阅读说明：本技术 一种液体中重金属浓度检测方法 (Method for detecting concentration of heavy metal in liquid ) 是由 邓松强 王连香 邹丽娜 于 2019-10-09 设计创作，主要内容包括：本发明提供一种液体中重金属浓度检测方法,包括如下步骤：(a)制备螯合树脂片；(b)将所述螯合树脂片置于所述液体中,以使所述液体中重金属富集在所述螯合树脂片内；(c)通过X射线荧光光谱仪检测富集有所述重金属的所述螯合树脂片,得到测定值；(d)根据所述测定值计算所述液体中的重金属浓度。根据本发明实施例的液体中重金属浓度检测方法,利用螯合树脂片,使水体与土壤浸出液中的重金属在其中进行富集浓缩,再通过X射线荧光光谱分析,简化了水体与土壤浸出液重金属污染检测操作流程,实现了水体与土壤浸出液重金属快速定性及半定量检测分析。(The invention provides a method for detecting the concentration of heavy metal in liquid, which comprises the following steps: (a) preparing a chelating resin sheet; (b) placing the chelating resin sheet in the liquid so as to enrich heavy metals in the liquid in the chelating resin sheet; (c) detecting the chelating resin sheet enriched with the heavy metal by an X-ray fluorescence spectrometer to obtain a measured value; (d) and calculating the concentration of the heavy metal in the liquid according to the measured value. According to the method for detecting the concentration of the heavy metal in the liquid, disclosed by the embodiment of the invention, the chelating resin sheet is utilized to enrich and concentrate the heavy metal in the water body and the soil leaching solution, and then the operation process of detecting the heavy metal pollution in the water body and the soil leaching solution is simplified through X-ray fluorescence spectrum analysis, so that the rapid qualitative and semi-quantitative detection and analysis of the heavy metal in the water body and the soil leaching solution are realized.)

1. A method for detecting the concentration of heavy metal in liquid is characterized by comprising the following steps:

(a) preparing a chelating resin sheet;

(b) placing the chelating resin sheet in the liquid so as to enrich heavy metals in the liquid in the chelating resin sheet;

(c) detecting the chelating resin sheet enriched with the heavy metal by an X-ray fluorescence spectrometer to obtain a measured value;

(d) and calculating the concentration of the heavy metal in the liquid according to the measured value.

2. The method for detecting the concentration of heavy metal in liquid according to claim 1, wherein the chelating resin sheet is prepared by the following method: and (2) fully mixing the chelate resin particles with the sol to obtain a mixed solution, and then gelling and forming the sol into a sheet with the thickness of 0.2-2.0mm to obtain the chelate resin sheet.

3. The method for detecting the concentration of a heavy metal in a liquid according to claim 2, wherein the concentration of the chelating resin in the chelating resin sheet is 10 to 50 wt%.

4. The method for detecting the concentration of heavy metal in liquid according to claim 2, wherein the sol comprises 0.5-5.0 wt% of agarose solution or carrageenan solution,

the gelation and shaping of the sol into a sheet having a thickness of 0.2 to 2.0mm specifically comprises: heating the mixed solution to boiling, injecting into a mold, and cooling while pressurizing to obtain a sheet with a thickness of 0.2-2.0 mm.

5. The method for detecting the concentration of heavy metal in liquid according to claim 2, wherein the sol is a sodium alginate solution with a concentration of 0.5-2.0 wt%,

the gelation and shaping of the sol into a sheet having a thickness of 0.2 to 2.0mm specifically comprises: adding water solution of soluble calcium compound into the mixed solution, mixing, and rapidly injecting into a mold for compression molding to obtain sheet with thickness of 0.2-2.0 mm.

6. The method as claimed in claim 1, wherein the chelating resin particles are selected from one or more of Chelex-100, D418 chelating resin, Tulsion CH-90 chelating resin and CR11 chelating resin, and have a particle size of 50-150 mesh.

7. The method according to claim 1, wherein in the step (b), the chelating resin sheet is placed or suspended in the liquid, and is taken out after standing for 10-120 min.

8. The method according to claim 1, wherein the liquid comprises: water inlet of a water treatment plant, water outlet of the water treatment plant, sewage water bodies of enterprises, heavy metal polluted underground water, heavy metal polluted surface water or heavy metal polluted soil leachate.

