Method for targeted removal of trace thallium

Abstract

The invention relates to the field of environmental functional materials, in particular to a method for targeted removal of trace thallium. The method comprises the following steps: firstly, adjusting the pH value of the thallium-containing water body to 7.0 + / -0.1, then adding an ammonium molybdenum phosphate solution, oscillating in a constant-temperature shaking table at a rotating speed, and filtering by using a 0.45 mu m filter head after oscillation is finished, so that trace thallium in the water body can be adsorbed and removed; the invention creatively provides the thallium removal agent for treating thallium-containing wastewater by using the pore channel confinement, and the result shows that the existence of most coexisting ions hardly affects thallium adsorption and slightly affects the thallium adsorption only when the concentration of K < + > is 10g / L, and the thallium can be completely adsorbed within 15 minutes according to adsorption kinetics. In an actual water body experiment, the concentration of Tl < + > is 3.94 ug / L after adsorption, which meets the standard of 5 ug / L. The method has the advantages of low cost, high selectivity, high speed and the like, can be widely used for treating thallium-containing wastewater of various water qualities, can realize advanced treatment of the thallium-containing wastewater, and is high in use value and good in application prospect.

Description

Technical Field

[0001] The invention relates to the field of environmental functional materials, and in particular to a method for targeted removal of trace thallium. Background Art

[0002] Thallium (Tl) is a highly toxic metal element. Exposure to it can cause serious health problems, such as cancer and neurological diseases. According to the World Health Organization (WHO), smelting wastewater is an important source of thallium. However, my country's thallium-containing deposits and thallium-related enterprises are widely distributed and mainly located near rivers, posing a huge threat to water safety. In recent years, my country has experienced a number of large-scale thallium pollution incidents, causing extremely adverse social impacts and huge economic losses. Therefore, thallium has become a major concern for environmental and health agencies around the world.

[0003] At present, the commonly used methods for removing thallium from water bodies include: solvent extraction, oxidation-reduction precipitation, flotation, electrochemical deposition, ion exchange and adsorption. Among them, the adsorption method has attracted widespread attention due to its high adsorption capacity, low energy consumption and environmental friendliness. Some adsorbents such as titanium-based, manganese-based, iron-based and other materials have shown excellent thallium removal performance in laboratory studies (up to 1123 mg / g). However, this type of material mainly removes thallium through ion exchange, surface complexation, oxidation precipitation and the coupling of these mechanisms. Therefore, coexisting ions will significantly inhibit its thallium removal effect, and the adsorption rate is generally slow. For example: when the coexisting ion Ca 2+ Mg 2+ , Cl - The concentration of Tl + When the γ-MnOOH composite material is 25 times of Tl + The removal rates of thallium and thallium in wastewater were reduced by about 37%, 33% and 35% respectively. Therefore, the difficulty in controlling thallium pollution is the targeted removal of trace thallium from wastewater. Summary of the invention

[0004] The invention provides a method for targeted removal of trace thallium in order to solve the technical problems that the existing method for removing thallium in water is affected by coexisting ions, resulting in poor thallium removal selectivity, poor effect, slow adsorption speed and the like.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for targeted removal of trace thallium, first adjusting the pH of the water containing thallium to 7.0±0.1, then adding ammonium molybdenum phosphate solution, oscillating at a high speed in a constant temperature shaker, and filtering with a 0.45μm filter head after the oscillation to adsorb and remove trace thallium in the water.

[0006] The present invention utilizes the confinement effect, that is, ions smaller than the pore size can quickly pass through the angstrom pore at a speed thousands of times faster than ordinary diffusion, while ions larger than the pore cannot pass through. Combined with the coexisting ions, the hydrated diameter is usually larger than Tl+ The large hydration diameter can achieve the effect of targeted removal of Tl+ and solve the problem of the influence of coexisting ions.

[0007] As a further limitation of the technical solution of the present invention, the concentration of the ammonium molybdenum phosphate solution is 200 mg / L.

