Method for adsorbing perfluorooctanoic acid in wastewater

Abstract

The present application relates to wastewater adsorption method technical field, specifically to a kind of method for adsorbing perfluorooctanoic acid in wastewater;The method comprises the following steps: S1, adding reagent to the wastewater containing perfluorooctanoic acid to adjust the pH value of wastewater;S2, after pH value adjustment is completed, copper sulfide solid particles are added to the wastewater containing perfluorooctanoic acid, then stirring is carried out under constant temperature condition to make copper sulfide solid particles adsorb perfluorooctanoic acid in wastewater;The best molar ratio of copper sulfide solid particles and perfluorooctanoic acid is 1:10.In the present application, the adsorption effect of copper sulfide on perfluorooctanoic acid is good, and other reagents do not need to be added in the reaction process.Under the condition of 30 DEG C and pH 11, when the initial concentration of PFOA is 1150mg / L, the adsorption capacity of copper sulfide to PFOA can reach 451.76mg / g.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater adsorption method, and particularly relates to a method for adsorbing perfluorooctanoic acid in wastewater. BACKGROUND

[0002] Perfluorinated compounds (PFCs) have high thermal stability and chemical stability, and are widely used in production and life, such as chemical industry, textile, leather, synthetic detergent, carpet stain repellent, mechanical lubricant, paint coating, cosmetics, paper food packaging material, chrome plating industry, fire-fighting foam, and synthesis of sulfonamide pesticides. Perfluorinated compounds persist in the environment and are hardly biodegraded, and have been listed as new persistent organic pollutants. Studies have shown that the accumulation level of perfluorinated compounds in organisms is much higher than that of known organochlorine pesticides and persistent organic pollutants such as dioxins. In addition, it also has reproductive toxicity, neurotoxicity and carcinogenicity, etc.

[0003] Perfluorinated compounds (PFCs) have the characteristics of wide pollution range, strong biological accumulation, strong chemical stability, and long decomposition time. Studies have shown that PFCs can be detected in all ocean waters around the world, of which the amount of perfluorooctanoic acid (PFOA) is the most, followed by perfluorooctanesulfonic acid (PFOS). In addition, researchers have also detected PFCs in tap water. In China, the pollution degree of PFCs is not optimistic, and different contents of PFCs have been detected in various water systems and basins. The southern region is more serious than the northern region, especially the economically developed Pearl River Delta region, and PFOA is the final conversion product of most perfluorinated compounds.

[0004] PFOA has strong chemical stability and physical stability, so PFOA in water is difficult to be effectively degraded by using conventional treatment methods such as oxidation-reduction and biological treatment. At present, the most reported and commonly used methods for degrading or removing PFOA are photodegradation, advanced oxidation, and biological degradation. However, these complex methods are difficult to implement in actual wastewater treatment, and very strict reaction conditions or very complex reaction equipment are required to achieve the degradation of PFOA. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a method for adsorbing perfluorooctanoic acid in wastewater.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A method for adsorbing perfluorooctanoic acid in wastewater, the method comprising the following steps:

[0008] S1, adding a reagent to wastewater containing perfluorooctanoic acid to adjust the pH value of the wastewater;

[0009] S2, after the pH value is adjusted, copper sulfide solid particles are added into the wastewater containing perfluorooctanoic acid, and then stirring is performed under constant temperature conditions to enable the copper sulfide solid particles to adsorb the perfluorooctanoic acid in the wastewater;

[0010] The molar ratio of the copper sulfide solid particles to the perfluorooctanoic acid is 1:10.

[0011] Preferably, in step S1, the reagent for adjusting the pH value is an HCl solution or an NaOH solution.

[0012] Preferably, the pH value at which the copper sulfide solid particles adsorb the perfluorooctanoic acid is 11.

[0013] Preferably, the preparation method of the copper sulfide solid particles is as follows: a sodium sulfide solution is added dropwise into a copper chloride solution, heating and stirring are performed to obtain a copper sulfide solution, and then the copper sulfide solution is precipitated, filtered, and dried to obtain the copper sulfide solid particles.

[0014] Preferably, the molar ratio of the sodium sulfide solution to the copper chloride solution is 2:3.

