Method for preparing adsorbent from electroplating sludge

Abstract

The invention relates to the technical field of adsorbents, in particular to a method for preparing an adsorbent from electroplating sludge. According to the specific technical scheme, the method comprises the following steps: 1) leaching the electroplating sludge with nitric acid; 2) adding sodium oleate into the electroplating sludge obtained in the step 1), carrying out a water bath reaction, after the reaction is completed, carrying out a reaction under a certain pressure, and after the reaction is completed, carrying out washing for multiple times; (3) carrying out mixed reaction on a ferrous iron source and the electroplating sludge in the step (2), and introducing nitrogen into the solution to keep a proper amount of dissolved oxygen; and 4) carrying out a water bath reaction on the mixed solution obtained in the step 3), adjusting the pH value of the mixed solution to 8.0-10.0, and after the reaction is completed, carrying out vacuum drying to obtain the adsorbent. The invention solves the problems of poor settleability, large sludge amount, difficult mud-water separation and the like when the electroplating sludge is directly applied to the wastewater as an adsorbent.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorbents, and particularly relates to a method for preparing an adsorbent by using electroplating sludge. Background Art

[0002] With the rapid development of social economy, electroplating technology has been widely applied in fields such as aerospace, mechanical manufacturing, and military industry. However, with the development of the electroplating industry, a series of environmental pollution problems also arise, such as electroplating wastewater. In China, more than about 4 billion cubic meters of electroplating wastewater is generated every year, mainly from heavy metal-containing wastewater generated in each unit during the electroplating process. Currently, the most commonly used method for treating electroplating wastewater is chemical precipitation, which converts the organic or inorganic pollutants in the wastewater into electroplating sludge.

[0003] The chemical composition of electroplating sludge is complex and contains a large amount of heavy metals such as Cu, Cr, Fe, etc. Heavy metals are easy to migrate and are likely to spread and flow into the environment. If not disposed of or treated improperly, it will cause environmental pollution and even endanger human health. Also, because of the abundant heavy metals in electroplating sludge, it is regarded as a "resource" that can be compared with ores. If electroplating sludge can be recycled, it can not only reduce its impact on the environment but also save resources.

[0004] Currently, electroplating sludge is mainly treated by methods such as landfill, solidification, and heat treatment technologies, but there are problems such as heavy metal leakage causing secondary pollution to the environment and high costs, and it also wastes precious metal resources. Therefore, most scholars study the recycling of electroplating sludge, focusing on the recovery of valuable metals in the sludge, believing that this is an economic and valuable method. However, the composition of electroplating sludge is diverse and complex. During the leaching process, various metals contained in the sludge are inevitably dissolved, and the separation cost of each metal is high, the process is complex, the recovery process is very difficult, and at the same time, a large amount of waste acid and waste alkali is generated, the treatment cost is high, and secondary pollution is easily formed. To address the above problems, if electroplating sludge can be converted into an environmental functional material with certain economic value, this is a new way of recycling electroplating sludge and has great significance and far-reaching value.

[0005] Since electroplating sludge contains a large amount of metal hydroxides and has a high surface area and ion exchange capacity, etc., if directly used as an adsorbent in sewage treatment, there are problems such as poor sedimentation performance, large amount of sludge residue, and difficulty in separating mud and water. Therefore, the present invention proposes to directionally transform the heavy metals in electroplating sludge and combine them with an iron source to prepare an adsorbent with a layered structure and excellent adsorption performance. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a method for preparing an adsorbent using electroplating sludge. Aiming at the problems such as the complexity of inorganic or organic components in electroplating sludge, the complex heavy metal separation process, high cost, extremely difficult recovery, and the simultaneous generation of a large amount of waste acid and waste alkali, which is prone to secondary pollution, it is proposed to first use an organic complexing agent without secondary pollution to fix the chromium ions in the sludge, and then react an iron source with the sludge containing a large amount of metal hydroxides to prepare a magnetic adsorbent with excellent adsorption performance.

