Adsorbent for purifying thallium-containing wastewater and application thereof

Abstract

The invention provides an adsorbent for thallium-containing wastewater purification and application thereof.The adsorbent is a co-intercalation kaolin-sodium alginate aerogel compound, and a preparation method of the adsorbent comprises the steps that 1, kaolin with crystal water removed is added into a dimethyl sulfoxide aqueous solution to be stirred and centrifugally washed, and a precursor is obtained; (2) adding the precursor into an ethanol solution, stirring, adding 3-aminopropyltriethoxysilane, reacting, adjusting the pH value to 8-9, and centrifugally washing to obtain amino intercalated kaolin; (3) adding the amino-intercalated kaolin into an oxalic acid solution, stirring, and centrifugally washing to obtain amino-carboxyl co-intercalated kaolin; and (4) mixing the amino-carboxyl co-intercalated kaolin with a sodium alginate solution, performing ultrasonic stirring, and performing freeze drying to obtain the composite material. The adsorbent provided by the invention has the advantages of high adsorption capacity, high thallium removal efficiency, good stability, good regeneration performance and good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and particularly relates to an adsorbent for purifying thallium-containing wastewater and its application. Background Art

[0002] The emission sources of thallium pollution mainly include natural and anthropogenic emission sources. Low levels of thallium can cause serious harm to the ecosystem. Thallium has extremely high biological toxicity to the human body, which can inactivate the potassium ion transport pump protein on the cell membrane, disrupt the human body's metabolic function, and accumulate in human bones, kidneys and nervous systems along the food chain. It is generally considered that 1.5 mg / L of thallium can be lethal to humans. If the thallium concentration in industrial thallium-containing wastewater exceeds 5 mg / L, it must be treated for thallium removal and purification.

[0003] Common treatment methods such as precipitation method, oxidation method, ion exchange method, membrane separation method, etc. have a certain thallium removal effect, but generally have the characteristics of high cost, a large amount of waste residue, high energy consumption, etc. The adsorption method has great application prospects in the field of water treatment due to its high adsorption capacity, fast adsorption rate and easy recycling. Therefore, the adsorption method is considered to be one of the most effective means for thallium removal and purification of industrial thallium-containing wastewater. However, the current adsorption materials are prone to agglomeration, have poor regeneration performance, the adsorption efficiency is not satisfactory, the amount of adsorbent used is large, and the cost is high, which restricts the development of the thallium-containing wastewater purification industry. Summary of the Invention

[0004] In view of this, the present invention proposes an adsorbent for purifying thallium-containing wastewater and its application.

[0005] The technical solution of the present invention is realized as follows:

[0006] An adsorbent for purifying thallium-containing wastewater, wherein the adsorbent is an intercalated kaolin-sodium alginate aerogel composite.

[0007] Further, the intercalated kaolin in the intercalated kaolin-sodium alginate aerogel composite is amino-carboxyl intercalated kaolin, wherein the intercalation rate of amino groups is 55%-60%, and the intercalation rate of carboxyl groups is 70%-80%.

[0008] Further, the preparation of the intercalated kaolin-sodium alginate aerogel composite includes the following steps:

[0009] (1) Adding kaolin from which crystal water has been removed to an aqueous solution of dimethyl sulfoxide, stirring, centrifuging and washing to obtain a precursor;

[0010] (2) Adding the precursor to an ethanol solution, stirring, adding 3-aminopropyltriethoxysilane to react, and simultaneously adjusting the pH to 8-9, centrifuging and washing to prepare amino-intercalated kaolin;

[0011] (3) Add the amino-intercalated kaolin into the oxalic acid solution, stir, centrifuge and wash to obtain the amino-carboxyl co-intercalated kaolin;

[0012] (4) Mix the amino-carboxyl co-intercalated kaolin and the sodium alginate solution, stir ultrasonically, and freeze-dry to obtain the co-intercalated kaolin-sodium alginate aerogel composite.

[0013] Further, in step (1), the solid-liquid ratio of the kaolin to the dimethyl sulfoxide aqueous solution is 1:30 - 40 g / mL; the volume ratio of dimethyl sulfoxide to water in the dimethyl sulfoxide aqueous solution is 1:8 - 10; the rotation speed of the stirring is 100 - 200 rpm, and the time is 30 - 40 min.