[0015] Preferably, the constant temperature conditions during the adsorption in step S2 are 15-45 DEG C.

[0016] An adsorbent includes the copper sulfide solid particles mentioned in the adsorption method.

[0017] An application of an adsorbent in adsorbing perfluorooctanoic acid in wastewater.

[0018] The beneficial effects of the present application are as follows:

[0019] 1. The material production process and reaction process in the present application have low energy consumption. The production of the copper sulfide material only needs to be completed in a 60 DEG C water bath, and the process of adsorbing perfluorooctanoic acid by the copper sulfide can be performed in a 30 DEG C or 15 DEG C low-temperature environment, thereby reducing energy consumption and pollution.

[0020] 2. The copper sulfide has good adsorption effect on perfluorooctanoic acid in the present application, and no other reagent needs to be added in the reaction process. When the initial concentration of PFOA is 1150 mg / L under the condition of 30 DEG C, the adsorption amount of the copper sulfide on PFOA can reach 451.76 mg / g. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0022] Figure 1 It is a scanning electron microscope image of the copper sulfide solid particles in the present application.

[0023] Figure 2 The influence of copper sulfide on the adsorption amount of perfluorooctanoic acid under different pH conditions in the application. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0025] Preparation of copper sulfide solid particles

[0026] Step 1: Prepare 0.01 mol / L copper chloride (CuCl2·2H2O) solution 1L; prepare 0.015 mol / L sodium sulfide (Na2S·9H2O) solution 1L (dissolve the weighed sodium sulfide solid in 100 ml distilled water and then dilute to 1L with anhydrous ethanol);

[0027] Step 2: Add the prepared sodium sulfide solution to a 3L three-necked flask, and add the copper chloride solution drop by drop using a separatory funnel under the condition of 60℃ water bath and constant stirring;

[0028] Step 3: Stop stirring after the dropwise addition is completed; filter after 2h of precipitation, and vacuum dry the precipitate for 12h to obtain copper sulfide solid particles.

[0029] Example 1

[0030] S1: Add reagents to wastewater containing perfluorooctanoic acid, and adjust the pH value of the wastewater to pH=3, 5, 10, 10.5, 11, 11.5, 12, 12.5, respectively;

[0031] S2: After the pH value is adjusted, add copper sulfide solid particles to the wastewater containing perfluorooctanoic acid, and then stir under the condition of constant temperature of 30℃ to make the copper sulfide solid particles adsorb perfluorooctanoic acid in the wastewater; the molar ratio of copper sulfide solid particles to perfluorooctanoic acid is 1:10;

[0032] Take the wastewater before and after adsorption to detect the concentration of perfluorooctanoic acid, and the detection steps are as follows:

[0033] Step M1: Prepare PFOA solutions with concentrations of 1, 2, 5, 10, 15, 20, 25, 30, 40, and 50 mg / L, respectively, measure TOC, and make a PFOA solution-TOC standard curve, and the R value of the obtained standard curve should be ≥0.999. 2

[0034] ​Step M2: measure the TOC value of the solution before and after CuS adsorbs PFOA, and bring the measured TOC value into the standard curve of step M1 to obtain the concentration before and after adsorption, and then calculate the adsorption amount.

[0035] The results show that when the initial concentration of PFOA is 500 mg / L, the adsorption effect of crystalline copper sulfide on perfluorooctanoic acid increases first and then decreases with the increase of pH at 30℃, and the adsorption effect of copper sulfide on PFOA is best at pH 11, which can reach 349.07 mg / g (such as Figure 2 ).

[0036] It can be seen that the crystalline copper sulfide material prepared by the present application has a very good adsorption effect on perfluorooctanoic acid at pH 11, and can be used for adsorption and removal of perfluorooctanoic acid in water.

[0037] Example 2

[0038] S1, a reagent is added to the wastewater containing perfluorooctanoic acid to adjust the pH value of the wastewater to pH 11;

[0039] S2, after the pH value is adjusted, copper sulfide solid particles are added to the wastewater containing perfluorooctanoic acid, and then stirring is carried out under constant temperature conditions of 15℃ to make the copper sulfide solid particles adsorb perfluorooctanoic acid in the wastewater; the molar ratio of copper sulfide solid particles to perfluorooctanoic acid is 1:10.

