Composite rare earth modified aluminum oxide fluorine removal agent as well as preparation method and application thereof

Abstract

The invention discloses a composite rare earth modified aluminum oxide fluorine removal agent as well as a preparation method and application thereof, and belongs to the technical field of wastewater treatment. The preparation method comprises the following steps: dipping Al2O3 powder into a rare earth nitrate solution, oscillating at constant temperature, filtering, washing, drying, grinding and sieving to obtain the composite rare earth modified aluminum oxide fluorine removal agent; the rare earth nitrate solution contains two or more rare earth nitrates. The rare earth nitrate solution is adopted to modify aluminum oxide, and active sites on the surface of the aluminum oxide are increased due to loading of rare earth metal elements, so that the chemical affinity of the aluminum oxide and fluorine ions is improved, the adsorption capacity of the aluminum oxide fluorine removal agent to the fluorine ions is improved, and the service life of the aluminum oxide fluorine removal agent is prolonged. Finally, the purpose of improving the fluorine removal efficiency and the fluorine removal capacity of the aluminum oxide fluorine removal agent is achieved, and meanwhile toxic and harmful chemical substances cannot be introduced into water.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a composite rare earth modified alumina defluorinating agent, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, new generation information technology industries such as integrated circuit manufacturing have developed rapidly. Due to the hydrofluoric acid and ammonium fluoride etching processes in the production process, a large amount of fluorine-containing wastewater is generated. Fluorine-containing wastewater is highly harmful to the human body. Long-term intake of fluorine elements will cause health problems such as dental fluorosis and skeletal fluorosis in the human body. At the same time, various environmental protection standards are becoming increasingly strict. Therefore, for the fluorine-containing wastewater generated by the electronics industry, it must be deeply and effectively treated before it can be discharged into the environmental water body.

[0003] Current industrial defluorination methods mainly include precipitation method, electrochemistry method, ion exchange method, adsorption method, etc. Among them, the precipitation method has a low treatment efficiency, and the generated fluorine-containing sludge belongs to solid waste, which not only cannot be recycled but also is difficult to dispose of. The electrochemistry method has the characteristics of environmental friendliness, but the treatment cost is generally high, and the economic burden on enterprises is large. The ion exchange method is affected by common ions in water, is difficult to apply to actual wastewater, and the exchange column needs to be backwashed regularly, further increasing the complexity of the treatment process. The adsorption method has great application space in the field of industrial wastewater defluorination due to its good treatment effect, simple operation, and easy preparation of adsorbents. Although the adsorption method has many advantages, problems such as adsorption capacity and adsorbent stability are still important factors restricting its industrial application. At the same time, existing adsorbents such as polyacrylamide will introduce other toxic and harmful chemical substances such as polyacrylamide into the water.

[0004] Therefore, there is an urgent need for an adsorbent with high defluorination efficiency, large defluorination capacity, and no introduction of toxic and harmful chemical substances into the water to solve the above problems. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a composite rare earth modified alumina defluorinating agent, a preparation method thereof, and an application thereof.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method of a composite rare earth modified alumina defluorinating agent, comprising the following steps:

[0008] Immerse Al2O3 powder into a rare earth nitrate solution at a solid-liquid ratio of 0.2 - 1.0 g / L, and obtain the composite rare earth modified alumina defluorinating agent through constant temperature oscillation, filtration, washing, drying, grinding, and sieving;

[0009] The rare earth nitrate solution contains two or more rare earth nitrates.

[0010] Preferably, the rare earth nitrate in the rare earth nitrate solution is two or more of La(NO3)3·6H2O, Ce(NO3)3·6H2O, and Pr(NO3)3·6H2O.

[0011] Preferably, the concentration of the rare earth nitrate solution is 0.1 - 0.3 mol / L.

[0012] Preferably, the rare earth nitrate in the rare earth nitrate solution is La(NO3)3·6H2O and Ce(NO3)3·6H2O.

[0013] Preferably, the preparation method of the Al2O3 powder includes the following steps: pulverize Al2O3 and then pass through a 60 - mesh sieve to obtain the Al2O3 powder.

[0014] Preferably, the temperature of the constant - temperature oscillation is room temperature, the oscillation rate is 80 - 100 r / min, and the time is 2 - 3 h.

