Method for degrading perfluorooctanoic acid in water by titanium-loaded molecular sieve and persulfate
By leveraging the synergistic effect of titanium-supported molecular sieves and persulfate, the problem of low PFOA degradation efficiency in existing technologies has been solved, achieving efficient and economical PFOA degradation with a degradation rate approaching 100% and a defluorination rate of 54.51%.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHAANXI NORMAL UNIV
- Filing Date
- 2025-03-13
- Publication Date
- 2026-06-19
AI Technical Summary
Existing technologies are difficult to efficiently degrade perfluorooctanoic acid (PFOA). A single technical route cannot simultaneously achieve degradation efficiency, economic efficiency, and environmental safety. Existing multi-technology combined systems suffer from problems such as high phosphotungstic acid loading, reliance on high-energy-consuming light sources, and low defluorination rates.
Titanium-loaded molecular sieves were synthesized via ion exchange using the synergistic effect of titanium-loaded molecular sieves and persulfate, and were used for the adsorption-oxidative degradation of PFOA, with the reaction carried out under suitable temperature and time conditions.
It achieves a high PFOA degradation rate of nearly 100%, with a defluorination rate of up to 54.51%. The degradation is thorough, low-cost, and simple and safe to operate.
Smart Images
Figure CN119930021B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmental pollution control technology, specifically relating to a method for the synergistic degradation of perfluorooctanoic acid in water by a titanium-supported molecular sieve catalyst and persulfate. Background Technology
[0002] Perfluorooctanoic acid (PFOA) is a typical representative of perfluorinated / polyfluoroalkyl compounds (PFAS). Due to its unique hydrophobic and oleophobic properties, it is widely used in industrial and civilian fields such as non-stick cookware coatings, waterproofing of textiles, surface modification of electronic components, and fire-fighting foam preparations. However, the extremely strong CF covalent bond (bond energy of about 460 kJ / mol) in the PFOA molecule endows it with extremely high chemical stability, making it difficult to degrade through natural pathways such as hydrolysis, photolysis, or biological metabolism, thus resulting in long-term residues in the environment. More seriously, PFOA can be amplified step by step in the food chain through bioaccumulation, eventually accumulating in human blood, liver, and other tissues, and is significantly associated with toxic effects such as increased cancer incidence, immune system suppression, and reproductive developmental abnormalities (Steenland K, et al. Environmental health perspectives, 2010, 118(8):1100-1108.). Currently, PFOA has been widely detected in global drinking water sources, farmland soils, and even extreme environments such as Arctic glaciers. Given its persistence, bioaccumulation and toxicity, it was officially included in Appendix A (List of Elimination Substances) of the Stockholm Convention on Persistent Organic Pollutants in 2019.
[0003] Current degradation technologies for PFOA mainly include physical adsorption, chemical oxidation, thermal degradation, and photocatalysis. However, due to the inherent limitations of individual technologies, practical applications face severe challenges. For example, while physical adsorption can rapidly enrich PFOA, it only achieves phase transfer of pollutants and fails to overcome the dual bottlenecks of low adsorbent regeneration efficiency and insufficient pollutant mineralization. Using O3 or persulfate chemical oxidants alone results in limited degradation efficiency. Thermal degradation, although thorough, is energy-intensive and easily produces toxic gases such as hydrogen fluoride (HF), making exhaust gas treatment complex. Photocatalytic degradation currently suffers from low light energy utilization and dependence on ultraviolet light (CN 112371143A). Therefore, a single technological approach cannot simultaneously achieve degradation efficiency, economic viability, and environmental safety. Thus, developing integrated technologies that couple multiple technologies has become an important direction for overcoming existing technological barriers.
[0004] CN107416943A achieves a maximum defluorination rate of 56.21% through the synergistic effect of SiO2-phosphotungstic acid and UVC ultraviolet light. However, this system suffers from drawbacks such as excessively high phosphotungstic acid loading (10%–50%) and reliance on high-energy-consuming UVC light sources. CN117550673A increases the PFOA degradation rate to nearly 100% through a combined technology of ferric iron-modified zeolite molecular sieve, persulfate, and simulated sunlight. However, under optimal conditions (ferric iron-modified zeolite molecular sieve dosage of 0.5 g / L), the degradation rate is still low. -1 With a sodium persulfate concentration of 0.2 mM and an initial PFOA concentration of 0.024 mM, after 12 hours of illumination, the defluorination rate was only 29.6%, indicating that the mineralization process was not yet complete. CN117123208A uses an mSiO2@CeO2 composite catalyst, achieving a 30% degradation rate of PFOA under ultraviolet light, but it does not disclose key defluorination rate data. Therefore, the efficiency of current methods combining multiple technologies for PFOA degradation is still unsatisfactory. Summary of the Invention
[0005] To address the low defluorination rate of existing technologies, this invention provides a method for the efficient degradation of PFOA in water using titanium-supported molecular sieves in conjunction with persulfate. This method utilizes adsorption-oxidation to degrade PFOA, resulting in high degradation efficiency and complete degradation.
