Method for removing divalent inorganic mercury

Abstract

The present invention belongs to the field of the treatment of mercury and provides a method for removing divalent inorganic mercury. In the present invention, under the condition of a pH value of 3-10, a mercapto reagent, sulfur powder, and a matrix having divalent inorganic mercury to be removed are mixed and undergo a reaction, wherein the mercapto reagent comprises one or more of 2-mercaptoethanol, L-cysteine, and glutathione. The elemental sulfur powder is used for generating divalent sulfur ions, and the divalent sulfur ions are bonded to divalent mercury ions to generate a mercury sulfide precipitate, so that the treatment of divalent-mercury-ion-related mercury pollution is realized. Directly using the elemental sulfur powder to treat divalent-mercury-ion-related mercury pollution has the problem of a low divalent sulfur ion generation efficiency. In order to improve the generation efficiency of divalent sulfur ions from the elemental sulfur powder in an aqueous solution, according to the present invention, by using a mercapto compound as a reducing agent, the mercapto compound and the elemental sulfur powder undergo a redox reaction at a suitable pH (3-10) to generate divalent sulfur ions, which react with the divalent mercury ions to form a mercury sulfide precipitate, thereby achieving the treatment of the divalent-mercury-ion-related mercury pollution.

Description

A method for removing divalent inorganic mercury

[0001] This application claims priority to a Chinese patent application filed with the Patent Office of China on November 3, 2023, with application number CN202311451182.X and invention name “A Method for Removing Divalent Inorganic Mercury”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to the technical field of mercury treatment, and in particular to a method for removing divalent inorganic mercury. Background Art

[0003] Mercury adsorption has caused widespread mercury pollution problems, such as mercury contamination in the production equipment of traditional pharmaceutical mercury-containing preparations and pipeline contamination caused by high mercury content samples in mercury content analysis. Existing technologies usually use high concentrations of hydrochloric acid and nitric acid to remove adsorbed mercury. For example, Mu Yi et al. disclosed a hydrochloric acid adsorption method for mercury removal (Mu Yi et al. Experimental study on the removal of mercury from mercury-containing byproducts by hydrochloric acid adsorption, Polyvinyl Chloride, 2015, 43(10):2.), and Xie Hongying disclosed a method for treating mercury in turbid water using an HNO3-HCl system digestion method (Xie Hongying. Treatment of mercury in turbid water using an HNO3-HCl system digestion method, North China Journal of Geology and Mineral Resources, 1996, 11(2):2.). However, high concentrations of hydrochloric acid and nitric acid both have problems with corrosiveness, safety, and reagent control.

[0004] The principle of mercury waste liquid treatment is mainly to use soluble sulfides to convert soluble mercury into extremely insoluble mercury sulfide. Soluble sulfides are strongly alkaline and will generate soluble polysulfides with divalent mercury ions, which cannot achieve efficient treatment of mercury waste liquid.

[0005] Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a method for removing divalent inorganic mercury. The present invention utilizes a thiol reagent and sulfur powder to achieve efficient removal of divalent inorganic mercury under mild pH conditions.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for removing divalent inorganic mercury, comprising the following steps:

[0009] Under the condition of pH value of 3-10, a sulfhydryl reagent, sulfur powder and a substrate to be removed from divalent inorganic mercury are mixed to react, wherein the sulfhydryl reagent comprises one or more of 2-mercaptoethanol, L-cysteine ​​and glutathione.

[0010] Preferably, the pH value is 6-10.

[0011] Preferably, the sulfhydryl group in the sulfhydryl reagent is incompatible with Hg in the matrix to be removed from the divalent inorganic mercury. 2+ The molar ratio is 2.5 to 3:1.

[0012] Preferably, the particle size of the sulfur powder is 3 to 300 μm.

[0013] Preferably, the particle size of the sulfur powder is 5 to 150 μm.

[0014] Preferably, the sulfur powder and the Hg in the matrix to be removed from the divalent inorganic mercury 2+ The molar ratio is 40-300:1.

[0015] Preferably, when the particle size of the sulfur powder is 3 to 5 μm, the sulfur powder and the Hg in the matrix to be removed from the divalent inorganic mercury 2+ The molar ratio is 80-120:1.

[0016] Preferably, when the particle size of the sulfur powder is 150 to 300 μm, the sulfur powder and the Hg in the matrix to be removed from the divalent inorganic mercury are separated. 2+ The molar ratio is 240-300:1.

[0017] Preferably, said pH value is achieved by adding a buffer salt.

[0018] Preferably, the substrate to be removed of divalent inorganic mercury is an aqueous solution containing divalent inorganic mercury or divalent inorganic mercury exists on the surface of the material.