[0015] Preferably, the drying temperature is 105 - 120 °C and the time is 12 - 15 h; and / or,

[0016] The sieving is through a 40 - 60 - mesh sieve.

[0017] The present invention provides a composite rare earth - modified alumina defluorinating agent prepared by the preparation method described in the above technical solution.

[0018] The present invention also provides the application of the composite rare earth - modified alumina defluorinating agent described in the above technical solution in treating fluorine - containing wastewater.

[0019] Preferably, the application of the composite rare earth - modified alumina defluorinating agent in treating fluorine - containing wastewater includes the following steps: adjust the pH of the fluorine - containing wastewater to 6 - 7, then add the composite rare earth - modified alumina defluorinating agent for reaction to complete defluorination.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] The present invention modifies the alumina adsorbent with rare earth elements, improving the defluorination efficiency and defluorination capacity of alumina. Due to the loading of rare earth metals, the active sites on the surface of alumina increase, improving the chemical affinity with fluoride ions, thereby enhancing the adsorption ability for fluoride ions. Moreover, the process for preparing the defluorinating agent in the present invention is simple and suitable for the efficient treatment of fluorine - containing wastewater generated in the actual industrial production process.

[0022] The present invention uses easily available raw materials and a simple modification method. The prepared defluorinating agent has a strong directional adsorption ability for fluoride ions, and can effectively capture and remove fluoride ions in water. In addition, the defluorinating agent provided by the present invention has a simple usage method, does not require complex reactors or structures, and is particularly suitable for industrial wastewater treatment scenarios. The simple operation saves labor and improves economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 It is a process flow chart of the preparation method of the composite rare earth modified alumina defluorinating agent in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0027] The embodiments of the present invention provide a preparation method of a composite rare earth modified alumina defluorinating agent, including the following steps:

[0028] Immerse the Al2O3 powder in the rare earth nitrate solution at a solid-liquid ratio of 0.2 - 1.0 g / L, and obtain the composite rare earth modified alumina defluorinating agent through constant temperature oscillation, filtration, washing, drying, grinding, and sieving;

[0029] The rare earth nitrate solution contains two or more rare earth nitrates.

[0030] The present invention modifies alumina with a rare earth nitrate solution. Due to the loading of rare earth metal elements, the active sites on the surface of alumina increase, thereby improving the chemical affinity of alumina with fluoride ions, and thus improving the adsorption ability of the alumina defluorinating agent for fluoride ions, and finally achieving the purpose of improving the defluorination efficiency and defluorination capacity of the alumina defluorinating agent.

[0031] In a preferred embodiment, the solid-liquid ratio of the Al2O3 powder and the rare earth nitrate solution is 0.2 to 1.0 g / L, more preferably 0.2 to 0.5 g / L. The solid-liquid ratio of the Al2O3 powder and the rare earth nitrate solution affects the modification effect. If the solid-liquid ratio is too low, that is, the amount of the rare earth nitrate solution is low, the modification effect is not obvious, and the purpose of improving the defluorination efficiency and defluorination capacity of the alumina defluorinating agent cannot be achieved; while if the solid-liquid ratio is too high, that is, the amount of the rare earth nitrate solution is high, too much rare earth metal element will be loaded on the surface of the alumina, which will affect the defluorination effect of the alumina defluorinating agent.

[0032] In a preferred embodiment, the rare earth nitrate in the rare earth nitrate solution is two or more of La(NO3)3·6H2O, Ce(NO3)3·6H2O, and Pr(NO3)3·6H2O; exemplarily, in a preferred embodiment of the present invention, the rare earth nitrate in the rare earth nitrate solution is La(NO3)3·6H2O and Ce(NO3)3·6H2O. The present invention uses two or more rare earth elements to synergistically modify Al2O3, which is more beneficial to improving the defluorination effect of the defluorinating agent compared with the method of modifying with a single rare earth element.

[0033] In a preferred embodiment, when the rare earth nitrate in the rare earth nitrate solution is La(NO3)3·6H2O and Ce(NO3)3·6H2O, the molar ratio of La(NO3)3·6H2O to Ce(NO3)3·6H2O is (2 to 4):1.

[0034] In a preferred embodiment, the concentration of the rare earth nitrate solution is 0.1 to 0.3 mol / L.

[0035] In a preferred embodiment, the preparation method of the Al2O3 powder comprises the following steps: pulverize the Al2O3 and then pass it through a 60-mesh sieve to obtain the Al2O3 powder.