9. The method according to claim 1, wherein the step (d) specifically comprises:

preparing a standard curve of the heavy metal standard solution;

and finding out the concentration of the heavy metal through the standard curve according to the measured value.

10. The method for detecting the concentration of the heavy metal in the liquid according to claim 9, wherein the method for obtaining the standard curve of the heavy metal standard solution specifically comprises:

preparing a series of standard solutions containing one or more of Zn, Ni, Cu, Mn, Cr, Pb and Cd heavy metals, determining the measured value of the standard solutions by adopting the steps (a) - (c), and establishing a linear relation between the measured value and the actual concentration of the heavy metals in the sample to obtain a standard curve of the heavy metal standard solution.

Technical Field

The invention relates to the technical field of environmental pollutant monitoring, in particular to a method for detecting the concentration of heavy metal in liquid.

Background

With the rapid development of economy and the acceleration of urbanization process, the problem of heavy metal pollution of water and soil in China is increasingly serious. Heavy metal pollution is not degradable and is easy to be biologically enriched, so that when reaching a certain concentration in water or soil, the heavy metal pollution can cause harm to the ecological environment and animal and plant systems, and finally, the heavy metal pollution can directly or indirectly harm human health through a food chain. Meanwhile, heavy metal pollution has the characteristic of concealment, the pollution condition and degree are difficult to observe by naked eyes, and the pollution condition can be known only through laboratory detection. Therefore, the monitoring of the heavy metals in the water body and the soil is a necessary premise and an important foundation for carrying out the work of preventing and controlling the heavy metal pollution.

Currently, the efficiency of heavy metal monitoring has become a bottleneck restricting the work of preventing and treating heavy metal pollution of water and soil. When a sewage treatment plant is impacted by heavy metal pollution load, the activity of activated sludge can be seriously inhibited, so that the removal efficiency of pollutants is reduced, the quality of effluent water does not reach the standard, and the sewage treatment process and the safety of drinking water are seriously influenced. When a heavy metal pollution event of a water body occurs, the type and the pollution degree of heavy metal are often required to be rapidly determined so as to be used for rapid emergency decision and disposal. On the other hand, in heavy metal contaminated soil remediation engineering, technologies such as solidification and stabilization are often adopted for remediation, and soil leaching toxicity detection is usually required to evaluate the remediation effect so as to determine whether the remediation effect reaches the standard. However, at present, the detection period of the heavy metals in the water body is usually 3-5 days, and the detection period of the heavy metals in the soil is usually 10-15 days, which becomes a key problem for restricting emergency response of heavy metal pollution events of the water body and evaluation work of soil remediation effect. Therefore, an efficient rapid and online detection technology for heavy metal is developed, the emergency disposal capacity of the heavy metal pollution accident of the water body can be effectively improved, and the soil pollution remediation engineering period is shortened.

The existing common heavy metal detection technology has certain defects when being applied to the rapid online detection of water and soil leachate. The traditional water body heavy metal analysis method comprises inductively coupled plasma mass spectrometry (ICP-MS), flame atomic absorption spectrometry, graphite furnace atomic absorption spectrometry and the like, has high accuracy and precision and mature technology, but needs to measure a sample in a laboratory, has the problems of complex pretreatment, low detection speed, high cost and the like, and cannot be used for field measurement. The rapid detection method of the heavy metal in the water body comprises a test paper analysis detection method, an anodic stripping voltammetry and the like, wherein the test paper analysis detection method has low cost and simple and convenient operation but has relatively high detection limit; the anodic stripping voltammetry has high sensitivity, but can only be used for directly detecting the heavy metals of clean water such as drinking water and the like, and has the defects of complicated sample pretreatment, more matched reagents and the like. Therefore, at present, there is an urgent need for those skilled in the art to develop new technology and new equipment for rapid on-line detection of heavy metals.

On the other hand, X-Ray Fluorescence spectroscopy (XRF) can simultaneously analyze a plurality of heavy metal elements, and can rapidly and efficiently detect heavy metals in solids. At present, the handheld XRF is widely applied to the field detection of heavy metals in various solids such as soil and the like, the sample does not need to be pretreated, the content of the heavy metals in the solids can be quickly detected in a short time, the accuracy of the handheld XRF is close to the laboratory result, and the handheld XRF has the advantages of small volume, light weight, convenience in carrying, high analysis speed, nondestructive analysis and the like. However, the concentration of heavy metals in water is usually very low, and a liquid sample is easy to generate a high X-ray background value, so that the detection limit of XRF for detecting heavy metals in water is high, and the sensitivity is low. Therefore, XRF cannot be directly applied to detection of heavy metals in water.