[0019] Preferably, when the substrate to be removed of divalent inorganic mercury is an aqueous solution containing divalent inorganic mercury, the removal method comprises the following steps:

[0020] The thiol reagent and sulfur powder are added to the aqueous solution containing divalent inorganic mercury, and then the solution is allowed to stand to allow the generated mercuric sulfide to precipitate, and the obtained product is separated into solid and liquid.

[0021] Preferably, when the matrix to be removed of divalent inorganic mercury is a material on which divalent inorganic mercury exists, the removal method comprises the following steps:

[0022] mixing the buffered saline solution with the sulfhydryl reagent to obtain a sulfhydryl reagent solution;

[0023] The surface of the material is cleaned with the mercapto reagent solution, and then sulfur powder is added and allowed to stand to allow the generated mercuric sulfide to precipitate, and the obtained product is separated into solid and liquid.

[0024] Preferably, when the matrix to be removed of divalent inorganic mercury is a material on which divalent inorganic mercury exists, the removal method comprises the following steps:

[0025] mixing a buffered saline solution, a thiol reagent and sulfur powder to obtain a suspension containing sulfur powder and the thiol compound;

[0026] The surface of the material is cleaned with the suspension of the sulfur-containing powder and the mercapto compound, and then the material is allowed to stand to allow the generated mercuric sulfide to precipitate, and the obtained product is separated into solid and liquid.

[0027] The present invention also provides a method for removing inorganic mercury from an organic mercury sample, comprising the following steps: mixing a sulfhydryl reagent, sulfur powder, and a matrix of divalent inorganic mercury to be removed for reaction at a pH value of 3 to 10, wherein the sulfhydryl reagent comprises one or more of 2-mercaptoethanol, L-cysteine, and glutathione.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The principle of the present invention is as follows: elemental sulfur powder is used to generate divalent sulfide ions, which are combined with divalent mercury ions to generate mercuric sulfide precipitates, thereby achieving the treatment of mercury pollution associated with divalent mercury ions. Directly using elemental sulfur powder to treat mercury pollution associated with divalent mercury ions has the problem of low divalent sulfide ion generation efficiency. In order to improve the divalent sulfide ion generation efficiency of elemental sulfur powder in aqueous solution, the present invention uses a sulfhydryl compound as a reducing agent under suitable pH conditions (3 to 10), generates divalent sulfide ions through the redox reaction of the sulfhydryl compound and elemental sulfur powder, and then generates mercuric sulfide precipitates with divalent mercury ions, thereby achieving the treatment of mercury pollution associated with divalent mercury ions.

[0030] The sulfhydryl group of the sulfhydryl compound of the present invention has a high binding affinity with divalent mercuric ions, and compared with other reducing agents, such as ascorbic acid, it can avoid reducing divalent mercuric ions in the aqueous solution to elemental mercury.

[0031] The thiol group of the thiol compound in the present invention has a high binding affinity with divalent mercury ions and can be used to remove divalent inorganic mercury adsorbed on the surface of materials, so that the present invention can be used for both aqueous solutions and for treating mercury pollution related to divalent inorganic mercury on the surface of materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a histogram of mercury concentration in Example 1;

[0033] Figure 2 is a physical diagram of each group in Example 1;

[0034] FIG3 is a histogram of mercury concentration in Example 2;

[0035] FIG4 is a bar graph of soluble mercury concentration in Example 3;

[0036] FIG5 is a histogram of mercury concentration in Example 4;

[0037] FIG6 is a bar graph showing mercury concentration using 3-5 μm sulfur powder in Example 5;

[0038] FIG7 is a bar graph showing mercury concentration using 150 μm sulfur powder in Example 5;

[0039] FIG8 is a histogram of mercury concentration in Example 6;

[0040] Figure 9 shows the Hg content of 8 different particles in Example 7. 2+ Cleared physical map. DETAILED DESCRIPTION

[0041] The present invention provides a method for removing divalent inorganic mercury, comprising the following steps:

[0042] Under the condition of pH value of 3-10, a sulfhydryl reagent, sulfur powder and a substrate to be removed from divalent inorganic mercury are mixed to react, wherein the sulfhydryl reagent comprises one or more of 2-mercaptoethanol, L-cysteine ​​and glutathione.

[0043] In the present invention, the pH value is preferably 6 to 8. In a specific embodiment of the present invention, the pH value may be 3, 4, 5, 6, 7, 8, 9 or 10.

[0044] In the present invention, the pH value is preferably achieved by adding a buffer salt, and the buffer salt preferably includes a phosphate buffer salt, and the pH value of the phosphate buffer salt is preferably 6-10.

