Magnetic adsorbent for selectively removing divalent mercury from smelting waste acid and preparation method thereof

Abstract

The application discloses a kind of selective removal of divalent mercury in smelting waste acid The preparation method of magnetic adsorbent belongs to the technical field of divalent mercury removal in smelting waste acid.The adsorbent described in the application is formed by loading copper sulfide (CuS) on Fe-Ti spinel by passing hydrogen sulfide gas into the mixed solution of Fe-Ti spinel (Fe-Ti spinel) and copper sulfate, and then calcining under nitrogen protection. The application significantly improves the ability of CuS / Fe-Ti spinel to remove divalent mercury by means of calcining under nitrogen protection. At the same time, the adsorbent has excellent selectivity for the removal of divalent mercury. In addition, the adsorbent has superparamagnetism and can be easily separated from smelting waste acid by an external magnetic field, making it easy to safely dispose of the mercury-containing adsorbent.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of selective removal of divalent mercury in smelting waste acid magnetic adsorbent and its preparation method, belong to the technical field of removal of divalent mercury in smelting waste acid. BACKGROUND

[0002] Mercury is commonly known as "quick silver", which is a toxic substance. Currently, two thousand tons of non-degradable metallic mercury is discharged into nature every year, causing significant pollution to the natural environment. Non-ferrous metal smelting industry is a major industry in terms of mercury emissions, and the waste acid generated during non-ferrous metal smelting process usually contains high concentrations of divalent mercury. Therefore, controlling the emission of divalent mercury in smelting waste acid is of great significance to solving the problem of mercury pollution.

[0003] Chemical precipitation method is a widely used method for removing heavy metals in smelting waste acid by adjusting the pH to neutral. Although this method has good mercury removal effect, a large amount of harmful sludge is generated during the process. Due to the high toxicity, metastability and volatility of mercury and its compounds, the presence of mercury can seriously affect the further development of these harmful sludge, and also affects the recovery of metal resources in the sludge. Therefore, it is urgent to remove divalent mercury from smelting waste acid before chemical precipitation. Adsorption method is a method with practical application prospect for removing divalent mercury in smelting waste acid, and the key is to develop a high-efficiency adsorbent suitable for smelting waste acid system. However, traditional adsorbents not only have poor ability to remove divalent mercury in strong acidic conditions, but also have poor selectivity for divalent mercury in the presence of other metal ions. At the same time, it is difficult to separate the adsorbent after removing divalent mercury from smelting waste acid, making it difficult to safely dispose of the mercury-containing adsorbent. Therefore, it is particularly important to develop a magnetic adsorbent with excellent selectivity for removing divalent mercury. SUMMARY

[0004] The present application aims to provide a preparation method of a magnetic adsorbent for selectively removing divalent mercury in smelting waste acid. By loading copper sulfide on iron-titanium spinel and calcining, an iron-titanium spinel loaded cuprous sulfide (Cu 2-x S / Fe-Ti spinel) adsorbent is prepared, which is used to remove divalent mercury in smelting waste acid, to solve the problems of poor ability of traditional adsorbents to remove divalent mercury in strong acidic conditions, poor selectivity, and difficulty in safely disposing of mercury-containing adsorbents.

[0005] To solve the above problems, the present application first provides a preparation method of a magnetic adsorbent for selectively removing divalent mercury in smelting waste acid. The method is to immerse iron-titanium spinel in a copper source solution, and then pass hydrogen sulfide gas into the solution, followed by solid-liquid separation and calcination, to obtain a Cu 2-x S / Fe-Ti spinel adsorbent.

