Polyaniline / zinc oxide composite adsorption material as well as preparation method and application thereof

Abstract

The invention provides a polyaniline / zinc oxide composite adsorption material as well as a preparation method and application thereof. A simple chemical oxidation method is adopted to prepare the polyaniline / zinc oxide composite adsorption material, and the material is simple to prepare, can be used as an adsorption material for treating a lead-polluted water source, can effectively remove lead in wastewater, is large in adsorption capacity and high in removal rate, can reduce the lead concentration to an extremely low level, can purify the wastewater to reach the discharge standard, and ensures the safety of a water environment; the polyaniline and the zinc oxide are compounded and have the characteristics of the polyaniline and the zinc oxide, the stability is enhanced, and acid and alkali resistance and environmental change resistance are achieved. The unique structure provides more active sites, accelerates the lead adsorption rate, can be repeatedly used, and reduces the treatment cost. The polyaniline / zinc oxide composite adsorption material is simple in preparation process and easy for large-scale production. The method is flexible in application in the field of lead-polluted wastewater treatment, can adapt to various treatment processes, provides an efficient, economic and sustainable solution for industrial wastewater treatment, and promotes development of the environmental protection industry.

Description

Technical Field

[0001] The invention relates to the technical field of material chemistry and environmental protection, and in particular to a polyaniline / zinc oxide composite adsorption material and a preparation method and application thereof. Background Art

[0002] Heavy metal pollution is an extremely serious global environmental problem. The harm of heavy metals to the ecosystem cannot be underestimated. Lead is one of the most difficult heavy metal pollutants in water bodies. In the process of rapid development of modern industry and agriculture, heavy metals have poured into water bodies in large quantities through industrial wastewater discharge (such as electroplating, leather making and other industries), agricultural non-point source pollution (the use of pesticides and fertilizers containing heavy metals), atmospheric deposition and improper disposal of solid waste, causing the heavy metal pollution in water bodies to become increasingly serious. In addition, heavy metal pollution has the characteristics of concealment, persistence and irreversibility. They can gradually enrich along the food chain, and ultimately seriously threaten human life and health and the balance and stability of the ecosystem. The control of heavy metal pollution in water bodies has become a top priority.

[0003] At present, the treatment methods for heavy metal pollution in water bodies mainly include chemical precipitation, ion exchange resin, reverse osmosis, membrane separation and adsorption, etc. Among them, the adsorption method is widely used due to its significant advantages such as high efficiency, low cost, convenient operation and little interference to the environment.

[0004] Polyaniline is a polymer material with special structure and properties. Its molecular chain contains abundant nitrogen-containing functional groups, such as amino (-NH2) and imine (=NH). These functional groups give polyaniline unique chemical activity, enabling it to interact strongly with heavy metal ions through electrostatic attraction, chelation and other methods, thereby achieving effective adsorption of heavy metal ions. At the same time, polyaniline can also be prepared and modified through a variety of synthetic methods to optimize its adsorption performance and physical and chemical properties, and it shows good stability and repeatability in practical applications.

[0005] At present, the main adsorption materials are activated carbon, organic modified materials and biochar. Activated carbon is mostly obtained by chemical activation method with high specific surface area, which is complicated and costly. Cleaning will produce secondary pollution of acid and alkali waste liquid. The modification process of organic modified materials is complicated. The adsorption performance of biochar is relatively weak, and the treatment effect of some low-concentration and complex pollutants is limited.

[0006] Chinese patent "A method for preparing ultra-high specific surface area activated carbon for heavy metal adsorption" (CN104150480A) discloses a method for preparing ultra-high specific surface area activated carbon for heavy metal adsorption. The method obtains activated carbon after microwave carbonization. This method consumes a lot of energy and is not suitable for large-scale promotion. Chinese patent "A method for preparing an adsorbent of polyaniline core-shell magnetic mesoporous nanomaterial" (CN113019340A) discloses a method for preparing a polyaniline / zinc oxide composite adsorbent material for heavy metal adsorption. The chitosan and aniline composite material after magnetization shows the ability to adsorb heavy metals. This preparation method is cumbersome and costly, and is not suitable for promotion. Summary of the invention

[0007] The invention provides a polyaniline / zinc oxide composite adsorption material and a preparation method and application thereof. The prepared polyaniline / zinc oxide composite adsorption material is applied to the restoration of lead-contaminated water and soil, achieving the purpose of efficiently treating lead pollution in water.