[0045] The present invention preferably further uses pH measuring supplies, more preferably pH test paper, to avoid mercury contamination of the pH measuring equipment.

[0046] In the present invention, the thiol group in the thiol reagent reacts with Hg in the matrix to be removed divalent inorganic mercury. 2+ The molar ratio is preferably 2.5 to 3:1. The present invention uses a thiol compound as a reducing agent, generates divalent sulfide ions through an oxidation-reduction reaction between the thiol compound and elemental sulfur powder, and then generates mercuric sulfide precipitates with divalent mercuric ions to treat mercury pollution associated with divalent mercury ions. Furthermore, the thiol group of the thiol compound has a high degree of binding with divalent mercuric ions. Compared with other reducing agents, it can avoid reducing divalent mercury ions in the aqueous solution to elemental mercury. It can also be used to remove divalent inorganic mercury adsorbed on the surface of materials.

[0047] In the present invention, the particle size of the sulfur powder is preferably 3 to 300 μm, more preferably 5 to 150 μm.

[0048] In the present invention, the sulfur powder and the Hg in the matrix to be removed from the divalent inorganic mercury 2+ The molar ratio is preferably 40 to 300:1. The present invention utilizes elemental sulfur powder to generate divalent sulfide ions, which are then combined with divalent mercury ions to generate mercury sulfide precipitation, thereby achieving the treatment of mercury pollution related to divalent inorganic mercury.

[0049] In the present invention, when the particle size of the sulfur powder is preferably 3 to 5 μm, the sulfur powder and the Hg in the matrix to be removed from the divalent inorganic mercury are separated.2+ The molar ratio of the sulfur powder is preferably 80 to 120:1; when the particle size of the sulfur powder is preferably 150 to 300 μm, the sulfur powder and the Hg in the matrix to be removed from the divalent inorganic mercury 2+ The molar ratio of is preferably 240 to 300:1.

[0050] Taking L-cysteine ​​as an example, the principle of the present invention is described:

[0051] L-cysteine ​​reduces sulfur powder to S 2- The reaction conditions are mild and the reaction is rapid. 2- With Hg 2+ It has high binding capacity and forms insoluble HgS. This reaction can be used to achieve Hg 2+ The harmless treatment, L-cysteine ​​reduces sulfur powder to S 2- The reaction equation is shown in Formula I:

[0052] In the present invention, the substrate to be removed of divalent inorganic mercury is preferably an aqueous solution containing divalent inorganic mercury or divalent inorganic mercury existing on the surface of the material.

[0053] In the present invention, the aqueous solution containing divalent inorganic mercury is preferably an aqueous solution of mercuric chloride.

[0054] In the present invention, when the substrate to be removed of divalent inorganic mercury is preferably an aqueous solution containing divalent inorganic mercury, the removal method comprises the following steps:

[0055] The thiol reagent and sulfur powder are added to the aqueous solution containing divalent inorganic mercury, and then the solution is allowed to stand to allow the generated mercuric sulfide to precipitate, and the obtained product is separated into solid and liquid.

[0056] In a specific embodiment of the present invention, the following steps are included: a first step, dissolving the buffer salt in the aqueous solution containing divalent inorganic mercury and mixing the solution; a second step, measuring the pH value of the resulting solution. When the pH value is preferably in the range of 6 to 8, the next step can be performed; a third step, adding 2.5 to 3 times the molar amount of a thiol compound and 40 to 120 times the molar amount of elemental sulfur powder based on the molar content of total mercury in the resulting solution and mixing the solution; a fourth step, allowing the generated mercuric sulfide to precipitate until the mercury content in the solution is less than 10 μg / L, and separating the solution from the precipitate; and a fifth step, the precipitate contains mercuric sulfide and excess elemental sulfur powder and can be directly buried.

[0057] In the present invention, the mixing speed in the third step is preferably 30 rpm, the mixing time is preferably 10 min, and the mixing is preferably performed at room temperature.

[0058] In the present invention, the mixing in the first and third steps is preferably performed in a long-axis mixer.

[0059] In the present invention, the standing time is preferably 12 hours, and the temperature is preferably room temperature.

[0060] In the present invention, when the substrate to be removed of divalent inorganic mercury is preferably a material on which divalent inorganic mercury exists on the surface, the removal method comprises the following steps:

[0061] mixing the buffered saline solution with the sulfhydryl reagent to obtain a sulfhydryl reagent solution;

[0062] The surface of the material is cleaned with the mercapto reagent solution, and then sulfur powder is added and allowed to stand to allow the generated mercuric sulfide to precipitate, and the obtained product is separated into solid and liquid.