[0014] Further, in step (2), the solid-liquid ratio of the precursor to the ethanol solution is 1:6 - 10 g / mL; the concentration of the ethanol solution is 60% - 70% v / v; the mass ratio of 3-aminopropyltriethoxysilane to the precursor is 0.2 - 0.4:1; the reaction is carried out at 50 - 60 °C for 6 - 10 h.

[0015] Further, in step (3), the solid-liquid ratio of the amino-intercalated kaolin to the oxalic acid solution is 1:10 - 15 g / mL; the concentration of the oxalic acid solution is 30% - 40% w / v; the rotation speed of the stirring is 250 - 350 rpm, and the time is 20 - 40 min.

[0016] Further, in step (4), the mass ratio of the amino-carboxyl co-intercalated kaolin to the sodium alginate solution is 1:2 - 4; the concentration of the sodium alginate solution is 20% - 30% w / v; the ultrasonic stirring is carried out at 20 - 30 kHz and 40 - 60 °C for 1 - 3 h.

[0017] Application of the above-mentioned adsorbent in purifying thallium-containing wastewater.

[0018] Further, when the adsorbent is used to purify thallium-containing wastewater, add the adsorbent into the thallium-containing wastewater and oscillate for adsorption.

[0019] Further, the speed of the oscillating adsorption is 100 - 200 rpm, and the time is 30 - 60 min.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. The co-intercalated kaolin-sodium alginate aerogel composite of the present invention intercalates amino and carboxyl groups into the interlayer spacing of kaolin, which can not only expand the interlayer spacing but also provide adsorption sites to achieve selective adsorption of thallium ions. Inserting the co-intercalated kaolin into the network of sodium alginate aerogel to form a rigid-flexible network structure can not only improve the stability of the adsorbent but also increase the affinity with thallium ions. The two work together to increase the adsorption sites, achieve the effect of quickly capturing thallium ions and deeply purifying thallium ions. Verified by examples, the co-intercalated kaolin-sodium alginate aerogel composite adsorbent of the present invention is not only applicable to the adsorption of trace thallium ions in water but also has good adsorption capacity for trace thallium ions in water.

[0022] 2. The adsorbent co-intercalated kaolin-sodium alginate aerogel composite of the present invention is applied in the field of purifying thallium-containing wastewater, with high adsorption capacity, significantly improving the treatment effect of thallium-containing wastewater, being convenient for recycling, having good stability and good regeneration performance, and having good application prospects in the field of purifying thallium-containing wastewater. Specific embodiments

[0023] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0024] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0025] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can all be obtained from commercial channels.

[0026] Example 1

[0027] The co-intercalated kaolin-sodium alginate aerogel composite adsorbent for purifying thallium-containing wastewater in this example is prepared by the following steps:

[0028] (1) According to the solid-liquid ratio of 1:35 g / mL, add kaolin without crystal water to the dimethyl sulfoxide aqueous solution (the volume ratio of dimethyl sulfoxide to water is 1:9), stir at 150 rpm for 35 min, and perform centrifugal washing to obtain a precursor;

[0029] (2) According to the solid-liquid ratio of 1:8 g / mL, add the precursor to a 65% v / v ethanol solution, stir for 30 min, add 3-aminopropyltriethoxysilane, and the mass ratio of 3-aminopropyltriethoxysilane to the precursor is 0.3:1. At the same time, adjust the pH to 8.5 ± 0.5 and react at 55 °C for 8 h. The product is centrifugally washed to obtain amino-intercalated kaolin;

[0030] (3) According to a solid-liquid ratio of 1:13 g / mL, add amino-intercalated kaolin into a 35% w / v oxalic acid solution, stir at 300 rpm for 30 min, centrifuge and wash to obtain amino-carboxyl co-intercalated kaolin, with an intercalation rate of 58% for amino groups and 75% for carboxyl groups;

[0031] (4) Mix the amino-carboxyl co-intercalated kaolin and a 25% w / v sodium alginate solution according to a mass ratio of 1:3, perform ultrasonic treatment at 25 kHz and 50 °C for 2 h, and freeze-dry to obtain a co-intercalated kaolin-sodium alginate aerogel composite.

