A method for deep removal of thallium from wastewater

Abstract

The present invention discloses a method for deeply removing thallium from wastewater. The method includes: using a thiol resin to adsorb and remove thallium from a thallium-containing solution, eluting and regenerating the thallium-adsorbed resin to obtain an elution waste liquid; adjusting the pH value of the elution waste liquid to ≤3, adding a sulfide for precipitation reaction, adjusting the pH value of the reaction system to ≥9, separating to obtain a filtrate and a filter residue, thereby completing the deep treatment of thallium in the wastewater. Compared with the removal methods, the method of the present invention uses a thiol resin as the thallium-adsorbing resin and has the following advantages: having good selectivity for thallium and wide applicability; having a high thallium adsorption and removal rate, and the effluent being far lower than the discharge standard; being convenient for regeneration; being able to directly adsorb and remove both Tl+ and Tl3+; having a low treatment cost, with the treatment cost per ton being less than 0.5 yuan. The method of the present invention has the advantages of simple process, convenient operation, low treatment cost, etc., can completely remove thallium, is convenient for the resource utilization of thallium, has good use value and application prospect.

Description

Technical Field

[0001] The invention belongs to the field of thallium-containing wastewater treatment and relates to a method for deeply removing thallium from wastewater. Background Art

[0002] Thallium is one of the most toxic and harmful rare dispersed elements at present, and it is bioaccumulative. Thallium and its compounds are mutagenic, carcinogenic and teratogenic to organisms, and their toxicity to humans is far greater than other heavy metal elements such as Hg, Cd, Pb, As, Sb, etc. Thallium can enter the human body through the digestive tract, respiratory system and skin contact, participate in human metabolism, and cause persistent damage to the human nervous system and central nervous system. Thallium is widely distributed in the earth's crust and has a low content, but it can coexist with many elements in many ores. When the ores are used, thallium enters the environment together with other elements. The industries involving thallium are mainly concentrated in lead and zinc smelting, steel smelting, chemical production, pigment manufacturing and other industries. Along with human activities, the environmental migration of thallium has been aggravated, causing some soil environments and natural watersheds to be polluted by thallium and thallium compounds.

[0003] According to the characteristics of thallium, the treatment technologies for thallium are mainly divided into electrochemical method, chemical precipitation method, ion exchange method, adsorption method, membrane method, biochemical method, etc.

[0004] Electrochemical method: mainly adopts electrocoagulation process and electrocatalytic oxidation process. In electrocoagulation process, cerium uses highly active polymeric metal hydroxide and its polymer produced by electrolysis for adsorption and coagulation. In electrocatalytic oxidation process, Tl + That is, it is oxidized to TI 3+ However, the process is long and requires complicated pretreatment steps.

[0005] Chemical precipitation method: There are oxidation precipitation method, adsorption precipitation method and sulfide precipitation method, using Tl(OH) 3 and Tl 2 Due to the very low solubility of S, it can be oxidized, neutralized or sulfided. However, a large amount of reagents need to be added. Generally, the effluent can only be stabilized at around 0.05 mg / L. Moreover, when the thallium removal rate needs to be increased, the maximum amount of reagents needs to be doubled. In addition, it is difficult to stably reduce thallium to below 0.005 mg / L.

[0006] Ion exchange method: Cation exchange resin can be used to + However, due to the influence of other metal ions such as Ca and Mg in water, conventional resins are difficult to completely separate thallium from other metals. Anion exchange resins can also be used to remove TlCl 4 - and Tl(SO 4 ) 2 -The anionic complex of trivalent thallium such as thallium is adsorbed and removed, but it can only be directed to the anionic complex of specific thallium, and the pre-treatment conditions are complicated, the removal rate of thallium is not high, and the purity of the obtained thallous chloride product is not high. In addition, the macroporous chelating resin containing sulfydryl is adopted in the prior art to have a poor adsorption effect on thallium ions in waste water, and thallium ions (Tl 3+ ) can be completely separated from wastewater, and the macroporous chelating resin containing mercapto groups can also adsorb other metal ions, especially thallium ions (Tl + ) has poor selectivity, which is not conducive to obtaining high-purity thallium products, and this also greatly limits the resource utilization of thallium in wastewater.

