Preparation method and application of fluorine-doped modified sludge defluorination adsorbent

Abstract

The present application discloses a preparation method and application of a fluorine-doped modified sludge defluorination adsorbent. Sludge dry powder and sodium aluminate dry powder are placed in a beaker, acetic acid solution is added to make the solid-liquid ratio of the sludge and the powder be 0.24-0.60:1, the powder is stirred with a glass rod and then transferred to a 50ml reactor for hydrothermal treatment at 180-200°C for 1-2 hours, the reactor is allowed to cool naturally, and the sample in the reactor is taken out for centrifugal washing; the sample is placed in a 60°C oven for drying for 12 hours; the sample is mixed with a 10mg / L sodium fluoride solution to make the solid-liquid ratio of the sample be 1:1; the pH value is adjusted to 6, magnetic stirring is performed for 5 hours, suction filtration is performed, and the sample is washed three times with distilled water; the sample is placed in a 60°C oven for drying for 12 hours, and the product is dried to a constant weight to obtain the fluorine-doped modified sludge defluorination adsorbent; the fluorine-doped modified sludge defluorination adsorbent is used for removing fluoride in water, has low cost, large adsorption capacity, wide pH application range, and can achieve waste treatment, thus opening up a new direction for sludge disposal.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection water treatment, and in particular relates to a preparation method and application of a fluorine-doped modified sludge defluorination adsorbent. Background Art

[0002] Fluoride ion is one of the most abundant anions in the aquatic environment. Its effect on the human body depends on the dose of fluoride ion. [1] Low fluoride ion intake can prevent tooth decay, but when the fluoride ion content in water is too high, it can cause dental fluorosis, skeletal fluorosis and nerve damage. In severe cases, it can endanger human health and even life. [2-4] The World Health Organization (WHO) believes that fluoride content in drinking water below 0.7 mg / L is beneficial, but above 1.5 mg / L is harmful. Therefore, many countries’ drinking water hygiene standards limit the fluoride concentration to no more than 1.0 mg / L. [5] Due to the excessive fluoride content in drinking water caused by the native environment, it has become an endemic fluorosis area. It is reported that more than 200 million people in the world drink drinking water with a fluoride concentration exceeding 1.5 mg / L. [6] The current situation of fluoride poisoning is worrying, with as many as 50 million people drinking high-fluoride water. In recent years, due to human factors, environmental governance and management levels have not kept up with the speed of fluoride pollution. The fluoride concentration in the water environment continues to increase. In some areas, the fluoride content in the water even exceeds 30 mg / L. The harm of high-fluoride water to human health continues to expand. Therefore, preventing fluoride poisoning is a global public health issue. [7] There is an urgent need to develop effective fluoride removal technology, improve the level of primary prevention, and ensure people’s water safety and public health.

[0003] At present, many effective key technologies for removing high fluoride have been successfully discovered, such as coagulation [8] ,precipitation [9] , ion exchange

[10] , membrane filtration [6] and electrodialysis

[11] Although these methods have shown good defluorination effects, they have problems in actual operation, such as high instrument requirements, complex operation, and limited scope of application.

[12] Among these technologies, adsorption has been widely studied and is generally considered to be the most promising defluorination technology due to its low cost, environmental friendliness and simple operation.

[13] .

[0004] As sewage treatment plants continue to increase their processing capacity, the lack of a stable and effective disposal destination for the generated sludge has become an increasingly serious problem. The current sludge disposal is mainly composting, landfilling, etc., but there are heavy metal pollution and capacity limitations. At present, a small number of environmental remediation and utilization methods have been developed, which are mainly based on the removal of organic matter and heavy metals. Sludge defluorination has not been reported.

[0005] The disposal rate of wastewater sludge is only 33%

[14] In the process of sewage treatment, sludge, an excess residual waste, will be generated. In view of the rapidly growing population needs and the rapidly increasing waste production, it is imperative to increase the intensity of sludge treatment and improve the level of sludge treatment.