[0063] In a specific embodiment of the present invention, the following steps are included: a first step of dissolving the buffer salt in water to prepare a buffer solution; a second step of using the buffer solution to prepare the thiol reagent solution; a third step of using the thiol reagent solution to clean the surface of the material to be treated; a fourth step of adding elemental sulfur powder, and then allowing the generated mercuric sulfide to precipitate until the mercury content in the solution is less than 10 μg / L, and separating the solution from the precipitate; and a fifth step of the precipitate containing mercuric sulfide and excess elemental sulfur powder, which can be directly buried for treatment.

[0064] In the present invention, when the substrate to be removed of divalent inorganic mercury is preferably a material on which divalent inorganic mercury exists on the surface, the removal method comprises the following steps:

[0065] mixing a buffered saline solution, a thiol reagent and sulfur powder to obtain a suspension containing sulfur powder and the thiol compound;

[0066] The surface of the material is cleaned with the suspension of the sulfur-containing powder and the mercapto compound, and then the material is allowed to stand to allow the generated mercuric sulfide to precipitate, and the obtained product is separated into solid and liquid.

[0067] In a specific embodiment of the present invention, the following steps are included: a first step of dissolving the buffer salt in water to prepare a buffer solution; a second step of using the buffer solution to prepare a suspension of the sulfur-containing powder and the thiol compound; a third step of using the suspension of the sulfur-containing powder and the thiol compound to clean the surface of the material to be treated, and then allowing the generated mercuric sulfide to precipitate until the mercury content in the solution is less than 10 μg / L, and separating the solution from the precipitate; and a fourth step of the precipitate containing mercuric sulfide and excess elemental sulfur powder, which can be directly buried for treatment.

[0068] In the present invention, the use of the suspension of the sulfur-containing powder and the mercapto compound can improve the removal efficiency.

[0069] In order to further illustrate the present invention, the method for removing divalent inorganic mercury provided by the present invention is described in detail below with reference to examples, but they should not be construed as limiting the scope of protection of the present invention.

[0070] Example 1: L-cysteine, mercaptoethanol and ascorbic acid were used in combination with sulfur powder to remove Hg 2+ Effect of mercury conversion to mercury sulfide

[0071] Implementation effect:

[0072] Mercaptoethanol and L-cysteine ​​can both be used in combination with sulfur powder to generate black mercuric sulfide precipitate from mercuric chloride in PBS solution. Ascorbic acid can reduce mercuric chloride in PBS solution to elemental mercury. When used in combination with sulfur powder, the black mercuric sulfide precipitate generated is less than that of mercaptoethanol and L-cysteine.

[0073] Experimental methods:

[0074] In a 50 mL conical-bottom centrifuge tube containing or not containing 150 mg of 100-mesh sulfur powder, add ultrapure water and 24 mL of L-cysteine ​​(200 μg / mL), ascorbic acid (300 μg / mL), and mercaptoethanol solution (200 μg / mL) prepared in PBS, respectively. Then, add 1 mL of 500 μg / mL mercuric chloride solution to a total volume of 25 mL. Mix at 30 rpm for 3 h, remove the tube and let it stand for 1 h. Take 1.0 mL from 1 cm below the liquid surface and transfer it to a 1.5 mL centrifuge tube. Dilute and determine the mercury content.

[0075] Experimental results:

[0076] The mercury concentration in the PBS solution was prepared at 20,000 ng / mL. Using sulfur powder, mercaptoethanol, or cysteine ​​alone did not change the mercury content in the PBS solution. Combining mercaptoethanol and L-cysteine ​​with sulfur powder resulted in the formation of a black mercuric sulfide precipitate, and the soluble mercury content decreased to 165.27 ng / mL and 136.36 ng / mL, respectively. Ascorbic acid alone reduced the mercury in the PBS solution to elemental mercury (resulting in a light pink solution), reducing the soluble mercury content to 760.85 ng / mL. Combining ascorbic acid with sulfur powder produced less black mercuric sulfide precipitate than did combining mercaptoethanol and L-cysteine ​​with sulfur powder, reducing the soluble mercury content to 833.43 ng / mL. The experimental results are shown in Figure 1.

[0077] FIG2 is a physical diagram of each group in Example 1.

[0078] Example 2: Effect of pH on the effect of L-cysteine ​​and sulfur powder on the Hg content in aqueous solution 2+ Effects of mercury conversion to insoluble mercury

[0079] Implementation effect:

[0080] When the pH value is between 6 and 10, L-cysteine ​​and sulfur powder are used together to remove Hg 2+The conversion of mercury to insoluble mercury sulfide is most effective.