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0008] The present invention discloses a method for preparing an adsorbent using electroplating sludge, and the steps are as follows:

[0009] 1) Leach the electroplating sludge with 5M nitric acid;

[0010] 2) Under normal temperature conditions, add sodium oleate to the electroplating sludge in step 1) for a water bath reaction. After the reaction is completed, react under a certain pressure. After the reaction is completed, perform multiple washes;

[0011] 3) Mix and react a divalent iron source with the electroplating sludge in step 2), and introduce nitrogen into the solution to maintain an appropriate amount of dissolved oxygen;

[0012] 4) Perform a water bath reaction on the mixed solution in step 3), adjust the pH value of the mixed solution to 8.0 - 10.0. After the reaction is completed, vacuum dry to obtain the adsorbent.

[0013] Preferably, in step 1), the mass-volume ratio of the electroplating sludge to concentrated nitric acid is 20 - 45 g / L, and the leaching time is 0.5 - 2 h.

[0014] Preferably, in step 2), the mass ratio of the sodium oleate to the electroplating sludge is 1:1.0 - 2.0.

[0015] Preferably, in step 2), the temperature of the water bath reaction is normal temperature, and the stirring time is 0.4 - 1.5 h.

[0016] Preferably, in step 2), react at a pressure of 0.5 MPa for 10 - 30 h, and the reaction temperature is 120 - 200 °C.

[0017] Preferably, in step 3), the mass ratio of the electroplating sludge to the divalent iron source is 0.5 - 2:1, and the concentration of the divalent iron source is 5 g / L.

[0018] Preferably, in step 4), the temperature of the water bath reaction is 25 - 35 °C, and the stirring time is 1 - 1.5 h.

[0019] Preferably, in step 4), the temperature of vacuum drying is 50-70 °C, and the drying time is 2-4 h.

[0020] Correspondingly, an application of an adsorbent prepared by the above preparation method in treating lead-containing wastewater.

[0021] Preferably, the dosage of the adsorbent is 0.1 g / L, and the concentration of lead ions is 250-300 mg / L.

[0022] The present invention has the following beneficial effects:

[0023] The present invention proposes a new way for the resource utilization of electroplating sludge: for electroplating sludge containing harmful substances and being unstable, the research focus has so far been on the recovery of valuable heavy metals from the sludge, which has been generally considered an economical and valuable method. However, this method has problems such as difficult separation and recovery of components in the sludge and high costs. Therefore, the present invention proposes to directly prepare electroplating sludge into an adsorbent, and synthesize a magnetic adsorbent using an iron source and electroplating sludge, which solves the problems of poor sedimentation, large amount of sludge residue, and difficult separation of mud and water when electroplating sludge is directly used as an adsorbent in wastewater, fixes the heavy metals in the electroplating sludge, and has a high recovery rate. Description of the Drawings

[0024] Figure 1 It is the SEM diagram of the adsorbent prepared in Example 1 of the present invention. Detailed Embodiments

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

[0026] If not specifically specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art.

[0027] The present invention discloses a method for preparing an adsorbent using electroplating sludge, and the steps are as follows:

[0028] 1) Mix electroplating sludge with 5M nitric acid, perform ultrasonic treatment on the mixture for leaching, and after 1 h, test the content of chromium ions in the supernatant by ICP-OES to determine the amount of sodium oleate added. As one implementation method, 1 g of electroplating sludge is mixed with 30 mL of 5M nitric acid.

[0029] 2) Under normal temperature conditions, first add a certain amount of pretreated electroplating sludge into the reaction flask, and add an appropriate amount of sodium oleate. The mass ratio of sodium oleate to electroplating sludge is 1:1.0 - 2.0. Then place the reaction flask in a constant temperature water bath magnetic stirrer at 25°C and stir for 0.4 - 1.5 h. After the stirring stops, pour the mixed solution into a stainless steel autoclave with a pressure of 0.5 Mpa and react for 10 - 30 h at a temperature of 120 - 200°C to fix the chromium metal in the sludge. After the reaction is completed, wash the precipitate with distilled water 3 times.

