A highly efficient synergistic treatment method of perfluorinated compounds and bisphenol compounds in water
By adsorbing and enriching perfluorinated compounds and bisphenol compounds with layered bimetallic hydroxide adsorbents, and then using ultraviolet light to excite hydrated electrons for synergistic degradation, the problem of efficient degradation of these two types of pollutants in water is solved, achieving green degradation without secondary pollution.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUZHOU UNIV OF SCI & TECH
- Filing Date
- 2025-07-31
- Publication Date
- 2026-05-22
AI Technical Summary
Existing technologies are insufficient for the efficient and synergistic degradation of perfluorinated compounds and bisphenol compounds in water. Traditional methods suffer from incomplete degradation or require the introduction of additional oxidants/reducing agents, leading to secondary pollution.
Layered bimetallic hydroxide (LDH) is used as an adsorbent. Taking advantage of its positive charge and aluminum hydroxyl properties, it adsorbs and enriches perfluorinated compounds and bisphenol compounds. It also generates hydrated electrons through ultraviolet excitation for synergistic degradation, protecting the hydrated electrons from interference by dissolved oxygen and hydrogen ions.
It achieves efficient synergistic degradation of perfluorinated compounds and bisphenol compounds, avoids the introduction of additional oxidants/reducants, reduces costs and avoids secondary pollution, and improves the utilization rate of hydrated electrons.
Smart Images
Figure CN120681921B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of environmental remediation technology, and in particular to a highly efficient synergistic treatment method for perfluorinated compounds and bisphenol compounds in water. Background Technology
[0002] PFAS (Perfluorinated Alkyl Sulfates) are synthetic organic compounds with strong thermal stability, chemical stability, and hydrophobic and oleophobic properties, widely used in fire-retardant foams, waterproof and oil-repellent coatings, and many other fields. However, these compounds can accumulate in the human body over a long period, interfering with the immune and endocrine systems, and may even increase the risk of cancer. Bisphenols (BPS) are compounds formed by two hydroxyphenyl groups bridged by other structures, and are widely used in food packaging, medical devices, and electronic product casings. As typical endocrine disruptors, BPS can damage neuroendocrine function, reproductive function, and cardiovascular health. Currently, these two compounds are frequently detected in the environment, posing a serious threat to ecosystems and human health. Traditional methods for treating perfluorinated compounds and BPS include adsorption and advanced oxidation / reduction methods. The former does not degrade pollutants, leading to difficulties in subsequent treatment; the latter requires the introduction of additional oxidants / reductants and catalysts, consuming large amounts of reagents and potentially causing secondary pollution. Therefore, developing a technology that enables the efficient and synergistic degradation of these two pollutants can effectively avoid the above problems.
[0003] Currently, hydrated electron reduction is considered one of the most promising methods for degrading perfluorinated compounds (PFASs). Hydrated electrons are the most potent known reducing radicals, capable of directly attacking CF bonds to achieve rapid degradation and defluorination of PFASs. Common hydrated electron donors include indole compounds and phenolic compounds, which lose electrons under ultraviolet irradiation to form free radicals, which are then gradually degraded through subsequent decarboxylation and ring-opening reactions. The lost electrons, when captured by water molecules, can form hydrated electrons to degrade PFASs. Bisphenolic compounds, containing two phenolic hydroxyl groups, have a high hydrated electron yield and the potential for synergistic degradation with PFASs. However, hydrated electrons are easily interfered with by reactive substances in water, such as dissolved oxygen, hydroxyl radicals, and hydrogen ions, resulting in extremely low utilization. Therefore, constructing a reaction space that can simultaneously accommodate PFASs and bisphenolic compounds, while eliminating interference from reactive substances in water, is crucial for achieving the synergistic degradation of both pollutants. Summary of the Invention
[0004] The purpose of this invention is to fully utilize the structural characteristics and degradation mechanisms of perfluorinated compounds and bisphenols to provide a method for the efficient synergistic degradation of these two pollutants, either in situ or ex-situ, without the need for additional oxidants / reducing agents and catalysts. This invention first requires the synthesis of a layered bimetallic hydroxide based on aluminum salts. This material has a layered structure (interlayer spacing of several angstroms), with a large amount of positively charged aluminum hydroxyl groups on its surface, exhibiting a strong affinity for both perfluorinated and bisphenolic compounds. It can efficiently adsorb these two types of compounds from water simultaneously or sequentially, enriching them in its interlayer spaces. Furthermore, the hydrophilicity and positive charge of the layered bimetallic hydroxide restrict the entry of dissolved oxygen and hydrogen ions into the interlayer spaces, effectively protecting hydrated electrons. Therefore, when the layered bimetallic hydroxide is simultaneously loaded with both pollutants, it can achieve efficient synergistic degradation of both under ultraviolet irradiation.