[0008] In a first aspect, the present invention provides a method for preparing a polyaniline / zinc oxide composite adsorption material. The polyaniline / zinc oxide composite adsorption material is obtained by mixing aniline and zinc oxide and then subjecting the mixture to oxidation treatment with ammonium persulfate.

[0009] Furthermore, the mass ratio of the aniline to the zinc oxide is 5:1.

[0010] In a second aspect, the present invention provides a method for preparing the above-mentioned polyaniline / zinc oxide composite adsorption material, the preparation method comprising the following steps: S1, heating zinc hydroxide to 300°C in a nitrogen environment and keeping the temperature for 2 hours, cooling it to room temperature and then taking it out to obtain the zinc oxide, grinding it into powder for later use; S2, dissolving ammonium persulfate in H 2 SO 4 The solution was stirred in an ice bath for 1 to 2 hours to obtain solution A; the zinc oxide was dissolved in deionized water by ultrasonic vibration to obtain solution B; the aniline solution was dissolved in H 2 SO 4 The solution was stirred for 10 minutes, then the solution B was poured into the solution and continued to be stirred for 10 minutes, and then the solution A was poured into the solution and continued to be stirred. After the stirring was completed, the solution was placed in an ice bath to obtain a mixed solution. The mixed solution was washed with deionized water and ethanol until it was neutral, and then dried and ground to obtain the polyaniline / zinc oxide composite adsorption material.

[0011] Furthermore, in step S1, the heating rate is 5°C / min.

[0012] Furthermore, in step S2, H 2 SO 4 The concentration of the solution is 1.5 mol / L.

[0013] Furthermore, in step S2, the temperature of the ice bath is 5°C.

[0014] Furthermore, in step S2, the power of ultrasonic oscillation is 500 W and the time is 15 min.

[0015] In a third aspect, the present invention provides the use of the above-mentioned polyaniline / zinc oxide composite adsorption material in the field of lead-containing wastewater treatment and lead-contaminated soil treatment.

[0016] Furthermore, the method for treating lead-containing wastewater includes: adding the polyaniline / zinc oxide composite adsorption material into a beaker containing lead-containing wastewater; placing the beaker on a water bath constant temperature oscillator, adjusting the speed to 180r / min and the temperature to 25°C; taking a sample after oscillating for 10-450min, taking 1mL of the solution through a 0.45μm needle filter into a 15mL centrifuge tube; diluting the solution 30 times, and measuring the concentration of the solution using a flame-atomic absorption spectrophotometer.

[0017] Furthermore, the preparation method of the lead-containing wastewater includes: weighing 1.6g of lead nitrate, dissolving it in 10mL of nitric acid solution, transferring it to a 1L volumetric flask, fixing the volume to the mark, shaking it well, and obtaining a 1000mg / L Pb stock solution; preparing 50mL of a 600mg / L solution with the Pb stock solution and adjusting the pH to 5 with 0.1M HCl and NaOH to obtain lead-containing wastewater; wherein the amount of the polyaniline / zinc oxide composite adsorption material used is 50mg.

[0018] In summary, the present invention has the following beneficial effects:

[0019] 1. The present invention adopts a simple chemical oxidation method to prepare a polyaniline / zinc oxide composite adsorption material. The material is easy to prepare and can be used as an adsorption material for treating lead-contaminated water sources. It can effectively remove lead from wastewater, has a large adsorption capacity and a high removal rate. The maximum adsorption capacity can reach 406.4 mg / L. Only 1.68 kg of material is required for each ton of lead-containing wastewater (lead concentration of 1000 mg / L), and the cost is reduced by 60% compared with methods such as activated carbon. The lead concentration can be reduced to an extremely low level, the wastewater can be purified to meet the discharge standard, and the safety of the water environment can be guaranteed.

[0020] 2. The polyaniline and zinc oxide in the present invention are composited, which has the characteristics of both, and has enhanced stability and resistance to acid, alkali and environmental changes. Its unique structure provides more active sites, accelerates the lead adsorption rate, and can be reused, reducing the processing cost.