[15] The current sludge disposal is mainly composting, landfilling, etc., but there is heavy metal pollution and capacity limitation in the sludge. A large amount of heavy metals, organic pollutants and other harmful substances will have a serious impact on the environment if not properly handled in time.

[16] . Sludge has both advantages and disadvantages for the development of the environment and society. At the same time, sludge is also a waste with great potential for value transfer. At present, a small number of environmental remediation and utilization methods have been developed, which are mainly based on the removal of organic matter and heavy metals. Sludge defluorination has not been reported. Therefore, how to effectively reuse sludge resources and research and invent a method that can both reasonably and effectively treat waste sludge and prepare high-efficiency defluorination adsorbents at low cost are of great significance for sludge disposal.

[0006] Currently, the mature adsorption defluorination technology is mainly activated alumina defluorination, but the cost of the defluorination adsorbent is high and the defluorination effect is not ideal. The adsorption capacity is about 10 mg / g, which is low, and it is only effective in the acidic range below pH 6.0. These defects limit its application.

[0007] References:

[0008] 1.Zhang,S.,et al.,Removal of fluoride from groundwater by adsorptiononto La(III)-Al(III)loaded scoria adsorbent.Applied Surface Science,2014.303:p.1-5.

[0009] 2.Mahramanlioglu,M.,I.Kizilcikli,and I.O.Bicer,Adsorption of fluoridefrom aqueous solution by acid treated spent bleaching earth.Journal ofFluorine Chemistry,2002.115(1):p.41-47.

[0010] 3.Zhang,Y.and K.Huang,Grape pomace as a biosorbent for fluorideremoval from groundwater.RSC Advances,2019.9(14):p.7767-7776.

[0011] 4.Ruan,Z.,et al.,Synthesis of hydroxyapatite / multi-walled carbonnanotubes for the removal of fluoride ions from solution.Applied SurfaceScience,2017.412:p.578-590.

[0012] 5.Wang,Y.and E.J.Reardon,Activation and regeneration of a soilsorbent for defluoridation of drinking water.Applied Geochemistry,2001.16(5):p.531-539.

[0013] 6.Yadav,A.K.,et al.,Removal of fluoride from aqueous solution andgroundwater by wheat straw,sawdust and activated bagasse carbon ofsugarcane.Ecological Engineering,2013.52:p.211-218.

[0014] 7.Loganathan,P.,et al.,Defluoridation of drinking water usingadsorption processes.J Hazard Mater,2013.248-249:p.1-19.

[0015] 8.Rajkumar,S.,et al.,Low-cost fluoride adsorbents prepared from arenewable biowaste:Syntheses,characterization and modeling studies.ArabianJournal of Chemistry,2019.12(8):p.3004-3017.

[0016] 9.Zhang,T.,et al.,Synthesis of Li–Al Layered Double Hydroxides(LDHs)for Efficient Fluoride Removal.Industrial&Engineering Chemistry Research,2012.51(35):p.11490-11498.

[0017] 10.Cui,H.,et al.,Defluoridation of water via electrically controlledanion exchange by polyaniline modified electrode reactor.Water Res,2011.45(17):p.5736-44.

[0018] 11.Lahnid,S.,et al.,Economic evaluation of fluoride removal byelectrodialysis.Desalination,2008.230(1-3):p.213-219.

[0019] 12.Hegde,R.M.,et al.,Bio-inspired materials for defluoridation ofwater:A review.Chemosphere,2020.253:p.126657.

[0020] 13. Medellin-Castillo, N. A., et al., Adsorption capacity of bone char for removing fluoride from water solution. Role of hydroxyapatite content, adsorption mechanism and competing anions. Journal of Industrial and Engineering Chemistry, 2014. 20(6): p. 4014-4021.

[0021] 14. Wang T, Zhu G, Li C, et al. Anaerobic digestion of sludge filtrate using anaerobic baffled reactor assisted by symbionts of short chain fatty acid-oxidation syntrophs and exoelectrogens: Pilot-scale verification[J]. Water research, 2020, 170: 115329.