[0006] In one embodiment of the present application, the method specifically comprises the following steps:

[0007] (1) mixing the iron titanium spinel with a copper source solution to obtain a mixed solution, wherein the mass ratio of the iron titanium spinel to the copper source in the mixed solution is 2:1-10:1;

[0008] (2) passing hydrogen sulfide gas into the mixed solution obtained in step (1), then performing solid-liquid separation, and washing and drying the solid obtained by the solid-liquid separation to obtain CuS / Fe-Ti spinel;

[0009] (3) placing the CuS / Fe-Ti spinel obtained in step (2) in a reactor, calcining the CuS / Fe-Ti spinel at 300°C under nitrogen protection for 1-2h to obtain CuS / Fe-Ti spinel adsorbent. 2-x

[0010] In one embodiment of the present application, the preparation method of the iron titanium spinel is as follows: iron source and titanium source are added to a precipitant, stirring is performed for 3h, the solid is collected, and the solid is washed, dried, and calcined at 500°C for 3h to obtain the iron titanium spinel (Fe-Ti spinel).

[0011] In one embodiment of the present application, the iron source includes ferrous sulfate and / or ferric chloride, the titanium source includes titanium sulfate and / or titanium tetrachloride, and the precipitant includes ammonia water.

[0012] In one embodiment of the present application, the mass ratio of the iron source to the titanium source is 1:1-4:1, and the mass ratio of the precipitant to the iron source is 2:1-4:1.

[0013] In one embodiment of the present application, the copper source includes any one of copper sulfate, copper nitrate, copper chloride, copper phosphate, copper carbonate, and copper acetate.

[0014] In one embodiment of the present application, the mass fraction of copper in the copper source relative to the iron titanium spinel is 10wt%-30wt%, and is preferably 20wt%.

[0015] In one embodiment of the present application, the drying in step (2) is performed under vacuum at a temperature of 40-60°C for 12-20h.

[0016] In one embodiment of the present application, in step (2), the concentration of the hydrogen sulfide gas is 1-5%, nitrogen is used as the carrier gas, the flow rate of the hydrogen sulfide gas is 0.5-2L / min, and the hydrogen sulfide gas is passed in for 1-2h.

[0017] In one embodiment of the present application, the reactor in step (2) includes a fixed bed reactor. ​

[0018] In one embodiment of the present application, the prepared Cu 2-x The S / Fe-Ti spinel adsorbent is sealed and stored.

[0019] A second object of the present application is to provide the Cu 2-x S / Fe-Ti spinel adsorbent prepared by the above preparation method.

[0020] A third object of the present application is to provide the Cu 2-x Application of the S / Fe-Ti spinel adsorbent in the field of removal of divalent mercury in smelting contaminated acid, wherein the divalent mercury is mainly mercury chloride.

[0021] In one embodiment of the present application, in the application, the Cu 2-x The addition amount of the S / Fe-Ti spinel adsorbent relative to the smelting contaminated acid is 0.4-0.8 g / L.

[0022] In one embodiment of the present application, in the application, the pH value of the smelting contaminated acid is in the range of 1-2, preferably pH 2.

[0023] Advantages of the present application

[0024] (1) The Cu 2-x S / Fe-Ti spinel prepared by the present application has excellent ability to remove divalent mercury under strong acidic conditions, and the removal efficiency of divalent mercury in contaminated acid can reach more than 70%;

[0025] (2) The Cu 2-x S / Fe-Ti spinel prepared by the present application has excellent selectivity in removing divalent mercury, and is basically not interfered by other metal ions in smelting contaminated acid. In the presence of other metal ions in the contaminated acid solution, the removal efficiency of divalent mercury by the adsorbent of the present application can still reach 70%.

[0026] (3) The Cu 2-x S / Fe-Ti spinel adsorbent prepared by the present application has good magnetism, and can be separated from smelting contaminated acid by an external magnetic field, which is convenient for safe disposal of the mercury-containing adsorbent. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Divalent mercury removal curve of the adsorbent in Examples 1-2 and Comparative Examples 1-2 in simulated smelting contaminated acid containing only metallic mercury at pH 2.

[0028] Figure 2 Divalent mercury removal curve of the adsorbent in Example 1 in simulated smelting contaminated acid containing other metal ions at pH 2.

[0029] Figure 3 Hysteresis loop of the adsorbent in Example 1.

