An environment-friendly wastewater treatment agent and its preparation method

Abstract

The present invention belongs to the technical field of the synthesis of wastewater treatment agents, and specifically refers to an environment-friendly wastewater treatment agent and its preparation method. The environment-friendly wastewater treatment agent is prepared from the following raw materials: 6-9 parts of corncob, 3-5 parts of natural zeolite, 8-10 parts of polyethylene glycol, 1-3 parts of NiFe2O4, 0.2-0.5 parts of GQDs, 1.5-2.5 parts of phosphoric acid solution, and 25 parts of N,N-dimethylformamide. In the present invention, activated carbon is prepared with corncob as the main raw material, natural zeolite is used to create pores and adsorb heavy metals, NiFe2O4 is selected as the magnetic material, and polyethylene glycol is used as the surfactant to treat the activated carbon to form an adsorption film to promote the adsorption of NiFe2O4. The presence of natural zeolite prevents NiFe2O4 from occupying the pores of the activated carbon. Then, GQDs are prepared from corn straw to broaden the light absorption range and improve the photocatalytic performance, enabling the wastewater treatment agent to be applied in multiple fields, integrating the characteristics of various materials, and enhancing the efficacy and application breadth of the wastewater treatment agent.

Description

Technical Field

[0001] The present invention belongs to the technical field of synthesis of wastewater treatment agents, and specifically refers to an environment-friendly wastewater treatment agent and a preparation method thereof. Background Art

[0002] With the rapid development of industry, the discharge of wastewater has increased sharply and the composition has become more complex.

[0003] At present, there are many types of materials for wastewater treatment, but there are often many limitations. For example, they may contain harmful substances themselves and will cause secondary pollution to the surrounding environment such as soil and water bodies during or after use, which goes against the original intention of environmental protection; moreover, the application fields of these materials are relatively single, the process efficiency of wastewater treatment is low, and it is difficult to meet the complex requirements of different types of wastewater treatment; the research and development and production costs of many new and efficient wastewater treatment materials are high, and it is difficult to produce them in large quantities.

[0004] Under this background, it is urgent to develop an environment-friendly wastewater treatment agent with high efficiency, environmental protection, low cost and wide applicability. Summary of the Invention

[0005] In view of the defects of the prior art, the present invention first starts from the concept of green environmental protection, selects corncob as the main material to prepare activated carbon. In order to obtain a porous activated carbon material, natural zeolite is selected as a pore-forming agent to form pores in the activated carbon. At the same time, natural zeolite itself can also be used as an adsorption material to realize the replacement of heavy metal materials in wastewater. In order to broaden the application range of the treatment agent, NiFe 2 O 4 is selected as a magnetic material. In order to improve the adsorption of NiFe 2 O 4 on the surface of the activated carbon material and achieve the maximum efficiency of wastewater treatment, polyethylene glycol is selected as a surfactant to treat the activated carbon material to form an adsorption film, enhance the adsorption of NiFe 2 O 4 . The presence of natural zeolite also avoids the situation that NiFe 2 O 4 material occupies too many pores of the activated carbon while being adsorbed on the surface of the activated carbon. Further, corn straw is selected as a raw material to prepare GQDs (graphene quantum dots), which broadens the light absorption range of the wastewater treatment agent, improves the optical performance of photocatalysis, and realizes the multi-field application of the wastewater treatment agent.

[0006] To achieve the above object, the technical solution adopted by the present invention is an environment-friendly wastewater treatment agent, which is prepared from the following raw materials: 6-9 parts of corncob, 3-5 parts of natural zeolite, 8-10 parts of polyethylene glycol, NiFe 2 O 41 - 3 parts, 0.2 - 0.5 parts of GQDs, 1.5 - 2.5 parts of phosphoric acid solution, and 25 parts of N,N - dimethylformamide;

[0007] Further, the preparation method of the NiFe 2 O 4 comprises the following steps:

[0008] (i) Weigh nickel nitrate and dissolve it in ethylene glycol and stir. The dosage ratio of nickel nitrate to ethylene glycol is 0.9 - 1.5 g:50 ml, the stirring speed is 500 r / min, and the stirring time is 30 min to obtain a nickel solution. Weigh iron nitrate and dissolve it in ethylene glycol and stir. The dosage ratio of iron nitrate to ethylene glycol is 3 - 4.5 g:50 ml, the stirring speed is 500 r / min, and the stirring time is 30 min to obtain an iron solution. Slowly pour the nickel solution into the iron solution, heat and stir. The heating temperature is 90 - 120 °C, the stirring time is 2 h, the stirring speed is 500 r / min, and cool to room temperature to obtain a nickel - iron mixed solution;

[0009] (ii) Slowly dropwise add nitric acid solution to the nickel - iron mixed solution obtained in step (i) to adjust the pH range to 2 - 5. The concentration of the nitric acid solution is 4 mol / L, heat and stir. The heating temperature is 60 - 80 °C, the heating time is 1 h, the stirring speed is 500 r / min. Perform drying treatment using a vacuum drying oven. The drying temperature is 90 °C, and the drying time is 24 h to obtain a nickel - iron activated body. Heat the nickel - iron activated body. The heating temperature is 400 - 500 °C, the heating time is 2 h, and the heating rate is 10 °C / min to obtain a NiFe 2 O 4 precursor. Re - heat the NiFe 2 O 4 precursor. The secondary heating temperature is 700 - 900 °C, the secondary heating rate is 5 °C / min, the heating time is 2 h, and naturally cool to room temperature to obtain NiFe 2 O 4 .

