Magnetic adsorption material and preparation method and method for treating heavy metal wastewater
A magnetic adsorption material was prepared by reacting potassium ferrate with nickel-containing electroplating wastewater, which solved the problem of difficult removal of complexed nickel, achieved efficient heavy metal recovery and simplified the process, and reduced the risk of secondary pollution.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-04
- Publication Date
- 2026-06-05
Abstract
Description
Technical Field
[0001] This invention relates to a magnetic adsorption material and a method for treating heavy metal wastewater using the same material, belonging to the field of wastewater treatment technology. Background Technology
[0002] With the widespread use of metallic materials, the concentration of heavy metals in the environment is constantly accumulating, potentially posing a significant threat to the health of humans, animals, and plants. Nickel, as a Class I pollutant, is non-degradable; its toxicity can only be reduced by altering its form. However, wastewater from electroless nickel plating typically contains large amounts of complexing agents, such as citric acid, tartaric acid, and EDTA, which combine with nickel ions to form various stable and readily recyclable metal complexes. Conventional chemical precipitation methods are ineffective in removing these complexed nickel compounds. Long-term accumulation in water or soil will have negative environmental impacts.
[0003] Magnetic adsorption materials refer to a class of materials with a large specific surface area, high surface energy, and certain magnetic properties. With the continuous development of adsorption technology, magnetic adsorption materials have become one of the most studied adsorption materials both domestically and internationally due to their unique paramagnetism, strong adsorption capacity, and easy recycling. Their research and application have expanded from the original field of chemical materials to multiple fields such as water treatment, medicine, and biochemistry. For example, Ren Zongli prepared iron, iron-cobalt, and iron-cobalt-zinc magnetic activated carbon adsorption materials using a one-step high-temperature treatment method, and achieved good results in adsorbing methylene blue and Acid Blue 80. Zhang Gaosheng et al. combined activated carbon with iron oxides. They impregnated the activated carbon in a mixed solution of ferrous sulfate and ferric chloride, precipitated it with sodium hydroxide, and obtained the adsorption material after washing and drying. In the experiment, the material showed good adsorption capacity for the azo dye Acid Orange. However, during the synthesis process, iron easily blocked the active sites of the activated carbon. At the same time, in practical applications, iron ions easily dissolve, making it unusable.
[0004] CN111644145A discloses a method for preparing this magnetic adsorbent. The method involves mixing organoaluminum and lithium chloride in a certain proportion, adding nanoscale magnetic materials, and removing some water using magnetic adsorption or centrifugation. The resulting solid substance is the magnetic adsorbent. This magnetic adsorbent attaches an aluminum-based adsorbent to the surface of a magnetic material, essentially linking the adsorbent to the magnetic material surface via molecular bonds. However, in practical applications, this can easily lead to the aluminum detaching from the magnetic carrier, causing secondary pollution.
[0005] CN111957301A discloses a method for preparing a magnetic chitosan nickel ion molecularly imprinted adsorbent. The method involves adding chitosan and iron(III) oxide to an aqueous acetic acid solution, mixing, adjusting the pH to 7.5 with NaOH solution, collecting the precipitate with a magnet, dispersing the precipitate in acetaldehyde solution, heating and shaking, adding epichlorohydrin, imprinting the resulting product in NiSO4 solution, adding glutaraldehyde solution for crosslinking, and washing to obtain the magnetic chitosan nickel ion molecularly imprinted adsorbent. This adsorbent has a certain adsorption effect on nickel ions in water, but the overall preparation process is relatively cumbersome and increases the complexity of the process. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention provides a magnetic adsorption material and its preparation method. The method involves reusing nickel-containing electroplating wastewater and preparing an adsorption material with potassium ferrate, simultaneously achieving wastewater reuse and the preparation of a high-performance magnetic adsorption material. The prepared magnetic adsorption material exhibits excellent performance in removing heavy metals from wastewater.