[0036] In a preferred embodiment, the Al2O3 is α-Al2O3.

[0037] In a preferred embodiment, the temperature of the constant-temperature oscillation is room temperature, the oscillation rate is 80 to 100 r / min, and the time is 2 to 3 h. The present invention performs constant-temperature oscillation at a certain rate, realizing the full modification of Al2O3 by rare earth elements and shortening the oscillation time at the same time.

[0038] In a preferred embodiment, the filtration method is suction filtration.

[0039] In a preferred embodiment, the washing is performed 3 to 5 times with ultrapure water.

[0040] In a preferred embodiment, the drying temperature is 105 to 120 °C and the time is 12 to 15 h.

[0041] In a preferred embodiment, the rotation speed of the grinding is 80 to 100 rpm and the time is 2 min. By grinding in the present invention, the particle size of the composite rare earth modified alumina defluorinating agent is reduced.

[0042] In a preferred embodiment, the sieving is through a 40-60 mesh sieve. By sieving in the present invention, a composite rare earth modified alumina defluorinating agent with a particle size of 40-60 mesh is obtained. The smaller particle size is beneficial to improving the activity of the defluorinating agent, and thus improves the adsorption capacity of the defluorinating agent for fluoride ions.

[0043] The present invention provides a composite rare earth modified alumina defluorinating agent prepared by the preparation method described in the above technical solution.

[0044] In a preferred embodiment, the particle size of the composite rare earth modified alumina defluorinating agent is 40-60 mesh.

[0045] The present invention also provides an application of the composite rare earth modified alumina defluorinating agent described in the above technical solution in treating fluorine-containing wastewater.

[0046] In a preferred embodiment, the application of the composite rare earth modified alumina defluorinating agent in treating fluorine-containing wastewater includes the following steps: adjusting the pH of the fluorine-containing wastewater to 6-7, and then adding the composite rare earth modified alumina defluorinating agent for reaction to complete defluorination.

[0047] In a preferred embodiment, the dosage of the composite rare earth modified alumina defluorinating agent is 0.2-0.5 g / 200 mL; the concentration of fluoride ions in the fluorine-containing wastewater is 5-50 mg / L.

[0048] In a preferred embodiment, the reaction time is 15-120 min, and more preferably 60-120 min.

[0049] In the examples of the present invention, room temperature refers to "25 ± 2 °C".

[0050] Unless otherwise specified, the raw materials in the examples of the present invention are all obtained through commercial channels.

[0051] Example 1

[0052] A preparation method of a composite rare earth modified alumina defluorinating agent, the process flow is shown in Figure 1 , and the specific steps are as follows:

[0053] (1) After pulverizing α-Al2O3, sieve it through a 60-mesh sieve to obtain α-Al2O3 powder;

[0054] (2) The α-Al2O3 powder obtained in step (1) was impregnated into a rare earth nitrate solution with a concentration of 1 mol / L at a solid-liquid ratio of 0.2 g / L (the rare earth nitrate in the rare earth nitrate solution was La(NO3)3·6H2O and Ce(NO3)3·6H2O, and the molar ratio of La(NO3)3·6H2O to Ce(NO3)3·6H2O was 2:1). It was constantly shaken at a shaking rate of 80 r / min at room temperature for 2 h, then filtered by suction. The obtained solid was washed 3 - 5 times with ultrapure water, then dried at 105 °C for 12 h, subsequently ground at a rotation speed of 100 rpm for 2 min, and passed through a 60-mesh sieve to obtain a rare earth composite modified alumina defluorination agent, denoted as La-Ce@Al2O3.

[0055] Comparative Example 1

[0056] The difference from Example 1 was that in step (2), the rare earth nitrate in the rare earth nitrate solution was Ce(NO3)3·6H2O, and the others were the same as in Example 1, denoted as Ce@Al2O3.

[0057] Comparative Example 2

[0058] The difference from Example 1 was that in step (2), the rare earth nitrate in the rare earth nitrate solution was La(NO3)3·6H2O, and the others were the same as in Example 1, denoted as La@Al2O3.

[0059] Comparative Example 3

[0060] The difference from Example 1 was that in step (2), the molar ratio of La(NO3)3·6H2O to Ce(NO3)3·6H2O was 1:3, and the others were the same as in Example 1.