[0010] Further, the preparation method of the GQDs comprises the following steps:

[0011] (a) Weigh the dosage ratios of 6 - 10 g:50 ml:2.5 - 5 ml and 10 - 15 ml of corn straw, absolute ethanol, nitric acid solution, and triethylamine respectively. Wash, dry, and crush the corn straw, and sieve it using a mesh screen. The mesh screen is 40 - mesh to obtain fine straw particles;

[0012] (b) Add the fine straw particles obtained in step (a) to absolute ethanol and stir for pretreatment, filter and dry to obtain a softened fine straw particle body;

[0013] (c) Add triethylamine to deionized water and stir evenly to obtain a mixed solution. Add the softened straw fine particles obtained in step (b) to the mixed solution and stir. Slowly add nitric acid solution to obtain a reaction mixed solution. Add the reaction mixed solution to a hydrothermal reactor for hydrothermal treatment. The hydrothermal temperature is 180 - 220 °C, and the hydrothermal time is 15 h. Cool to room temperature to obtain the precursor solution of GQDs;

[0014] (d) Centrifuge the precursor solution of GQDs obtained in step (c) at a centrifugal speed of 15000 r / min for 30 min to obtain the supernatant. Dialyze the obtained supernatant. The molecular weight cut-off of the dialysis bag used for dialysis is 300D - 500D, and the dialysis time is 24 h to obtain the dialysis solution. Dry the dialysis solution at a drying temperature of 65 °C for 24 h to obtain GQDs.

[0015] The present invention also provides a preparation method of an environment-friendly wastewater treatment agent, including the following steps:

[0016] Step 1: Weigh 6 - 9 parts of corncobs, 3 - 5 parts of natural zeolite, 8 - 10 parts of polyethylene glycol, 1 - 3 parts of NiFe 2 O 4 1, 0.2 - 0.5 parts of GQDs, 1.5 - 2.5 parts of phosphoric acid solution, and 25 parts of N,N-dimethylformamide. Wash, dry, and crush the corncobs, and sieve them with a mesh screen. The mesh screen is 20 mesh to obtain corncob fine particles. Pretreat the natural zeolite and sieve it with a mesh screen. The mesh screen is 80 mesh to obtain zeolite fine powder;

[0017] Step 2: Immerse the corncob fine particles obtained in step 1 in N,N-dimethylformamide for 6 h, add the zeolite fine powder obtained in step 1, stir, and perform ultrasonic treatment. The ultrasonic power is 20 - 40 kHz, and the ultrasonic time is 30 min. Filter and dry to obtain a powder material;

[0018] Step 3: Grind the powder material obtained in step 2 and perform carbonization treatment under an argon atmosphere. The carbonization temperature is 300 - 500 °C, the carbonization time is 2 h, and the heating rate is 10 °C / min. Cool to room temperature to obtain a carbonized powder;

[0019] Step 4: Add the carbonized powder obtained in step 3 to deionized water and stir evenly. The dosage ratio of activated carbon to deionized water is 1 g:10 ml. Slowly add phosphoric acid solution, and then perform activation treatment. Cool to room temperature, add sodium carbonate solution to adjust the pH to neutral, stir, filter, wash, and dry to obtain an optimized carbonized powder;

[0020] Step 5: Add the polyethylene glycol weighed in Step 1 to deionized water and stir evenly. The dosage ratio of polyethylene glycol to water is 1:15 to obtain an activated aqueous solution. Add the optimized carbonized powder obtained in Step 4 to the activated aqueous solution and stir. Then add GQDs and continue stirring. After that, add NiFe 2 O 4 and perform ultrasonic treatment to obtain a mixed reaction solution. Further hydrothermally treat the mixed reaction solution at a hydrothermal treatment temperature of 110 - 150 °C for 12 h, cool to room temperature to obtain a precipitate, wash and dry the precipitate to obtain an environmentally friendly wastewater treatment agent.

