Adsorbent for purification of thallium-containing wastewater and application thereof

Abstract

The application provides an adsorbent for purifying wastewater containing thallium and application thereof, and the adsorbent is a co-intercalated kaolin-sodium alginate aerogel compound, and a preparation method thereof comprises the following steps: (1) stirring kaolin from which crystal water is removed in dimethyl sulfoxide water solution, centrifuging and washing to obtain a precursor; (2) stirring the precursor in ethanol solution, adding 3-aminopropyl triethoxysilane to react, adjusting pH to 8-9 at the same time, centrifuging and washing to prepare amino-intercalated kaolin; (3) stirring the amino-intercalated kaolin in oxalic acid solution, centrifuging and washing to obtain amino-carboxyl co-intercalated kaolin; and (4) mixing the amino-carboxyl co-intercalated kaolin and sodium alginate solution, ultrasonic stirring and freeze-drying to obtain the product. The adsorbent 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 application relates to the technical field of wastewater treatment, in particular to an adsorbent for purifying wastewater containing thallium and application thereof. BACKGROUND

[0002] The main sources of thallium pollution are natural and man-made emissions. Low content of thallium can cause serious harm to the ecosystem. Thallium has great biological toxicity to the human body, which can inactivate the potassium ion transport pump protein on the cell membrane, disrupt the body's metabolic function, and accumulate in the human body's bones, kidneys and nervous system along the food chain. It is generally believed that 1.5mg / L of thallium can cause death. If the concentration of thallium in industrial wastewater containing thallium exceeds 5mg / L, the thallium must be removed and purified.

[0003] Common treatment methods such as precipitation method, oxidation method, ion exchange method and membrane separation method have certain thallium removal effect, but generally have the characteristics of high cost, much waste residue and high energy consumption. The adsorption method has great application prospect in the field of water treatment due to high adsorption capacity, fast adsorption rate and easy recycling. Therefore, the adsorption method is considered as one of the most effective means for removing thallium from industrial wastewater containing thallium. However, the current adsorption material is easy to agglomerate, has poor regeneration performance, unsatisfactory adsorption efficiency, large amount of adsorbent used and high cost, which limits the development of thallium-containing wastewater purification industry. SUMMARY

[0004] In view of this, the present application provides an adsorbent for purifying wastewater containing thallium and application thereof.

[0005] The technical scheme of the present application is as follows:

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

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

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

[0009] (1) stirring kaolin with removed crystal water in dimethyl sulfoxide aqueous solution, centrifugal washing to obtain a precursor;

[0010] (2) stirring the precursor in ethanol solution, adding 3-aminopropyl triethoxysilane to react while adjusting pH to 8-9, centrifugal washing to prepare amino-intercalated kaolin;

[0011] (3) stirring the amino-intercalated kaolin into oxalic acid solution, centrifugal washing to obtain amino-carboxyl co-intercalated kaolin;

[0012] (4) mixing the amino-carboxyl co-intercalated kaolin and sodium alginate solution, ultrasonic stirring, freeze-drying to obtain co-intercalated kaolin-sodium alginate aerogel composite.

[0013] Further, in step (1), the solid-liquid ratio of the kaolin and 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 stirring speed is 100-200 rpm, and the time is 30-40 min.

[0014] Further, in step (2), the solid-liquid ratio of the precursor and 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-aminopropyl triethoxysilane to the precursor is 0.2-0.4:1; the reaction is carried out at 50-60℃ for 6-10 h.

[0015] Further, in step (3), the solid-liquid ratio of the amino-intercalated kaolin and 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.

[0016] Further, in step (4), the mass ratio of the amino-carboxyl co-intercalated kaolin and 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, 40-60℃ for 1-3 h.

[0017] The adsorbent is used for purifying thallium-containing wastewater.

[0018] Further, when the adsorbent is used for purifying thallium-containing wastewater, the adsorbent is added into the thallium-containing wastewater, and oscillation adsorption is carried out.