[0007] Adsorption method: Use adsorption materials such as activated carbon or metal oxides for adsorption removal. For example, nano-scale manganese ferrite adsorbent can reduce thallium to 0.02 mg / L, but the raw water needs to be oxidized first.

[0008] Membrane method: mainly uses nanofiltration membrane or reverse osmosis membrane, which can intercept various salts such as thallium, colloids, microorganisms, organic matter, etc., but its investment and operation costs are high, especially when the raw water has a high salinity.

[0009] Biochemical method: Utilize the metabolism of microorganisms to carry out indirect or direct redox reactions with pollutants, but the treatment effect is general and the impact resistance is poor.

[0010] Therefore, obtaining a method for deep removal of thallium from wastewater with simple process, convenient operation and low treatment cost is of great significance for completely solving the thallium pollution problem and improving the resource utilization rate of thallium. Summary of the invention

[0011] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for deep removal of thallium from wastewater with simple process, convenient operation and low treatment cost.

[0012] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0013] A method for deep removal of thallium from wastewater comprises the following steps:

[0014] S1, using a thallium adsorption resin to adsorb thallium from a thallium-containing solution to remove thallium, thereby obtaining a thallium-free solution; the thallium adsorption resin is a thiol resin;

[0015] S2, eluting and regenerating the thallium adsorption resin adsorbed with thallium to obtain elution waste liquid and unloaded thallium adsorption resin;

[0016] S3. Adjust the pH value of the eluted waste liquid to ≤3, add sulfide for precipitation reaction, adjust the pH value of the reaction system to ≥9, separate, obtain filtrate and filter residue, and complete the deep treatment of thallium in the wastewater.

[0017] The above method for deep removal of thallium from wastewater is further improved. In S1, the thallium adsorption resin is filled in an adsorption column, and a plurality of the adsorption columns are connected in series for adsorption; and the thiol resin is methyl thiol resin.

[0018] The above method for deep removal of thallium from wastewater is further improved in that, in S1, the speed at which the thallium-containing solution flows through the adsorption column is 1 BV / h to 40 BV / h.

[0019] The above method for deep removal of thallium from wastewater is further improved in that, in S1, the initial concentration of thallium in the thallium-containing solution is 0.0001 mg / L to 100 mg / L; and the pH of the thallium-containing solution is ≥1.

[0020] The above-mentioned method for deep removal of thallium from wastewater is further improved. In S1, the thallium-containing solution also includes the following treatment before adsorption: filtering the thallium-containing solution with a filter membrane with a pore size of ≤1μm to remove suspended matter in the solution; and discharging the thallium-removed solution after meeting the standards.

[0021] The above-mentioned method for deep removal of thallium from wastewater is further improved. In the S2, an eluent is used to elute and regenerate the thallium adsorption resin adsorbed with thallium; the eluent includes at least one of a hydrochloric acid solution with a mass concentration of 1% to 36%, a sulfuric acid solution with a mass concentration of 1% to 50%, and a mixed solution of hydrochloric acid / chloride salt; the mass concentration of hydrochloric acid in the mixed solution of hydrochloric acid / chloride salt is 0.1% to 5%, and the mass concentration of chloride salt is 10% to 30%; the chloride salt is at least one of sodium chloride, potassium chloride, calcium chloride, and magnesium chloride; the amount of the eluent is 3BV to 10BV; the speed of the eluent is 1BV / h to 10BV / h.

[0022] The above method for deep removal of thallium from wastewater is further improved in that in S2, the unloaded thallium adsorption resin is returned to S1 to be used for adsorbing and removing thallium from the thallium-containing solution.

[0023] The above-mentioned method for deep removal of thallium from wastewater is further improved in that in S3, an alkaline substance is used to adjust the pH value of the elution waste liquid and the reaction system; the alkaline substance is at least one of lime, sodium hydroxide, potassium hydroxide, and magnesium hydroxide.

[0024] The above method for deep removal of thallium from wastewater is further improved, wherein the sulfide in S3 is at least one of sodium sulfide, sodium hydrosulfide, calcium sulfide, magnesium sulfide, and hydrogen sulfide.