[0030] Figure 4 Divalent mercury removal curve of the adsorbent in Example 1 in simulated smelting waste acid with pH of 2. DETAILED DESCRIPTION

[0031] In order to better illustrate the present application, facilitate the understanding of the technical solutions of the present application, the technical solutions of the present application are described more clearly by the following examples.

[0032] Determination method of divalent mercury concentration: divalent mercury is reduced to gaseous zero-valent mercury by stannous chloride solution, then the concentration of gaseous zero-valent mercury is measured by Lumex R915M mercury analyzer, finally the concentration of divalent mercury is obtained by integrating the concentration of gaseous zero-valent mercury. The removal efficiency of divalent mercury = the ratio of the difference between the concentrations of divalent mercury in smelting waste acid before and after treatment and the initial concentration of divalent mercury.

[0033] Determination method of magnetic intensity of adsorbent: measured by vibrating sample magnetometer.

[0034] Example 1

[0035] A preparation method of a magnetic adsorbent for selectively removing divalent mercury in smelting waste acid, comprising the following steps:

[0036] (1) taking ferrous sulfate heptahydrate and titanium sulfate as iron source and titanium source respectively, and taking ammonia water as precipitant, stirring for 3h, wherein the molar ratio of ammonia water, ferrous sulfate heptahydrate and titanium sulfate is 2:1:1; after the reaction is completed, the solid is collected, washed, dried, and then calcined at 500℃ for 3h to obtain iron titanium spinel (Fe-Ti spinel);

[0037] (2) mixing the Fe-Ti spinel obtained in step (1) with 2g / L copper sulfate solution, wherein the mass ratio of copper sulfate to Fe-Ti spinel is 1:3, and introducing 1% hydrogen sulfide gas into the mixed solution for 1h (flow rate 1L / min, nitrogen as carrier gas); after the reaction is completed, the solid is collected, washed, and dried at 50℃ for 20h to obtain CuS / Fe-Ti spinel;

[0038] (3) calcining the CuS / Fe-Ti spinel prepared in step (2) at 300℃ for 2h under nitrogen protection to obtain Cu 2-x S / Fe-Ti spinel adsorbent.

[0039] Example 2

[0040] A preparation method of a magnetic adsorbent for selectively removing divalent mercury in smelting waste acid, comprising the following steps:

[0041] (1) Ferrous sulfate heptahydrate and titanium tetrachloride were used as the iron source and titanium source, respectively, and ammonia water was used as the precipitant. The mixture was stirred for 3 hours, and the molar ratio of ammonia water, ferrous sulfate heptahydrate and titanium tetrachloride was 3:1:1. After the reaction was completed, the solid was collected, washed, dried and then calcined at 500℃ for 3 hours to obtain iron-titanium spinel (Fe-Ti spinel).

[0042] (2) The Fe-Ti spinel obtained in step (1) is mixed with a 1 g / L copper chloride solution, wherein the mass ratio of copper chloride to Fe-Ti spinel is 1:4. Hydrogen sulfide gas with a concentration of 3% is introduced into the mixed solution for 1 h (flow rate 0.5 L / min, carrier gas is nitrogen). After the reaction is completed, the solid is collected, washed, and dried at 60 °C for 15 h to obtain CuS / Fe-Ti spinel.

[0043] (3) The CuS / Fe-Ti spinel prepared in step (2) was calcined at 300℃ for 2 hours under nitrogen protection to obtain Cu 2-x S / Fe-Ti spinel adsorbent.

[0044] Example 3 Evaluation of Divalent Mercury Removal Activity

[0045] The adsorbents prepared in Examples 1 and 2 were ground into powder and their removal activity for divalent mercury was evaluated in conical flasks. The adsorbent dosage was 0.15 g / L, and the reaction was carried out at room temperature in simulated smelting waste acid with a pH of 2, a divalent mercury concentration of 100 mg / L, a solution volume of 200 mL, and a background electrolyte of 10 mmol / L NaCl for 2 h. The concentration of divalent mercury was measured, and the removal efficiency was calculated according to the following formula. The results are shown in [Figure number missing]. Figure 1 See Table 1.