[0007] To achieve the above technical objectives, the technical solution of the present invention is as follows:
[0008] The first aspect of the present invention aims to provide a method for preparing a magnetic adsorption material, comprising:
[0009] An alkaline alcoholic solution of potassium ferrate is added to nickel-containing electroplating wastewater. After mixing, acid or alkali is added to adjust the pH of the mixture to 10-12. The mixture reacts to form a precipitate, which is then aged, filtered, washed, dried, and calcined to obtain the magnetic adsorption material.
[0010] Nickel plating wastewater contains a lot of complexed nickel, which is difficult to recover. This invention dissolves potassium ferrate in an alkaline alcohol solution, controls the degree of hydrolysis of potassium ferrate in the solution, and mixes it with nickel plating wastewater. The strong oxidizing property of potassium ferrate is used to destroy the complexed nickel in the wastewater. Then, the alkalinity is increased to cause a co-precipitation reaction, thus obtaining a magnetic adsorption material.
[0011] Furthermore, the alkaline alcohol solution comprises an alkali, an alcohol, and water, wherein the alcohol is selected from at least one of methanol and ethanol, and the alkali is selected from at least one of sodium hydroxide and potassium hydroxide, preferably sodium hydroxide.
[0012] Furthermore, the alkali content in the alkaline alcohol solution is 0.5-5 mol / L, preferably 1-3 mol / L; based on the weight of the alkaline alcohol solution, the alcohol content is 5%-30%, preferably 10-20%.
[0013] Furthermore, in the alkaline alcoholic solution of potassium ferrate, the concentration of potassium ferrate is 30 mg / L-10 g / L, preferably 100 mg / L-5 g / L, and most preferably 120-200 mg / L.
[0014] Furthermore, the alkaline alcoholic solution of potassium ferrate is added dropwise to the nickel-containing electroplating wastewater. Adding the alkaline alcoholic solution of potassium ferrate dropwise to the nickel plating wastewater effectively breaks down the complexed state of nickel in the wastewater. A more preferred embodiment is to add the alkaline alcoholic solution of potassium ferrate while stirring at a speed of 300 rpm-900 rpm, preferably 500 rpm-700 rpm.
[0015] The nickel-containing electroplating wastewater mainly consists of wastewater from cleaning plated parts, which accounts for the largest proportion of the electroplating wastewater and is the main source of nickel plating wastewater. This wastewater has a pH of 3.5-5.0, a nickel content of 50-500 mg / L, and a complex composition. Furthermore, to ensure the plating solution's stability and long-lasting effect, it contains a large amount of complexing agents and buffers.
[0016] Furthermore, the amount of potassium ferrate added depends on the nickel content in the nickel-containing electroplating wastewater, so that the molar ratio of total nickel to iron in potassium ferrate is 2.5-6:1, preferably 3.5-4.5:1.
[0017] Furthermore, the acid or base used to adjust the pH of the mixture to 10-12 is selected from at least one of sulfuric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the mass concentration of the acid or base is 1-10%, preferably 5-8%.
[0018] Furthermore, acid or alkali can be added to adjust the pH to 10-12 to ensure complete precipitation of metallic nickel and iron in the wastewater; preferably, the pH should be adjusted to 11-12.
[0019] Furthermore, the washing is performed with deionized water until neutral, and the drying is performed at 60°C-80°C.
[0020] Furthermore, the calcination is carried out at 200℃-350℃ for 1-4 hours, preferably at 250℃-300℃, and preferably for 2-3 hours.
[0021] Furthermore, it also includes the process of grinding dried or calcined solids into powder.
[0022] The second aspect of the present invention aims to provide a magnetic adsorption material prepared by the above-described preparation method.
[0023] The technical objective of the third aspect of this invention is to provide a method for treating heavy metal wastewater, wherein the magnetic adsorption material is mixed with the heavy metal wastewater to adsorb metal ions therein.
[0024] Furthermore, the heavy metal wastewater contains at least one of chromium, lead, copper, vanadium and mercury. The wastewater may also inevitably contain a certain amount of organic pollutants. During the treatment process, the concentration of other pollutants will be reduced in a synergistic way to improve the wastewater treatment efficiency.