[0021] The beneficial effects achieved by the present invention are as follows:

[0022] For the environmentally friendly wastewater treatment agent prepared by the present invention, during the research and development of the wastewater treatment agent, the focus is on the rich and renewable resource of corncobs. For the first time, it is determined as the main material to prepare activated carbon. In order to endow the activated carbon with an ideal porous structure, natural zeolite is selected as the pore-forming agent. During the preparation process, natural zeolite plays a key role. Its unique structure interacts with the activated carbon, successfully constructing rich pores inside the activated carbon, greatly increasing the specific surface area. At the same time, natural zeolite itself has excellent adsorption performance. During wastewater treatment, it can effectively undergo a displacement reaction with heavy metal ions therein, thereby separating heavy metals from the wastewater, achieving both the optimization of the activated carbon structure and directly participating in the removal of wastewater pollutants, laying a solid foundation for the entire wastewater treatment system.

[0023] For the environmentally friendly wastewater treatment agent prepared by the present invention, in order to further expand the application breadth and depth of the treatment agent, NiFe 2 O 4 is introduced for the first time as a magnetic material. Considering that NiFe 2 O 4 can be efficiently adsorbed on the surface of the activated carbon material to maximize the wastewater treatment efficiency, polyethylene glycol is selected as the surfactant. Polyethylene glycol can form a uniform and stable adsorption film on the surface of the activated carbon, providing good attachment sites for NiFe 2 O 4 and significantly enhancing its adsorption effect. It is worth mentioning that due to the presence of natural zeolite, in NiFe 2 O 4During the process of adsorption onto the surface of activated carbon, it can effectively prevent its excessive occupation of the pores of activated carbon, ensuring the integrity of the activated carbon structure and the stability of the adsorption performance. On this basis, corn straw is also used as a raw material to prepare GQDs. The addition of GQDs broadens the light absorption range of the wastewater treatment agent, greatly improving the optical properties of photocatalysis, enabling the treatment agent to play an important role in the field of photocatalysis, thus realizing its wide application in the treatment of wastewater in multiple fields and providing a comprehensive innovative solution to solve complex wastewater pollution problems.

[0024] The environmentally friendly wastewater treatment agent prepared by the present invention takes environmental protection, high efficiency, and low cost as the key considerations for the first time, and can better meet the needs of wastewater treatment. Brief Description of the Drawings

[0025] Figure 1 It is a process diagram of the preparation method of the embodiment of the present invention;

[0026] Figure 2 It is the NiFe 2 O 4 phase spectrum diagram prepared in the embodiment of the present invention;

[0027] Figure 3 It is the SEM diagram of the environmentally friendly wastewater treatment agent prepared by the present invention;

[0028] Figure 4 It is the TEM diagram of the environmentally friendly wastewater treatment agent;

[0029] Figure 5 It is the high-resolution TEM diagram of the environmentally friendly wastewater treatment agent;

[0030] Figure 6 It is the photocatalytic removal diagram of tetracycline in wastewater under photocatalytic conditions by the environmentally friendly wastewater treatment agent;

[0031] Figure 7 It is the removal diagram of heavy metal ions adsorbed by the environmentally friendly wastewater treatment agent;

[0032] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. Detailed Embodiments

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with 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 of 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.

[0034] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described can be applied to the present invention. The preferred methods and materials described herein are for illustrative purposes only and do not limit the content of this application.

[0035] The preparation methods in the following examples refer to Figure 1 , unless otherwise specified, they are all conventional methods; the materials used in the following examples, unless otherwise specified, the saturated solutions in the present invention are all the solubility of the materials corresponding to 25 °C, and the prepared solutions select mordenite as natural zeolite.

[0036] Example 1: An environmentally friendly wastewater treatment agent is prepared from the following raw materials in parts by weight: 6 parts of corncob, 3 parts of mordenite, 8 parts of polyethylene glycol, 1 part of NiFe 2 O 4 1, 0.2 part of GQDs, 1.5 parts of phosphoric acid solution and 25 parts of N,N-dimethylformamide;

[0037] The preparation method of NiFe 2 O 4 includes the following steps:

[0038] (i) Weigh 0.9 g of nickel nitrate hexahydrate and dissolve it in 50 ml of ethylene glycol. Stir at a speed of 500 r / min for 30 min to obtain a nickel solution. Weigh 3 g of iron nitrate nonahydrate and dissolve it in 50 ml of ethylene glycol. Stir at a speed of 500 r / min for 30 min to obtain an iron solution. Slowly pour the nickel solution into the iron solution, heat the temperature to 90 °C and stir at a speed of 500 r / min for 2 h, and then cool naturally to room temperature to obtain a nickel-iron mixed solution;

[0039] (ii) Slowly add nitric acid solution to the nickel-iron mixed solution obtained in step (i) to adjust the pH value to 2. The concentration of the nitric acid solution is 4 mol / L. Heat the temperature to 60 °C and stir at a speed of 500 r / min. The heating time is 1 h. Perform drying treatment at 90 °C for 24 h using a vacuum drying oven to obtain a nickel-iron activated body. Put the nickel-iron activated body into a muffle furnace and heat it from room temperature to 400 °C and keep it for 2 h. The heating rate is 10 °C / min to obtain a NiFe 2 O 4 precursor. Heat the NiFe 2 O 4 precursor to 700 °C for 2 h for the second time. The heating rate for the second heating is 5 °C / min to obtain NiFe 2 O 4 .