[0081] Experimental methods:

[0082] In a 50-mL centrifuge tube, add 0.3 mL of a 0.1 mg / mL divalent inorganic mercury solution, and then add 30 mL of a pH 1.2, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, or 10.0 buffer solution containing 30 mg of 150-μm sulfur powder and 50 μg / mL of L-cysteine, respectively. Set up three parallel controls for each group. Use a long-axis homogenizer to mix at 30 rpm for 4 h. Let it stand for 12 h. Take 0.5 mL of the supernatant and determine the total mercury content using a Milestone DMA-80 direct mercury analyzer.

[0083] Experimental results:

[0084] Figure 3 shows the total mercury concentrations in each buffer solution after the aforementioned treatment. The total mercury concentration in each solution was 1000 ng / mL. As the pH value increased, starting at pH 5.0, the soluble mercury concentration decreased. Within the pH range of 6.0 to 10.0, the mercury concentrations were below 90 ng / mL, reaching 11.35, 10.16, 85.57, 9.89, and 7.04 ng / mL, respectively.

[0085] Example 3: L-cysteine ​​and Hg 2+ The molar ratio of L-cysteine ​​and sulfur powder is used to reduce the Hg 2+ Effects of mercury conversion to insoluble mercury

[0086] Implementation effect:

[0087] L-cysteine ​​and Hg 2+ When the molar ratio is greater than 2, L-cysteine ​​and sulfur powder are used in combination to remove Hg 2+ The best effect is to convert mercury into insoluble mercuric sulfide. Considering the oxidation loss of L-cysteine, in actual application, L-cysteine ​​and Hg 2+ The molar ratio is recommended to be greater than 2.5.

[0088] Experimental methods:

[0089] In a 50 mL centrifuge tube, different volumes of divalent inorganic mercury solution were added, and ultrapure water was added to make the total volume 15 mL. Then, 15 mL of a pH 6.0 solution containing 100 μg / mL of L-cysteine ​​and 300 mg of 3-5 μm sulfur powder was added. The total mercury concentrations in the solutions were 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, and 50 μg / mL, respectively. Three parallel controls were set up for each group. The tubes were mixed at 30 rpm for 10 min using a long-axis homogenizer, allowed to stand for 20 min, 1.3 mL of the supernatant was collected, and the tubes were centrifuged at 15,000 rpm for 20 min. 0.5 mL of the supernatant was collected and the total mercury content was determined using a Milestone DMA-80 direct mercury analyzer.

[0090] Experimental results:

[0091] After the above treatment, the soluble mercury concentrations of mercury solutions with different concentrations are shown in Figure 4. It can be seen that when the added mercury concentration is not higher than 36μg / mL, the total mercury concentration in the solution is lower than 5ng / mL. When the added mercury concentration reaches 38μg / mL, the soluble mercury begins to rise significantly. The added mercury concentration and L-cysteine ​​concentration are converted into molar concentrations. The molar concentration corresponding to the mercury concentration of 36μg / mL is 0.1795mM, and the molar concentration corresponding to the L-cysteine ​​concentration of 50μg / mL is 0.4127mM. Taking into account the oxidation loss of L-cysteine, it can be inferred that the L-cysteine ​​and Hg 2+ The molar ratio of L-cysteine ​​to Hg is 2:1. In actual use, in order to ensure the conversion rate of soluble mercury to insoluble mercury in the solution, it is recommended to 2+ The reaction ratio is not less than 2.5.

[0092] Example 4: Effect of sulfur powder particle size on the Hg content in aqueous solution when L-cysteine ​​and sulfur powder are used in combination 2+ Effects of mercury conversion to insoluble mercury

[0093] Implementation effect:

[0094] Sulfur powder with particle size of 3-5μm and 150μm can remove Hg 2+ The effect of mercury conversion into insoluble mercury sulfide is better than that of sulfur powder with a particle size of 50nm.

[0095] Experimental methods:

[0096] In a 50-mL centrifuge tube, add 0.3 mL of a 0.1 mg / mL divalent inorganic mercury solution, followed by 30 mL of a pH 6.0 buffer solution containing 30 mg of sulfur powder with particle sizes of 150 μm, 3-5 μm, and 50 nm, and 50 μg / mL of L-cysteine. Set up three parallel controls for each group. Use a long-axis mixer to mix at 30 rpm for 4 h. Let it stand for 12 h. Take 0.5 mL of the supernatant and determine the total mercury content using a Milestone DMA-80 direct mercury analyzer.