[0021] 3. The preparation process of the polyaniline / zinc oxide composite adsorption material in the present invention is simple and easy to mass produce. It is flexible in application in the field of lead-contaminated wastewater treatment and can be adapted to a variety of treatment processes, providing efficient, economical and sustainable solutions for industrial wastewater treatment and promoting the development of the environmental protection industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is the XRD diagram of Example 1, Comparative Example 1, Comparative Example 2 of the present invention, and the XRD diagram of Example 1 after adsorbing lead ions;

[0023] Figure 2 1 and 2 are SEM images of Example 1, Comparative Example 1, and Comparative Example 2 of the present invention, and a SEM image of Example 1 after adsorbing lead ions; wherein (a) is a SEM image of Example 1, (b) is a SEM image of Comparative Example 1, (c) is a SEM image of Comparative Example 2, and (d) is a SEM image of Example 1 after adsorbing lead ions;

[0024] Figure 3 is the adsorption kinetics model of Application Example 1 of the present invention;

[0025] Figure 4 is the adsorption isotherm of Application Example 1 of the present invention;

[0026] Figure 5 It is the curve of the adsorption amount changing with time of Application Example 1, Application Example 2, Comparative Example 1 and Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the examples. It is particularly noted that if no specific conditions are specified in the following examples, the reactions are carried out according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources.

[0028] Example

[0029] Example 1

[0030] (1) Preparation of zinc oxide: Weigh zinc hydroxide (analytical grade, purity ≥ 99%) and place it in a tube furnace. Connect nitrogen and heat the temperature to 300°C at a rate of 5°C / min. Keep the temperature for 2 hours. After cooling to room temperature in the instrument, take it out and grind it into powder using a mortar.

[0031] (2) Preparation of polyaniline / zinc oxide composite adsorption material: Dissolve ammonium persulfate in 1.5 mol / L H 2 SO 4 The solution was stirred in an ice bath for 1 h to obtain solution A, and zinc oxide was dissolved in deionized water by ultrasonic vibration to obtain solution B. The aniline solution was dissolved in 1.5 mol / L H 2 SO 4Stir for 10 minutes, then pour solution B and continue stirring for 10 minutes, then pour solution A and continue stirring, ice bath after stirring, the ratio of aniline to zinc oxide is 5:1. Wash it with deionized water and ethanol until it is neutral, dry it in an oven at 60℃, and grind it with a mortar to obtain a polyaniline / zinc oxide composite adsorption material, recorded as PANI / ZNO.

[0032] Example 2

[0033] (1) Preparation of zinc oxide: 5.0 g of zinc hydroxide (analytical grade, purity ≥ 99%) was weighed and placed in a tube furnace. The temperature was raised to 300° C. at a rate of 5° C. / min and kept at that temperature for 2 hours. The mixture was cooled to room temperature in the instrument and then taken out and ground into powder using a mortar.

[0034] (2) Preparation of polyaniline / zinc oxide composite adsorption material: Dissolve ammonium persulfate in 1.5 mol / L H 2 SO 4 The solution was stirred in an ice bath for 1 h to obtain solution A, and zinc oxide was dissolved in deionized water by ultrasonic vibration to obtain solution B. The aniline solution was dissolved in 1.5 mol / L H 2 SO 4 Stir for 10 minutes, then pour solution B and continue stirring for 10 minutes, then pour solution A and continue stirring, ice bath after stirring, the ratio of aniline to zinc oxide is 10:1. Wash it with deionized water and ethanol until it is neutral, dry it in an oven at 60℃, and grind it with a mortar to obtain a polyaniline / zinc oxide composite adsorption material, recorded as PANI / 0.1ZNO.

[0035] Comparative Example

[0036] Comparative Example 1

[0037] Preparation of zinc oxide: Weigh zinc hydroxide (analytical grade, purity ≥99%) and place it in a tube furnace. Connect nitrogen and heat the temperature to 300°C at a rate of 5°C / min. Keep warm for 2 hours. After cooling to room temperature in the instrument, take it out and grind it into powder in a mortar, recorded as ZNO.

[0038] Comparative Example 2

[0039] Preparation of polyaniline: Dissolve ammonium persulfate in 1.5 mol / L H 2 SO 4 The solution was stirred in an ice bath for 1 h to obtain solution A. The aniline solution was dissolved in 1.5 mol / L H 2 SO 4 Stir for 10 minutes, then pour solution A into it and stir continuously for 3 hours, and then put it in an ice bath. Wash it with deionized water and ethanol until it is neutral, dry it in an oven at 60°C, and grind it with a mortar to obtain a polyaniline composite adsorbent material, which is recorded as PANI.