[0030] 3) Add the divalent iron source and the electroplating sludge in step 2) to the reaction flask in a certain proportion, and introduce nitrogen into the solution to maintain an appropriate dissolved oxygen (for example, introduce nitrogen at a flow rate of 1.0 L / min for 6 - 8 min), and prepare the adsorbent after mixing and reacting. The mass ratio of electroplating sludge to divalent iron source is set to 0.5 - 2:1, and the concentration of the divalent iron source is 5 g / L. The divalent iron source includes but is not limited to FeSO4·7H2O and FeCl2.

[0031] 4) Place the mixed solution in step 3) in a constant temperature water bath magnetic stirrer at 25°C and react for 1 h. Use sodium hydroxide and hydrochloric acid to adjust the pH value of the mixed solution to keep it at a constant value, and the set range of the pH value is 8.0 - 10.0.

[0032] 5) Place the reaction product in step 4) in a vacuum drying oven for drying for subsequent characterization. The temperature setting range of the vacuum drying oven is 50 - 70°C, and the drying time is 2 - 4 h.

[0033] 6) Treat the simulated lead-containing wastewater with the prepared magnetic adsorbent. The dosage of the adsorbent is 0.1 g / L, and the concentration of lead ions is 250 - 300 mg / L.

[0034] The following further elaborates the present invention in combination with specific embodiments.

[0035] In the following examples, all the reagents used are commercially available. According to the above preparation method, the treatment process of step 2) is as follows: Under normal temperature conditions, first add a certain amount of pretreated electroplating sludge into the reaction flask, add an appropriate amount of sodium oleate. The mass ratio of sodium oleate to electroplating sludge is 1:1.5. Then place the reaction flask in a constant temperature water bath magnetic stirrer at 25°C and stir for 40 min. After the stirring stops, pour the mixed solution into a stainless steel autoclave with a pressure of 0.5 Mpa and react for 20 h at a temperature of 160°C to fix the chromium metal in the sludge. After the reaction is completed, wash the precipitate with distilled water 3 times. All the following examples use the electroplating sludge treated in this step 2).

[0036] Example 1

[0037] A method for preparing an adsorbent using electroplating sludge, the steps are as follows:

[0038] Under normal temperature conditions, according to the mass ratio of electroplating sludge to divalent iron ions of 1:1, weigh 5.0 g of the electroplating sludge in step 2) above and add it to a FeSO4·7H2O solution with an iron mass concentration of 5.0 g / L, introduce nitrogen, adjust the pH to 9.0, and synthesize the product. Separate the synthesized product from the solution by magnetic separation method, repeatedly wash the synthesized product with deionized water and absolute ethanol respectively, and then place it in a vacuum drying oven at a temperature of 60 °C for 2.5 h of drying. The obtained product is a copper-containing composite ferrite. Analyze with the sedimentation rate of the product, and the sedimentation rate is 88%.

[0039] Apply the prepared adsorbent to the treatment of simulated cadmium-containing wastewater, and characterize it with the removal rate of lead ions. The adsorbent dosage is 0.1 g / L, and the lead ion removal rate is 100%.

[0040] Example 2

[0041] A method for preparing an adsorbent using electroplating sludge, the steps are as follows:

[0042] Under normal temperature and pH = 9.0 conditions, according to the mass ratio of electroplating sludge to divalent iron ions of 0.5:1, weigh 2.5 g of the electroplating sludge in step 2) and add it to a FeSO4·7H2O solution with an iron mass concentration of 5 g / L, introduce nitrogen, carry out the synthesis reaction, separate the synthesized product from the solution by magnetic separation method, repeatedly wash the synthesized product with deionized water and absolute ethanol respectively, and then place it in a vacuum drying oven at a temperature of 60 °C for 2.5 h of drying. The obtained product is a copper-containing composite ferrite. Analyze with the sedimentation rate of the product, and the sedimentation rate is 89%. Due to the large amount of iron source added, the sedimentation rate of Example 2 is slightly higher than that of Example 1.