[0022] 15. Shi S, Xu G, Yu H, et al. Strategies of valorization of sludge from wastewater treatment[J]. Journal of Chemical Technology & Biotechnology, 2018, 93(4): 936-944.

[0023] 16. Zhou Z, Yang Y, Li X, et al. Characterization of drinking water treatment sludge after ultrasound treatment[J]. Ultrasonics sonochemistry, 2015, 24: 19-26. Summary of the Invention

[0024] Technical problems to be solved:

[0025] The present application aims at the deficiencies of the prior art and solves the technical problems that the current defluorination technology has high instrument requirements, high detection costs, limited scope of application, high cost of adsorption defluorination agents, unsatisfactory defluorination effects, low adsorption capacity of about 10 mg / g, and is only effective within the acidic range below pH 6.0. A preparation method and application of a fluorine-doped modified sludge defluorination adsorbent is provided for the removal of fluoride in water, which has low cost, large adsorption capacity, and a wide pH application range. It also achieves waste treatment with waste and opens up a new direction for sludge disposal.

[0026] Technical solution:

[0027] To achieve the above objectives, this application is implemented through the following technical solutions:

[0028] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0029] Step 1: Weigh 1g of sludge dry powder and 0.1-0.3g of sodium aluminate dry powder in a beaker according to the mass-volume ratio.

[0030] Add 2-5 ml of acetic acid solution to make the solid-liquid ratio 0.24-0.60:1, and stir with a glass rod for 1 minute;

[0031] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reaction kettle and heat at 180-200°C for 1-2 hours;

[0032] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor and wash it by centrifugation;

[0033] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0034] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0035] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0036] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0037] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight.

[0038] Fluoride removal adsorbent for sludge.

[0039] Furthermore, the centrifugal speed in the third step is 12000 rpm.

[0040] Furthermore, the specific steps of centrifugal washing in the third step are first centrifuging to remove the supernatant, then washing with distilled water and centrifuging to remove

[0041] Remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid

[0042] Washing liquid: distilled water.

[0043] Furthermore, the preparation method of the 10 mg / L sodium fluoride solution in the fifth step is to dissolve 2.21 g NaF (analytical grade) in 1000 mL deionized water to prepare a 1 g / L sodium fluoride stock solution. The stock solution is diluted to prepare a sodium fluoride solution with a concentration of 10 mg / L.

[0044] Furthermore, the reagent for adjusting pH in the sixth step is 0.1 mol / L NaOH and / or 0.1 mol / L HNO3.

[0045] Furthermore, in the sixth step, the magnetic stirring speed is 400 rpm.

[0046] The present application also discloses the use of the fluorine-doped modified sludge defluorination adsorbent prepared by any of the above preparation methods in water treatment and defluorination.

[0047] Furthermore, when the modified sludge defluorination adsorbent doped with fluorine at a dosage of 1g / L is placed under adsorption conditions of an initial fluoride ion concentration of 10mg / L and a pH of 3-10, the defluorination rate of the modified sludge defluorination adsorbent doped with fluorine is 85.41-97.23%, and the experimental adsorption amount is 8.89-9.84mg / g.

[0048] Beneficial effects:

[0049] The present application provides a preparation method and application of a fluorine-doped modified sludge defluorination adsorbent, which has the following beneficial effects compared with the prior art:

[0050] 1. The present invention provides a fluorine-doped modified sludge carbon product and a preparation method thereof, which is used for removing fluoride in water, has low cost, large adsorption capacity, wide pH application range, and realizes waste treatment with waste, opening up a new direction for sludge disposal;

[0051] 2. The preparation process of the defluorination adsorbent prepared by the present invention is controllable, the preparation time is short, the energy consumption is low, the components of the adsorption material can be adjusted, and no harm is caused to the environment;