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

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] 1.The co-intercalated kaolinite-sodium alginate aerogel composite of the present application can not only expand the interlayer spacing, but also provide adsorption sites by co-intercalating amino and carboxyl groups in the interlayer spacing of kaolinite, realizing selective adsorption of thallium ions. By inserting the co-intercalated kaolinite into the network of the sodium alginate aerogel, a rigid-flexible network structure is formed, which can not only improve the stability of the adsorbent, but also increase the affinity with thallium ions, both of which synergistically increase the adsorption sites, realize rapid capture of thallium ions, and deep purification of thallium ions. It has been verified by examples that the co-intercalated kaolinite-sodium alginate aerogel composite adsorbent of the present application is not only suitable for 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 kaolinite-sodium alginate aerogel composite of the present application is applied in the field of purifying thallium-containing wastewater, has high adsorption capacity, significantly improves the treatment effect of thallium-containing wastewater, is convenient to recover, has good stability, good regeneration performance, and has good application prospect in the field of purifying thallium-containing wastewater. DETAILED DESCRIPTION

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

[0024] The experimental methods used in the examples of the present application are all conventional methods unless otherwise specified.

[0025] The materials, reagents, etc. used in the examples of the present application can be obtained from commercial channels unless otherwise specified.

[0026] Example 1

[0027] The co-intercalated kaolinite-sodium alginate aerogel composite adsorbent for purifying thallium-containing wastewater of the present embodiment has a preparation method comprising the following steps:

[0028] (1) According to the solid-liquid ratio of 1:35 g / mL, the kaolinite with removed crystal water is added into the dimethyl sulfoxide aqueous solution (the volume ratio of dimethyl sulfoxide to water is 1:9), stirred at 150 rpm for 35 min, centrifuged and washed to obtain a precursor;

[0029] (2) According to the solid-liquid ratio of 1:8 g / mL, the precursor is added into the 65% v / v ethanol solution and stirred for 30 min, 3-aminopropyl triethoxysilane is added, the mass ratio of 3-aminopropyl triethoxysilane to the precursor is 0.3:1, the pH is adjusted to 8.5±0.5 at the same time, and the product is reacted at 55℃ for 8 h, and then the product is centrifuged and washed to obtain the amino-intercalated kaolinite;

[0030] (3) According to the solid-liquid ratio of 1: 13 g / mL, the amino intercalated kaolin is added into 35% w / v oxalic acid solution, stirred at 300 rpm for 30 min, centrifuged and washed to obtain the amino-carboxyl co-intercalated kaolin, the intercalation rate of amino is 58%, and the intercalation rate of carboxyl is 75%;

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

[0032] Example 2

[0033] The preparation method of the co-intercalated kaolin-sodium alginate aerogel composite adsorbent for purification of thallium-containing wastewater in this embodiment comprises the following steps:

[0034] (1) According to the solid-liquid ratio of 1:30 g / mL, the kaolin with removed crystal water is added into dimethyl sulfoxide aqueous solution (the volume ratio of dimethyl sulfoxide to water is 1:8), stirred at 100 rpm for 30 min, centrifuged and washed to obtain the precursor;

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

[0036] (3) According to the solid-liquid ratio of 1:10 g / mL, the amino intercalated kaolin is added into 30% w / v oxalic acid solution, stirred at 250 rpm for 20 min, centrifuged and washed to obtain the amino-carboxyl co-intercalated kaolin, the intercalation rate of amino is 55%, and the intercalation rate of carboxyl is 70%;

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

[0038] Example 3

[0039] The preparation method of the co-intercalated kaolin-sodium alginate aerogel composite adsorbent for purification of thallium-containing wastewater in this embodiment comprises the following steps:

[0040] (1) According to the solid-liquid ratio 1:40 g / mL, the dehydrated kaolin is added into the dimethyl sulfoxide aqueous solution (the volume ratio of dimethyl sulfoxide to water is 1:10), stirred at 200 rpm for 40 min, centrifuged and washed, and dried to obtain the precursor;

[0041] (2) According to the solid-liquid ratio 1:10 g / mL, the precursor is added into the 70% v / v ethanol solution, stirred for 30 min, 3-aminopropyl triethoxysilane is added, the mass ratio of 3-aminopropyl triethoxysilane to the precursor is 0.4:1, and the pH is adjusted to 8.5±0.5, and the reaction is carried out at 60°C for 10 h. The product is centrifuged and washed to obtain the amino-intercalated kaolin;