[0040] Preparation method of GQDs, comprising the following steps:

[0041] (a) Weigh 6 g of corn straw, clean, dry and crush it, and sieve it using a 40-mesh screen to obtain fine straw particles;

[0042] (b) Add the fine straw particles obtained in step (a) to 50 ml of anhydrous ethanol, stir and pretreat for 30 min, filter and place it in a blast drying oven for drying treatment at 55 °C for 24 h to obtain a softened fine straw body;

[0043] (c) Measure 10 ml of triethylamine, add it to 50 ml of deionized water and stir evenly to obtain a mixed solution. Add the softened fine straw body obtained in step (b) to the mixed solution and stir. Slowly add 2.5 ml of nitric acid solution with a concentration of 3 mol / L to obtain a reaction mixed solution. Add the reaction mixed solution to a hydrothermal reactor and carry out hydrothermal treatment at 180 °C for 15 h, and naturally cool to room temperature to obtain a precursor solution of GQDs;

[0044] (d) Centrifuge the precursor solution of GQDs obtained in step (c) at a speed of 15000 r / min for 30 min to obtain a supernatant. Dialyze the obtained supernatant using a dialysis bag with a molecular weight cut-off of 300 D for 24 h to obtain a dialysate. Dry the dialysate in a blast drying oven at 65 °C for 24 h to obtain GQDs.

[0045] This embodiment also provides a preparation method of an environment-friendly wastewater treatment agent, comprising the following steps:

[0046] Step 1: Weigh 6 parts of corncob and 3 parts of mordenite. Clean, dry and crush the corncob, and sieve it using a 20-mesh screen to obtain fine corncob particles. Pretreat the mordenite and sieve it using an 80-mesh screen to obtain fine zeolite powder;

[0047] Step 2: Add the fine corncob particles obtained in Step 1 to 25 parts of N,N-dimethylformamide and soak for 6 h. Add the fine zeolite powder obtained in Step 1 and stir at a speed of 500 r / min for 30 min, and carry out ultrasonic treatment at a power of 20 kHz for 30 min. Filter and dry in a blast drying oven at 55 °C for 24 h to obtain a powder material;

[0048] Step 3: Grind the powder material obtained in Step 2 and carbonize it in a tubular furnace at 300 °C for 2 h in an argon atmosphere at a rate of 100 ml / min, with a heating rate of 10 °C / min, and naturally cool to room temperature to obtain a carbonized powder;

[0049] Step 4: Add the carbonized powder obtained in Step 3 into deionized water and stir evenly. The dosage ratio of activated carbon to deionized water is 1 g:10 ml. Slowly add 1.5 parts of phosphoric acid solution with a concentration of 2 mol / L. Then, perform activation treatment, naturally cool to room temperature, add saturated sodium carbonate solution to adjust the pH to neutral, stir and filter. Wash with deionized water 3 times and dry in a blast drying oven at 55 °C for 24 h to obtain the optimized carbonized powder;

[0050] Step 5: Weigh 8 parts of polyethylene glycol - 400 and add it to 48 ml of deionized water and stir evenly to obtain an activated aqueous solution. Add the optimized carbonized powder obtained in Step 4 into the activated aqueous solution and stir for 30 min. Then add 0.2 parts of GQDs and continue to stir for 30 min. After that, add 1 part of NiFe 2 O 4 Add and perform ultrasonic treatment for 30 min under the condition of a power of 20 kHz. Further heat to 110 °C and perform hydrothermal treatment in a hydrothermal autoclave for 12 h. Naturally cool to room temperature to obtain a precipitate. Wash the precipitate with deionized water 3 times and dry in a blast drying oven at 55 °C for 24 h to obtain an environmentally friendly wastewater treatment agent.

[0051] Example 2: An environmentally friendly wastewater treatment agent is prepared from the following raw materials in parts by weight: 7.5 parts of corncob, 4 parts of mordenite, 9 parts of polyethylene glycol, 2 parts of NiFe 2 O 4 2, 0.35 parts of GQDs, 2 parts of phosphoric acid solution and 25 parts of N,N - dimethylformamide;

[0052] NiFe 2 O 4 The preparation method of includes the following steps:

[0053] (i) Weigh 1.2 g of nickel nitrate hexahydrate and dissolve it in 50 ml of ethylene glycol. Stir at a rotation speed of 500 r / min for 30 min to obtain a nickel solution. Weigh 3.8 g of iron nitrate nonahydrate and dissolve it in 50 ml of ethylene glycol. Stir at a rotation speed of 500 r / min for 30 min to obtain an iron solution. Slowly pour the nickel solution into the iron solution, heat the temperature to 110 °C and stir at a rotation speed of 500 r / min for 2 h. Naturally cool to room temperature to obtain a nickel - iron mixture;