[0005] This invention provides a highly efficient synergistic treatment method for perfluorinated compounds and bisphenol compounds in water, comprising the following steps:
[0006] Step (1): LDH is synthesized using a co-precipitation method based on aluminum salt. A solution containing a certain proportion of aluminum salt and divalent metal salt is slowly added to an alkaline solution, followed by heating to obtain LDH precipitate.
[0007] Step (2): The obtained layered bimetallic hydroxide is added sequentially to wastewater containing perfluorinated compounds and bisphenol compounds respectively, or directly added to wastewater containing both perfluorinated compounds and bisphenol compounds, to complete the adsorption of the two pollutants.
[0008] Step (3): Use ultraviolet light to irradiate the layered bimetallic hydroxide loaded with two pollutants simultaneously to achieve efficient synergistic degradation of the two pollutants.
[0009] In the above scheme, the principle of the present invention is as follows: under the conditions of appropriate proportions, alkaline solution, and heating, the AI in the solution... 3+ It can co-precipitate with divalent metal ions to form LDH. LDH has a structure similar to brucite, but some of the divalent cations are converted by Al. 3+The replaced clay minerals result in LDH carrying a positive charge and possessing numerous aluminum hydroxyl structures on its surface, enabling it to adsorb pollutants through electrostatic interactions and hydrogen bonding. Typical perfluorinated compounds exist in anionic form, generating strong electrostatic interactions with LDH. Bisphenolic compounds are neutral molecules within the normal pH range, forming hydrogen bonds between their phenolic hydroxyl groups and aluminum hydroxyl groups; under high pH conditions, bisphenolic compounds deprotonate, acquiring a negative charge, leading to stronger electrostatic interactions with LDH and subsequent adsorption in large quantities. Furthermore, the positively charged layered structure of LDH effectively prevents interference from dissolved oxygen and hydrogen ions in water, improving the utilization rate of hydrated electrons. Therefore, the LDH synthesized by this method provides an excellent reaction site for the efficient synergistic degradation of perfluorinated and bisphenolic compounds. Bisphenolic compounds, possessing two phenolic hydroxyl groups, generate hydrated electrons under ultraviolet irradiation and gradually decompose themselves during subsequent reactions. The generated hydrated electrons are largely consumed by the perfluorinated compounds, enabling their degradation and defluorination. This step further promotes the generation of hydrated electrons in bisphenolic compounds, leading to their own decomposition. Therefore, this method fully utilizes the structural characteristics and degradation pathways of perfluorinated compounds and bisphenols, and cleverly employs layered bimetallic hydroxides as the reaction site for both pollutants by controlling the pH of the aquatic environment, achieving highly efficient synergistic degradation. No similar methods have been reported to date. This method requires no additional oxidants / reducing agents or catalysts, effectively reducing costs and avoiding secondary pollution.
[0010] Furthermore, in step (1), the method for preparing LDH is as follows:
[0011] The aluminum salt used in the preparation of LDH is aluminum chloride or aluminum nitrate, and the divalent metal salt used is the chloride or nitrate of magnesium, zinc, calcium, or ferrous iron. The molar ratio of the two is 0.25 to 0.5, preferably 0.5.
[0012] The aluminum salt and divalent metal salt are mixed to prepare a solution, which is then slowly added, preferably dropwise, to the alkaline solution. Throughout the process, a protective gas such as nitrogen is purged and NaOH is used to maintain the pH of the alkaline solution above 10. After the addition is complete, the resulting suspension is heated to 95 °C for 18 h, and the resulting precipitate is LDH.
[0013] In the above scheme, by setting the LDH preparation method, it is possible to ensure the stable crystallization and precipitation of LDH. Its structure contains more aluminum hydroxide and positive charge, and the interlayer anions are all monovalent anions, which is conducive to the adsorption of perfluorinated compounds and bisphenol compounds.
[0014] Furthermore, in step (2), the method for adding LDH to the wastewater is as follows:
[0015] LDH is added sequentially to wastewater containing perfluorinated compounds and bisphenol compounds, or both. If LDH is added directly to wastewater containing both PFAS and bisphenol compounds, centrifugation is unnecessary. If LDH is added sequentially to wastewater containing PFAS and bisphenol compounds separately, centrifugation is required after the first adsorption equilibrium before adding it to the next wastewater. After adding LDH, the pH of the wastewater needs to be adjusted to above 9.5, preferably 10.5. The concentration of LDH added each time is 0.05~0.2 g / L, preferably 0.1 g / L. The mass ratio of perfluorinated compounds to bisphenol compounds in the wastewater is 0.7~2, preferably 1.5.