[0025] The above method for deep removal of thallium from wastewater is further improved in that in S3, the filtrate is returned to S1 for further treatment.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] In view of the defects of the existing ion exchange method, such as complex process, difficult operation, high treatment cost and difficulty in completely removing thallium, the present invention creatively proposes a method for deeply removing thallium from wastewater, using mercaptan resin as thallium adsorption resin, which has the following advantages: (a) it has good selectivity for thallium, is not affected by elements such as calcium and magnesium, has wide applicability, can completely separate thallium from other impurity elements in the solution, and has good adaptability to natural water bodies with high salinity and low thallium concentration, and industrial wastewater, and can also remove thallium from high-salinity and low-concentration thallium-containing water. (b) The thallium adsorption removal rate is high, which can reach more than 99.99%, and the thallium concentration in the effluent (liquid after thallium removal) can be reduced to below 0.0001 mg / L, which is far below the emission standard; (c) The regeneration is convenient. After the thallium adsorption resin is saturated with adsorption, it can be regenerated with only a small amount of low-concentration acid. The resin can be recycled, which is beneficial to reducing the processing cost. The thallium-containing eluate obtained after elution has a high thallium concentration and high purity, which is beneficial to obtaining a high-purity thallium product; (d) It is not affected by the thallium ion form. For Tl + and Tl 3+ All of them can be directly adsorbed and removed, so there is almost no need to pre-treat the thallium-containing solution, and the process is simpler; (f) the adsorption capacity is large and the saturation time is long, so the treatment cost is low, and the treatment cost per ton is less than 0.5 yuan. The method for deep removal of thallium in wastewater of the present invention has the advantages of simple process, convenient operation, low treatment cost, etc., can completely remove thallium in different solutions, and is convenient for realizing the resource utilization of thallium, with good use value and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0029] Figure 1 The present invention is a flowchart of the process for resource recovery of thallium in the thallium-containing solution in Example 3. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0031] In the following examples, unless otherwise specified, the materials and instruments used are commercially available, the processes used are conventional processes, the equipment used are conventional equipment, and the data obtained are the average values ​​of more than three repeated experiments.

[0032] Example 1

[0033] Investigate the adsorption effect of different resins on different thallium-containing solutions

[0034] First, the thallium-containing solution is the wastewater from the acid neutralization of a zinc smelter, with a pH of 6.8. It is filtered with 1um and set aside. Take 2g of thallium adsorption resin, mercapto resin, aminophosphonic acid resin, iminodiacetic acid resin, cationic resin, and anionic resin, and add 100mL of thallium-containing solution to each. After 6 hours of vibration adsorption, take the liquid after thallium removal for analysis.

[0035] Among them, the thallium adsorption resin is a mercaptan resin, specifically methyl mercaptan resin (R-CH 2 SH, wherein R is a polystyrene polymer), the same below; the mercapto resin is a macroporous chelating resin containing mercapto groups.

[0036] The results are shown in Table 1 below.

[0037] Table 1 The adsorption effect of different resins on thallium in thallium-containing solutions

[0038]

[0039] Second, the thallium-containing solution is the acid neutralization wastewater from a smelter with a pH of 7.1. It is filtered with 1um and set aside.

[0040] Take 0.5g of thallium adsorption resin and mercapto resin respectively, add 100mL of thallium-containing solution to each, shake and adsorb for 6h, and take the solution after thallium removal for analysis.

[0041] The results are shown in Table 2 below.

[0042] Table 2 The adsorption effect of thallium adsorption resin and mercapto resin on thallium in thallium-containing solution

[0043] project Tl concentration (mg / L) Tl adsorption rate Original solution 0.113 — Thallium adsorption resin <0.00002 99.99％ Mercapto resin 0.0187 83.5％

[0044] Third, the thallium-containing solution is the wastewater from the neutralization of dirty acid in a smelter, with a pH of 7.1. It is filtered with 1um and set aside. Take the original solution, add the reducing agent, stir and reduce, filter and set aside. Take 0.5g of thallium adsorption resin and mercapto resin respectively, and add 100mL of thallium-containing solution respectively. After 6h of vibration adsorption, take the liquid after thallium removal for analysis.

[0045] The results are shown in Table 3 below.