Disclosure of Invention

In view of the above, the invention provides a rapid and convenient method for detecting the concentration of heavy metals in liquids such as water and soil leachate.

In order to solve the technical problems, the invention adopts the following technical scheme:

the method for detecting the concentration of the heavy metal in the liquid comprises the following steps:

(a) preparing a chelating resin sheet;

(b) placing the chelating resin sheet in the liquid so as to enrich heavy metals in the liquid in the chelating resin sheet;

(c) detecting the chelating resin sheet enriched with the heavy metal by an X-ray fluorescence spectrometer to obtain a measured value;

(d) and calculating the concentration of the heavy metal in the liquid according to the measured value.

Preferably, the chelating resin sheet is prepared by the following method: and (2) fully mixing the chelate resin particles with the sol to obtain a mixed solution, and then gelling and molding the sol into a sheet with the thickness of 0.2-2.0mm to obtain the chelate resin sheet.

Preferably, in the chelating resin sheet, the concentration of the chelating resin is 10 to 50 wt%.

Preferably, the sol comprises an agarose solution or a carrageenan solution having a concentration of 0.5-5.0 wt%. When the concentration of the sol is too low, the chelating resin sheet is difficult to form, and when the concentration of the sol is too high, the sol is difficult to be uniformly mixed with the chelating resin particles, and the sol is easy to become brittle, so that the hardness is influenced, and the specific concentration can be properly selected according to the concentration of the chelating resin.

When an agarose solution or a carrageenan solution is used as the sol, the gelling and molding of the sol into a sheet having a thickness of 0.2 to 2.0mm specifically includes: heating the mixed solution to boiling, injecting into a mold, cooling, and simultaneously performing pressure molding to obtain a sheet with a thickness of 0.2-2.0 mm. Preferably, in order for gelation to sufficiently proceed while also considering reduction of production cycle, production cost, etc., aging is continued for 2 to 24 hours after cooling to room temperature, followed by demolding.

Preferably, the sol is a sodium alginate solution with a concentration of 0.5-2.0 wt%, when the concentration of the sol is too low, the chelating resin sheet is difficult to form, and when the concentration of the sol is too high, the sol is difficult to be uniformly mixed with the chelating resin particles, and the sol is easy to become brittle, so that the hardness is influenced, and the specific concentration can be properly selected according to the concentration of the chelating resin.

When a sodium alginate solution is used as the sol, the gelation and molding of the sol into a sheet having a thickness of 0.2 to 2.0mm specifically comprises: adding water solution of soluble calcium compound into the mixed solution, mixing, and rapidly injecting into a mold for pressure molding to obtain sheet with thickness of 0.2-2.0 mm. Preferably, in order for gelation to sufficiently proceed while also considering reduction of production cycle, production cost, and the like, the mold release is continued after aging for 2 to 24 hours after the press molding.

The pressure molding may be cold isostatic pressing, injection molding, compression molding, etc., and the pressure is not particularly limited and may be 40 to 130MPa, etc.

Wherein the water solution of soluble calcium compound can be calcium chloride water solution, calcium bicarbonate water solution, calcium gluconate water solution, etc.

The concentration of the aqueous solution of the soluble calcium compound is not particularly limited, and from the viewpoint of improving the uniformity of the produced chelating agent resin sheet, it is preferable to use an aqueous solution of the soluble calcium compound at a low concentration, for example, 1 to 5 wt%, more preferably 2.5 wt%.

Further, as long as the added aqueous solution of the soluble calcium compound can gel the sol, there is no particular limitation to the specific amount thereof, for example, the aqueous solution of the soluble calcium compound: the mixed solution is 1:2 to 10, preferably 1: 5.

Preferably, the chelating resin particles may be selected from one or more of Chelex-100, D418 chelating resin, TulsionCH-90 chelating resin, CR11 chelating resin.

Chelex-100 is a chemical chelating resin composed of styrene and divinylbenzene copolymer, contains paired iminodiacetate ions, and can chelate multivalent ions, especially high affinity and chelation to high-valence metal ions.