[0032] Example 2

[0033] The adsorbent of the co-intercalated kaolin-sodium alginate aerogel composite for purifying thallium-containing wastewater in this example is prepared by the following steps:

[0034] (1) According to a solid-liquid ratio of 1:30 g / mL, add kaolin with crystal water removed into an aqueous dimethyl sulfoxide solution (volume ratio of dimethyl sulfoxide to water is 1:8), stir at 100 rpm for 30 min, centrifuge and wash to obtain a precursor;

[0035] (2) According to a solid-liquid ratio of 1:6 g / mL, add the precursor into a 60% v / v ethanol solution, stir for 30 min, add 3-aminopropyltriethoxysilane, the mass ratio of 3-aminopropyltriethoxysilane to the precursor is 0.2:1, and at the same time adjust the pH to 8.5 ± 0.5, react at 50 °C for 6 h, and the product is centrifuged and washed to obtain amino-intercalated kaolin;

[0036] (3) According to a solid-liquid ratio of 1:10 g / mL, add the amino-intercalated kaolin into a 30% w / v oxalic acid solution, stir at 250 rpm for 20 min, centrifuge and wash to obtain amino-carboxyl co-intercalated kaolin, with an intercalation rate of 55% for amino groups and 70% for carboxyl groups;

[0037] (4) Mix the amino-carboxyl co-intercalated kaolin and a 20% w / v sodium alginate solution according to a mass ratio of 1:2, perform ultrasonic treatment at 20 kHz and 40 °C for 1 h, and freeze-dry to obtain a co-intercalated kaolin-sodium alginate aerogel composite.

[0038] Example 3

[0039] The adsorbent of the co-intercalated kaolin-sodium alginate aerogel composite for purifying thallium-containing wastewater in this example is prepared by the following steps:

[0040] (1) According to the solid-liquid ratio of 1:40 g / mL, add kaolin without crystal water into the dimethyl sulfoxide aqueous solution (the volume ratio of dimethyl sulfoxide to water is 1:10), stir at 200 rpm for 40 min, centrifuge and wash, and dry to obtain the precursor;

[0041] (2) According to the solid-liquid ratio of 1:10 g / mL, add the precursor into a 70% v / v ethanol solution and stir for 30 min. Add 3-aminopropyltriethoxysilane, and the mass ratio of 3-aminopropyltriethoxysilane to the precursor is 0.4:1. At the same time, adjust the pH to 8.5 ± 0.5, react at 60 °C for 10 h, and the product is centrifuged and washed to obtain amino-intercalated kaolin;

[0042] (3) According to the solid-liquid ratio of 1:15 g / mL, add the amino-intercalated kaolin into a 40% w / v oxalic acid solution, stir at 350 rpm for 40 min, centrifuge and wash to obtain amino-carboxyl co-intercalated kaolin, with the intercalation rate of amino being 60% and the intercalation rate of carboxyl being 80%;

[0043] (4) Mix the amino-carboxyl co-intercalated kaolin and a 30% w / v sodium alginate solution according to the mass ratio of 1:4, perform ultrasonic treatment at 30 kHz and 60 °C for 3 h, and freeze-dry to obtain the co-intercalated kaolin-sodium alginate aerogel composite.

[0044] Test Example 1 - Influence of Different Initial pH Values of Thallium-Containing Wastewater on the Adsorption of Thallium by the Adsorbent

[0045] Treat thallium-containing wastewater with a thallium concentration of 20 μg / L and initial pH values of 4, 5, 6, 7, 8, and 9. Add the adsorbent prepared in Example 1 at 25 °C, with a dosage of 0.6 g / L. After oscillating at 150 rpm for 30 min, take samples to test the thallium removal rate. The results are shown in Table 1.

[0046] Table 1

[0047]

[0048] As can be seen from Table 1, the thallium removal rates of the adsorbent prepared in Example 1 are different in thallium-containing wastewater environments with different pH values. When the pH is 5 - 9, the thallium removal rate is greater than 96%, showing good thallium adsorption effect.

[0049] Test Example 2 - Influence of Different Initial Thallium Concentrations of Thallium-Containing Wastewater on the Adsorption of Thallium by the Adsorbent

[0050] 1. Treat 30 mL of thallium-containing wastewater with thallium concentrations of 1, 5, 10, 20, 50, 80, and 100 μg / L and an initial pH = 7 respectively. Add the adsorbent prepared in Example 1 at 25 °C, with a dosage of 18 mg. After oscillating at 150 rpm for 60 min, take samples to test the thallium removal rate. The results are shown in Table 2.

[0051] Table 2

[0052]

[0053] As can be seen from Table 2, the adsorbent prepared by the present invention has good thallium adsorption effect in wastewater with different initial thallium concentrations, and can be applied to treat trace thallium in water bodies.

