Sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent and its preparation method and application

Abstract

The present invention discloses a sodium pyrophosphate-modified water purification sludge / zeolite composite adsorbent, its preparation method and application. The preparation method of the sodium pyrophosphate-modified water purification sludge / zeolite composite adsorbent comprises the following steps: mixing water purification sludge powder and zeolite powder, then adding the mixture into a sodium pyrophosphate solution for impregnation and then putting it into an oven for drying, and then adding water to form a sludge mixture; granulating and calcining the sludge mixture to obtain the sodium pyrophosphate-modified water purification sludge / zeolite composite adsorbent. The adsorbent is used for the adsorption treatment of ammonia nitrogen wastewater, and has a high ammonia nitrogen removal rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment by adsorption method, and particularly relates to a sodium pyrophosphate modified purified water sludge / zeolite composite adsorbent for treating ammonia nitrogen in water, its preparation method and application. Background Art

[0002] With the increasing demand for tap water in people's life and production, the water supply capacity of water treatment plants is increasing day by day, and the output of purified water sludge is also increasing. In addition, the content of toxic substances and organic matters in raw water from rivers and lakes has increased sharply, the water quality has been deteriorating day by day, and the quality of sludge discharged from water treatment plants has become worse and worse. If the purified water sludge is directly discharged into the nearby water body, it will not only cause the river channel to silt up and the riverbed height to rise, causing

[0003] adverse effects on flood discharge and navigation, but also pollute the water source, damage the ecological balance and affect environmental sanitation.

[0004] Ammonia nitrogen is an oxygen-consuming pollutant. Excessive ammonia nitrogen content will cause eutrophication of water bodies. Eutrophication of water bodies brings many negative impacts in terms of environment, economy and ecology. The content of ammonia nitrogen in water has become an important indicator of water body eutrophication. Eutrophication has caused serious harm to water quality and the survival and growth of aquatic organisms. In addition, nitrite nitrogen will also damage organs such as the liver, spleen and kidneys of humans and animals, causing their functions to malfunction, leading to physical exhaustion and mental listlessness. Therefore, in order to reduce water pollution and protect the ecological

[0005] environment, the nitrogen-containing wastewater needs to be treated up to the standard before being discharged.

[0006] Making the purified water sludge into an adsorbent and using it for the adsorption of ammonia nitrogen in wastewater not only effectively solves the problem of water pollution, but also reduces the environmental pollution and resource waste caused by the traditional treatment method of sludge, achieving the purpose of turning waste into treasure. Therefore, using purified water sludge to prepare adsorbents has positive significance for environmental protection, human

[0007] health and economic development. Summary of the Invention

[0008] The present invention discloses a new sludge composite adsorbent. Using zeolite as a doping agent, the obtained adsorbent has a significantly improved water treatment capacity compared with the original sludge; further, on the basis of zeolite doping, sodium pyrophosphate is used as a modifier to make the water treatment capacity of the adsorbent higher.

[0009] The present invention adopts the following technical scheme:

[0010] A purified water sludge / zeolite composite adsorbent, and the preparation method of the purified water sludge / zeolite composite adsorbent comprises the following steps: mixing the purified water sludge powder and the zeolite powder for granulation, and then calcining to obtain the purified water sludge / zeolite composite adsorbent.

[0011] A sodium pyrophosphate modified water purification sludge composite adsorbent, and the preparation method of the sodium pyrophosphate modified water purification sludge composite adsorbent comprises the following steps: adding water purification sludge powder into an aqueous sodium pyrophosphate solution, then drying, regranulating and calcining to obtain the sodium pyrophosphate modified water purification sludge composite adsorbent.

[0012] A sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent, and the preparation method of the sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent comprises the following steps: adding a mixture of water purification sludge powder and zeolite powder into an aqueous sodium pyrophosphate solution, then drying, regranulating and calcining to obtain the sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent.

[0013] A wastewater treatment method, adding an adsorbent into wastewater, oscillating and then standing to complete wastewater treatment; the adsorbent is the above-mentioned water purification sludge / zeolite composite adsorbent or the above-mentioned sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent.

[0014] The present invention discloses the application of the above-mentioned water purification sludge / zeolite composite adsorbent or sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent in wastewater treatment.

[0015] In the present invention, the wastewater is ammonia nitrogen-containing wastewater.

[0016] In the present invention, the weight ratio of zeolite powder to water purification sludge powder is 1:2 - 8, preferably 1:5 - 6; the particle sizes of both zeolite powder and water purification sludge powder are 100 - 200 mesh. The preparation method of water purification sludge powder is to dry and pulverize and sieve the water purification sludge of existing waterworks to obtain water purification sludge powder.