The D418 chelating resin is prepared by adding weak acidic aminophosphonic acid group (-CH) on the copolymer of styrene-divinylbenzene with special macroporous structure₂NHCH₂PO₃-) of chelating resins. The product can fix and chelate one or more specific cations in a wide range even from a high-concentration solution, and has high selectivity on calcium and magnesium.

Tulsion CH-90 is a macroporous selective chelate with iminodiacetic acid functionality and is very durable. Tulsion CH-90 is particularly suitable for the removal of cationic heavy metals. The macroporous resin structure ensures superiority of ion diffusion, thereby giving high-efficiency complete removability and regeneration performance. Such resins can remove metals from water having a lower pH and are a more cost effective process. The pH is adjusted to within a suitable range to remove the metals, but must be kept below 6 to prevent the formation of metal oxide and hydroxide precipitates. This resin has a higher affinity for nickel, with the following selectivity sequence: ni > Zn > Co > Mg > Ca > Na.

Mitsubishi CR11 chelate resin is a porous polystyrene matrix, CR11 uses iminodiacetic acid functional group to capture metal ions, and CR11 has very high selectivity to divalent ions, especially transition metal elements such as copper, iron, etc.

By utilizing the selectivity of the different chelating resins for different heavy metals, a plurality of the chelating resins can be mixed and used.

Further, the particle diameter of the chelate resin particles is preferably 50 to 150 mesh. When the particle size is too large, the specific surface area is reduced, which is not beneficial to the enrichment of heavy metal elements; when the particle size is too small, the cost is high on one hand, and on the other hand, the particles are not beneficial to dispersion and easy to agglomerate in the mixed solution, so that the enrichment of heavy metal elements is not beneficial.

Preferably, in the step (b), the chelating resin sheet is placed or hung in the liquid, and is taken out after standing for 10-120 min.

Preferably, the liquid comprises: water inlet of a water treatment plant, water outlet of the water treatment plant, sewage water bodies of enterprises, heavy metal polluted underground water, heavy metal polluted surface water or heavy metal polluted soil leachate.

Preferably, the step (d) specifically comprises:

preparing a standard curve of the heavy metal standard solution;

and finding out the concentration of the heavy metal through the standard curve according to the measured value.

Preferably, the method for obtaining the standard curve of the heavy metal standard solution specifically comprises the following steps:

preparing a series of standard solutions containing one or more of Zn, Ni, Cu, Mn, Cr, Pb and Cd heavy metals, determining the measured value of the standard solutions by adopting the steps (a) - (c), and establishing a linear relation between the measured value and the actual concentration of the heavy metals in the sample to obtain a standard curve of the heavy metal standard solution.

For example, taking a chelating resin sheet prepared using Chelex-100 as an example, different heavy metal concentrations were set according to the differences in the Chelex-100 sensitivity to different heavy metal accumulations, where:

zn concentration gradient is set to be 20, 40, 60 and 80 mg/L;

the Ni concentration gradient is 40, 60, 80 and 100 mg/L;

the Cu concentration gradient is 20, 40, 60, 80 and 100 mg/L;

the Mn concentration gradient is 20, 40, 60, 80 and 100 mg/L;

the Cr concentration gradient is 40, 80, 120, 160 and 200 mg/L;

the Pb concentration gradient is 40, 80, 120, 160 and 200 mg/L;

the concentration gradient of Cd is 100, 150, 200 and 250mg/L,

and (c) measuring the measured value of the standard solution by adopting the steps (a) - (c), establishing a linear relation between the measured value and the actual concentration of the heavy metal in the sample, and obtaining a standard curve of the heavy metal standard solution of the measured value of the instrument.

The technical scheme of the invention at least has one of the following beneficial effects:

according to the method for detecting the concentration of the heavy metal in the liquid, disclosed by the embodiment of the invention, the chelating resin sheet is utilized to enrich and concentrate the heavy metal in the water body and the soil leaching solution, and then the operation process of detecting the heavy metal pollution in the water body and the soil leaching solution is simplified through X-ray fluorescence spectrum analysis, so that the rapid qualitative and semi-quantitative detection and analysis of the heavy metal in the water body and the soil leaching solution are realized. In addition, the method is suitable for rapidly detecting the concentration of single or multiple heavy metals such as zinc (Zn), nickel (Ni), copper (Cu), manganese (Mn), chromium (Cr), lead (Pb), cadmium (Cd) and the like in water and soil leaching liquor. In addition, the method for detecting the concentration of the heavy metal in the liquid has the advantages of rapidness, convenience, low cost and the like.