[0046] Table 3 The adsorption effect of thallium adsorption resin and mercapto resin on thallium in thallium-containing solution after reduction treatment

[0047] project Tl concentration (mg / L) Tl adsorption rate Original solution 0.113 — Thallium adsorption resin <0.00002 99.99％ Mercapto resin 0.0047 95.84％

[0048] As can be seen from Table 1-3, the thallium adsorption resin (methyl mercaptan resin) used in the present invention has an adsorption rate of thallium as high as 99.99%, and has a very weak adsorption capacity for other ions, and has good selectivity. At the same time, after being treated with the thallium adsorption resin (methyl mercaptan resin), the thallium ion concentration in the effluent water can be reduced to below 0.0001 mg / L. In addition, because the thallium element in the wastewater is neutralized by the waste acid as Tl + Mainly, containing a small amount of Tl 3+ Aminophosphonic acid resin, iminodiacetic acid resin and cationic resin have a certain adsorption capacity for thallium, but also have a strong adsorption capacity for metal ions such as Ca and Mg. Although mercapto resin (macroporous chelating resin containing mercapto group) has a strong adsorption capacity for thallium (Tl + ) also has a good adsorption effect, but it also adsorbs zinc, and the adsorption capacity of mercapto resin is very small, and it has a good adsorption effect only on low concentration solutions, and cannot adsorb thallium ions (Tl 3+ ). In addition, the adsorption capacity of anion resin for thallium is very weak.

[0049] Embodiment 2:

[0050] Investigating the adsorption effect of thallium adsorption resin on different thallium-containing solutions

[0051] First, the thallium-containing solution is the acid neutralization wastewater from a zinc smelter, with a pH of 6.7 and a conductivity of 31700us / cm. It is filtered with 1um and set aside.

[0052] First stage adsorption: 50g of new thallium adsorption resin was filled into the resin column with a filling height of 27cm. Then, the filtered thallium-containing solution was continuously pumped in at a speed of 20BV / h, and then samples were taken every 500mL for analysis.

[0053] The results obtained from the first stage adsorption are shown in Table 4 below.

[0054] Table 4 Adsorption effect of thallium adsorption resin on different elements in thallium-containing solution

[0055]

[0056]

[0057] The average concentration of thallium in the first-stage thallium-removed liquid was 0.00021 mg / L, and the thallium adsorption rate was 99.992%.

[0058] Second stage adsorption: Take 50g of new thallium adsorption resin and fill it into the resin column. Pump the first stage thallium removal liquid into the resin column to obtain the second stage thallium removal liquid, and take samples for analysis.

[0059] The results obtained from the second stage adsorption are shown in Table 5 below.

[0060] Table 5 The adsorption effect of thallium adsorption resins in series on thallium in thallium-containing solutions

[0061] project Tl concentration (mg / L) Tl adsorption rate Original solution 2.66625 — Level 1 thallium removal liquid (average value) 0.00021 99.992％ Second level thallium removal liquid (average value) 0.00005 99.998％

[0062] Second, the thallium-containing solution is high-salt wastewater from a zinc-germanium smelter, with a pH of 7.1, a potassium chloride content of about 200g / L, a sodium chloride content of about 100g / L, and a fluorine content of about 10g / L. It is filtered with 1um and set aside.

[0063] First-stage adsorption: 50 g of new thallium adsorption resin is filled into the resin column, and the filtered thallium-containing solution is pumped into the resin column to obtain the first-stage thallium-removed liquid, which is sampled and analyzed.

[0064] Second stage adsorption: Take 50g of new thallium adsorption resin and fill it into the resin column. Pump the first stage thallium removal liquid into the resin column to obtain the second stage thallium removal liquid, and take samples for analysis.

[0065] The results are shown in Table 6 below.

[0066] Table 6 The adsorption effect of thallium adsorption resins in series on thallium in thallium-containing solutions

[0067] project Tl concentration (mg / L) Tl adsorption rate Original solution 52.93 — 1st level thallium removal liquid 0.167 99.68％ 2nd level thallium removal liquid 0.00014 99.999％

[0068] Third, the thallium-containing solution is a zinc sulfate solution from a zinc sulfate smelter with a pH of 5.0 and a zinc content of about 67.3 g / L. It is filtered with 1 um and set aside.

[0069] First-stage adsorption: 50 g of new thallium adsorption resin is filled into the resin column, and the filtered thallium-containing solution is pumped into the resin column to obtain the first-stage thallium-removed liquid, which is sampled and analyzed.

[0070] Second stage adsorption: Take 50g of new thallium adsorption resin and fill it into the resin column. Pump the first stage thallium removal liquid into the resin column to obtain the second stage thallium removal liquid, and take samples for analysis.