[0061] Comparative Example 4

[0062] The difference from Example 1 was that in step (2), the α-Al2O3 powder obtained in step (1) was impregnated into a rare earth nitrate solution with a concentration of 1 mol / L at a solid-liquid ratio of 1 g / L, and the others were the same as in Example 1.

[0063] Comparative Example 5

[0064] The difference from Example 1 was that in step (2), the α-Al2O3 powder obtained in step (1) was impregnated into a rare earth nitrate solution with a concentration of 1 mol / L at a solid-liquid ratio of 0.05 g / L, and the others were the same as in Example 1.

[0065] Comparative Example 6

[0066] The difference from Example 1 is that in step (2), the rare earth nitrate in the rare earth nitrate solution is Nd(NO3)3·5H2O and Ce(NO3)3·6H2O, and the molar ratio of Nd(NO3)3·5H2O to Ce(NO3)3·6H2O is 2:1. Other conditions are the same as those in Example 1, denoted as Nd-Ce@Al2O3.

[0067] Application Example 1

[0068] Prepare fluoride-containing wastewater with NaF, and set the initial fluoride ion concentrations to 50 mg / L, 25 mg / L, 20 mg / L, 15 mg / L, 10 mg / L, and 5 mg / L respectively. Take 200 mL of fluoride-containing wastewater with different concentrations, adjust the pH to 6, and then add 0.5 g of the α-Al2O3 powder in step (1) of Example 1, La-Ce@Al2O3 prepared in Example 1, Ce@Al2O3 prepared in Comparative Example 1, La@Al2O3 prepared in Comparative Example 2, and Nd-Ce@Al2O3 prepared in Comparative Example 6 to them respectively. React at room temperature for 90 min, and measure the remaining fluoride ion concentration in the fluoride-containing wastewater. The results are shown in Table 1.

[0069] Table 1 Defluorination effects of α-Al2O3 powder, the defluorinating agents prepared in Example 1 and Comparative Examples 1-2, and Comparative Example 6 at different initial fluoride ion concentrations

[0070]

[0071] As can be seen from Table 1, in Example 1, La and Ce were used to compound and modify Al2O3, and the defluorination effect was good. However, if α-Al2O3 was not modified or modified with a single rare earth element, the defluorination effect would be reduced.

[0072] Application Example 2

[0073] Prepare fluoride-containing wastewater with an initial fluoride ion concentration of 20 mg / L using NaF, adjust the pH to 6, and then add 0.5 g of La-Ce@Al2O3 prepared in Example 1, Ce@Al2O3 prepared in Comparative Example 1, and La@Al2O3 prepared in Comparative Example 2 to 200 mL of the above-mentioned fluoride-containing wastewater respectively. React at room temperature for 5 min, 30 min, 60 min, 90 min, and 120 min respectively, and measure the remaining fluoride ion concentration in the fluoride-containing wastewater. The results are shown in Table 2.

[0074] Table 2 Defluorination effects of the defluorinating agents prepared in Example 1 and Comparative Examples 1-2 at different reaction times

[0075]

[0076]

[0077] As can be seen from Table 2, under different reaction times, the La-Ce@Al2O3 prepared in Example 1 still exhibits better defluorination performance than the single rare earth modified alumina defluoridants prepared in Comparative Examples 1 and 2.

[0078] Application Example 3

[0079] NaF was used to prepare fluorine-containing wastewater with an initial fluoride ion concentration of 20 mg / L, and the pH was adjusted to 6 and 7, respectively. Then, 0.2 g of the composite rare earth modified alumina defluoridant La-Ce@Al2O3 prepared in Example 1 was added to 200 mL of the above fluorine-containing wastewater. The reaction was carried out at room temperature for 90 minutes. The residual fluoride ion concentration of the fluorine-containing wastewater was measured. The results are shown in Table 3.

[0080] Comparative Application Example 3

[0081] NaF was used to prepare fluorine-containing wastewater with an initial fluoride ion concentration of 20 mg / L, and the pH was adjusted to 5, 8, 9, and 10, respectively. Then, 0.2 g of the composite rare earth modified alumina defluoridant La-Ce@Al2O3 prepared in Example 1 was added to 200 mL of the above fluorine-containing wastewater. The reaction was carried out at room temperature for 90 minutes, and the residual fluoride ion concentration of the fluorine-containing wastewater was measured. The results are shown in Table 3.