[0008] As a further limitation of the technical solution of the present invention, the time for adsorption and removal of thallium in water is 30 minutes, and after adsorption, Tl + The concentration is no more than 3.94ug / L.

[0009] As a further limitation of the technical solution of the present invention, the preparation method of ammonium molybdenum phosphate is: (NH4)6Mo7O 24 Dissolve in distilled water and filter to remove impurities; add H3PO4 to the filtrate and adjust the pH value of the solution to 1 with concentrated HNO3; then stir the mixture at room temperature for 1.5 hours to obtain a yellow precipitate, then age it at room temperature for 20 hours, filter it, wash it 3 times with 1 mol / L HNO3 solution, wash it once with distilled water, and finally dry it to obtain ammonium molybdenum phosphate.

[0010] As a further limitation of the technical solution of the present invention, the (NH4)6Mo7O 24 The molar ratio of (NH4)6Mo7O to H3PO4 is 6:5; 24 The solubility after dissolving in distilled water is 0.06mol / L.

[0011] As a further limitation of the technical solution of the present invention, the final drying condition during the preparation of ammonium molybdenum phosphate is drying at 40° C. for 6 hours.

[0012] Compared with the prior art, the present invention has the following beneficial effects: In view of the defects and shortcomings of the existing thallium removal agents, such as poor thallium removal selectivity and slow adsorption rate, the present invention creatively provides a thallium removal agent for treating thallium-containing wastewater using pore confinement. The results show that the presence of most coexisting ions has little effect on thallium adsorption. Only in K + When the concentration is 10g / L, there is a slight effect. According to the adsorption kinetics, the adsorption can be completed in 30 minutes. In the actual water experiment, after the adsorption, Tl + The concentration is 3.94ug / L, which meets the standard of 5ug / L. The invention has the advantages of low cost, high selectivity, high speed, etc. Ammonium molybdenum phosphate is a new type of composite thallium removal agent that does not require oxidation conversion treatment and has good thallium removal effect. It can be widely used to treat thallium-containing wastewater of various water qualities, and can achieve deep treatment of these thallium-containing wastewaters. It has high use value and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1This is a schematic diagram of the removal rate of thallium in the presence of different coexisting ions in Example 2.

[0014] Figure 2 Schematic diagram of adsorption kinetics of Example 3.

[0015] Figure 3 This is a diagram of the actual water body experiment in Example 4.

[0016] Figure 4 This is the adsorption isotherm diagram of Example 5. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with specific embodiments.

[0018] Example 1

[0019] Synthesis of ammonium phosphomolybdate (AMP): 0.012 mol (NH4)6Mo7O 24 Dissolve in 200ml distilled water, filter to remove impurities; add 0.01molH3PO4 to the filtrate, and adjust the pH value of the solution to 1 with concentrated HNO3; stir the mixture at room temperature for 1.5h to obtain a yellow precipitate, then age at room temperature for 20h, filter, wash 3 times with 1mol / L HNO3 solution, wash once with distilled water, and finally dry at 40℃ for 6h to obtain the target synthetic ammonium molybdenum phosphate, with the chemical formula (NH4)3PMo 12 O 40 .

[0020] Example 2

[0021] Effect of coexisting ions on adsorption Prepare 0.1g / L, 1g / L, and 10g / L of Na + , K + 、Zn 2+ , Pb 2+ A certain amount of Tl standard solution was added to prepare 100 mL of Tl (I) solution with an initial concentration of 1 mg / L. The initial pH of the solution was adjusted to 7.0 ± 0.1, and 20 mg (200 mg / L) AMP was added. The solution was shaken at 125 r / min at 25 ° C in a constant temperature shaker for 2 h. After shaking, the supernatant was removed and filtered with a 0.45 μm filter head to determine the Tl (I) content in the filtrate. Figure 1 As shown, the presence of most coexisting ions has little effect on the adsorption of thallium, only in K + There is a slight effect when the concentration is 10g / L.