[0071] The results are shown in Table 7 below.

[0072] Table 7 The adsorption effect of thallium adsorption resins in series on thallium in thallium-containing solutions

[0073] project Tl concentration (mg / L) Tl adsorption rate Original solution 32.33 — 1st level thallium removal liquid 0.523 98.38％ 2nd level thallium removal liquid 0.00175 99.995％

[0074] Fourth, the thallium-containing solution is the desulfurization wastewater from a cold steel plant. After being filtered with 1um, it is pumped into a resin column filled with 25g of thallium adsorption resin. Four thallium-removed liquid samples are taken continuously every 200mL for analysis.

[0075] The results are shown in Table 8 below.

[0076] Table 8 The adsorption effect of thallium adsorption resin on thallium in thallium-containing solution

[0077]

[0078]

[0079] Fifth, the thallium-containing solution is a natural water body. After being filtered with 1um, it is pumped into a resin column filled with 25g of thallium adsorption resin. Five thallium-removed liquid samples are taken continuously every 200mL for analysis.

[0080] The results are shown in Table 9 below.

[0081] Table 9 The adsorption effect of thallium adsorption resin on thallium in thallium-containing solution

[0082] project Tl concentration (mg / L) Tl adsorption rate Original solution 0.019 — Thallium removal liquid 1 0.00008 99.58％ Thallium removal liquid 2 0.00004 99.79％ Thallium removal liquid 3 0.00007 99.63％ Thallium removal liquid 4 0.00003 99.84％ Thallium removal liquid 5 0.00007 99.63％

[0083] Embodiment 3:

[0084] A method for deep removal of thallium from wastewater, such as Figure 1 As shown, the following steps are included:

[0085] (1) The thallium-containing solution is wastewater from the neutralization of dirty acid in a zinc smelter with a pH of 7.1. The thallium-containing solution is pumped into a filter and filtered (precision filtration) using a filter membrane with a pore size of 1 μm to remove suspended matter in the solution.

[0086] (2) The filtered thallium-containing solution was continuously pumped into two adsorption columns (each adsorption column was filled with 25 L of adsorption resin) connected in series at a speed of 20 BV / h, and the Tl in the solution was adsorbed by the thallium adsorption resin connected in series. + and Tl 3+ , and obtain the thallium adsorption resin adsorbing thallium and the thallium-removed liquid. The original solution and the thallium-removed liquid samples were analyzed, and the results are shown in Table 10. As can be seen from Table 10, after being treated with the thallium adsorption resin, the adsorption removal rate of thallium in the thallium-containing solution is 99.99%, and the concentration of thallium in the thallium-removed liquid is 0.00037 mg / L, which meets the relevant emission requirements and can be directly discharged.

[0087] Table 10 Comparison of the contents of each component in the thallium-containing solution before and after adsorption

[0088]

[0089]

[0090] (3) 200L of 5% hydrochloric acid solution (eluent, eluent) is continuously pumped into the adsorption column containing thallium adsorption resin at a flow rate of 3BV / h, and the thallium adsorption resin adsorbed with thallium is eluted and regenerated to obtain an empty thallium adsorption resin and elution waste liquid. In this step, the obtained empty thallium adsorption resin is returned to step (1) and is continuously used to adsorb and remove thallium from the thallium-containing solution.

[0091] (4) The pH of the eluted waste liquid is adjusted to 2.0 with lime, sodium sulfide is added for precipitation separation, and then the pH of the solution (reaction system) is adjusted to 10 with lime, filtered and separated to obtain a filtrate and a filter residue, thereby completing the deep treatment of thallium in the waste water. In this step, the obtained filtrate is returned to (1) for further treatment.