[0042] (3) According to the solid-liquid ratio 1:15 g / mL, the amino-intercalated kaolin is added into the 40% w / v oxalic acid solution, stirred at 350 rpm for 40 min, and centrifuged and washed to obtain the amino-carboxyl co-intercalated kaolin, the intercalation rate of amino is 60%, and the intercalation rate of carboxyl is 80%;

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

[0044] Test Example 1-Influence of different initial pH of thallium-containing wastewater on adsorption of thallium by adsorbent

[0045] The thallium-containing wastewater with a thallium concentration of 20 μg / L and an initial pH of 4, 5, 6, 7, 8, and 9 is treated by adding the adsorbent prepared in Example 1 under the condition of 25°C, the dosage is 0.6 g / L, and the sample is taken after oscillation at 150 rpm for 30 min, and the removal rate of thallium is tested, and the results are shown in Table 1.

[0046] Table 1

[0047]

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

[0049] Test Example 2-Influence of different initial thallium concentrations of thallium-containing wastewater on adsorption of thallium by adsorbent

[0050] 1. 30 mL of thallium-containing wastewater with a thallium concentration of 1, 5, 10, 20, 50, 80, and 100 μg / L and an initial pH of 7 is treated, respectively, the adsorbent prepared in Example 1 is added under the condition of 25°C, the dosage is 18 mg, and the sample is taken after oscillation at 150 rpm for 60 min, and the removal rate of thallium is tested, and the results are shown in Table 2.

[0051] Table 2

[0052]

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

[0054] 2. Respectively treat 30 mL of thallium-containing wastewater with thallium concentration of 1, 5, 10, 20, 50, 80, 100 mg / L and initial pH = 7, add the adsorbent prepared in Example 1 under the condition of 25℃, the dosage is 18 mg, take sample after oscillation at 150 rpm for 60 min, test the removal rate of thallium, and 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 in the application on thallium in wastewater with different initial thallium concentrations is not the same, 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 removal rate of thallium decreases, and the adsorption gradually saturates. Therefore, the adsorbent prepared in Example 1 of the application can be applied to treat trace thallium (1-10 mg / L) in water bodies.

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

[0059] Treat thallium-containing wastewater with thallium concentration of 20 μg / L and initial pH = 7, add the adsorbent prepared in Example 1 under the condition of 25℃, the dosage is 0.2, 0.4, 0.6, 0.8, 1.0 g / L, take sample after oscillation at 150 rpm for 30 min, test the removal rate of thallium, and the results are shown in Table 4.

[0060] Table 4

[0061]

[0062] As can be seen from Table 4, with the increase of the dosage of the adsorbent prepared in Example 1 of the application, the removal rate of thallium increases, when the dosage is greater than 0.8 g / L, the adsorption efficiency slightly decreases, but is all 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 intercalated kaolin is replaced by dimethyl sulfoxide intercalated kaolin, and the others are the same as Example 1.

[0065] The preparation method of the adsorbent for purifying wastewater containing thallium in the present comparative example comprises:

[0066] (1) The kaolin with removed crystal water was added into the dimethyl sulfoxide aqueous solution (the volume ratio of dimethyl sulfoxide to water was 1:9) according to the solid-liquid ratio of 1:35 g / mL, stirred at 150 rpm for 35 min, centrifuged and washed, and dried to obtain the dimethyl sulfoxide intercalated kaolin;

[0067] (2) The dimethyl sulfoxide intercalated kaolin and the 25% w / v sodium alginate solution were mixed according to the mass ratio of 1:3, ultrasonically treated at 25 kHz and 50°C for 2 h, and freeze-dried to obtain the target adsorbent.

[0068] Comparative Example 2

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

[0070] The preparation method of the adsorbent for purifying wastewater containing thallium in the present comparative example comprises:

[0071] The 25% w / v sodium alginate solution was ultrasonically treated at 25 kHz and 50°C for 2 h, and freeze-dried to obtain the target adsorbent.