Drawings

FIG. 1 shows the effect of different enrichment times on the results of measurements of different concentrations of heavy metals in a liquid;

FIG. 2 shows standard curves for different heavy metals;

FIG. 3 shows the correlation between the detection result of the leaching solution of the chromium-contaminated soil obtained by the detection method of the invention and the ICP detection result;

FIG. 4 shows the correlation between the detection result of the zinc-contaminated soil leachate obtained by the detection method of the present invention and the ICP detection result.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few 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 described embodiments of the invention, are within the scope of the invention.

It should be noted that the following examples and examples merely illustrate the detection of the concentration of heavy metal in liquid by using Chelex-100 chelating resin sheet for the sake of simplicity, but the chelating resin sheet prepared by using D418 chelating resin, Tulsion CH-90 chelating resin, CR11 chelating resin, and a mixture of one or more of the above resins can also be used in the method for detecting the concentration of heavy metal in liquid of the present invention, and one of them is omitted.

Effect of enrichment and concentration time in heavy metal concentration detection method

In order to study the influence of the enrichment concentration time in the heavy metal concentration detection method, the following studies were performed:

a) multiple Chelex-100 chelating resin sheets were made for use.

0.05g of Chelex-100 chelate resin (100 meshes) is fully mixed with 1.0mL of 0.5 wt% agarose, then the mixture is heated to boiling, and then the mixture is injected into a mold to be pressed and molded while being naturally cooled, wherein the pressure is 0.5MPa, the pressing time is 5min, and the cooling time is 10min, so that the Chelex-100 chelate resin sheet with the thickness of 0.2mm is obtained.

Background values for heavy metals in Chelex-100 chelate resin sheets were determined using hand-held XRF.

b) Preparing 100mg/L heavy metal mixed solution (comprising Zn, Ni, Cu, Mn, Cr, Pb and Cd), wherein the concentration of each heavy metal is 100 mg/L. Each group of 3 treatments was performed in parallel, each heavy metal mixed solution system was 1.0L,

after that, placing or hanging the Chelex-100 chelating resin sheet in a metal solution, standing for different time and taking out (setting the placing time of the Chelex-100 chelating resin sheet to be 0, 10, 20, 30 and 60 minutes);

c) after the Chelex-100 chelating resin sheet is taken out, the heavy metal content of the Chelex-100 chelating resin sheet is measured by using a handheld XRF, and the background value is deducted to be used as an instrumental measurement value.

FIG. 1 shows the effect of different enrichment times on the results of measurements of different concentrations of heavy metals in a liquid, and furthermore, Table 1 shows the relative standard deviations of the measurements of different heavy metals calculated on the basis of the results of FIG. 1 as a function of time.

As shown in fig. 1 and table 1, the measured values of different heavy metals in the solution gradually increased with the increase of the enrichment time with the increase of time, and after 20min, the standard deviation decreased to an acceptable level, and the measured values tended to be stable. Therefore, 20-60min is more suitable enrichment and concentration time, and the longer the time is, the higher the stability of the measured value is, and the more accurate and efficient the measurement can be selected according to the requirements of actual detection work. When the time is increased to 20min, the result basically tends to be stable, and the enrichment concentration time of 20min is basically enough to meet the requirement from the aspects of reducing the cost and improving the test speed.

TABLE 1 relative standard deviation of the measurements of different heavy metals as a function of time

(II) establishment of standard curves of different heavy metal standard solutions in the heavy metal concentration detection method based on the invention

a) Multiple Chelex-100 chelating resin sheets were made for use.

0.5g of Chelex-100 chelate resin (80 meshes) is fully mixed with 1.0mL of 5 wt% agarose, then the mixture is heated to boiling, and then the mixture is injected into a mold to be pressed and molded while being naturally cooled, wherein the pressure is 1MPa, the pressing time is 10min, and the cooling time is 20min, so that the Chelex-100 chelate resin sheet with the thickness of 2mm is obtained.