[0016] In the above scheme, pH control ensures that the structure of LDH is not destroyed, while also allowing a higher proportion of bisphenol compounds to exist in a deprotonated form, enhancing their affinity for LDH. Controlling the LDH dosage ensures that most PFAS and bisphenol compounds in the water are adsorbed into the LDH interlayer. Controlling the mass of PFAS and bisphenol compounds ensures that both are efficiently degraded simultaneously, avoiding the introduction of additional oxidants / reducants.
[0017] Furthermore, in step (3), the method for the synergistic degradation of the two pollutants is as follows:
[0018] The selected UV lamp had a wavelength of 254 nm and a power of 36 W. The solution needed to be stirred at a rate of 200–400 rpm during the degradation process, with a degradation time of 4–8 h.
[0019] In the above scheme, limiting the ultraviolet wavelength effectively excites bisphenol compounds and increases the yield of hydrated electrons. Setting the stirring rate and degradation time allows LDH to fully receive ultraviolet radiation, enabling most PFAS and bisphenol compounds to degrade completely, thus avoiding waste of light source energy.
[0020] The advantages of this invention are:
[0021] Perfluorinated compounds and bisphenols are two classes of pollutants that have attracted much attention. Currently, one of the main degradation methods for perfluorinated compounds is hydrated electron reduction, which requires the introduction of hydrated electron donors such as indole derivatives; bisphenols, on the other hand, are degraded using advanced oxidation technologies, which require the continuous addition of Fe. 2+And substances such as H2O2. This not only consumes a large amount of reagents but may also cause secondary pollution. To address this problem, this invention provides a highly efficient synergistic treatment method for perfluorinated compounds and bisphenol compounds in water. It utilizes the characteristics of layered bimetallic hydroxides (LDHs) carrying positive charges and having a large amount of aluminum hydroxyl groups on their surface to efficiently adsorb perfluorinated compounds and bisphenol compounds in water and concentrate them in the interlayer. Bisphenol compounds are excited by ultraviolet light, causing them to lose electrons and gradually mineralize and decompose. The lost electrons are captured by water molecules to form hydrated electrons, which can directly attack CF bonds, leading to rapid degradation and defluorination of perfluorinated compounds. Furthermore, the hydrophilicity and positive charge of LDHs protect hydrated electrons from interference by dissolved oxygen and hydrogen ions, significantly improving the utilization rate of hydrated electrons, ultimately achieving highly efficient synergistic degradation of perfluorinated compounds and bisphenol compounds. This invention fully utilizes the respective structural characteristics and degradation pathways of perfluorinated compounds and bisphenol compounds, achieving highly efficient synergistic degradation of the two pollutants without the need for additional oxidants / reducing agents and catalysts. It avoids secondary pollution and saves raw materials, providing a new approach to achieving green degradation of pollutants.
[0022] Terminology Explanation:
[0023] LDH is a layered bimetallic hydroxide;
[0024] PFOA stands for perfluorooctanoic acid;
[0025] PFOS stands for perfluorooctanoic acid;
[0026] BPA stands for Bisphenol A.
[0027] BPS stands for Bisphenol S. Attached Figure Description
[0028] Figure 1 The kinetics of simultaneous adsorption of PFOA and BPA by LDH;
[0029] Figure 2 Degradation and defluorination kinetics of PFOA in the synergistic degradation system with BPA and in the control experimental group;
[0030] Figure 3 Degradation kinetics of BPA in the synergistic degradation system with PFOA and in the control experimental group;
[0031] Figure 4 The kinetics of LDH adsorption of PFOS and BPS, respectively;
[0032] Figure 5 Degradation and defluorination kinetics of PFOS in the synergistic degradation system with BPS and in the control experimental group;
[0033] Figure 6Degradation kinetics of BPS in the synergistic degradation system with PFOS and in the control experimental group;
[0034] Figure 7 The images show the electron paramagnetic resonance (EPR) images of LDH and its respective loads of BPA and BPS, where the green spheres represent the signals of hydrated electrons.