[0017] In the present invention, the dosage ratio of water purification sludge powder to aqueous sodium pyrophosphate solution is 50g:1L; the concentration of the aqueous sodium pyrophosphate solution is 0.5% - 10%, preferably, the concentration of the aqueous sodium pyrophosphate solution is 1% - 2%.

[0018] In the present invention, the dosage ratio of the mixture of water purification sludge powder and zeolite powder to aqueous sodium pyrophosphate solution is 50g:1L; the concentration of the aqueous sodium pyrophosphate solution is 0.5% - 10%, preferably, the concentration of the aqueous sodium pyrophosphate solution is 1% - 2%.

[0019] In the present invention, the calcination temperature is 400 - 600°C and the time is 2 - 4 hours; preferably, the calcination temperature is 600°C, the time is 2 hours, and the heating rate during calcination is 8°C / min.

[0020] In the present invention, in the preparation of the sodium pyrophosphate-modified purified water sludge / zeolite composite adsorbent, a mixture of purified water sludge powder and zeolite powder is added to an aqueous sodium pyrophosphate solution, impregnated for 20 to 30 h, then dried in an oven for 5 h, then water is added, granulated and calcined to obtain the modified purified water sludge / zeolite composite adsorbent.

[0021] In the present invention, during the oscillation and subsequent static settling, the oscillation is carried out at room temperature, the rotation speed is 100 r / min to 150 r / min, and the time is 20 to 30 h.

[0022] The adsorbent of the present invention has a good removal rate for NH4 + , the total surface area and total active sites of the adsorbent are high, so the removal rate of NH4 + is good. After modification with sodium pyrophosphate, Na + replaces K + , Ca 2+ , Mg 2+ and other cations in the pores of the purified water sludge. The ionic radius of Na + is small and its properties are active, so it is easier to come out of the pores and undergo ion exchange with NH4 + in the solution. When the dosage of the modified composite adsorbent is 80 g / L, the ammonia nitrogen removal rate can reach 98.9%. Description of the Drawings

[0023] Figure 1 is the SEM image of the original sludge adsorbent;

[0024] Figure 2 shows the removal effect of ammonia nitrogen with different ratios of zeolite to purified water sludge;

[0025] Figure 3 is the SEM image of the sodium pyrophosphate-modified purified water sludge / zeolite composite adsorbent;

[0026] Figure 4 shows the removal effect of ammonia nitrogen by the sodium pyrophosphate-modified purified water sludge / zeolite composite adsorbent. Detailed Embodiments

[0027] In the present invention, the purified water sludge powder and zeolite powder are mixed and granulated, and then calcined to obtain the purified water sludge / zeolite composite adsorbent; or the purified water sludge powder is added to an aqueous sodium pyrophosphate solution, then dried, granulated and calcined to obtain the sodium pyrophosphate-modified purified water sludge composite adsorbent; or a mixture of purified water sludge powder and zeolite powder is added to an aqueous sodium pyrophosphate solution, then dried, granulated and calcined to obtain the sodium pyrophosphate-modified purified water sludge / zeolite composite adsorbent. Without the need for other reagents or steps, the obtained adsorbent has a very good adsorption treatment effect on ammonia nitrogen in water.

[0028] The purified water sludge obtained from a water treatment plant (existing raw material) is dried at 100 °C for 24 h, then crushed by a crusher, and particles with a particle size of 100 - 200 mesh are taken as powdered purified water sludge for the following examples and comparative examples. In the present invention, granulation is a conventional technique. Water is added to the powder, and granulation is carried out using an existing granulator. The dosage ratio of the powder to water is 50 g∶50 mL; in the examples and comparative examples, the heating rate during calcination is 8 °C / min, from room temperature to the set temperature; during calcination, the amount of particles in each crucible is the same.

[0029] The zeolite powder is natural clinoptilolite, produced in Xinyang, Henan, and the particle size is 100 - 200 mesh.

[0030] The adsorbent is added to the ammonia nitrogen water body to complete the treatment of the ammonia nitrogen water body. For example, 1.0 g of the adsorbent is weighed and placed into a conical flask containing 50 mL of an NH4Cl aqueous solution with a concentration of 50 mg / L. The conical flask is placed in a constant temperature oscillator, the temperature is set at 25 °C, the rotation speed is set at 120 r / min, and constant temperature oscillation is carried out for 24 h. The adsorbed solution is allowed to stand and then centrifuged. The supernatant is taken to measure the absorbance, and the adsorption capacity of the composite adsorbent for ammonia nitrogen is calculated. In the present invention, a 50 mg∙L -1 ammonium chloride aqueous solution is used to simulate actual wastewater, and the concentration of ammonia nitrogen is measured by the Nessler's reagent - spectrophotometry method; this is a conventional technique.