Background values for heavy metals in Chelex-100 chelate resin sheets were determined using hand-held XRF.

b) According to the difference of the Chelex-100 chelating resin piece in the sensitivity of different heavy metal accumulations, different heavy metal concentrations are set, a single heavy metal solution is prepared,

wherein the Zn concentration gradient is set to be 20, 40, 60 and 80 mg/L;

the Ni concentration gradient is 40, 60, 80 and 100 mg/L;

the Cu concentration gradient is 20, 40, 60, 80 and 100 mg/L;

the Mn concentration gradient is 20, 40, 60, 80 and 100 mg/L;

the Cr concentration gradient is 40, 80, 120, 160 and 200 mg/L;

the Pb concentration gradient is 40, 80, 120, 160 and 200 mg/L;

the concentration gradient of Cd is 100, 150, 200 and 250 mg/L.

Three parallel concentration gradients were set up, 1.0L for each single heavy metal solution system.

After that, the Chelex-100 chelating resin sheet is placed or hung in the heavy metal solution with different concentration gradients, and is taken out after standing for 60 min.

c) After removal, the heavy metal content of the Chelex-100 chelate resin sheet was determined using a handheld XRF, and the background value was subtracted as an instrumental measurement.

The instrumental measurement value in the Chelex-100 chelating resin sheet is taken as the abscissa, and the standard heavy metal gradient concentration is taken as the ordinate, so that a standard curve (shown in figure 2) of different heavy metals is established.

The standard curve obtained based on the fig. 2 fitting is as follows:

the standard curve of Zn is y-0.4091 x +17.971 (r-0.9865);

the standard curve of Ni is y-0.0662 x +29.296 (r-0.9529);

the standard curve for Cu is y-0.0586 x +25.935 (r-0.9855);

the standard curve of Mn is y ═ 0.0506x +12.725(r ═ 0.9618);

the standard curve of Cr is y-0.1574 x +17.234 (r-0.9866);

the standard curve for Pb is y-0.0558 x +33.913 (r-0.9844);

the standard curve for Cd is y-17.343 x +106.58 (r-0.9647).

The instrumental measurement value of the Chelex-100 chelating resin sheet has a remarkable correlation (p is less than 0.05) with the concentration of the heavy metal in the liquid, which shows that the detection method of the invention can accurately measure the concentration of the heavy metal in the liquid.

(III) determination of detection limit of method for detecting concentration of heavy metal in liquid

a) Multiple Chelex-100 chelating resin sheets were made for use.

0.1g of Chelex-100 chelate resin (150 meshes) and 1.0mL of 2.0 wt% agarose are fully mixed, heated to boiling, injected into a mold, and subjected to pressure forming while being naturally cooled, wherein the pressure is 0.8MPa, the pressing time is 15min, and the cooling time is 20min, so that the Chelex-100 chelate resin sheet with the thickness of 1mm is obtained.

Background values for heavy metals in Chelex-100 chelate resin sheets were determined using hand-held XRF.

b) The expected detection limits of different heavy metals are estimated by combining the physical properties of the Chelex-100 chelating resin sheet used in the invention, and a single heavy metal solution with corresponding concentration is prepared. Wherein the expected detection limits of Zn and Cu are 20mg/L, the expected detection limits of Ni and Mn are 40mg/L, the expected detection limits of Cr and Pb are 60mg/L, and the expected detection limit of Cd is 100 mg/L.

The detection limit of the detection method is determined by 2 times of the expected detection limit, namely single heavy metal solutions of Zn 40mg/L, Ni 80mg/L, Cu 40mg/L, Mn 80mg/L, Cr 120mg/L, Pb 120mg/L, Cd 200mg/L are respectively configured, the concentration of each heavy metal is set to be 7 in parallel, and the system of each single heavy metal solution is 1.0L.

Thereafter, the Chelex-100 chelate resin sheet was placed in a metal solution and left to stand for 30min and then taken out.

c) After removal, the heavy metal content of the Chelex-100 chelate resin sheet was determined using a handheld XRF, and the background value was subtracted as an instrumental measurement.

The detection limits of different heavy metals were calculated according to the following calculation formula (1):

detection limit of 3 × standard deviation of measured value × actual concentration value/average value of measured value (1)

The following are obtained by calculation: the detection limit of Zn is 19.1 mg/L; the detection limit of Ni is 38.6 mg/L; the detection limit of Cu is 5.60 mg/L; the detection limit of Mn is 27.3 mg/L; the detection limit of Cr is 61.2 mg/L; the detection limit of Pb is 36.2 mg/L; the detection limit of Cd was 50.9 mg/L.