[0025] Furthermore, the method also includes a process of separating the adsorbent from the wastewater using the magnetism of the adsorbent material. The adsorbent material prepared by this invention has strong magnetism and a high separation and recovery rate.
[0026] Compared with the prior art, the present invention has the following advantages:
[0027] (1) This invention uses nickel in nickel-containing electroplating wastewater as raw material to reuse nickel ions in the wastewater, and achieves a high nickel recovery rate, while also saving the cost of wastewater treatment.
[0028] (2) The alkaline alcoholic solution of potassium ferrate prepared in this invention effectively controls the degree of hydrolysis of potassium ferrate in water by controlling the solution ratio and concentration, successfully destroying the complex state of nickel in nickel plating wastewater, which is conducive to nickel recovery.
[0029] (3) The present invention synthesizes iron-nickel magnetic adsorption material directly in nickel plating wastewater by co-precipitation method. The process is simple, easy to operate, and has a good adsorption effect on heavy metals in wastewater.
[0030] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation
[0031] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.
[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.
[0033] The pH value in this invention was determined using the glass electrode method for determining pH value in water (GB / T6920), and the metal ion content was determined using the microwave digestion / inductively coupled plasma mass spectrometry (ICP-MS) method. The specific surface area and average pore size of the material were determined using the biogas adsorption method (BET).
[0034] In this embodiment of the invention, the nickel-containing electroplating wastewater was taken from a chemical plant, with a pH of 4.2 and a total nickel content of 240 mg / L. The wastewater may also contain small amounts of other pollutants. The heavy metal wastewater described in this invention takes vanadium-containing wastewater as an example. This vanadium-containing wastewater was taken from a refinery, with a pH of 6.5 and a total vanadium content of 25 mg / L. The wastewater may also contain a certain amount of other metals and organic pollutants.
[0035] Example 1
[0036] Sodium hydroxide was dissolved in a 20% aqueous ethanol solution to prepare a 0.5 mol / L alkaline alcohol solution. Potassium ferrate was added to this solution at a concentration of 160 mg / L and stirred until completely dissolved. Nickel-containing electroplating wastewater was taken and added dropwise to the potassium ferrate alkaline alcohol solution at 500 rpm. After the addition was complete, the solution was mixed thoroughly. The pH of the wastewater was adjusted to 10 with a 5% sodium hydroxide solution. Precipitation continuously formed during the reaction. After complete reaction, the solution was aged for 8 hours, filtered, repeatedly rinsed with deionized water until neutral, and dried at 60℃. After grinding, the solution was calcined at 250℃ for 2 hours to obtain the iron-nickel magnetic adsorbent material. The nickel content in the nickel-containing electroplating wastewater before and after treatment was measured, and the nickel recovery rate was calculated to be 90.3%.
[0037] Vanadium metal adsorption test in wastewater: Take the above-mentioned alum-containing wastewater and add the prepared iron-nickel magnetic adsorbent at 0.5 g / L at room temperature. After adsorption for 2 hours, take the supernatant and test the total vanadium content, which is 0.47 mg / L.
[0038] Example 2
[0039] Sodium hydroxide was dissolved in a 10% aqueous ethanol solution to prepare a 1.5 mol / L alkaline alcohol solution. Potassium ferrate was added to this solution at a concentration of 120 mg / L and stirred until completely dissolved. Nickel-containing electroplating wastewater was taken and added dropwise to the potassium ferrate alkaline alcohol solution at 550 rpm. After the addition was complete, the solution was mixed thoroughly. The pH of the wastewater was adjusted to 11 with a 5% sodium hydroxide solution. Precipitation continuously formed during the reaction. After complete reaction, the solution was aged for 8 hours, filtered, repeatedly rinsed with deionized water until neutral, dried at 60℃, ground, and calcined at 250℃ for 2 hours to obtain the iron-nickel magnetic adsorbent material. The nickel content in the nickel-containing electroplating wastewater before and after treatment was measured, and the nickel recovery rate was calculated to be 95.2%.