[0054] (ii) Slowly add a nitric acid solution to the nickel-iron mixed solution obtained in step (i), adjust the pH value to 3.5, the concentration of the nitric acid solution is 4 mol / L, heat the temperature to 70 °C and stir at a rotation speed of 500 r / min, the heating time is 1 h, perform drying treatment at 90 °C for 24 h using a vacuum drying oven to obtain a nickel-iron activator, put the nickel-iron activator into a muffle furnace and heat it from room temperature to 450 °C and keep it for 2 h, the heating rate is 10 °C / min to obtain NiFe 2 O 4 precursor, for NiFe 2 O 4 precursor, heat the secondary heating temperature to 800 °C and keep it for 2 h, the secondary heating rate is 5 °C / min to obtain NiFe 2 O 4 .

[0055] The preparation method of GQDs includes the following steps:

[0056] (a) Weigh 8 g of corn straw, clean, dry and crush it, and sieve it using a 40-mesh screen to obtain straw fine particles;

[0057] (b) Add the straw fine particles obtained in step (a) to 50 ml of absolute ethanol and stir for pretreatment for 30 min, filter and put it into a blast drying oven and dry it at 55 °C for 24 h to obtain a softened straw fine particle body;

[0058] (c) Measure 13 ml of triethylamine and add it to 50 ml of deionized water and stir evenly to obtain a mixed solution. Add the softened straw fine particle body obtained in step (b) to the mixed solution and stir, slowly add 4 ml of a nitric acid solution with a concentration of 3 mol / L to obtain a reaction mixed solution. Add the reaction mixed solution to a hydrothermal kettle and perform hydrothermal treatment at 200 °C for 15 h, and naturally cool to room temperature to obtain a GQDs precursor solution;

[0059] (d) Centrifuge the GQDs precursor solution obtained in step (c) for 30 min under the condition of a rotation speed of 15000 r / min to obtain a supernatant. Perform dialysis treatment on the obtained supernatant using a dialysis bag with a cut-off molecular weight of 400 D for 24 h to obtain a dialysis solution. Dry the dialysis solution in a blast drying oven at 65 °C for 24 h to obtain GQDs.

[0060] This embodiment also provides a preparation method of an environment-friendly wastewater treatment agent, including the following steps:

[0061] Step 1: Weigh 7.5 parts of corncob and 4 parts of mordenite. Clean, dry and crush the corncob, and sieve it using a 20-mesh screen to obtain corncob fine particles. Pretreat the mordenite and sieve it using an 80-mesh screen to obtain zeolite fine powder;

[0062] Step 2: Add the fine corn cob particles obtained in Step 1 to 25 parts of N,N-dimethylformamide and soak for 6 h. Add the fine zeolite powder obtained in Step 1 and stir for 30 min under the condition of a rotation speed of 500 r / min, and perform ultrasonic treatment for 30 min under the condition of a power of 30 kHz. Filter and dry in a blast drying oven at 55 °C for 24 h to obtain a powder material;

[0063] Step 3: Grind the powder material obtained in Step 2 and carbonize it in a tubular furnace at 400 °C for 2 h in an argon atmosphere at a rate of 100 ml / min, with a heating rate of 10 °C / min, and naturally cool to room temperature to obtain a carbonized powder;

[0064] Step 4: Add the carbonized powder obtained in Step 3 to deionized water and stir evenly. The dosage ratio of activated carbon to deionized water is 1 g:10 ml. Slowly add 2 parts of a phosphoric acid solution with a concentration of 2 mol / L, then perform activation treatment, naturally cool to room temperature, add saturated sodium carbonate solution to adjust the pH to neutral, stir and filter, wash 3 times with deionized water and dry in a blast drying oven at 55 °C for 24 h to obtain an optimized carbonized powder;

[0065] Step 5: Weigh 9 parts of polyethylene glycol-400 and add it to 54 ml of deionized water and stir evenly to obtain an activated aqueous solution. Add the optimized carbonized powder obtained in Step 4 to the activated aqueous solution and stir for 30 min. Add 0.35 parts of GQDs and continue to stir for 30 min. Then add 2 parts of NiFe 2 O 4 Add and perform ultrasonic treatment for 30 min under the condition of a power of 20 kHz, further heat to 130 °C and perform hydrothermal treatment in a hydrothermal autoclave for 12 h, naturally cool to room temperature to obtain a precipitate, wash the precipitate 3 times with deionized water and dry in a blast drying oven at 55 °C for 24 h to obtain an environmentally friendly wastewater treatment agent.