[0082] Table 3 Fluoride removal effect of the defluoridation agent prepared in Example 1 at different pH values

[0083] pH of fluorine-containing wastewater Residual fluoride ion concentration / mg / L 6 1.57 7 2.18 5 3.21 8 2.79 9 3.26 10 3.94

[0084] As can be seen from Table 3, the pH of fluorine-containing wastewater will also affect the defluoridation effect. When the pH of fluorine-containing wastewater is 6-7, the concentration of residual fluoride ions after the reaction is low, and the defluoridation effect is better. When the pH of fluorine-containing wastewater is lower than 6 or higher than 7, the defluoridation effect will deteriorate.

[0085] Comparative Application Example 4

[0086] NaF was used to prepare fluorine-containing wastewater with an initial fluoride ion concentration of 20 mg / L, and the pH was adjusted to 6. Then, 0.2 g of the defluoridating agent prepared in Comparative Examples 3 to 5 was added to 200 mL of the above fluorine-containing wastewater, and the reaction was carried out at room temperature for 90 minutes. The residual fluoride ion concentration of the fluorine-containing wastewater was measured. The results are shown in Table 4.

[0087] Table 4 Fluoride removal effect of the defluoridation agents prepared in Comparative Examples 3 to 5

[0088] Fluoride remover Residual fluoride ion concentration / mg / L Comparative example 3 1.71 Comparative example 4 1.95 Comparative example 5 1.86

[0089] As can be seen from Table 4, compared with Example 1, in Comparative Example 3, the molar ratio of La(NO3)3·6H2O and Ce(NO3)3·6H2O was changed, and the defluorination effect was reduced; in Comparative Example 4 and Comparative Example 5, the solid-liquid ratio of Al2O3 powder and rare earth nitrate solution was changed, and the defluorination effect was also reduced.

[0090] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A preparation method of a composite rare earth modified alumina defluorinating agent, characterized in that, It includes the following steps: Impregnate Al2O3 powder into the rare earth nitrate solution at a solid-liquid ratio of 0.2 - 1.0 g / L, and obtain the composite rare earth modified alumina defluorinating agent through constant temperature oscillation, filtration, washing, drying, grinding and sieving. The rare earth nitrate solution contains two or more rare earth nitrates.

2. The preparation method of the composite rare earth modified alumina defluorinating agent according to claim 1, characterized in that, The rare earth nitrates in the rare earth nitrate solution are two or more of La(NO3)3·6H2O, Ce(NO3)3·6H2O, Pr(NO3)3·6H2O.

3. The preparation method of the composite rare earth modified alumina defluorination agent according to claim 1, characterized in that, The concentration of the rare earth nitrate solution is 0.1 - 0.3 mol / L.

4. The preparation method of the composite rare earth modified alumina defluorinating agent according to claim 1, characterized in that, The rare earth nitrates in the rare earth nitrate solution are La(NO3)3·6H2O and Ce(NO3)3·6H2O.

5. The preparation method of the composite rare earth modified alumina defluorinating agent according to claim 1, characterized in that, The preparation method of the Al2O3 powder includes the following steps: Crush Al2O3 and sieve it through a 60-mesh sieve to obtain the Al2O3 powder.

6. The preparation method of the composite rare earth modified alumina defluorinating agent according to claim 1, characterized in that, The temperature of the constant temperature oscillation is room temperature, the oscillation rate is 80 - 100 r / min, and the time is 2 - 3 h.

7. The preparation method of the composite rare earth modified alumina defluorinating agent according to claim 1, characterized in that, The drying temperature is 105 - 120 °C, and the time is 12 - 15 h; and / or The sieving is through a 40 - 60-mesh sieve.

8. A composite rare earth modified alumina defluorinating agent prepared by the preparation method according to any one of claims 1 - 7.

9. An application of the composite rare earth modified alumina defluorinating agent according to claim 8 in treating fluoride-containing wastewater.

10. Use of the composite rare earth modified alumina defluorinating agent according to claim 9 in treating fluorine-containing wastewater, characterized in that, It includes the following steps: Adjust the pH of the fluoride-containing wastewater to 6 - 7, then add the composite rare earth modified alumina defluorinating agent according to claim 8 for reaction to complete defluorination.

Images