[0035] Figure 8 This is a schematic diagram illustrating the efficient synergistic degradation mechanism achieved by simultaneously loading perfluorinated compounds and bisphenol compounds onto LDH under ultraviolet irradiation. Detailed Implementation
[0036] To make the objectives, solutions, and advantages of this invention more intuitive, the solutions of this invention will be described more clearly and completely in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of this invention, not all of it. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Example 1
[0037] This implementation example provides a highly efficient synergistic treatment method for perfluorinated compounds and bisphenol compounds in water, which includes the following steps:
[0038] Step (1): Mix magnesium nitrate and aluminum nitrate solutions with a molar ratio of 2:1. Then add the mixture dropwise to deionized water with a pH of 11 while continuously purging with nitrogen gas. Throughout the addition process, continuously adjust the pH to >11 using NaOH. After the addition is complete, place the suspension in a 95 ℃ oven for 18 h. The resulting precipitate is LDH.
[0039] Step (2) Add 0.3 g of the obtained LDH to 300 mL of PFOA solution containing 10 mg / L and bisphenol A solution containing 10 mg / L, adjust the pH to 10.5, stir at 350 rpm / min, and equilibrate for 1 h.
[0040] Step (3) Insert a UV lamp with a wavelength of 254 nm and a power of 36 W into the solution and irradiate for 4 h to achieve in-situ synergistic degradation of PFOA and bisphenol A.
[0041] This study also included three control groups: Control Group 1 was degraded by ultraviolet radiation in the presence of only PFOA and BPA; Control Group 2 was degraded by ultraviolet radiation in the presence of only LDH and PFOA; and Control Group 3 was degraded by ultraviolet radiation in the presence of only LDH and BPA.
[0042] Figure 1The kinetics of LDH adsorption of PFOA and BPA were demonstrated. It can be seen that LDH can adsorb all PFOA in water within minutes and continuously adsorb BPA in water, thus completing the enrichment of PFOA and BPA. Figure 2 This study demonstrates the synergistic degradation system of PFOA in the presence of both LDH and BPA, as well as the degradation and defluorination rates in the control system. It can be seen that when BPA is absent from the system, PFOA undergoes almost no degradation or defluorination. When only PFOA and BPA are present in the system, a small amount of PFOA degradation is observed, with degradation and defluorination rates of 45% and 11%, respectively, at 240 min. This indicates that the hydrated electrons generated by BPA under UV irradiation are crucial for PFOA degradation. This can also be seen from... Figure 7 The signal of hydrated electrons was confirmed. When LDH, PFOA, and BPA were present in the system simultaneously, the degradation rate of PFOA was significantly increased, reaching 85% and 60% at 240 min, respectively. This indicates that the enrichment of PFOA and BPA by LDH and the protection of hydrated electrons promoted the degradation and defluorination of PFOA. Figure 3 The synergistic degradation system of BPA in the presence of both LDH and PFOA, as well as the degradation kinetics in the control system, were demonstrated. It can be seen that when PFOA is absent, the degradation rate of BPA is low, with only 85% degradation occurring within 40 min. When only PFOA and BPA are present, the degradation rate of BPA increases, reaching 93% degradation within 40 min. When LDH, PFOA, and BPA are present simultaneously, the rate at which PFOA consumes hydrated electrons accelerates, further promoting BPA decomposition and enabling it to achieve over 95% degradation within 15 min. The combined degradation kinetics of PFOA and BPA indicate that this method can achieve efficient synergistic degradation of PFOA and BPA. Example 2
[0043] This implementation case provides a highly efficient synergistic treatment method for perfluorinated compounds and bisphenol compounds in water. The difference from implementation case 1 is that this method uses PFOS as the perfluorinated compound and BPS as the bisphenol compound, and the dosing method is changed to LDH first adsorbing PFOS and then adsorbing bisphenol S.
[0044] Step (1): Same as in Implementation Case (1)
[0045] Step (2): Add 0.3 g LDH to 300 mL of PFOS solution containing 10 mg / L and equilibrate at 300 rpm / min for 1 h. After centrifuging to separate LDH, add it to 300 mL of BPS solution containing 10 mg / L and equilibrate at 350 rpm / min for 1 h.
[0046] Step (3): Insert a UV lamp with a wavelength of 254 nm and a power of 36 W into the solution and irradiate for 4 h to achieve efficient synergistic degradation of PFOS and BPS.
[0047] This study also included three control groups: Control Group 1 consisted of a mixture of PFOS and BPS at the same concentration but without the addition of LDH, which underwent UV irradiation degradation. Control Group 2 consisted of UV irradiation degradation with only LDH and PFOS present. Control Group 3 consisted of UV irradiation degradation with only LDH and BPS present.
