working electrode (5), described reference electrode (6) is connected with described auxiliary electrode (7), described electrochemical workstation (3) is connected with described microcomputer PC (4).

2. the device of on-line checking low concentration deliquescent metal thallium according to claim 1, it is characterized in that, described working electrode (5) is hanging mercury electrode, the Ag/AgCl electrode that described reference electrode (6) is saturated potassium chloride, described auxiliary electrode (7) is platinum filament.

3. the method for the on-line checking low concentration deliquescent metal thallium realized based on device as claimed in claim 2, it is characterised in that comprise the following steps:

Taking 1mL testing sample and be placed in electrolysis cup, concentration is designated as C_Sample, add 1mL electrolyte, 7mL screening agent A, 1mL screening agent B, turn on agitator, mixing speed is 2000r min, opens electrochemical workstation, is enriched with 3min under-0.80V current potential, stand 10s, with the scanning speed of 2.44mV/s, anodic stripping between-0.80��-0.20V;

The dissolution peak of thallium is around-0.5V, and the data of electrochemical workstation collection are transferred to microcomputer PC and carry out later data process, obtains treating to be designated as h by the dissolution peak height of test sample_Sample, the dissolution peak height of a concentration known standard specimen is measured by same process, dissolution peak is designated as h_{Standard specimen}, concentration is designated as C_{Standard specimen}, then the concentration of unknown sample can be calculated by following equation:

Wherein, screening agent A is: 0.35mol/LEATA and 0.015%PEG20000; Electrolyte is: 1.50mol/LKCl and 0.50mol/LNaAc and 0.25mol/LHAc; Screening agent B is: dissolves 4g ascorbic acid in water, is dissolved to 100mL.