[0097] Experimental results:

[0098] After the above treatment, the total mercury concentration in each solution is shown in Figure 5. It can be seen that compared with the solution without sulfur powder, the mercury concentration in the sulfur powder solutions of different particle sizes decreased significantly. The total mercury concentration in the solution containing 3-5μm sulfur powder particles was the lowest, at 0.55ng / mL; followed by the solution containing 150μm sulfur powder particles, at 0.64ng / mL; and the total mercury concentration in the solution containing 50nm sulfur powder particles was the highest, at 72.77ng / mL. This experimental result shows that the role of sulfur powder has two aspects. One is to react with L-cysteine ​​to form S 2- , and secondly, the mercury sulfide generated by the adsorption reaction accelerates the sedimentation process.

[0099] Example 5: L-cysteine ​​and sulfur powder are used in combination to reduce Hg in aqueous solution. 2+ Mercury is converted into insoluble mercury by sulfur powder of different particle sizes and Hg 2+ The molar ratio

[0100] Implementation effect:

[0101] Sulfur powder with particle sizes of 3 to 5 μm and 150 μm converts Hg2+ mercury in aqueous solution into insoluble mercuric sulfide. The molar ratio of sulfur powder to L-cysteine ​​should be greater than 80 and 240, respectively.

[0102] Experimental methods:

[0103] In a 50-mL centrifuge tube, add 1 mL of 0.5 mg / mL mercury solution, followed by 29 mL of pH 6.0 buffer solution containing 2 mg, 5 mg, 10 mg, 20 mg, 30 mg, 40 mg, 50 mg, and 60 mg of sulfur powder with a particle size of 3-5 μm and a concentration of 25 μg / mL of L-cysteine, or 29 mL of pH 6.0 buffer solution containing 40 mg, 60 mg, 80 mg, 100 mg, 140 mg, and 180 mg of sulfur powder with a particle size of 150 μm and a concentration of 25 μg / mL of L-cysteine. Set up three parallel controls for each group. Use a long-axis homogenizer to mix at 30 rpm for 10 min, 30 min, 1 h, 2 h, and 4 h, respectively. Let it stand for 20 min, collect 1.3 mL of the supernatant, centrifuge at 15,000 rpm for 20 min, collect 0.5 mL of the supernatant, and determine the total mercury content using a Milestone DMA-80 direct mercury analyzer.

[0104] Experimental results:

[0105] After the above treatment, the total mercury concentration in the solution is shown in Figures 6 and 7. Before treatment, the soluble mercury content in the solution was approximately 16.67 μg / mL. When sulfur powder with a particle size of 3-5 μm was added in an amount greater than 60 mg, the total mercury concentration in the solution decreased by over 99%, to below 40 ng / mL. When sulfur powder with a particle size of 150 μm was added in an amount greater than 180 mg, the total mercury concentration in the solution decreased by over 99%, to below 25 ng / mL. The L-cysteine ​​concentration was 25 μg / mL. The molar ratios of sulfur powder with a particle size of 3-5 μm and 150 μm to L-cysteine ​​should be greater than 80 and 240, respectively.

[0106] Example 6: Treatment time for the combination of L-cysteine ​​and sulfur powder to reduce the Hg 2+ Effects of mercury conversion to insoluble mercury

[0107] Implementation effect:

[0108] L-cysteine ​​and sulfur powder are used together, and the treatment time is more than 10 minutes, which can reduce the Hg 2+ The conversion rate of mercury into insoluble mercury sulfide is greater than 99.5%.

[0109] Experimental methods:

[0110] In a 50-mL centrifuge tube, add 0.3 mL of a 0.1 mg / mL divalent inorganic mercury solution, and then add 30 mL of a pH 6.0 buffer solution containing 30 mg of 3-5 μm sulfur powder and 50 μg / mL of L-cysteine. Set up three parallel controls for each group. Use a long-axis mixer to mix at 30 rpm for 10 min, 1 h, 2 h, and 4 h, respectively. Let it stand for 20 min, collect 1.3 mL of the supernatant, centrifuge at 15,000 rpm for 20 min, collect 0.5 mL of the supernatant, and determine the total mercury content using a Milestone DMA-80 direct mercury analyzer.

[0111] Experimental results:

[0112] After the above treatment, the total mercury concentration in the solution after different mixing times is shown in Figure 8. It can be seen that the conversion rate of soluble mercury to insoluble mercury increases with time at different mixing times. The total mercury concentration in the solution is always below 5 ng / mL, and the conversion rate of soluble mercury to insoluble mercury is always greater than 99.5%, indicating that the reaction proceeds rapidly and does not require a large amount of mixing energy.