[0092] Based on the above results, it can be seen that in the present invention, the use of mercaptan resin as thallium adsorption resin has the following advantages: (a) it has good selectivity for thallium, is not affected by elements such as calcium and magnesium, has wide applicability, can completely separate thallium from other impurity elements in the solution, and has good adaptability to natural water bodies with high salinity and low thallium concentration and industrial wastewater, and can also completely separate thallium from high-salinity and low-concentration thallium-containing water bodies; (b) the thallium adsorption removal rate is high, which can reach 99. 99%, and the lowest thallium concentration in the effluent (liquid after thallium removal) can be reduced to below 0.0001 mg / L, which is far below the discharge standard; (c) convenient regeneration, after the thallium adsorption resin is saturated with adsorption, only a small amount of low-concentration acid and alkali can be used to achieve regeneration, the resin can be recycled, which is beneficial to reduce the processing cost, and the thallium-containing eluent obtained after elution has a high thallium concentration and high purity, which is beneficial to obtain a high-purity thallium product; (d) it is not affected by the form of thallium ions, for Tl + and Tl 3+ All of them can be directly adsorbed and removed, so there is almost no need to pre-treat the thallium-containing solution, and the process is simpler; (f) the adsorption capacity is large and the saturation time is long, so the treatment cost is low, and the treatment cost per ton is less than 0.5 yuan. Therefore, the method for deep removal of thallium in wastewater of the present invention has the advantages of simple process, convenient operation, low treatment cost, high income, etc., and can recover thallium in different solutions, which is convenient for realizing the resource utilization of thallium, and has good use value and application prospects.

[0093] The above is only a preferred embodiment of the present invention, but it is not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above. Therefore, any simple modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for deep removal of thallium from wastewater, It is characterized in that The following steps are involved: S1, using a thallium adsorption resin to adsorb thallium from a thallium-containing solution to remove thallium, to obtain a thallium-removed solution; the thallium adsorption resin is filled in an adsorption column, and a plurality of the adsorption columns are connected in series for adsorption; the thallium adsorption resin is a thiol resin; the thiol resin is a methylthiol resin, which is selective for thallium; S2, eluting and regenerating the thallium adsorption resin adsorbed with thallium to obtain elution waste liquid and unloaded thallium adsorption resin; S3. Adjust the pH value of the eluted waste liquid to ≤3, add sulfide for precipitation reaction, adjust the pH value of the reaction system to ≥9, separate, obtain filtrate and filter residue, and complete the deep treatment of thallium in the wastewater.

2. The method for deep removal of thallium in waste water according to claim 1, It is characterized in that In S1, the thallium-containing solution flows through the adsorption column at a speed of 1 BV / h to 40 BV / h.

3. The method for deep removal of thallium from wastewater according to claim 2, It is characterized in that In S1, the initial concentration of thallium in the thallium-containing solution is 0.0001 mg / L to 100 mg / L; and the pH of the thallium-containing solution is ≥1.

4. The method for deep removal of thallium from waste water according to claim 3, It is characterized in that In S1, the thallium-containing solution further includes the following treatments before adsorption: filtering the thallium-containing solution with a filter membrane with a pore size of ≤1 μm to remove suspended matter in the solution; and discharging the thallium-removed solution after it meets the standards.

5. The method for deep removal of thallium from wastewater according to any one of claims 1 to 4, It is characterized in that In S2, an eluent is used to elute and regenerate the thallium adsorption resin adsorbed with thallium; the eluent includes at least one of a hydrochloric acid solution with a mass concentration of 1% to 36%, a sulfuric acid solution with a mass concentration of 1% to 50%, and a mixed solution of hydrochloric acid / chloride salt; the mass concentration of hydrochloric acid in the mixed solution of hydrochloric acid / chloride salt is 0.1% to 5%, and the mass concentration of chloride salt is 10% to 30%; the chloride salt is at least one of sodium chloride, potassium chloride, calcium chloride, and magnesium chloride; the amount of the eluent is 3BV to 10BV; the speed of the eluent is 1BV / h to 10BV / h.

6. The method for deep removal of thallium from wastewater according to any one of claims 1 to 4, It is characterized in that In S2, the unloaded thallium adsorption resin is returned to S1 to adsorb and remove thallium from the thallium-containing solution.

7. The method for deep removal of thallium from wastewater according to any one of claims 1 to 4, It is characterized in that In S3, an alkaline substance is used to adjust the pH value of the elution waste liquid and the reaction system; the alkaline substance is at least one of lime, sodium hydroxide, potassium hydroxide, and magnesium hydroxide.

8. The method for deep removal of thallium from wastewater according to any one of claims 1 to 4, It is characterized in that In S3, the sulfide is at least one of sodium sulfide, sodium hydrosulfide, calcium sulfide, magnesium sulfide, and hydrogen sulfide.

9. The method for deep removal of thallium from wastewater according to any one of claims 1 to 4, It is characterized in that In S3, the filtrate is returned to S1 for further treatment.

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