[0054] 2. Treat 30 mL of thallium-containing wastewater with thallium concentrations of 1, 5, 10, 20, 50, 80, and 100 mg / L and an initial pH = 7 respectively. Add the adsorbent prepared in Example 1 under the condition of 25 °C, with an addition amount of 18 mg. After oscillating at 150 rpm for 60 min, take samples and test the thallium removal rate. The results are shown in Table 3.

[0055] Table 3

[0056]

[0057] As can be seen from Table 3, the adsorption effect of the adsorbent prepared by the present invention on thallium in wastewater with different initial thallium concentrations is different. When the initial concentration is 1 - 10 mg / L, the adsorbent prepared in Example 1 can still achieve an adsorption effect of more than 80%. When the concentration exceeds 10 mg / L, the thallium removal rate decreases and the adsorption gradually saturates. Therefore, the adsorbent prepared in Example 1 of the present invention can be applied to treat trace thallium (1 - 10 mg / L) in water bodies.

[0058] Test Example 3 - Influence of Dosage of Different Adsorbents on Thallium Adsorption in Thallium-Containing Wastewater

[0059] Treat thallium-containing wastewater with a thallium concentration of 20 μg / L and an initial pH = 7. Add the adsorbent prepared in Example 1 under the condition of 25 °C, with addition amounts of 0.2, 0.4, 0.6, 0.8, and 1.0 g / L. After oscillating at 150 rpm for 30 min, take samples and test the thallium removal rate. The results are shown in Table 4.

[0060] Table 4

[0061]

[0062] As can be seen from Table 4, for the adsorbent prepared in Example 1 of the present invention, with the increase of the addition amount, the thallium removal rate increases. When the addition amount is greater than 0.8 g / L, the adsorption efficiency slightly decreases, but is greater than 95%, which can meet the discharge standard of industrial thallium-containing wastewater.

[0063] Comparative Example 1

[0064] The difference from Example 1 is that the amino-carboxyl co-intercalated kaolin is replaced by dimethyl sulfoxide intercalated kaolin, and the others are the same as in Example 1.

[0065] That is, the preparation method of the adsorbent for purifying thallium-containing wastewater in this comparative example includes:

[0066] (1) According to a solid-liquid ratio of 1:35 g / mL, add kaolin with crystal water removed to an aqueous dimethyl sulfoxide solution (the volume ratio of dimethyl sulfoxide to water is 1:9), stir at 150 rpm for 35 min, centrifuge and wash, and dry to obtain dimethyl sulfoxide intercalated kaolin;

[0067] (2) Mix the dimethyl sulfoxide intercalated kaolin and a 25% w / v sodium alginate solution in a mass ratio of 1:3, perform ultrasonic treatment at 25 kHz and 50 °C for 2 h, and freeze-dry to obtain the target adsorbent.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that the adsorbent is sodium alginate aerogel, and the others are the same as in Example 1.

[0070] That is, the preparation method of the adsorbent for purifying thallium-containing wastewater in this comparative example includes:

[0071] Perform ultrasonic treatment on a 25% w / v sodium alginate solution at 25 kHz and 50 °C for 2 h, and freeze-dry to obtain the target adsorbent.

[0072] Comparative Example 3

[0073] The difference from Example 1 is that the adsorbent is co-intercalated kaolin, and the others are the same as in Example 1.

[0074] That is, the preparation method of the adsorbent for purifying thallium-containing wastewater in this comparative example includes:

[0075] (1) According to a solid-liquid ratio of 1:35 g / mL, add kaolin with crystal water removed to an aqueous dimethyl sulfoxide solution (the volume ratio of dimethyl sulfoxide to water is 1:9), stir at 150 rpm for 35 min, centrifuge and wash to obtain a precursor;

[0076] (2) According to a solid-liquid ratio of 1:8 g / mL, add the precursor to a 65% v / v ethanol solution, stir for 30 min, add 3-aminopropyltriethoxysilane, the mass ratio of 3-aminopropyltriethoxysilane to the precursor is 0.3:1, and at the same time adjust the pH to 8.5 ± 0.5, react at 55 °C for 8 h, and the product is centrifuged and washed to obtain amino-intercalated kaolin;

[0077] (3) According to a solid-liquid ratio of 1:13 g / mL, add the amino-intercalated kaolin to a 35% w / v oxalic acid solution, stir at 300 rpm for 30 min, centrifuge and wash to obtain amino-carboxyl co-intercalated kaolin, the intercalation rate of amino groups is 58%, and the intercalation rate of carboxyl groups is 75%.