It should be noted that the detection limit and the calibration curve of the chelate resin sheet of different specifications (including the size, the concentration of the chelate resin therein, the particle diameter, etc.) cannot be uniformly applied to the samples of different media. The above examples are merely to demonstrate the feasibility of the detection method of the present invention, and experiments have confirmed that the detection method of the present invention is feasible.

In actual inspection, the standard curve must be re-drawn for different sizes of chelating resin sheets. In fact, the same applies to the conventional monitoring method and the instruments commonly used in the laboratory at present, and the standard curve must be made again when the instruments are replaced, people are replaced or experiments in different batches are carried out.

(IV) detection of heavy metal concentration in multiple heavy metal mixed liquid

a) Multiple Chelex-100 chelating resin sheets were made for use.

0.2g of Chelex-100 chelate resin (50 meshes) and 1.0mL of 3.0 wt% agarose are fully mixed, heated to boiling, injected into a mold, and subjected to pressure forming while being naturally cooled, wherein the pressure is 0.6MPa, the pressing time is 10min, and the cooling time is 20min, so that the Chelex-100 chelate resin sheet with the thickness of 1.5mm is obtained.

Background values for heavy metals in Chelex-100 chelate resin sheets were determined using hand-held XRF.

b) According to different heavy metals, high, medium and low concentrations are set respectively to prepare various heavy metal mixed solutions. Wherein the high, medium and low concentrations of Zn, Ni, Cu and Mn are respectively 30, 60 and 90mg/L, the high, medium and low concentrations of Cr and Pb are respectively 40, 80 and 160mg/L, and the high, medium and low concentrations of Cd are respectively 100, 200 and 300 mg/L.

Different heavy metals and different concentrations are randomly combined, three heavy metal solutions are arranged in parallel in each combination, and the system of each heavy metal solution is 1.0L.

Thereafter, the Chelex-100 chelate resin sheet was left to stand or suspended in a metal solution for 60min and then taken out.

c) After removal, the heavy metal content of the Chelex-100 chelate resin sheet was determined using a handheld XRF, and the initial background value was subtracted as an instrumental measurement.

And converting the measured value of the instrument into the concentration of the heavy metal in the water body through a standard curve of the heavy metal standard solution, and comparing the concentration with the theoretical concentration value of the heavy metal in the water body, wherein the result is shown in table 2.

TABLE 2 verification of the multiple heavy metals Mixed solution method (mg/L)

TABLE 2 verification of the multiple heavy metals Mixed solution method (mg/L)

The results in table 2 show that the method of the present invention can determine the concentration of heavy metals accurately (table 2).

The method for detecting the concentration of heavy metal in a liquid according to the present invention will be specifically described below with reference to specific examples.

Example 1 Rapid detection of chromium concentration in leachate of chromium-contaminated soil

The method comprises the following specific steps:

a) multiple Chelex-100 chelating resin sheets were made for use.

0.3g of Chelex-100 chelate resin (100 meshes) and 1.0mL of 4.0 wt% agarose are fully mixed, heated to boiling, injected into a mold, and subjected to pressure forming while being naturally cooled, wherein the pressure is 0.6MPa, the pressing time is 10min, and the cooling time is 30min, so that the Chelex-100 chelate resin sheet with the thickness of 1.0mm is obtained.

The initial heavy metal background value in a Chelex-100 chelating resin sheet was determined using hand-held XRF.

b) Soil containing different Cr concentrations was collected as samples.

Toxic leaching is carried out on different polluted soils according to a solid waste leaching toxic leaching method, namely a sulfuric acid-nitric acid method HJ/T299-2007, three leaching solutions are arranged in parallel, and each leaching solution is 1.0L.

And placing the Chelex-100 chelating resin sheet prepared in the step into the prepared heavy metal polluted soil leachate, standing for 30min, and taking out.

c) After removal, the heavy metal content of the Chelex-100 chelated resin sheet was determined using a handheld XRF, and the background value was subtracted as the measured value.

d) And determining a standard curve through the Cr standard solution, and finding out the Cr concentration (rapid detection value) in the soil leachate according to the measured value through the standard curve.

Meanwhile, 2.0mL of original soil leachate is filtered by a 0.45-micrometer filter membrane, and the heavy metal content is directly measured by adopting ICP-OES, so that the measured value of ICP is obtained.