[0043] Apply the prepared adsorbent to the treatment of simulated cadmium-containing wastewater, and characterize it with the removal rate of lead ions. The adsorbent dosage is 0.01 g / L, and the lead ion removal rate is 78%.

[0044] Example 3

[0045] A method for preparing an adsorbent using electroplating sludge, the steps are as follows:

[0046] Under normal temperature and pH = 9.0 conditions, according to the mass ratio of electroplating sludge to divalent iron ions of 2:1, 10 g of the electroplating sludge in step 2) was weighed and added to a FeSO4·7H2O solution with an iron mass concentration of 5 g / L. Nitrogen was introduced for the synthesis reaction. The synthesized product was separated from the solution by magnetic separation method, and the synthesized product was repeatedly washed with deionized water and absolute ethanol, and then placed in a vacuum drying oven at 60 °C for 2.5 h of drying. The obtained product was a copper-containing composite ferrite. Analyzed by the sedimentation rate of the product, the sedimentation rate was 15%.

[0047] The prepared adsorbent was applied to the treatment of simulated cadmium-containing wastewater, characterized by the removal rate of lead ions. The dosage of the adsorbent was 0.01 g / L, and the removal rate of lead ions was 100%. Its treatment effect was the same as that of Example 1, but the amount of sludge produced after treatment was large, and the sludge-water separation effect was worse than that of Example 1.

[0048] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing an adsorbent using electroplating sludge, characterized in that: The steps are as follows: 1) Leach the electroplating sludge with 5M nitric acid; 2) At room temperature, add sodium oleate to the electroplating sludge in step 1) and carry out a water bath reaction. After the reaction is completed, carry out a reaction under a certain pressure. After the reaction is completed, carry out multiple washings; 3) Mix and react the divalent iron source with the electroplating sludge in step 2), and introduce nitrogen into the solution to maintain an appropriate dissolved oxygen; 4) Carry out a water bath reaction on the mixed solution in step 3), adjust the pH value of the mixed solution to 8.0 - 10.

0. After the reaction is completed, carry out vacuum drying to obtain the adsorbent.

2. The method for preparing an adsorbent using electroplating sludge according to claim 1, wherein: In step 1), the mass-volume ratio of the electroplating sludge to concentrated nitric acid is 20 - 45 g / L, and the leaching time is 0.5 - 2 h.

3. A method for preparing an adsorbent using electroplating sludge according to claim 1, characterized in that: In step 2), the mass ratio of the sodium oleate to the electroplating sludge is 1:1.0 - 2.

0.

4. A method for preparing an adsorbent using electroplating sludge according to claim 1, characterized in that: In step 2), the temperature of the water bath reaction is room temperature, and the stirring time is 0.4 - 1.5 h.

5. A method for preparing an adsorbent using electroplating sludge according to claim 1, characterized in that: In step 2), carry out a reaction at a pressure of 0.5 MPa for 10 - 30 h, and the reaction temperature is 120 - 200 °C.

6. A method for preparing an adsorbent using electroplating sludge according to claim 1, characterized in that: In step 3), the mass ratio of the electroplating sludge to the divalent iron source is 0.5 - 2:1, and the concentration of the divalent iron source is 5 g / L.

7. A method for preparing an adsorbent using electroplating sludge according to claim 1, characterized in that: In step 4), the temperature of the water bath reaction is 25 - 35 °C, and the stirring time is 1 - 1.5 h.

8. A method for preparing an adsorbent using electroplating sludge according to claim 1, characterized in that: In step 4), the temperature of the vacuum drying is 50 - 70 °C, and the drying time is 2 - 4 h.

9. Application of the adsorbent prepared by the preparation method according to any one of claims 1 - 8 in treating lead-containing wastewater.

10. The application according to claim 9, wherein: The dosage of the adsorbent is 0.1 g / L, and the concentration of lead ions is 250 - 300 mg / L.

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