[0022] Example 3 Adsorption kinetics Prepare 500mL of Tl (I) solution with an initial concentration of 1mg / L, adjust the initial pH of the solution to 7.0±0.1, add 100mg (200mg / L) AMP, shake at 125 r / min in a constant temperature shaker at 25℃ for 48h, take 1mL of supernatant at 1min, 5min, 10min, 30min, 60min, 120min, 240min, 480min, 720min, 1440min, 2160min, and 2880min, filter with a 0.45μm filter head, and dilute five times to determine the Tl (I) content in the filtrate. Figure 2 As shown, according to the adsorption kinetics, the adsorption is complete in 30 minutes.

[0023] Example 4

[0024] Actual water experiment Take Fenhe River water, filter it with a 0.45μm filter head, and prepare 100mL of Tl (I) wastewater solution with an initial concentration of 0.1mg / L. Adjust the initial pH of the solution to 7.0±0.1, add 20mg (200mg / L) AMP, and shake it at 25℃ in a constant temperature shaker at a speed of 125r / min for 2h. After shaking, remove the supernatant and filter it with a 0.45μm filter head to determine the Tl (I) content in the filtrate. The results are as follows Figure 3 As shown, in the actual water experiment, after adsorption, Tl + The concentration is 3.94ug / L, which meets the standard of 5ug / L.

[0025] Example 5

[0026] Adsorption isotherm studies Prepare 100 mL of Tl (I) solution with initial concentrations of 100 mg / L, 80 mg / L, 60 mg / L, 400 mg / L, 20 mg / L, 10 mg / L, 1 mg / L, and 0.1 mg / L, adjust the initial pH of the solution to 7.0 ± 0.1, add 20 mg (200 mg / L) AMP, and shake at 125 r / min for 2 h in a constant temperature shaker at 25 ° C. After shaking, remove the supernatant and filter it with a 0.45 μm filter head to determine the Tl (I) content in the filtrate. The results are as follows Figure 4 As shown, the maximum adsorption capacity is 176.933 mg / g, which is consistent with the Langmuir isotherm adsorption model.

Claims

1. A method for targeted removal of trace thallium, characterized in that: First, adjust the pH of the water containing thallium to 7.0±0.1, then add ammonium molybdenum phosphate solution, oscillate at a high speed in a constant temperature shaker, and filter with a 0.45μm filter head after the oscillation to adsorb and remove trace thallium in the water.

2. A method for targeted removal of trace thallium according to claim 1, characterized in that: The concentration of the ammonium molybdenum phosphate solution is 200 mg / L.

3. A method for targeted removal of trace thallium according to claim 1, characterized in that: The time for adsorption and removal of thallium in water is 30 minutes. After adsorption, Tl + The concentration is no more than 3.94ug / L.

4. A method for targeted removal of trace thallium according to claim 1, characterized in that: The preparation method of ammonium molybdenum phosphate is as follows: (NH4)6Mo7O 24 Dissolve in distilled water and filter to remove impurities; add H3PO4 to the filtrate and adjust the pH value of the solution to 1 with concentrated HNO3; then stir the mixture at room temperature for 1.5 hours to obtain a yellow precipitate, then age it at room temperature for 20 hours, filter it, wash it 3 times with 1 mol / L HNO3 solution, wash it once with distilled water, and finally dry it to obtain ammonium molybdenum phosphate.

5. A method for targeted removal of trace thallium according to claim 4, characterized in that: The (NH4)6Mo7O 24 The molar ratio of (NH4)6Mo7O to H3PO4 is 6:5; 24 The solubility after dissolving in distilled water is 0.06mol / L.

6. A method for targeted removal of trace thallium according to claim 4, characterized in that: The final drying condition during the preparation of ammonium molybdenum phosphate is drying at 40°C for 6 hours.

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