[0113] Example 7: Effect of L-cysteine ​​PBS solution and 5% hydrochloric acid on the surface of material Hg 2+ Comparison of cleaning effects

[0114] Implementation effect:

[0115] The cleaning effect of L-cysteine ​​PBS solution on stainless steel, glass, silicone, nitrile rubber, polyurethane, polyetheretherketone and plastic is better than or equivalent to that of 5% hydrochloric acid aqueous solution.

[0116] Experimental methods:

[0117] Materials: Stainless steel balls, 6 mm in diameter; glass balls, 6.1 mm in diameter; nitrile rubber cylindrical pellets, 5 mm in diameter and height; silicone cylindrical pellets, 5 mm in diameter and height; polyurethane cylindrical pellets, 6 mm in diameter and height; fluororubber cylindrical pellets, 5 mm in diameter and height; polytetrafluoroethylene cylindrical pellets, 5 mm in diameter and height; polyetheretherketone (PEEK) cylindrical pellets, 5.6 mm in diameter and height; plastic centrifuge tubes (50 mL)

[0118] Cleaning solution: ultrapure water, 5% HCl aqueous solution, 200 μg / mL L-cysteine ​​PBS solution

[0119] (1) Wash the above eight particles (excluding plastic) three times with 200 μg / mL L-cysteine ​​in PBS in a 50 mL centrifuge tube;

[0120] (2) Wash five times with 30 mL of ultrapure water to remove residual L-cysteine ​​and measure the mercury content. The mercury concentration in the washing solution should be less than 20 ng / mL.

[0121] (3) Prepare 300 mL of 2 mg / mL mercury solution using ultrapure water;

[0122] (4) Add 100 particles of each of the eight types of particles mentioned above to 50 mL centrifuge tubes, leaving one tube empty, for a total of 9 tubes;

[0123] (5) Add 30 mL of 2 mg / mL divalent inorganic mercury solution to each, rotate and mix using a long-axis rotary mixer at 10 rpm for 1 h, and let it soak for 49 h;

[0124] (6) Wash with 30 mL of ultrapure water five times to remove high concentration mercury solution;

[0125] (7) Pour the above 8 kinds of particles into disposable bacterial culture dishes, divide each kind of particles into 3 tubes, and transfer them to 50mL centrifuge tubes. Take 30 particles of each 5mm cylindrical particles, 21 particles of each 6mm cylindrical particles, 24 particles of each 5.6mm cylindrical particles, 27 particles of each 6mm spherical particles, and 26 particles of each 6.1mm spherical particles. Take 3 50mL centrifuge tubes for immersion as experimental objects of plastic materials;

[0126] (8) Add 25 mL of ultrapure water, 5% HCl, and 200 μg / mL cysteine ​​PBS solution to three centrifuge tubes of each type of particles, respectively, and use a long-axis rotary mixer at 30 rpm to rotate and soak for 4 h;

[0127] (9) After stopping, take one aliquot of the solution from each centrifuge tube and transfer it to a 1.5 mL centrifuge tube, with each aliquot being 1 mL.

[0128] (10) The mercury content was determined using a DMA-80 mercury analyzer.

[0129] Experimental results:

[0130] After the above treatment, the total mercury concentration in the cleaning solution is shown in Table 1. It can be seen that the 200 μg / mL L-cysteine ​​PBS solution is more effective than ultrapure water for cleaning all nine materials. It is better than 5% hydrochloric acid solution for cleaning stainless steel, glass, and silicone. It is comparable to 5% hydrochloric acid solution for cleaning nitrile rubber, polyurethane, polyetheretherketone, and plastics. However, it is less effective than 5% hydrochloric acid solution for cleaning fluororubber and polytetrafluoroethylene.

[0131] Figure 9 shows eight different types of Hg on the surface of particles. 2+ Cleared physical map.

[0132] Table 1 Effect of L-cysteine ​​PBS solution and 5% hydrochloric acid on Hg on the surface of materials 2+ Comparison of cleaning effects

[0133] Example 8: The combined use of L-cysteine ​​and elemental sulfur powder in aqueous solution and 5% hydrochloric acid to treat Hg on the silica gel surface 2+ Comparison of cleaning effects

[0134] Implementation effect:

[0135] L-cysteine ​​and elemental sulfur powder are used together, and the treatment time is more than 10 minutes to reduce the Hg 2+ The conversion rate of mercury into insoluble mercury sulfide is greater than 99.5%.