[0066] Example 3:

[0067] An environmentally friendly wastewater treatment agent is prepared from the following raw materials: 9 parts of corn cob, 5 parts of mordenite, 10 parts of polyethylene glycol, 3 parts of NiFe 2 O 4 3, 0.5 part of GQDs, 2.5 parts of phosphoric acid solution and 25 parts of N,N-dimethylformamide;

[0068] NiFe 2 O 4 The preparation method of includes the following steps:

[0069] (i)Weigh 1.5 g of nickel nitrate hexahydrate and dissolve it in 50 ml of ethylene glycol. Stir for 30 min at a rotation speed of 500 r / min to obtain a nickel solution. Weigh 4.5 g of iron nitrate nonahydrate and dissolve it in 50 ml of ethylene glycol. Stir for 30 min at a rotation speed of 500 r / min to obtain an iron solution. Slowly pour the nickel solution into the iron solution, heat the temperature to 120 °C and stir at a rotation speed of 500 r / min for 2 h, and then naturally cool to room temperature to obtain a nickel-iron mixed solution;

[0070] (ii)Slowly add a nitric acid solution to the nickel-iron mixed solution obtained in step (i) to adjust the pH value to 5. The concentration of the nitric acid solution is 4 mol / L. Heat the temperature to 80 °C and stir at a rotation speed of 500 r / min. The heating time is 1 h. Perform a drying treatment at 90 °C for 24 h using a vacuum drying oven to obtain a nickel-iron activated body. Place the nickel-iron activated body in a muffle furnace and heat it from room temperature to 500 °C and keep it for 2 h. The heating rate is 10 °C / min to obtain a NiFe 2 O 4 precursor. Heat the NiFe 2 O 4 precursor to 900 °C for a second time and keep it for 2 h. The heating rate for the second heating is 5 °C / min to obtain NiFe 2 O 4 .

[0071] The preparation method of GQDs includes the following steps:

[0072] (a)Weigh 10 g of corn straw, clean, dry and crush it, and sieve it using a 40-mesh screen to obtain straw fine particles;

[0073] (b)Add the straw fine particles obtained in step (a) to 50 ml of absolute ethanol and stir for 30 min for pretreatment. Filter and place it in a blast drying oven for drying treatment at 55 °C for 24 h to obtain a softened straw fine particle body;

[0074] (c)Measure 15 ml of triethylamine and add it to 50 ml of deionized water and stir evenly to obtain a mixed solution. Add the softened straw fine particle body obtained in step (b) to the mixed solution and stir. Slowly add 5 ml of a nitric acid solution with a concentration of 3 mol / L to obtain a reaction mixed solution. Add the reaction mixed solution to a hydrothermal autoclave and perform hydrothermal treatment at 220 °C for 15 h, and then naturally cool to room temperature to obtain a GQDs precursor solution;

[0075] (d) Centrifuge the precursor solution of GQDs obtained in step (c) at a rotational speed of 15,000 r / min for 30 min to obtain a supernatant. Dialyze the obtained supernatant using a dialysis bag with a molecular weight cut-off of 500 D for 24 h to obtain a dialysate. Dry the dialysate in a forced-air drying oven at 65 °C for 24 h to obtain GQDs.

[0076] This embodiment also provides a preparation method of an environmentally friendly wastewater treatment agent, which includes the following steps:

[0077] Step 1: Weigh 9 parts of corncobs and 5 parts of mordenite. Wash, dry, and crush the corncobs, and sieve them using a 20-mesh sieve to obtain fine corncob particles. Pretreat the mordenite and sieve it using an 80-mesh sieve to obtain fine zeolite powder.

[0078] Step 2: Immerse the fine corncob particles obtained in step 1 in 25 parts of N,N-dimethylformamide for 6 h. Add the fine zeolite powder obtained in step 1 and stir for 30 min at a rotational speed of 500 r / min, and perform ultrasonic treatment for 30 min at a power of 40 kHz. Filter and dry in a forced-air drying oven at 55 °C for 24 h to obtain a powder material.

[0079] Step 3: Grind the powder material obtained in step 2 and carbonize it in a tubular furnace at 500 °C for 2 h in an argon atmosphere at a flow rate of 100 ml / min. The heating rate is 10 °C / min, and naturally cool it to room temperature to obtain a carbonized powder.

[0080] Step 4: Add the carbonized powder obtained in step 3 to deionized water and stir evenly. The dosage ratio of activated carbon to deionized water is 1 g:10 ml. Slowly add 2.5 parts of a phosphoric acid solution with a concentration of 2 mol / L, then perform activation treatment, and naturally cool it to room temperature. Add a saturated sodium carbonate solution to adjust the pH to neutral, stir and filter, wash 3 times with deionized water, and dry in a forced-air drying oven at 55 °C for 24 h to obtain an optimized carbonized powder.

[0081] Step 5: Weigh 10 parts of polyethylene glycol-400 and add it to 60 ml of deionized water and stir evenly to obtain an activated aqueous solution. Add the optimized carbonized powder obtained in step 4 to the activated aqueous solution and stir for 30 min. Add 0.5 part of GQDs and continue to stir for 30 min. Then add 3 parts of NiFe 2 O 4 and perform ultrasonic treatment for 30 min at a power of 20 kHz, further heat it to 150 °C, and perform hydrothermal treatment in a hydrothermal autoclave for 12 h. Naturally cool it to room temperature to obtain a precipitate. Wash the precipitate 3 times with deionized water and dry it in a forced-air drying oven at 55 °C for 24 h to obtain an environmentally friendly wastewater treatment agent.