[0040] The wastewater before and after adsorption is taken for perfluorooctanoic acid concentration detection, and the detection steps are the same as those in Example 1, and the detection results are shown in Table 1.

[0041] Example 3

[0042] S1, a reagent is added to the wastewater containing perfluorooctanoic acid to adjust the pH value of the wastewater to pH 11;

[0043] S2, after the pH value is adjusted, copper sulfide solid particles are added to the wastewater containing perfluorooctanoic acid, and then stirring is carried out under constant temperature conditions of 30℃ to make the copper sulfide solid particles adsorb perfluorooctanoic acid in the wastewater; the molar ratio of copper sulfide solid particles to perfluorooctanoic acid is 1:10.

[0044] The wastewater before and after adsorption is taken for perfluorooctanoic acid concentration detection, and the detection steps are the same as those in Example 1, and the detection results are shown in Table 1.

[0045] Example 4

[0046] S1, a reagent is added to the wastewater containing perfluorooctanoic acid to adjust the pH value of the wastewater to pH 11;

[0047] S2, after the pH value adjustment is completed, copper sulfide solid particles are added to the wastewater containing perfluorooctanoic acid, and then stirring is performed under the constant temperature condition of 45 DEG C to enable the copper sulfide solid particles to adsorb the perfluorooctanoic acid in the wastewater; the molar ratio of the copper sulfide solid particles to the perfluorooctanoic acid is 1:10;

[0048] The wastewater before and after adsorption is taken to detect the perfluorooctanoic acid concentration, and the detection steps are the same as those in the detection steps in Example 1, and the detection results are shown in Table 1.

[0049] Comparative Example 1

[0050] S1, a reagent is added to the wastewater containing perfluorooctanoic acid to adjust the pH value of the wastewater to pH=11;

[0051] S2, after the pH value adjustment is completed, copper sulfide solid particles are added to the wastewater containing perfluorooctanoic acid, and then stirring is performed under the constant temperature condition of 5 DEG C to enable the copper sulfide solid particles to adsorb the perfluorooctanoic acid in the wastewater; the molar ratio of the copper sulfide solid particles to the perfluorooctanoic acid is 1:10;

[0052] The wastewater before and after adsorption is taken to detect the perfluorooctanoic acid concentration, and the detection steps are the same as those in the detection steps in Example 1, and the detection results are shown in Table 1.

[0053] Comparative Example 2

[0054] S1, a reagent is added to the wastewater containing perfluorooctanoic acid to adjust the pH value of the wastewater to pH=3, 5, 10, 10.5, 11, 11.5, 12, 12.5;

[0055] S2, after the pH value adjustment is completed, copper sulfide solid particles are added to the wastewater containing perfluorooctanoic acid, and then stirring is performed under the constant temperature condition of 60 DEG C to enable the copper sulfide solid particles to adsorb the perfluorooctanoic acid in the wastewater; the molar ratio of the copper sulfide solid particles to the perfluorooctanoic acid is 1:10;

[0056] The wastewater before and after adsorption is taken to detect the perfluorooctanoic acid concentration, and the detection steps are the same as those in the detection steps in Example 1, and the detection results are shown in Table 1.

[0057] Comparative Example 3

[0058] S1, a reagent is added to the wastewater containing perfluorooctanoic acid to adjust the pH value of the wastewater to pH=6;

[0059] S2, after the pH value adjustment is completed, copper sulfide solid particles are added to the wastewater containing perfluorooctanoic acid, and then stirring is performed under the constant temperature condition of 30 DEG C to enable the copper sulfide solid particles to adsorb the perfluorooctanoic acid in the wastewater; the molar ratio of the copper sulfide solid particles to the perfluorooctanoic acid is 1:10;

[0060] The wastewater before and after adsorption was taken to detect the concentration of perfluorooctanoic acid, and the detection steps were the same as those in Example 1. The detection results are shown in Table 1.