[0031] Example 1: Ammonia nitrogen removal effect of the purified water sludge / zeolite composite adsorbent

[0032] Zeolite powder with a particle size of 100 - 200 mesh and powdered purified water sludge are mixed at a weight ratio of 1:2, 1:4, 1:6, and 1:8 respectively. An equal amount of distilled water is added, stirred evenly, granulated in a granulator, then dried in an oven for 5 h, and the particles are calcined in a muffle furnace at 600 °C for 2 h to prepare the purified water sludge / zeolite composite adsorbent. The powdered purified water sludge is granulated, dried, and calcined at 600 °C for 2 hours in the same way to obtain the undoped original sludge adsorbent. The SEM image is shown in Figure 1 .

[0033] 1.0 g of the adsorbent is weighed and placed into different conical flasks containing 50 mL of an NH4Cl solution with a concentration of 50 mg / L. The conical flasks are placed in a constant temperature oscillator, the temperature is set at 25 °C, the rotation speed is set at 120 r / min, and constant temperature oscillation is carried out for 24 h. The adsorbed solution is allowed to stand for 5 hours, and conventional centrifugation is carried out. The supernatant is taken to measure the absorbance, and the adsorption capacity of the composite adsorbent for ammonia nitrogen is calculated. Figure 2 The ammonia nitrogen treatment results at different weight ratios of zeolite powder to powdered purified water sludge are shown in Figure 2It can be seen that the adsorption capacity of ammonia nitrogen by the zeolite powder and the purified water sludge doped in the present invention is significantly improved. In particular, when the zeolite powder and the purified water sludge powder are mixed at a weight ratio of 1:6, an adsorption capacity of 1.025 mg / g is obtained.

[0034] Example 2 Removal effect of the purified water sludge / zeolite composite adsorbent on ammonia nitrogen

[0035] Mix zeolite powder with a particle size of 100 - 200 mesh and purified water sludge powder at a weight ratio of 1:6, add an equal amount of distilled water, stir evenly, put it into a granulator to make it granulated, and then dry it in an oven for 5 h. Then, calcine the particles in a muffle furnace for 2 h respectively to prepare the purified water sludge / zeolite composite adsorbent; the calcination temperatures are 400 °C and 800 °C respectively.

[0036] Weigh 1.0 g of the adsorbent and put it into different conical flasks containing 50 mL of NH4Cl solution with a concentration of 50 mg / L. Place the conical flasks in a constant temperature oscillator, set the temperature to 25 °C, the rotation speed to 120 r / min, and oscillate at a constant temperature for 24 h. Let the adsorbed solution stand for 5 hours, and then perform conventional centrifugal separation. Take the supernatant to measure the absorbance, and calculate the adsorption capacity of the composite adsorbent for ammonia nitrogen. The adsorption capacities obtained at the calcination temperatures of 400 °C and 800 °C are 0.916 mg / g and 0.833 mg / g respectively.

[0037] Example 3 Removal effect of the purified water sludge / zeolite composite adsorbent on ammonia nitrogen

[0038] Mix zeolite powder with a particle size of 100 - 200 mesh and purified water sludge powder at a weight ratio of 1:6, add an equal amount of distilled water, stir evenly, put it into a granulator to make it granulated, and then dry it in an oven for 5 h. Then, calcine the particles in a muffle furnace at 600 °C for 3 hours to prepare the purified water sludge / zeolite composite adsorbent; weigh 1.0 g of the adsorbent and put it into different conical flasks containing 50 mL of NH4Cl solution with a concentration of 50 mg / L. Place the conical flasks in a constant temperature oscillator, set the temperature to 25 °C, the rotation speed to 120 r / min, and oscillate at a constant temperature for 24 h. Let the adsorbed solution stand for 5 hours, and then perform conventional centrifugal separation. Take the supernatant to measure the absorbance, and calculate the adsorption capacity of the composite adsorbent for ammonia nitrogen, which is 0.923 mg / g.

[0039] Example 4 Removal effect of the sodium pyrophosphate-modified purified water sludge composite adsorbent on ammonia nitrogen

[0040] Add 25 g of water purification sludge powder with a mesh size of 100 - 200 to 500 mL of a sodium pyrophosphate aqueous solution with a mass concentration of 2%, and immerse it for 24 h. After immersion, rinse it twice with distilled water, place it in an oven to dry for 5 h, then add an equal amount of water and granulate it in a granulator. After drying, calcine it in a muffle furnace at 600 °C for 2 h to obtain a sodium pyrophosphate modified water purification sludge adsorbent. Weigh 1.0 g of the adsorbent and put it into a conical flask containing 50 mL of an NH₄Cl solution with a concentration of 50 mg / L. Place the conical flask in a constant temperature oscillator, set the temperature to 25 °C, the rotation speed to 120 r / min, and oscillate at a constant temperature for 24 h. Let the adsorbed solution stand and then centrifuge it. Take the supernatant to measure the absorbance, and calculate that the adsorption capacity of the sodium pyrophosphate modified water purification sludge adsorbent for ammonia nitrogen is 1.578 mg / g.