The rapid test values obtained by the method according to the invention described above were compared with the actual heavy metal concentration values (ICP test values), the results of which are shown in fig. 3. It can be seen from fig. 3 that there is a significant correlation between the fast detection value and the ICP measurement value. I.e., y-14.382 x +218.29, where r-0.9873. Therefore, the rapid detection method can be used for rapidly, qualitatively and semi-quantitatively detecting the heavy metals in the soil leaching solution, and further rapidly evaluating the soil solidification/stabilization effect, shortening the detection period and reducing the corresponding cost.

Example 2 Rapid detection of Zinc concentration in Zinc-contaminated soil leachate

The method comprises the following specific steps:

a) multiple Chelex-100 chelating resin sheets were made for use.

0.2g of Chelex-100 chelate resin (100 meshes) and 1.0mL of 2.0 wt% agarose are fully mixed, heated to boiling, injected into a mold, and subjected to pressure forming while being naturally cooled, wherein the pressure is 0.6MPa, the pressing time is 10min, and the cooling time is 30min, so that the Chelex-100 chelate resin sheet with the thickness of 0.5mm is obtained.

The initial heavy metal background value in a Chelex-100 chelating resin sheet was determined using hand-held XRF.

b) Collecting Zn-polluted soil with different concentrations as samples.

Toxic leaching is carried out on different polluted soils according to a solid waste leaching toxic leaching method, namely a sulfuric acid-nitric acid method HJ/T299-2007, three leaching solutions are arranged in parallel, and each leaching solution is 1.0L.

Suspending the Chelex-100 chelating resin sheet prepared in the above step in a heavy metal contaminated soil leaching solution, standing for 80min, and taking out.

c) After removal, the heavy metal content of the Chelex-100 chelated resin sheet was determined using a handheld XRF, and the background value was subtracted as the measured value.

d) And (4) determining a standard curve through the Zn standard solution, and finding out the Zn concentration in the soil leachate according to the measured value (quick detection value).

Meanwhile, 2.0mL of original soil leachate is filtered by a 0.45-micrometer filter membrane, and the heavy metal content is directly measured by adopting ICP-OES, so that the measured value of ICP is obtained.

The rapid test values obtained by the method according to the invention described above were compared with the actual heavy metal concentration values (ICP test values) and the results are shown in fig. 4. It can be seen from fig. 4 that there is a significant correlation between the fast detection value and the ICP measurement value. I.e., y-0.2831 x-6.0533, where r-0.9638. Therefore, the rapid detection method can be used for rapidly, qualitatively and semi-quantitatively detecting the heavy metals in the soil leachate, and further rapidly evaluating the soil solidification/stabilization effect, so that the corresponding cost is reduced.

Example 3 Rapid detection of lead concentration in leachate of lead-contaminated soil

The method comprises the following specific steps:

a) multiple Chelex-100 chelating resin sheets were made for use.

0.4g of Chelex-100 chelate resin (100 meshes) and 1.0mL of 3.0 wt% agarose are fully mixed, heated to boiling, injected into a mold, and subjected to pressure forming while being naturally cooled, wherein the pressure is 0.6MPa, the pressing time is 10min, and the cooling time is 30min, so that the Chelex-100 chelate resin sheet with the thickness of 1.5mm is obtained.

The initial heavy metal background value in a Chelex-100 chelating resin sheet was determined using hand-held XRF.

b) And collecting Pb-polluted soil with different concentrations as samples.

Toxic leaching is carried out on different polluted soils according to a solid waste leaching toxic leaching method, namely a sulfuric acid-nitric acid method HJ/T299-2007, three leaching solutions are arranged in parallel, and each leaching solution is 1.0L.

Suspending the Chelex-100 chelating resin sheet in the heavy metal contaminated soil leachate, standing for 20min, and taking out.

c) After removal, the heavy metal content of the Chelex-100 chelated resin sheet was determined using a handheld XRF, and the background value was subtracted as the measured value.

Meanwhile, 2.0mL of original soil leachate is filtered by a 0.45-micrometer filter membrane, and the heavy metal content is directly determined by adopting ICP-OES.

The concentration of Pb in the leachate of the Pb-polluted soil is low, and the rapid detection and the ICP determination are not detected, so that the results are consistent.

The above-described embodiments are merely preferred embodiments of the present invention, which should not be construed as limiting the invention. Various changes and modifications may be made by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present invention. Therefore, the technical solutions obtained by means of equivalent substitution or equivalent transformation all fall within the protection scope of the present invention.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.