[0052] 3. The raw materials of the defluoridation agent are cheap and easy to obtain. The sludge is derived from the wastewater treatment plant in the process of treating sewage. It has a large output and is generally backfilled, occupying a large area and lacking high-value utilization methods;

[0053] 4. Reasonable use of sludge can not only effectively control pollution, but also recycle resources;

[0054] 5. The aluminum source in the sludge is fully utilized to prepare the adsorbent in combination with the external aluminum source, which acts synergistically to remove fluoride ions in water, achieving the effect of "1+1>2";

[0055] 6. The preparation scheme of the defluorination adsorbent is novel. For the first time, the target adsorbent fluoride solution is used as one of the raw materials. The hydrothermal product is fully mixed with the sodium fluoride solution to obtain the adsorbent, which has the unique effect of "fighting poison with poison";

[0056] 7. In practical applications, the defluorination adsorbent has low cost, excellent performance, high defluorination efficiency, excellent regeneration performance, and can be regenerated and used repeatedly;

[0057] 8. Excellent regeneration performance, can be recycled repeatedly, after three regenerations, the fluorine removal rate is still maintained above 77%, with unexpected technical effects, further saving water treatment costs in practical applications;

[0058] 9. Convenient preparation, low cost, and easy process control. The present invention uses a small amount of raw materials, a few types, and simple steps. It can be obtained by hydrothermal method and subsequent fluorine doping, and simultaneously completes the hydrothermal activation of sludge and the loading of effective defluorination components. The synthesis reaction time is short, the energy consumption is low, the components of the adsorption material can be adjusted, the toxicity is low, and the carbon content is low, and it will not cause harm to the environment;

[0059] 10. Treat waste with waste, with high environmental benefits. One of the raw materials of the present invention is sludge, which is derived from the wastewater treatment plant in the process of treating sewage. It has a large output in my country and is cheap and easy to obtain. Reasonable use of sludge can not only effectively control pollution, but also recycle resources;

[0060] 11. Excellent performance, high fluorine removal efficiency, low cost of use. The adsorbent of the present invention only needs 1g / L of adsorbent to achieve a fluorine removal rate of more than 85%, meeting the needs of general fluorine removal applications. Compared with traditional alumina, the amount of activated alumina is 3-17 times more than that of traditional alumina with less dosage;

[0061] 12. The pH application range is wide, and the defluorination effect is significantly better than that of traditional activated alumina. It has a high adsorption capacity for fluoride ion solutions between pH 3 and 10. In practical applications, it can be used without adjusting the pH value of water, which further saves water treatment costs. Currently, the commercially available activated alumina defluorination adsorbent is only effective in the acidic range below pH 6;

[0062] 13. Under the conditions of initial fluoride concentration of 10 mg / L, adsorbent dosage of 1 g / L and pH of 5, the defluorination rate of the defluoridation agent can reach 94.77%, and the maximum adsorption capacity is as high as 256.4 mg / g, which is a significant technical improvement over the adsorption capacity of 7 mg / g of traditional activated alumina defluoridation agent;

[0063] 14. Excellent regeneration performance, can be recycled repeatedly. After 3 regeneration cycles, the fluorine removal rate is still above 77%, which has unexpected technical effects and further saves water treatment costs in practical applications. DETAILED DESCRIPTION

[0064] In order to further illustrate the present invention, the present invention is further described in detail below in conjunction with embodiments.

[0065] Embodiment 1:

[0066] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0067] Step 1: Weigh 1g of sludge dry powder and 0.1g of sodium aluminate dry powder separately in a beaker, add 3ml of acetic acid solution to make the solid-liquid ratio 0.37:1, and stir with a glass rod for 1min;

[0068] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 180 °C for 1 h;

[0069] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0070] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0071] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0072] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0073] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0074] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, obtaining product P01.

[0075] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the above-mentioned P01 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 6, the defluorination rate of the sample can reach 85.41%, and the experimental adsorption amount is 8.93 mg / g.