[0046] Divalent mercury removal efficiency = (Divalent mercury concentration before treatment - Divalent mercury concentration after treatment) / Divalent mercury concentration before treatment

[0047] from Figure 1 As can be seen from the data in Table 1, when the adsorbent prepared by the method of the present invention is used to treat divalent mercury in smelting acid wastewater, the removal efficiency of divalent mercury can reach more than 65%.

[0048] Comparative Example 1: Preparation of CuS / Fe-Ti spinel adsorbent

[0049] The difference between Comparative Example 1 and Example 1 is that step (3) is omitted.

[0050] Comparative Example 2 Cu 2-x Preparation of S+Fe-Ti spinel adsorbent

[0051] A method for preparing a magnetic adsorbent includes the following steps:

[0052] (1) with ferrous sulfate heptahydrate and titanium sulfate as iron source and titanium source respectively, ammonia water as precipitant, stirring for 3h, wherein the molar ratio of ammonia water, ferrous sulfate heptahydrate and titanium sulfate is 2:1:1; after the reaction, the solid is collected, washed, dried, and then calcined at 500°C for 3h to obtain iron titanium spinel (Fe-Ti spinel);

[0053] (2) with copper sulfate as copper source, hydrogen sulfide gas with a concentration of 1% is bubbled into the copper source solution for 1h (flow rate 1L / min, nitrogen as carrier gas); after the reaction, the solid is collected, washed, dried, and then calcined at 300°C for 2h under nitrogen protection to obtain cuprous sulfide (Cu 2-x S);

[0054] (3) the Fe-Ti spinel obtained in step (1) and the cuprous sulfide (Cu 2-x S) in step (2) are directly mixed and ground uniformly to obtain Cu 2-x S+Fe-Ti spinel adsorbent, wherein the mass ratio of copper element to Fe-Ti spinel is 20%.

[0055] From Figure 1 and the data in Table 1, it can be seen that when preparing the adsorbent, if the adsorbent is not calcined or only cuprous sulfide and spinel are simply mixed, the removal efficiency of divalent mercury of the prepared adsorbent is poor, far lower than that of the adsorbent in the examples. These results show that calcination under nitrogen protection can significantly improve the performance of CuS / Fe-Ti spinel in removing divalent mercury; the loading of cuprous sulfide method is superior to the physical mixing method, which indicates that the introduction method of cuprous sulfide is very important, and an inappropriate introduction method will have a negative impact on the adsorbent.

[0056] Table 1 Removal efficiency of divalent mercury in smelting waste acid by adsorbents in Example 1 and Comparative Examples 1-2

[0057] Adsorbent Removal efficiency Example 1 71％ Example 2 65％ Comparative Example 1 39％ Comparative Example 2 45％

[0058] Example 4 Selectivity test:

[0059] The adsorbent prepared in Example 1 is ground into powder, and the selectivity evaluation of divalent mercury removal is carried out in an Erlenmeyer flask. The adsorbent B is added at a dosage of 0.15g / L, and the reaction is carried out in a simulated smelting waste acid with pH value equal to 2, and the composition is: divalent mercury concentration is 100mg / L, zinc ion concentration is 200mg / L, cadmium ion concentration is 50mg / L, copper ion concentration is 50mg / L, nickel ion concentration is 50mg / L, lead ion concentration is 20mg / L, solution volume is 200mL, and background electrolyte NaCl is 10mmol / L at room temperature for 2h.

[0060] The concentration of divalent mercury in the solution was determined, and the results are shown in Table 1. Figure 2 The removal efficiency of divalent mercury was calculated, and the results are shown in Table 2.

[0061] Table 2 Removal efficiency of divalent mercury in the polluted acid containing other metal ions by the adsorbent in Example 1

[0062] Removal efficiency Other metal ions 70％

[0063] As shown in Table 1 and Table 2, under the same reaction conditions, the presence of metal ions such as zinc, cadmium, nickel and lead hardly affects the removal efficiency of divalent mercury by the adsorbent in Example 1, indicating that the adsorbent prepared by the method of the present application has excellent selectivity in removing divalent mercury.