[0048] Figure 4 The kinetics of LDH adsorbing PFOS and PBS were demonstrated, showing that LDH can adsorb all PFOS within minutes and can continuously adsorb PBS, thereby enriching PFOS and PBS in its interlayer. Figure 5 The degradation and defluorination rates of PFOS in the LDH-co-loaded system with both PFOS and BPS, and in the control system, were compared. It can be seen that PFOS undergoes almost no degradation or defluorination in the absence of BPS. In the solution containing both PFOS and PBS, PFOS is slowly degraded, with degradation and defluorination rates of 36% and 10%, respectively, at 4 h. This indicates that the hydrated electrons generated by PBS under UV irradiation are crucial for PFOS degradation, a point that can also be confirmed by... Figure 7 The degradation rate of PFOS was significantly increased in the LDH-loaded system containing both PFOS and PBS, with degradation and defluorination rates reaching 80% and 41% at 4 h, respectively. This indicates that the enrichment of PFOS and PBS by LDH and the protection of hydrated electrons promoted the degradation of PFOS. Figure 6 The degradation kinetics of BPS in a system simultaneously loaded with PFOS and PBS in LDH, as well as in a control system, were presented. It can be seen that the degradation rate is low when BPS is present alone, with 92% degradation occurring within 40 min. When BPS and PFOS are present in the solution simultaneously, the degradation rate of BPS increases, with 96% degradation occurring within 40 min. In the system simultaneously loaded with PFOS and BPS in LDH, BPS can be completely degraded within approximately 15 min. Combining the degradation kinetics of PFOS and PBS, this method demonstrates that it can achieve efficient synergistic degradation of PFOS and BPS.
Claims
1. A highly efficient synergistic treatment method for perfluorinated compounds and bisphenol compounds in water, characterized in that, Includes the following steps, Step (1): Based on aluminum salt, LDH is synthesized by co-precipitation method: the solution of aluminum salt and magnesium salt is slowly added to alkaline solution, and then heated to obtain LDH precipitate; Step (2): The obtained LDH is added sequentially to wastewater containing perfluorinated compounds and bisphenol compounds respectively, or directly added to wastewater containing both perfluorinated compounds and bisphenol compounds to complete the adsorption of the two pollutants. Step (3): Use ultraviolet light to irradiate the layered bimetallic hydroxide that simultaneously adsorbs the two pollutants, thereby completing the efficient synergistic degradation of the two pollutants; In step (1), the slow addition to the alkaline solution is called dropwise addition. During the dropwise addition process, NaOH is used to maintain the pH of the alkaline solution > 10, and nitrogen or other protective gases are continuously introduced. In step (1), the molar ratio of aluminum salt to magnesium salt is 0.25 to 0.5; The mass ratio of bisphenol compounds to perfluorinated compounds is 0.7~2; In step (2), the dosage of LDH is 0.05~0.2 g / L; In step (2), the wastewater needs to be adjusted to pH > 9.
5.
2. The method for the efficient synergistic treatment of perfluorinated compounds and bisphenol compounds in water according to claim 1, characterized in that, In step (1), the aluminum salt is aluminum chloride or aluminum nitrate.
3. The method for the efficient synergistic treatment of perfluorinated compounds and bisphenol compounds in water according to claim 1, characterized in that, In step (1), the magnesium salt is a magnesium chloride salt or a magnesium nitrate salt.
4. The method for the efficient synergistic treatment of perfluorinated compounds and bisphenol compounds in water according to claim 1, characterized in that, In step (1), the molar ratio of aluminum salt to magnesium salt is 0.
5.
5. The method for the efficient synergistic treatment of perfluorinated compounds and bisphenol compounds in water according to claim 1, characterized in that, The temperature must be maintained at 95℃ for 18 hours during the heating process.
6. The method for the efficient synergistic treatment of perfluorinated compounds and bisphenol compounds in water according to claim 1, characterized in that, In step (2), LDH is added sequentially to wastewater containing perfluorinated compounds and bisphenol compounds, or to wastewater containing both perfluorinated compounds and bisphenol compounds, with a mass ratio of bisphenol compounds to perfluorinated compounds of 1.
5.
7. The method for efficient synergistic treatment of perfluorinated compounds and bisphenol compounds in water according to claim 1, characterized in that, In step (2), the dosage of LDH is 0.1 g / L.
8. The method for the efficient synergistic treatment of perfluorinated compounds and bisphenol compounds in water according to claim 1, characterized in that, In step (2), the wastewater needs to be adjusted to pH 10.
5.
9. A highly efficient synergistic treatment method for perfluorinated compounds and bisphenol compounds in water according to claim 1, characterized in that, In step (3), the ultraviolet light source is a 36 W low-pressure mercury lamp with a wavelength of 254 nm.
10. A highly efficient synergistic treatment method for perfluorinated compounds and bisphenol compounds in water according to claim 1, characterized in that, In step (3), stirring is required at 200-400 rpm for a degradation time of 4-8 h.