[0072] Comparative Example 3

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

[0074] The preparation method of the adsorbent for purifying wastewater containing thallium in the present comparative example comprises:

[0075] (1) The kaolin with removed crystal water was added into the dimethyl sulfoxide aqueous solution (the volume ratio of dimethyl sulfoxide to water was 1:9) according to the solid-liquid ratio of 1:35 g / mL, stirred at 150 rpm for 35 min, centrifuged and washed, and dried to obtain the dimethyl sulfoxide intercalated kaolin;

[0076] (2) The precursor was added into the 65% v / v ethanol solution according to the solid-liquid ratio of 1:8 g / mL, stirred for 30 min, 3-aminopropyl triethoxysilane was added, the mass ratio of 3-aminopropyl triethoxysilane to the precursor was 0.3:1, the pH was adjusted to 8.5±0.5, and the reaction was carried out at 55°C for 8 h, and the product was centrifuged and washed to obtain the amino intercalated kaolin;

[0077] (3) The amino intercalated kaolin was added into the 35% w / v oxalic acid solution according to the solid-liquid ratio of 1:13 g / mL, stirred at 300 rpm for 30 min, and centrifuged and washed to obtain the amino-carboxyl co-intercalated kaolin, the intercalation rate of the amino group was 58%, and the intercalation rate of the carboxyl group was 75%.

[0078] Test Example 4

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

[0080] Specific method: thallium-containing wastewater with a thallium concentration of 20 μg / L and an initial pH of 7 was added into a 100 mL centrifuge tube, and the adsorbents prepared in Examples 1-3 and Comparative Examples 1-3 were added at a dosage of 0.6 g / L under the condition of 25°C, and the sample was taken after oscillation at 150 rpm for 30 min, and the removal rate of thallium was tested, and 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 application have good effect of removing thallium ions, and the removal effect of thallium ions by the adsorbents prepared in Comparative Examples 1-3 is obviously decreased.

[0084] The above description is merely preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An adsorbent for purification of thallium-containing wastewater, characterized by, The adsorbent is a co-intercalated kaolin-sodium alginate aerogel composite; The intercalated kaolin in the co-intercalated kaolin-sodium alginate aerogel composite is amino-carboxyl co-intercalated kaolin, wherein the intercalation rate of amino is 55%-60%, and the intercalation rate of carboxyl is 70%-80%; The preparation of the co-intercalated kaolin-sodium alginate aerogel composite comprises the following steps: (1) stirring kaolin with removed crystal water in dimethyl sulfoxide aqueous solution, centrifugal washing to obtain a precursor; (2) stirring the precursor in ethanol solution, adding 3-aminopropyl triethoxysilane and adjusting pH to 8-9, centrifugal washing to obtain amino-intercalated kaolin; (3) stirring the amino-intercalated kaolin in oxalic acid solution, centrifugal washing to obtain amino-carboxyl co-intercalated kaolin; (4) mixing the amino-carboxyl co-intercalated kaolin and sodium alginate solution, ultrasonic stirring, freeze-drying to obtain the co-intercalated kaolin-sodium alginate aerogel composite.

2. The adsorbent for purification of thallium-containing wastewater according to claim 1, characterized by, 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 stirring speed is 100-200 rpm, and the stirring time is 30-40 min.

3. The adsorbent for purification of thallium-containing wastewater according to claim 1, characterized by, 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-aminopropyl triethoxysilane to the precursor is 0.2-0.4:1; the reaction is carried out at 50-60℃ for 6-10 h.

4. The adsorbent for purification of thallium-containing wastewater according to claim 1, wherein 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 stirring time is 20-40 min.

5. The adsorbent for purification of thallium-containing wastewater as claimed in claim 1, wherein 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℃ for 1-3 h.

6. The adsorbent according to any one of claims 1-5 for purifying wastewater containing thallium.

7. Use according to claim 6, wherein When the adsorbent is used for purifying wastewater containing thallium, the adsorbent is added to the wastewater containing thallium, and then oscillation adsorption is carried out.

8. Use according to claim 7, wherein the compound is ###0002### The oscillation adsorption is carried out at a speed of 100-200 rpm for 30-60 min.

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