[0076] Embodiment 2:

[0077] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0078] Step 1: Weigh 1g of sludge dry powder and 0.2g of sodium aluminate dry powder separately in a beaker, add 2ml of acetic acid solution to make the solid-liquid ratio 0.6:1, and stir with a glass rod for 1min;

[0079] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 200 °C for 2 h;

[0080] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0081] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0082] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0083] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0084] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0085] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, obtaining product P02.

[0086] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the above-mentioned P02 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 6, the defluorination rate of the sample can reach 89.94%, and the experimental adsorption amount is 9.40 mg / g.

[0087] Example 3

[0088] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0089] Step 1: Weigh 1g of sludge dry powder and 0.2g of sodium aluminate dry powder separately into a beaker, add 5ml of acetic acid solution to make the solid-liquid ratio 0.24:1, and stir with a glass rod for 1min;

[0090] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 180 °C for 2 h;

[0091] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0092] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0093] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0094] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0095] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0096] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, obtaining product P03.

[0097] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the above-mentioned P03 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 6, the defluorination rate of the sample can reach 87.83%, and the experimental adsorption amount is 8.89 mg / g.

[0098] Embodiment 4:

[0099] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0100] Step 1: Weigh 1g of sludge dry powder and 0.3g of sodium aluminate dry powder separately into a beaker, add 3ml of acetic acid solution to make the solid-liquid ratio 0.43:1, and stir with a glass rod for 1min;

[0101] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 200 °C for 1 h;

[0102] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0103] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0104] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0105] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0106] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0107] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, obtaining product P04.

[0108] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the above-mentioned P04 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 3, the defluorination rate of the sample can reach 97.23%, and the experimental adsorption amount is 9.84 mg / g.

[0109] Embodiment 5:

[0110] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0111] Step 1: Weigh 1g of sludge dry powder and 0.3g of sodium aluminate dry powder separately into a beaker, add 3ml of acetic acid solution to make the solid-liquid ratio 0.43:1, and stir with a glass rod for 1min;

[0112] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 200 °C for 1 h;

[0113] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0114] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0115] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0116] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0117] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0118] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, obtaining product P05.

[0119] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the above-mentioned P05 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 4, the defluorination rate of the sample can reach 95.49%, and the experimental adsorption amount is 9.66 mg / g.

[0120] Embodiment 6:

[0121] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0122] Step 1: Weigh 1g of sludge dry powder and 0.3g of sodium aluminate dry powder separately into a beaker, add 3ml of acetic acid solution to make the solid-liquid ratio 0.43:1, and stir with a glass rod for 1min;

[0123] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 200 °C for 1 h;

[0124] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0125] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0126] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0127] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0128] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0129] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, obtaining product P06.

[0130] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the above-mentioned P06 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 5, the defluorination rate of the sample can reach 94.77%, and the experimental adsorption amount is 9.59 mg / g.

[0131] Embodiment 7:

[0132] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0133] Step 1: Weigh 1g of sludge dry powder and 0.3g of sodium aluminate dry powder separately into a beaker, add 3ml of acetic acid solution to make the solid-liquid ratio 0.43:1, and stir with a glass rod for 1min;

[0134] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 200 °C for 1 h;

[0135] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0136] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0137] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0138] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0139] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0140] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, obtaining product P07.

[0141] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the above-mentioned P07 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 6, the defluorination rate of the sample can reach 91.73%, and the experimental adsorption amount is 9.28 mg / g.

[0142] Embodiment 8:

[0143] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0144] Step 1: Weigh 1g of sludge dry powder and 0.3g of sodium aluminate dry powder separately into a beaker, add 3ml of acetic acid solution to make the solid-liquid ratio 0.43:1, and stir with a glass rod for 1min;

[0145] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 200 °C for 1 h;

[0146] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0147] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0148] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0149] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0150] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0151] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, and the obtained product is P08.

[0152] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the above-mentioned P08 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 7, the defluorination rate of the sample can reach 88.88%, and the experimental adsorption amount is 8.99 mg / g.