[0040] The XRD patterns and SEM images of ZNO, PANI, PANI / ZNO and PANI / ZNO adsorbing Pb are shown in Figure 1 and Figure 2 As shown, in Figure 1 It can be clearly seen that ZNO and PANI were successfully prepared, but the XRD of PANI / ZNO is consistent with that of PANI. This is because the amorphous structure of PANI makes it impossible for the low-proportion ZNO to be reflected. The peak of lead sulfate appears after PANI / ZNO absorbs Pb. Figure 2 The successful composite of PANI / ZNO can be clearly seen in the figure, and the lead sulfate plate-like structure also appears after adsorption.

[0041] Application Examples

[0042] Application Example 1

[0043] Step 1: Accurately weigh 1.6 g of lead nitrate and dissolve it in a small amount of water. Then add 10 mL of nitric acid to dissolve it. Then transfer it to a 1 L volumetric flask, dilute it to the mark, and shake it well to prepare a 1000 mg / L Pb stock solution.

[0044] Step 2: Prepare 50 mL of 600 mg / L lead solution with Pb stock solution and adjust the pH to 5 with 0.1 M HCl and NaOH. Weigh 50 mg of PANI / ZNO in Example 1 and add it to a beaker containing 50 mL of 600 mg / L Pb solution.

[0045] Step 3: Place the beaker on a water bath constant temperature oscillator, adjust the speed to 180r / min, and the temperature to 25°C;

[0046] Step 4: Take samples after oscillating for 10, 30, 60, 90, 150, 210, 330, and 450 min, and take 1 mL of the solution through a 0.45 μm syringe filter into a 15 mL centrifuge tube;

[0047] Step 5: Dilute the solution 30 times and measure the concentration of the solution using a flame-atomic absorption spectrophotometer (AAS).

[0048] Application Example 2

[0049] Step 2: Prepare 50 mL of 600 mg / L lead solution with Pb stock solution and adjust the pH to 5 with 0.1 M HCl and NaOH. Weigh 50 mg of PANI / 0.1 ZNO in Example 1 and add it to a beaker containing 50 mL of 600 mg / L Pb solution.

[0050] The other steps are the same as those in Application Example 1.

[0051] Comparative application example 1

[0052] Step 2: Prepare 50 mL of 600 mg / L lead solution with Pb stock solution and adjust the pH to 5 with 0.1 M HCl and NaOH. Weigh 50 mg of ZNO in Example 1 and add it to a beaker containing 50 mL of 600 mg / L Pb solution.

[0053] The other steps are the same as those in Application Example 1.

[0054] Comparative Application Example 2

[0055] Step 2: Prepare 50 mL of 600 mg / L lead solution with Pb stock solution and adjust the pH to 5 with 0.1 M HCl and NaOH, weigh 50 mg of PANI in Example 1 and add it to a beaker containing 50 mL of 600 mg / L Pb solution;

[0056] The other steps are the same as those in Application Example 1.

[0057] Performance Testing

[0058] The polyaniline / zinc oxide composite adsorption material PANI / ZNO prepared in Example 1 was used for the adsorption of lead ions, and the adsorption effect was evaluated by adsorption experiments such as kinetics and thermodynamics;

[0059] 1. Kinetics experiment

[0060] Prepare multiple 50mL lead solutions with a concentration of 600mg / L, and add 50mg of the polyaniline / zinc oxide composite adsorbent prepared in Example 1 respectively. Sampling tests are carried out at different times. At each time point, three samples are taken out for testing and the average value is taken. The test results are as follows: Figure 3 As shown in Table 1;

[0061] Table 1 Adsorption performance of the composite material obtained in Example 1 at different times

[0062]

[0063] From Table 1 and Figure 3 It can be seen that the polyaniline / zinc oxide composite adsorption material prepared by the present invention has a good adsorption effect, and its pseudo-first-order kinetic parameter R2 is low, and the pseudo-second-order kinetic equation is fitted to obtain R 2 ≥0.99, which is significantly larger than the pseudo-first-order model, and the fitted equilibrium adsorption amount is closer to the measured value than the pseudo-first-order model, indicating that the adsorption of Cd by the three materials is more consistent with the pseudo-second-order kinetic model, and the adsorption process is mainly chemical adsorption.