[0078] Test Example 4

[0079] Removal efficiency of thallium by adsorbents prepared in Test Examples 1-3 and Comparative Examples 1-3.

[0080] Specific method: Add thallium-containing wastewater with a thallium concentration of 20 μg / L and an initial pH = 7 into a 100 mL centrifuge tube. Under the condition of 25 °C, add the adsorbents prepared in Examples 1-3 and Comparative Examples 1-3 respectively, with a dosage of 0.6 g / L. After shaking at 150 rpm for 30 min, take samples and test the removal rate of thallium. The results are shown in Table 5.

[0081] Table 5

[0082] Group Removal rate of thallium / % Example 1 99.5 Example 2 99.3 Example 3 99.2 Comparative Example 1 45.5 Comparative Example 2 30.6 Comparative Example 3 65.7

[0083] As can be seen from Table 5, the adsorbents prepared in Examples 1-3 of the present invention have good effects on removing thallium ions, while the removal effects of the adsorbents prepared in Comparative Examples 1-3 on thallium ions have significantly decreased.

[0084] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An adsorbent for purifying thallium-containing wastewater, characterized in that, The adsorbent is an intercalated kaolin-sodium alginate aerogel composite.

2. The adsorbent for purifying thallium-containing wastewater according to claim 1, characterized in that, The intercalated kaolin in the intercalated kaolin-sodium alginate aerogel composite is amino-carboxyl intercalated kaolin, where the intercalation rate of amino groups is 55%-60%, and the intercalation rate of carboxyl groups is 70%-80%.

3. The adsorbent for purifying thallium-containing wastewater according to claim 2, wherein, The preparation of the intercalated kaolin-sodium alginate aerogel composite includes the following steps: (1) Add kaolin from which crystal water has been removed to an aqueous solution of dimethyl sulfoxide, stir, centrifuge and wash to obtain a precursor; (2) Add the precursor to an ethanol solution, stir, add 3-aminopropyltriethoxysilane to react, and at the same time adjust the pH to 8-9, centrifuge and wash to prepare amino-intercalated kaolin; (3) Add the amino-intercalated kaolin to an oxalic acid solution, stir, centrifuge and wash to obtain amino-carboxyl intercalated kaolin; (4) Mix the amino-carboxyl intercalated kaolin and the sodium alginate solution, stir ultrasonically, and freeze-dry to obtain an intercalated kaolin-sodium alginate aerogel composite.

4. The adsorbent for purifying thallium-containing wastewater according to claim 3, characterized in that, In step (1), the solid-liquid ratio of the kaolin to the aqueous solution of dimethyl sulfoxide is 1:30-40 g / mL; the volume ratio of dimethyl sulfoxide to water in the aqueous solution of dimethyl sulfoxide is 1:8-10; the stirring speed is 100-200 rpm, and the time is 30-40 min.

5. The adsorbent for purifying thallium-containing wastewater according to claim 3, characterized in that, In step (2), the solid-liquid ratio of the precursor to the ethanol solution is 1:6-10 g / mL; the concentration of the ethanol solution is 60%-70% v / v; the mass ratio of 3-aminopropyltriethoxysilane to the precursor is 0.2-0.4:1; the reaction is carried out at 50-60 °C for 6-10 h.

6. The adsorbent for purifying thallium-containing wastewater according to claim 3, characterized in that, In step (3), the solid-liquid ratio of the amino-intercalated kaolin to the oxalic acid solution is 1:10-15 g / mL; the concentration of the oxalic acid solution is 30%-40% w / v; the stirring speed is 250-350 rpm, and the time is 20-40 min.

7. The adsorbent for purifying thallium-containing wastewater according to claim 3, characterized in that, In step (4), the mass ratio of the amino-carboxyl intercalated kaolin to the sodium alginate solution is 1:2-4; the concentration of the sodium alginate solution is 20%-30% w / v; the ultrasonic stirring is carried out at 20-30 kHz and 40-60 °C for 1-3 h.

8. The application of the adsorbent according to any one of claims 1-7 in purifying thallium-containing wastewater.

9. The application according to claim 8, wherein When the adsorbent is used to purify thallium-containing wastewater, add the adsorbent to the thallium-containing wastewater and oscillate for adsorption.

10. The application according to claim 9, characterized in that, The speed of the oscillating adsorption is 100-200 rpm, and the time is 30-60 min.

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