[0136] Experimental methods:

[0137] (1) Prepare 100 mL of a 2 mg / mL divalent inorganic mercury solution using ultrapure water;

[0138] (2) Add 100 silica gel particles into 50 mL centrifuge tubes;

[0139] (3) Add 30 mL of 2 mg / mL divalent inorganic mercury solution to each, rotate and mix using a long-axis rotary mixer at 10 rpm for 1 h, and let it soak for 49 h;

[0140] (4) Wash with 30 mL of ultrapure water five times to remove high-concentration mercury solution;

[0141] (5) Pour the silica gel particles in Example 7 into a disposable bacterial culture dish, divide into 4 tubes, take 25 particles from each tube, and transfer to a 50 mL centrifuge tube;

[0142] (6) Add 25 mL of ultrapure water, 5% HCl, 200 μg / mL cysteine ​​PBS solution, and 200 μg / mL cysteine ​​PBS solution + 200 mg of elemental sulfur powder with a particle size of 3-5 μm to four centrifuge tubes, respectively, and rotate and soak for 4 h using a long-axis rotary mixer at 30 rpm;

[0143] (7) After stopping, transfer the silica gel particles into a new 50 mL centrifuge tube;

[0144] (8) The mercury content of individual silica gel particles was determined using a DMA-80 mercury analyzer.

[0145] Experimental results:

[0146] After the above treatment, the total mercury concentration of the silica gel particles is shown in Table 2. It can be seen that the total mercury content of the silica gel particles after washing with 200 μg / mL cysteine ​​PBS solution and 200 mg of elemental sulfur with a particle size of 3-5 μm was lower than that of the silica gel particles washed with ultrapure water, 5% hydrochloric acid, and 200 μg / mL L-cysteine ​​PBS solution.

[0147] Table 2 Effect of L-cysteine ​​and sulfur powder combination with 5% hydrochloric acid on Hg on the surface of materials 2+ Comparison of cleaning effects

[0148] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A method for removing divalent inorganic mercury, characterized in that: The following steps are involved: Under the condition of pH value of 3-10, a thiol reagent, sulfur powder and a substrate to be removed of divalent inorganic mercury are mixed for reaction, wherein the thiol reagent comprises one or more of 2-mercaptoethanol, L-cysteine ​​and glutathione.

2. The removal method according to claim 1, characterized in that: The pH value is 6-8.

3. The removal method according to claim 1, characterized in that: The thiol group in the thiol reagent reacts with Hg in the matrix to be removed divalent inorganic mercury. 2+ The molar ratio is 2.5 to 3:

1.

4. The removal method according to claim 1, characterized in that: The particle size of the sulfur powder is 3 to 300 μm.

5. The removal method according to claim 4, characterized in that: The particle size of the sulfur powder is 5 to 150 μm.

6. The removal method according to claim 1 or 4, characterized in that: The sulfur powder and the Hg in the matrix to be removed from the divalent inorganic mercury 2+ The molar ratio is 40-300:

1.

7. The removal method according to claim 5, characterized in that: When the particle size of the sulfur powder is 3 to 5 μm, the sulfur powder and the Hg 2+ The molar ratio is 80-120:

1.

8. The removal method according to claim 5, characterized in that: When the particle size of the sulfur powder is 150 to 300 μm, the sulfur powder and the Hg 2+ The molar ratio is 240-300:

1.

9. The removal method according to claim 1 or 2, characterized in that: The pH value is achieved by adding buffer salts.

10. The removal method according to claim 1, characterized in that: The matrix to be removed of divalent inorganic mercury is an aqueous solution containing divalent inorganic mercury or divalent inorganic mercury exists on the surface of the material.

11. The removal method according to claim 10, characterized in that: When the substrate to be removed of divalent inorganic mercury is an aqueous solution containing divalent inorganic mercury, the removal method comprises the following steps: The thiol reagent and sulfur powder are added to the aqueous solution containing divalent inorganic mercury, and then the solution is allowed to stand to precipitate the generated mercuric sulfide, and the obtained product is separated into solid and liquid.

12. The removal method according to claim 10, characterized in that: When the substrate to be removed of divalent inorganic mercury is a material on which divalent inorganic mercury exists, the removal method comprises the following steps: mixing the buffered saline solution with the thiol reagent to obtain a thiol reagent solution; The surface of the material is cleaned with the mercapto reagent solution, and then sulfur powder is added and allowed to stand to precipitate the generated mercuric sulfide, and the obtained product is separated into solid and liquid.

13. The removal method according to claim 10, characterized in that: When the substrate to be removed of divalent inorganic mercury is a material on which divalent inorganic mercury exists, the removal method comprises the following steps: mixing a buffered saline solution, a thiol reagent and sulfur powder to obtain a suspension containing sulfur powder and a thiol compound; The material surface is cleaned with the suspension of the sulfur-containing powder and the mercapto compound, and then the material is allowed to stand to precipitate the generated mercuric sulfide, and the obtained product is separated into solid and liquid.

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