[0064] 2. Isotherm experiment

[0065] 50 mg of the polyaniline / zinc oxide composite adsorbent prepared in Example 1 was added to 50 mL of a lead solution with a concentration of 100 to 1000 mg / L, and then the test was performed after shaking on a shaker for 8 hours; each group was repeated three times and the average value was taken; the test results were as follows: Figure 4 As shown in Table 2;

[0066] Table 2 Adsorption performance of the polyaniline / zinc oxide composite adsorbent obtained in Example 1 for lead solutions of different concentrations

[0067]

[0068]

[0069] From Table 2 and Figure 4 It can be seen that the polyaniline / zinc oxide composite adsorption material of the present invention has a good adsorption effect on lead ions. By fitting it with the Langmuir model, Freundlich model, Temkin model and Dubinin-Radushkevich model, the Langmuir equation fitting coefficient is higher, indicating that there are uniformly distributed strong binding sites on the surface of the material, which is consistent with the monolayer chemical adsorption mechanism.

[0070] The curve of the adsorption amount of the material changing with time is as follows Figure 5 As shown in the figure, it is not difficult to see that the material quickly adsorbs lead ions in the solution in the first 2 hours, and reaches adsorption equilibrium within about 4 hours.

[0071] The above is only an exemplary embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A polyaniline / zinc oxide composite adsorption material, characterized in that: The polyaniline / zinc oxide composite adsorption material is obtained by mixing aniline and zinc oxide and then performing oxidation treatment with ammonium persulfate.

2. The polyaniline / zinc oxide composite adsorption material according to claim 1, characterized in that: The mass ratio of the aniline to the zinc oxide is 5:

1.

3. The method for preparing the polyaniline / zinc oxide composite adsorption material according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: S1, heating zinc hydroxide to 300° C. in a nitrogen environment and keeping the temperature for 2 hours, then cooling to room temperature and taking it out to obtain the zinc oxide, grinding it into powder for later use; S2. Dissolve ammonium persulfate in H2SO4 solution, and stir in an ice bath for 1 to 2 hours to obtain solution A; dissolve the zinc oxide in deionized water by ultrasonic vibration to obtain solution B; dissolve aniline solution in H2SO4 solution, stir for 10 minutes, pour in solution B and continue stirring for 10 minutes, then pour in solution A and continue stirring, and place in an ice bath after stirring to obtain a mixed solution; wash the mixed solution with deionized water and ethanol until it is neutral, dry and grind to obtain the polyaniline / zinc oxide composite adsorption material.

4. The method for preparing the polyaniline / zinc oxide composite adsorption material according to claim 3, characterized in that: In the step S1, the heating rate is 5°C / min.

5. The method for preparing the polyaniline / zinc oxide composite adsorption material according to claim 3, characterized in that: In step S2, the concentration of the H2SO4 solution is 1.5 mol / L.

6. The method for preparing the polyaniline / zinc oxide composite adsorption material according to claim 3, characterized in that: In step S2, the temperature of the ice bath is 5°C.

7. The method for preparing the polyaniline / zinc oxide composite adsorption material according to claim 3, characterized in that: In step S2, the power of ultrasonic oscillation is 500W and the time is 15 minutes.

8. Use of the polyaniline / zinc oxide composite adsorption material as claimed in claim 1 or 2 in the field of lead-containing wastewater treatment and lead-contaminated soil treatment.

9. The use according to claim 8, characterized in that: Methods for treating lead-containing wastewater include: Adding the polyaniline / zinc oxide composite adsorption material into a beaker containing lead-containing wastewater; Place the beaker on a water bath constant temperature oscillator, adjust the speed to 180r / min, and the temperature to 25°C; After shaking for 10-450 min, take a sample and pass 1 mL of the solution through a 0.45 μm syringe filter into a 15 mL centrifuge tube; The solution was diluted 30 times and the concentration was measured using a flame atomic absorption spectrophotometer.

10. The use according to claim 9, characterized in that: The preparation method of the lead-containing wastewater comprises: weighing 1.6 g of lead nitrate, dissolving it in 10 mL of nitric acid solution, transferring it to a 1 L volumetric flask, fixing the volume to the mark, and shaking it well to obtain a 1000 mg / L Pb stock solution; The Pb stock solution is used to prepare 50 mL of a 600 mg / L solution and the solution is adjusted to pH=5 with 0.1 M HCl and NaOH to obtain lead-containing wastewater; Wherein, the usage of the polyaniline / zinc oxide composite adsorption material is 50 mg.

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