[0061] Comparative Example 4

[0062] S1, a reagent was added to the wastewater containing perfluorooctanoic acid, and the pH value of the wastewater was adjusted to pH = 13;

[0063] S2, after the pH value adjustment was completed, copper sulfide solid particles were added to the wastewater containing perfluorooctanoic acid, and then stirring was performed under constant temperature conditions at 30°C to enable the copper sulfide solid particles to adsorb the perfluorooctanoic acid in the wastewater; the molar ratio of the copper sulfide solid particles to the perfluorooctanoic acid was 1:10;

[0064] The wastewater before and after adsorption was taken to detect the concentration of perfluorooctanoic acid, and the detection steps were the same as those in Example 1. The detection results are shown in Table 1.

[0065] Comparative Example 5

[0066] S1, a reagent was added to the wastewater containing perfluorooctanoic acid, and the pH value of the wastewater was adjusted to pH = 11;

[0067] S2, after the pH value adjustment was completed, zinc oxide solid particles were added to the wastewater containing perfluorooctanoic acid, and then stirring was performed under constant temperature conditions at 30°C to enable the zinc oxide solid particles to adsorb the perfluorooctanoic acid in the wastewater; the molar ratio of the zinc oxide solid particles to the perfluorooctanoic acid was 1:10;

[0068] The wastewater before and after adsorption was taken to detect the concentration of perfluorooctanoic acid, and the detection steps were the same as those in Example 1. The detection results are shown in Table 1.

[0069]

[0070] It can be seen from the data in the adsorption steps of Example 1 and Figure 2 It can be seen from the data in the adsorption steps of Example 1 and

[0071] It can be seen from the data in Table 1 that under the condition of pH 11, the copper sulfide solid particles have good adsorption effects on PFOA at 15°C, 30°C and 45°C, and the adsorption effect is best at 30°C, and the adsorption capacity can reach 451.76 mg / g; the adsorption effect is second at 15°C, and the adsorption capacity can reach 439.58 mg / g; the adsorption effect is worst at 45°C, and the adsorption capacity can reach 356.14 mg / g; when the temperature during adsorption is lower than 15°C or higher than 45°C, the adsorption capacity of the copper sulfide solid particles for the perfluorooctanoic acid in the wastewater will decrease obviously; and the adsorption capacity of the copper sulfide solid particles for the perfluorooctanoic acid in the wastewater is also greatly related to the pH value during adsorption.

[0072] Comparing the data in Comparative Example 5 with the data in Example 3, it can be seen that under the same adsorption conditions, the adsorption capacity of the copper sulfide solid particles is significantly higher than that of the zinc oxide solid particles.

[0073] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0074] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A method for adsorbing perfluorooctanoic acid (PFOA) from wastewater, characterized in that, The method includes the following steps: S1. Add reagents to the wastewater containing perfluorooctanoic acid to adjust the pH value of the wastewater; S2. After pH adjustment, copper sulfide solid particles are added to the wastewater containing perfluorooctanoic acid (PFOA), and then stirred under constant temperature to allow the copper sulfide solid particles to adsorb PFOA in the wastewater. The constant temperature condition for adsorption in step S2 is 15~45℃. The molar ratio of copper sulfide solid particles to perfluorooctanoic acid is 1:

10.

2. The adsorption method according to claim 1, characterized in that: In step S1, the reagent used to adjust the pH value is an HCl solution or a NaOH solution.

3. The adsorption method according to claim 1, characterized in that: The optimal pH for copper sulfide solid particles to adsorb perfluorooctanoic acid is 11.

4. The adsorption method according to claim 1, characterized in that: The method for preparing the copper sulfide solid particles is as follows: sodium sulfide solution is added dropwise to copper chloride solution, heated and stirred to obtain copper sulfide solution, and the copper sulfide solution is precipitated, filtered and dried to obtain copper sulfide solid particles.

5. The adsorption method according to claim 4, characterized in that: The molar ratio of the sodium sulfide solution to the copper chloride solution is 2:

3.

6. An adsorbent comprising the copper sulfide solid particles mentioned in any of the adsorption methods of claims 1-5.

7. The application of the adsorbent as described in claim 6 in the adsorption of perfluorooctanoic acid in wastewater.

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