[0040] Vanadium metal adsorption test in wastewater: Take the above-mentioned alum-containing wastewater and add the prepared iron-nickel magnetic adsorbent at 0.5 g / L at room temperature. After adsorption for 2 hours, take the supernatant and test the total vanadium content, which is 1.71 mg / L.
[0041] Example 3
[0042] Sodium hydroxide was dissolved in a 10% aqueous ethanol solution to prepare a 2 mol / L alkaline alcohol solution. Potassium ferrate was added to this solution at a concentration of 150 mg / L and stirred until completely dissolved. Nickel-containing electroplating wastewater was taken and added dropwise to the potassium ferrate alkaline alcohol solution at 600 rpm. After the addition was complete, the solution was mixed thoroughly. The pH of the wastewater was adjusted to 12 with a 5% sodium hydroxide solution. Precipitation continuously formed during the reaction. After complete reaction, the solution was aged for 8 hours, filtered, repeatedly rinsed with deionized water until neutral, and dried at 60℃. After grinding, the solution was calcined at 250℃ for 2 hours to obtain the iron-nickel magnetic adsorbent material. The nickel content in the nickel-containing electroplating wastewater before and after treatment was measured, and the nickel recovery rate was calculated to be 99.2%.
[0043] Vanadium metal adsorption test in wastewater: Take the above-mentioned alum-containing wastewater and add the prepared iron-nickel magnetic adsorbent at 0.5 g / L at room temperature. After adsorption for 2 hours, take the supernatant and test the total vanadium content, which is 0.16 mg / L.
[0044] Example 4
[0045] Sodium hydroxide was dissolved in a 10% aqueous ethanol solution to prepare a 2 mol / L alkaline alcohol solution. Potassium ferrate was added to this solution at a concentration of 150 mg / L and stirred until completely dissolved. Nickel-containing electroplating wastewater was taken and added dropwise to the potassium ferrate alkaline alcohol solution at 600 rpm. After the addition was complete, the solution was mixed thoroughly. The pH of the wastewater was adjusted to 10 with a 5% sodium hydroxide solution. Precipitation continuously formed during the reaction. After complete reaction, the solution was aged for 8 hours, filtered, repeatedly rinsed with deionized water until neutral, and dried at 60℃. After grinding, the solution was calcined at 250℃ for 2 hours to obtain the iron-nickel magnetic adsorbent material. The nickel content in the nickel-containing electroplating wastewater before and after treatment was measured, and the nickel recovery rate was calculated to be 91.3%.
[0046] Vanadium metal adsorption test in wastewater: Take the above-mentioned alum-containing wastewater and add the prepared iron-nickel magnetic adsorbent at 0.5 g / L at room temperature. After adsorption for 2 hours, take the supernatant and test the total vanadium content, which is 0.95 mg / L.
[0047] Example 5
[0048] Sodium hydroxide was dissolved in a 10% aqueous ethanol solution to prepare a 2 mol / L alkaline alcohol solution. Potassium ferrate was added at a concentration of 160 mg / L and stirred until completely dissolved. Nickel-containing electroplating wastewater was taken and added dropwise to the potassium ferrate alkaline alcohol solution at 600 rpm. After the addition was complete, the solution was mixed thoroughly. The pH of the wastewater was adjusted to 11.5 with a 5% sodium hydroxide solution. Precipitation continuously formed during the reaction. After complete reaction, the solution was aged for 8 hours, filtered, repeatedly rinsed with deionized water until neutral, and dried at 60℃. After grinding, the solution was calcined at 350℃ for 2 hours to obtain the iron-nickel magnetic adsorbent material. The nickel content in the nickel-containing electroplating wastewater before and after treatment was measured, and the nickel recovery rate was calculated to be 97.4%. The magnetic adsorbent material in water exhibited good magnetic recovery performance.