[0064] Example 5 Magnetic test:

[0065] The hysteresis loop of the adsorbent in Example 1 was measured by the oscillating sample method, and the results are shown in Table 3. Figure 3

[0066] The adsorbent in Example 1 has superparamagnetic property, and has no magnetism without an external magnetic field, so it can be fully dispersed in liquid phase and is not easy to agglomerate. The saturation magnetism of the adsorbent reaches 14.7 emu / g, so it is easy to be separated by an external magnetic field.

[0067] Example 6 Removal of simulated smelting polluted acid

[0068] The pH value of the smelting polluted acid is generally 1-2, and the concentration of divalent mercury is about 80-120 mg / L.

[0069] 20 mg of the adsorbent prepared in Example 1 was taken, and reacted in a simulated smelting polluted acid at room temperature for 1 h, wherein the composition was: the volume of the solution was 50 mL, the pH was 2, the concentration of divalent mercury was 100 mg / L, the background electrolyte NaCl was 10 mmol / L, and the coexisting ions were 200 mg / L Zn 2+ + 50 mg / L Cd 2 + + 50 mg / L Cu 2+ + 50 mg / L Ni 2+ + 20 mg / L Pd 2+ The removal curve of divalent mercury in the simulated smelting polluted acid by the adsorbent in Example 1 is shown in Table 4. Figure 4 Figure 4 As shown in Table 4, after adding 0.4 g / L of the adsorbent in Example 1, the removal efficiency of divalent mercury by the adsorbent can reach 100% within 10 min.

[0070] ​​Although the present application has been disclosed in its preferred embodiments with reference to the accompanying drawings, it is not intended to limit the present application thereto, and various modifications and alterations can be made thereto by those skilled in the art without departing from the spirit and scope of the present application, and the scope of protection of the present application should be defined by the appended claims.

Claims

1. A method for preparing a magnetic adsorbent for selectively removing divalent mercury from smelting contaminated acid, characterized by, The iron titanium spinel is immersed in a copper source solution, hydrogen sulfide gas is introduced into the solution, then solid-liquid separation is performed, the obtained solid is washed, dried, calcined at 300 DEG C for 1-2 hours under nitrogen protection, and Cu 2-x S / Fe-Ti spinel adsorbent is obtained. The preparation method of the iron-titanium spinel comprises the following steps: adding an iron source and a titanium source into ammonia water, stirring and reacting for 3 hours, collecting the solid, washing and drying, and calcining at 500 DEG C for 3 hours to obtain the iron-titanium spinel, wherein the mass ratio of the precipitant and the iron source is 2:1-4:1, and the mass ratio of the iron source and the titanium source is 1:1-4:

1.

2. The method of claim 1, wherein, The mass ratio of the iron-titanium spinel and the copper source is 2:1-10:

1.

3. The method of claim 1, wherein, The copper source comprises any one of copper sulfate, copper nitrate, copper chloride, copper phosphate, copper carbonate and copper acetate, and the mass fraction of copper in the copper source relative to the iron-titanium spinel is 10-30 wt%.

4. The method of claim 1, wherein, The iron source comprises ferrous sulfate and / or ferric chloride, the titanium source comprises titanium sulfate and / or titanium tetrachloride, and the precipitant comprises ammonia water.

5. The method of claim 1, wherein, The concentration of the hydrogen sulfide gas is 1-5%, the carrier gas is nitrogen, the flow rate of the gas is 0.5-2 L / min, and the time for passing in is 1-2 hours.

6. The method of claim 1, wherein, The drying is performed under vacuum at a temperature of 40-60 DEG C for 12-20 hours.

7. Cu prepared according to the method of any one of claims 1 to 6 2-x S / Fe-Ti spinel sorbents.

8. The Cu of claim 7 2-x Application of S / Fe-Ti spinel sorbents in the field of divalent mercury removal from smelter contaminated acid.

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