[0041] In the above method, replace the water purification sludge powder with zeolite powder and keep the rest unchanged. The adsorption capacity of the sodium pyrophosphate modified zeolite powder for ammonia nitrogen is 1.508 mg / g.

[0042] Example Five Removal Effect of Sodium Pyrophosphate Modified Water Purification Sludge / Zeolite Composite Adsorbent on Ammonia Nitrogen

[0043] Mix zeolite powder with a mesh size of 100 - 200 and water purification sludge powder in a weight ratio of 1:6. Take 25 g of the mixed powder and add it to 500 mL of sodium pyrophosphate aqueous solutions with different mass concentrations, and immerse it for 24 h. After immersion, rinse it twice with distilled water, place it in an oven to dry for 5 h, then add an equal amount of water and granulate it in a granulator. After drying, calcine it in a muffle furnace at 600 °C for 2 h to obtain a sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent. The mass concentrations of the sodium pyrophosphate aqueous solution are 0.5%, 1%, 2%, and 5% respectively. The SEM of the 2% sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent is shown in Figure 3 .

[0044] Weigh 1.0 g of the adsorbent and put it into a conical flask containing 50 mL of an NH₄Cl solution with a concentration of 50 mg / L. Place the conical flask in a constant temperature oscillator, set the temperature to 25 °C, the rotation speed to 120 r / min, and oscillate at a constant temperature for 24 h. Let the adsorbed solution stand and then centrifuge it. Take the supernatant to measure the absorbance, and calculate the adsorption capacity of the sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent for ammonia nitrogen. See Figure 4 . The adsorbent with a 2% mass concentration of sodium pyrophosphate aqueous solution has an adsorption capacity of 1.980 mg / g. Using 0.5 g of the 2% sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent, the ammonia nitrogen removal rate is 58.6%; using 1.5 g of the 2% sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent, the ammonia nitrogen removal rate is 92.1%.

[0045] Example Six

[0046] On the basis of Example 5, sodium pyrophosphate was replaced with sodium hydroxide, sodium chloride, and zinc chloride. Using the same method, sodium hydroxide-modified water purification sludge / zeolite composite adsorbent, sodium chloride-modified water purification sludge / zeolite composite adsorbent, and zinc chloride-modified water purification sludge / zeolite composite adsorbent were obtained at a concentration of 2%. After the same tests, the adsorption capacities of the sodium hydroxide-modified water purification sludge / zeolite composite adsorbent, sodium chloride-modified water purification sludge / zeolite composite adsorbent, and zinc chloride-modified water purification sludge / zeolite composite adsorbent were 1.612 mg / g, 0.701 mg / g, and 1.022 mg / g, respectively.

[0047] Example 7

[0048] After the first adsorption experiment, the two saturated adsorbents (raw sludge adsorbent, 2% sodium pyrophosphate-modified water purification sludge / zeolite composite adsorbent) were taken out, and were desorbed with 50 mL of NaOH (1M), KCl (0.5M), and HCl (0.5M) aqueous solutions respectively. After conventional oscillating desorption for 24 h, they were filtered and dried. The two desorbed adsorbents were re-put into 50 mL of ammonia nitrogen solution with a concentration of 50 mg / L for the second adsorption experiment (the same as the first experiment). The above adsorption and desorption steps were repeated multiple times to measure the change in the ammonia nitrogen removal rate. The results are as follows:

[0049] 。

Claims

1. A pyrophosphate-modified purified water sludge / zeolite composite adsorbent, characterized in that, The preparation method of the sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent comprises the following steps: Mix zeolite powder with a particle size of 100-200 meshes and water purification sludge powder in a weight ratio of 1:

6. Take 25 g of the mixed powder and add it to 500 mL of an aqueous sodium pyrophosphate solution for impregnation for 24 h. After the impregnation is completed, rinse it twice with distilled water, place it in an oven for drying for 5 h, then add an equal amount of water and granulate it in a granulator. After drying, calcine it in a muffle furnace at 600 °C for 2 h to obtain the sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent; the mass concentrations of the aqueous sodium pyrophosphate solutions are 0.5%, 1%, 2%, and 5% respectively; the zeolite powder is natural clinoptilolite.

2. Application of the sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent according to claim 1 in wastewater treatment.

3. A wastewater treatment method, characterized in that, Add the adsorbent to the wastewater, shake it and then let it stand to complete the wastewater treatment; the adsorbent is the sodium pyrophosphate modified water purification sludge / zeolite composite adsorbent according to claim 1.

4. The wastewater treatment method according to claim 3, wherein The wastewater is ammonia nitrogen-containing wastewater.

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