[0082] Comparative Example:

[0083] The difference between Comparative Example 1 and Example 2 is that no mordenite is added, and the rest is the same as Example 2;

[0084] The difference between Comparative Example 2 and Example 2 is that no NiFe is added 2 O 4 , the rest is the same as in Example 2;

[0085] The difference between Comparative Example 3 and Example 2 is that no GQDs are added, and the rest is the same as Example 2;

[0086] The difference between Comparative Example 4 and Example 2 is that no NiFe 2 O 4 and GQDs, and the rest is the same as in Example 2;

[0087] The difference between Comparative Example 5 and Example 2 is that no mordenite and NiFe 2 O 4 , the rest is the same as in Example 2;

[0088] The difference between Comparative Example 6 and Example 2 is that no mordenite, NiFe 2 O 4 and GQDs, and the rest is the same as Example 2.

[0089] Figure 2 NiFe 2 O 4 The phase spectrum of Figure 2 Can NiFe 2 O 4 The diffraction peaks at diffraction angles of 18.39°, 30.29°, 35.69°, 43.36°, 57.35°, and 62.91° correspond to NiFe 2 O 4 -JCPDS # The 111, 220, 311, 400, 511 and 440 crystal planes of 10-0325 indicate that NiFe 2 O 4 was successfully prepared, and no other impurity peaks appeared in the figure, indicating that NiFe 2 O 4 Higher purity; Figure 3 The SEM image of the prepared environmentally friendly wastewater treatment agent shows no large pieces of material, indicating that the material is dispersed relatively evenly; Figure 4 This is the TEM image of the environmentally friendly wastewater treatment agent. It can be seen that the environmentally friendly wastewater treatment agent has a higher porosity. Figure 5High-resolution TEM image of the environmentally friendly wastewater treatment agent. From the distribution area of the lattice fringes, the corresponding size of the lattice fringes is measured as D = 0.293 nm, which corresponds to the size of the (220) crystal plane of NiFe 2 O 4 , further indicating that NiFe 2 O 4 has been successfully prepared. At the same time, it can be seen through Figure 5 that there is a tight connection between NiFe 2 O 4 , activated carbon and GQDs, further indicating that the environmentally friendly wastewater treatment agent has been successfully prepared.

[0090] To verify the treatment effect of the prepared environmentally friendly wastewater treatment agent on wastewater, a 50 mg / L tetracycline solution was prepared by simulating the wastewater environment. 30 mg of the environmentally friendly wastewater treatment agent was weighed and added to 100 ml of the tetracycline solution. Under visible light conditions with a 300 w xenon lamp, the optical degradation of tetracycline by the environmentally friendly wastewater treatment agent was measured. Through Figure 6 it can be seen that for the examples, after 30 min of degradation, the content of the tetracycline solution is almost zero. For the prepared comparative examples, their catalytic activity is significantly weaker than that of the examples. To further test the performance of the environmentally friendly wastewater treatment agent in the field of adsorption, a mixed solution with concentrations of 10 mg / L of lead (Pb 2+ ), cadmium (Cd 2+ ), and mercury (Hg 2+ ) was prepared. 30 mg of the environmentally friendly wastewater treatment agent was weighed and added to 100 ml of the above-prepared mixed solution. Through Figure 7 it can be seen that the environmentally friendly wastewater treatment agent prepared in the examples shows good performance during the adsorption of heavy metal ions. At 40 min, the heavy metal ions in the solution are almost zero.

[0091] A 20 mg / L iron oxide nanoparticle wastewater mixture was further prepared. 30 mg of the environmentally friendly wastewater treatment agent was weighed and added to 100 ml of the above-prepared wastewater mixture, and the environmentally friendly wastewater treatment agent was used to adsorb the magnetic material.

[0092] Table 1 shows the adsorption result data of the environmentally friendly wastewater treatment agent for iron oxide nanoparticles:

[0093]

[0094] It can be seen from Table 1 that in Example 2, after 20 min of adsorption, the adsorption rate of iron oxide nanoparticles reached 99.3%, showing high adsorption activity.

[0095] Based on the above analysis, it can be obtained that the prepared environment-friendly wastewater treatment agent exhibits high performance in different fields.

[0096] Obviously, the above comparative examples and embodiments are only a part of the comparative examples and embodiments of the present invention, and the scope of protection of the present invention includes all comparative examples and embodiments based on such references.

[0097] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0098] The above description of the present invention and its embodiments is not restrictive. What is shown in the drawings is only one of the embodiments of the present invention, and the actual applications are not limited thereto. In general, if those of ordinary skill in the art are inspired by it and design similar ways and embodiments without creative efforts without departing from the purpose of the present invention, they shall fall within the scope of protection of the present invention.