[0049] Vanadium metal adsorption test in wastewater: Take the above-mentioned alum-containing wastewater and add the prepared iron-nickel magnetic adsorbent at 0.5 g / L at room temperature. After adsorption for 2 hours, take the supernatant and test the total vanadium content, which is 0.33 mg / L.
[0050] Example 6
[0051] Sodium hydroxide was dissolved in a 10% aqueous ethanol solution to prepare a 1.5 mol / L alkaline alcohol solution. Potassium ferrate was added at a concentration of 150 mg / L and stirred until completely dissolved. Nickel-containing electroplating wastewater was taken and added dropwise to the potassium ferrate alkaline alcohol solution at 600 rpm. After the addition was complete, the solution was mixed thoroughly. The pH of the wastewater was adjusted to 11.5 with a 5% sodium hydroxide solution. Precipitation continuously formed during the reaction. After complete reaction, the solution was aged for 8 hours, filtered, repeatedly rinsed with deionized water until neutral, and dried at 60℃. After grinding, the solution was calcined at 250℃ for 3 hours to obtain an iron-nickel magnetic adsorbent material. The specific surface area of the adsorbent material was measured to be 63.2 m². 2 / g, with an average pore size of 6.07nm. The nickel recovery rate was calculated to be 97.0% by determining the nickel content in the nickel-containing electroplating wastewater before and after treatment.
[0052] Vanadium metal adsorption test in wastewater: Take the above-mentioned alum-containing wastewater and add the prepared iron-nickel magnetic adsorbent at 0.5 g / L at room temperature. After adsorption for 2 hours, take the supernatant and test the total vanadium content, which is 0.42 mg / L.
[0053] Example 7
[0054] A small amount of heavy metal wastewater was taken from a refinery. The wastewater had a pH of 4.9 and contained 65 mg / L of total cadmium and 23 mg / L of copper. The wastewater may also contain other metals and organic pollutants. At room temperature, 2.0 g / L of the magnetic adsorption material prepared in Example 6 was added to the wastewater. After adsorption for 2 hours, the supernatant was collected, and the total cadmium content was found to be 7.34 mg / L and the copper content 0.97 mg / L.
[0055] Comparative Example 1
[0056] A 1.5 mol / L sodium hydroxide aqueous solution was prepared, and 150 mg / L potassium ferrate was added and stirred until completely dissolved. Nickel-containing electroplating wastewater was taken and added dropwise to the alkaline alcoholic solution of potassium ferrate at 600 rpm. After the addition was complete, the solution was mixed thoroughly. The pH of the wastewater was adjusted to 11.5 with a 5% sodium hydroxide solution. Precipitation continuously formed during the reaction. After complete reaction, the solution was aged for 8 hours, filtered, repeatedly rinsed with deionized water until neutral, and dried at 60℃. After grinding, the solution was calcined at 250℃ for 3 hours to obtain the iron-nickel magnetic adsorbent material. The specific surface area of the adsorbent material was measured to be 56.1 m². 2 / g, with an average pore size of 4.97nm. The nickel recovery rate was calculated to be 88.5% by measuring the nickel content in the nickel-containing electroplating wastewater before and after treatment.
[0057] Vanadium metal adsorption test in wastewater: Take the above-mentioned alum-containing wastewater and add the prepared iron-nickel magnetic adsorbent at 0.5 g / L at room temperature. After adsorption for 2 hours, take the supernatant and test the total vanadium content, which is 3.15 mg / L.
[0058] The results of Example 6 and Comparative Example 1 show that adding alcohol when preparing potassium ferrate solution not only controls the hydrolysis of potassium ferrate, but also reduces the aggregation of metal oxides, increases the specific surface area of the material, provides more effective adsorption sites, and improves the removal effect of heavy metals from wastewater.
[0059] Comparative Example 2
[0060] The process for preparing the iron-nickel magnetic adsorbent material is the same as in Example 6, except that the calcination is carried out at 400°C for 3 hours to obtain the iron-nickel magnetic adsorbent material.