[0153] Embodiment 9:

[0154] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0155] Step 1: Weigh 1g of sludge dry powder and 0.3g of sodium aluminate dry powder separately into a beaker, add 3ml of acetic acid solution to make the solid-liquid ratio 0.43:1, and stir with a glass rod for 1min;

[0156] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 200 °C for 1 h;

[0157] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0158] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0159] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0160] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0161] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0162] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, obtaining product P09.

[0163] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the above-mentioned P09 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 8, the defluorination rate of the sample can reach 86.91%, and the experimental adsorption amount is 8.79 mg / g.

[0164] Embodiment 10:

[0165] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0166] Step 1: Weigh 1g of sludge dry powder and 0.3g of sodium aluminate dry powder separately into a beaker, add 3ml of acetic acid solution to make the solid-liquid ratio 0.43:1, and stir with a glass rod for 1min;

[0167] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 200 °C for 1 h;

[0168] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0169] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0170] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0171] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0172] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0173] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, and the obtained product is P010.

[0174] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the above-mentioned P010 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 9, the defluorination rate of the sample can reach 90.37%, and the experimental adsorption amount is 9.14 mg / g.

[0175] Embodiment 11:

[0176] A method for preparing a fluorine-doped modified sludge defluorination adsorbent specifically comprises the following steps:

[0177] Step 1: Weigh 1g of sludge dry powder and 0.3g of sodium aluminate dry powder separately into a beaker, add 3ml of acetic acid solution to make the solid-liquid ratio 0.43:1, and stir with a glass rod for 1min;

[0178] Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 200 °C for 1 h;

[0179] Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor, centrifuge to remove the supernatant, then wash with distilled water and centrifuge to remove the washing liquid distilled water, then wash with ethanol and centrifuge to remove the washing liquid ethanol, finally wash again with distilled water and centrifuge to remove the washing liquid distilled water;

[0180] Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h;

[0181] Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1;

[0182] Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 hours;

[0183] Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water;

[0184] Step 8: Place the sample obtained in step 7 in a 60°C oven and dry for 12 hours until the product has a constant weight, and the obtained product is P011.

[0185] The invention discloses an application of a fluorine-doped modified sludge defluorination adsorbent in water treatment and defluorination. When the P011 sample is placed under the adsorption conditions of 10 mg / L initial fluoride ion concentration, 1 g / L adsorbent dosage, and pH 10, the defluorination rate of the sample can reach 94.44%, and the experimental adsorption amount is 9.55 mg / g.

[0186] Comparative Example 1:

[0187] An application of activated alumina in water treatment and fluoride removal, with an initial fluoride ion concentration of 5 mg / L, an activated alumina adsorbent dosage of 3 g / L, and an adsorption condition of pH 5 (optimal pH condition), the activated alumina fluoride removal rate reaches 55%. The adsorption capacity is only 0.75 mg / g.

[0188] Comparative Example 2:

[0189] An application of activated alumina in water treatment and fluoride removal, with an initial fluoride ion concentration of 5 mg / L, an activated alumina adsorbent dosage of 5 g / L, and an adsorption condition of pH 5 (optimal pH condition), the fluoride removal rate of activated alumina reaches 61%. The adsorption capacity is only 0.39 mg / g.

[0190] Comparative Example 3:

[0191] An application of activated alumina in water treatment and fluoride removal, with an initial fluoride ion concentration of 5 mg / L, an activated alumina adsorbent dosage of 7 g / L, and an adsorption condition of pH 5 (optimal pH condition), the fluoride removal rate of activated alumina reaches 73%. The adsorption capacity is only 0.19 mg / g.

[0192] Comparative Example 4:

[0193] An application of activated alumina in water treatment and fluoride removal, with an initial fluoride ion concentration of 5 mg / L, an activated alumina adsorbent dosage of 17 g / L, and an adsorption condition of pH 5 (optimal pH condition), the fluoride removal rate of activated alumina reaches 83%. The adsorption capacity is only 0.05 mg / g.