Claims

1. An environmentally friendly wastewater treatment agent, characterized in that: The method is prepared from the following raw materials in parts by weight: 6-9 parts of corn cobs, 3-5 parts of natural zeolite, 8-10 parts of polyethylene glycol, 1-3 parts of NiFe2O4, 0.2-0.5 parts of GQDs, 1.5-2.5 parts of phosphoric acid solution and 25 parts of N,N-dimethylformamide; The method for preparing the environmentally friendly wastewater treatment agent comprises the following steps: Step 1, weigh 6-9 parts of corn cobs, 3-5 parts of natural zeolite, 8-10 parts of polyethylene glycol, 1-3 parts of NiFe2O4, 0.2-0.5 parts of GQDs, 1.5-2.5 parts of phosphoric acid solution and 25 parts of N,N-dimethylformamide, crush and sieve the corn cobs to obtain corn cob fine particles, pre-treat and sieve the natural zeolite to obtain zeolite fine powder; Step 2: soak the corncob granules obtained in step 1 in N,N-dimethylformamide, add the zeolite powder obtained in step 1 thereto, stir and ultrasonicate, filter and dry to obtain a powder material; Step 3: Grinding and carbonizing the powder material obtained in step 2, and cooling to room temperature to obtain carbonized powder; Step 4: Add the carbonized powder obtained in step 3 into deionized water and stir evenly, slowly add phosphoric acid solution, then activate it, cool it to room temperature, adjust the pH to neutral, stir and filter it, wash and dry it to obtain optimized carbonized powder; Step 5: Add the polyethylene glycol weighed in step 1 to deionized water and stir evenly to obtain an activated aqueous solution, add the optimized carbonized powder obtained in step 4 to the activated aqueous solution and stir, add GQDs and continue stirring, then add NiFe2O4 to ultrasound to obtain a mixed reaction solution, hydrothermally heat the mixed reaction solution, cool it to room temperature, obtain a precipitate, wash and dry the precipitate, and obtain an environmentally friendly wastewater treatment agent; The raw materials for preparing NiFe2O4 include nickel nitrate and iron nitrate; The preparation method of NiFe2O4 comprises the following steps: (i) weighing nickel nitrate and dissolving it in ethylene glycol and stirring to obtain a nickel liquid, weighing ferric nitrate and dissolving it in ethylene glycol and stirring to obtain an iron liquid, slowly pouring the nickel liquid into the iron liquid, heating and stirring, and cooling to room temperature to obtain a nickel-iron mixed liquid; (ii) adjusting the pH of the nickel-iron mixed solution obtained in step (i), heating and stirring, and drying to obtain a nickel-iron activated body, heating the nickel-iron activated body to obtain a NiFe2O4 precursor, reheating the NiFe2O4 precursor, and cooling to room temperature to obtain NiFe2O4.

2. An environmentally friendly wastewater treatment agent according to claim 1, characterized in that: The nickel nitrate and ethylene glycol in step (i) are used in a ratio of 0.9-1.5 g:50 ml, the iron nitrate and ethylene glycol in a ratio of 3-4.5 g:50 ml, and the pH range in step (ii) is 2-5.

3. An environmentally friendly wastewater treatment agent according to claim 1, characterized in that: The raw materials for preparing the GQDs include corn stalks and triethylamine; The preparation method of GQDs comprises the following steps: (a) weighing corn stalks, crushing and screening to obtain stalk fine particles; (b) measuring anhydrous ethanol, adding the anhydrous ethanol to pre-treat the straw fine particles obtained in step (a) to obtain a softened straw fine particle body; (c) adding triethylamine to deionized water and stirring evenly to obtain a mixed solution, adding the softened straw fine particles obtained in step (b) to the mixed solution and stirring, slowly adding nitric acid solution dropwise to obtain a reaction mixed solution, subjecting the reaction mixed solution to hydrothermal treatment, and cooling to room temperature to obtain a GQDs precursor solution; (d) Centrifuging the GQDs precursor solution obtained in step (c) to obtain a supernatant, dialyzing the obtained supernatant to obtain a dialysate, and drying the dialysate to obtain GQDs.

4. An environmentally friendly wastewater treatment agent according to claim 3, characterized in that: The raw material corn stalk and triethylamine are used in a ratio of 6-10 g:10-15 ml, the hydrothermal temperature in step (c) is 180-220° C., the hydrothermal time is 15 h, the dialysis bag used in the dialysis treatment in step (d) has a molecular weight cutoff of 300D-500D, and the dialysis time is 24 h.

5. An environmentally friendly wastewater treatment agent according to claim 1, characterized in that: The carbonization temperature in step three is 300-500°C, the carbonization time is 2h, the ratio of activated carbon to deionized water in step four is 1:10, the ratio of polyethylene glycol to water in step five is 1:6, the hydrothermal treatment temperature is 110-150°C, and the hydrothermal treatment time is 12h.

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