[0061] Vanadium metal adsorption test in wastewater: The above-prepared iron-nickel magnetic adsorbent was added to the above-mentioned alum-containing wastewater at 0.5 g / L at room temperature. After adsorption for 2 hours, the supernatant was taken, and the total vanadium content was measured to be 1.12 mg / L. After the magnetic materials of Example 6 and Comparative Example 2 adsorbed the wastewater, they were recovered using a magnet, dried at 80°C, weighed, and after removing the weight of adsorbed vanadium, the recovery rate of the adsorbent material in Example 6 was 95.7%, and the recovery rate of the adsorbent material in Comparative Example 2 was 82.6%. Therefore, the higher calcination temperature weakened the magnetism of the magnetic adsorbent material.
[0062] Comparative Example 3
[0063] No alkali was added when preparing the potassium ferrate solution. Potassium ferrate was dissolved in a 10% aqueous ethanol solution to prepare a 150 mg / L potassium ferrate alcohol solution. The remaining steps and operating conditions were the same as in Example 6, thus obtaining the iron-nickel magnetic adsorbent material. The nickel recovery rate was calculated to be 76.3% by measuring the nickel content in the nickel-containing electroplating wastewater before and after treatment.
[0064] Vanadium metal adsorption test in wastewater: Take the above-mentioned alum-containing wastewater and add the prepared iron-nickel magnetic adsorbent at 0.5 g / L at room temperature. After adsorption for 2 hours, take the supernatant and test the total vanadium content, which is 10.97 mg / L.
Claims
1. A method for preparing a magnetic adsorption material, comprising: An alkaline alcoholic solution of potassium ferrate is added to nickel-containing electroplating wastewater. After mixing, acid or alkali is added to adjust the pH of the mixture to 10-12. The mixture reacts to form a precipitate, which is then aged, filtered, washed, dried, and calcined to obtain the magnetic adsorption material.
2. The preparation method according to claim 1, characterized in that, The alkaline alcohol solution comprises an alkali, an alcohol, and water, wherein the alcohol is selected from at least one of methanol and ethanol, and the alkali is selected from at least one of sodium hydroxide and potassium hydroxide.
3. The preparation method according to claim 1, characterized in that, The alkaline alcohol solution contains 0.5-5 mol / L of alkali.
4. The preparation method according to claim 1, characterized in that, Based on the weight of the alkaline alcohol solution, the alcohol content is 5%-30%.
5. The preparation method according to claim 1, characterized in that, The concentration of potassium ferrate in the alkaline alcoholic solution is 30 mg / L-10 g / L.
6. The preparation method according to claim 5, characterized in that, The concentration of potassium ferrate in the alkaline alcoholic solution is 100 mg / L to 5 g / L.
7. The preparation method according to claim 1, characterized in that, The nickel-containing electroplating wastewater has a pH of 3.5-5.0 and a nickel content of 50-500 mg / L.
8. The preparation method according to claim 1, characterized in that, The amount of potassium ferrate added makes the molar ratio of total nickel to iron in potassium ferrate 2.5-6:
1.
9. The preparation method according to claim 1, characterized in that, The acid or base used to adjust the pH of the mixture to 10-12 is selected from at least one of sulfuric acid, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the mass concentration of the acid or base is 1-10%.
10. The preparation method according to claim 1, characterized in that, The roasting is carried out at 200℃-350℃ for 1-4 hours.
11. The preparation method according to claim 10, characterized in that, The roasting is carried out at 250℃-300℃ for 2-3 hours.
12. The magnetic adsorption material prepared by the preparation method according to any one of claims 1-11.
13. A method for treating heavy metal wastewater, comprising mixing the magnetic adsorption material of claim 12 with the heavy metal wastewater to adsorb metal ions therein.
14. The method according to claim 13, characterized in that, The heavy metal wastewater contains at least one of chromium, lead, copper, vanadium, and mercury.
15. The method according to claim 13, characterized in that, The method also includes the process of separating the adsorbent from the wastewater using the magnetism of the adsorbent material.