[0194] The fluorine-doped modified sludge defluorination adsorbent of the present application has a fluorine removal rate of more than 85% when the pH is 3-10 and the dosage of the fluorine-doped modified sludge defluorination adsorbent is 1g / L, and the experimental adsorption amount is 8.79-9.84mg / g, far exceeding the experimental adsorption amount of activated alumina 0.05-0.75mg / g. It has achieved technical characteristics such as low dosage, high fluorine removal rate, wide applicable pH range, and large adsorption amount (theoretical value is up to 256.4mg / g), and has significant technical progress.

[0195] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A method for preparing a fluorine-doped modified sludge defluorination adsorbent, characterized in that: The specific steps include: Step 1: Weigh 1 g of sludge dry powder and 0.1-0.3 g of sodium aluminate dry powder in a beaker according to the mass-volume ratio, add 2-5 ml of acetic acid solution to make the solid-liquid ratio 0.24-0.60:1, and stir with a glass rod for 1 min. The sludge comes from the derivation of the wastewater treatment plant in the process of treating sewage; Step 2: Transfer the stirred mixed solution obtained in the first step to a 50 ml reactor and heat at 180-200°C for 1-2h; Step 3: After the hydrothermal treatment, wait for the reactor to cool naturally, take out the sample from the reactor and wash it by centrifugation; Step 4: After centrifugal washing, the sample was placed in a 60°C oven and dried for 12 h; Step 5: Mix the dried product in step 4 with 10 mg / L sodium fluoride solution to make the solid-liquid ratio 1:1; Step 6: Adjust the pH of the sample solution mixed in step 5 to 6 and stir magnetically for 5 h; Step 7: Filter the magnetically stirred sample obtained in step 6, and then wash it three times with distilled water; Step 8: Place the sample obtained in step 7 in a 60°C oven and dry it for 12 h until the product has a constant weight, thereby obtaining a fluorine-doped modified sludge defluorination adsorbent.

2. The method for preparing the fluorine-doped modified sludge defluorination adsorbent according to claim 1, characterized in that: The centrifugal speed in the third step is 12000 rpm.

3. The method for preparing the fluorine-doped modified sludge defluorination adsorbent according to claim 1, characterized in that: The specific steps of centrifugal washing in the third step are first centrifugally removing the supernatant, then washing with distilled water and then centrifugally removing the washing liquid distilled water, then washing with ethanol and then centrifugally removing the washing liquid ethanol, and finally washing again with distilled water and then centrifugally removing the washing liquid distilled water.

4. The method for preparing the fluorine-doped modified sludge defluorination adsorbent according to claim 1, characterized in that: The preparation method of the 10 mg / L sodium fluoride solution in the fifth step is to dissolve 2.21 g of NaF in 1000 mL of deionized water to prepare a 1 g / L sodium fluoride stock solution, and the stock solution is diluted to prepare a sodium fluoride solution with a concentration of 10 mg / L.

5. The method for preparing the fluorine-doped modified sludge defluorination adsorbent according to claim 1, characterized in that: The reagent for adjusting pH in the sixth step is 0.1 mol / L NaOH and / or 0.1 mol / L HNO3.

6. The method for preparing the fluorine-doped modified sludge defluorination adsorbent according to claim 1, characterized in that: The magnetic stirring speed in the sixth step is 400 rpm.

7. Use of the fluorine-doped modified sludge defluorination adsorbent prepared by the preparation method according to any one of claims 1 to 6 in water treatment defluorination.

8. The use according to claim 7, characterized in that: When the modified sludge defluorination adsorbent doped with fluorine at a dosage of 1 g / L was placed under the adsorption conditions of an initial fluoride ion concentration of 10 mg / L and a pH of 3-10, the fluorine removal rate of the modified sludge defluorination adsorbent doped with fluorine was 85.41-97.23%, and the experimental adsorption capacity was 8.89 -9.84 mg / g.