[0006] The method for synergistic degradation of PFOA in water by titanium-supported molecular sieves and persulfate provided by this invention includes the following steps:
[0007] Step 1: Add the matrix molecular sieve to an aqueous solution of titanium dichlorodicyclopentadiene, stir, filter, wash, and dry to obtain a titanium-supported molecular sieve;
[0008] Step 2: Add titanium-supported molecular sieves and persulfate to an aqueous solution containing PFOA, and degrade them at 60–150°C for 12–48 h.
[0009] Furthermore, in step 1, the matrix molecular sieve of the titanium-loaded molecular sieve is preferably ZSM-5 molecular sieve or USY molecular sieve, with a titanium element loading rate of 0.1% to 2%.
[0010] Further, in step 1, the concentration of the titanium dioxide dichlorodichlorodicarbonate aqueous solution is preferably 0.002–0.02 mol / L.
[0011] Furthermore, in step 1, the stirring time is preferably 24 to 96 hours.
[0012] Furthermore, in step 2, the concentration of PFOA in the PFOA-containing aqueous solution is preferably 1-5 g / L.
[0013] Furthermore, in step 2, the preferred mass ratio of the titanium-supported molecular sieve to PFOA is 0.5 to 10:1.
[0014] Further, in step 2, the persulfate is preferably sodium persulfate and potassium persulfate, and the mass ratio of the persulfate to PFOA is 1 to 60:1.
[0015] Furthermore, in step 2, the degradation temperature is preferably 80–100°C, and the reaction time is preferably 15–30 h.
[0016] The beneficial effects of this invention are as follows:
[0017] 1. This invention uses commercially available molecular sieves as the matrix material and titanium dichlorodicyclopentadiene, which is stable, inexpensive, and readily available, as the titanium source. Titanium-supported molecular sieves are synthesized via ion exchange. All raw materials are low-cost, the synthesis method is simple, convenient to operate, and highly safe, with low equipment requirements. Furthermore, the titanium-supported molecular sieves exhibit stable properties.
[0018] 2. This invention uses titanium-supported molecular sieve-persulfate synergistic degradation of PFOA in water, which has the advantages of high degradation efficiency and thorough degradation, with a degradation rate close to 100% and a defluorination rate of up to 54.51%. Attached Figure Description
[0019] Figure 1 This is the XPS full spectrum of the titanium-supported molecular sieve Ti-Z5 prepared in Example 1.
[0020] Figure 2 This is a scanning electron microscope image of the titanium-supported molecular sieve Ti-Z5 prepared in Example 1.
[0021] Figure 3 This is a comparison of the XRD patterns of the titanium-supported molecular sieve Ti-Z5 prepared in Example 1 and the matrix molecular sieve ZSM-5.
[0022] Figure 4 The attached diagram shows the N2 adsorption-desorption of the titanium-supported molecular sieve Ti-Z5 prepared in Example 1.
[0023] Figure 5 This is the XPS full spectrum of the titanium-supported molecular sieve Ti-A prepared in Example 2.
[0024] Figure 6 This is a scanning electron microscope image of the titanium-supported molecular sieve Ti-A prepared in Example 2.
[0025] Figure 7 This is a comparison of the XRD patterns of the titanium-supported molecular sieve Ti-A prepared in Example 2 and the matrix molecular sieve USY.
[0026] Figure 8 The attached diagram shows the N2 adsorption-desorption of the titanium-supported molecular sieve Ti-A prepared in Example 2. Detailed Implementation
[0027] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The specific embodiments described herein are used to explain the present invention and are not intended to limit the present invention.
[0028] Example 1
[0029] Step 1: Add 20g of ZSM-5 molecular sieve to 160mL of 0.01mol / L titanium dichlorophenoxyacetate aqueous solution, stir at room temperature for 72h, centrifuge, filter, wash the solid with ultrapure water, and dry at 100℃ for 72h to obtain titanium-loaded molecular sieve Ti-Z5, in which the titanium loading rate is 0.4%. Figure 1 The presence of titanium signals indicates that Ti-Z5 was successfully synthesized. Figure 2 It can be seen that it is flattened hexagonal prism, which is consistent with the morphology of ZSM-5 molecular sieve, indicating that the structure of ZSM-5 molecular sieve did not change significantly during the loading of titanium. Figure 3 It can be seen that the main peaks of the ZSM-5 molecular sieve did not change, indicating that the structure of the ZSM-5 molecular sieve did not change significantly during the titanium loading process. Figure 4 As can be seen, Ti-Z5 is a microporous material, and its S... BET 333.301m 2 g -1 The pore size is 0.1592 cc g. -1 .
[0030] Step 2: Add 6 mL of 3.45 g / L PFOA aqueous solution, 0.59524 g of sodium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-Z5 sequentially to a round-bottom flask. React at 80 °C for 24 h to degrade PFOA. The results show that the PFOA degradation rate is nearly 100%, and the defluorination rate is 54.51%.
[0031] The degradation effect of this embodiment was compared with that without adding titanium-supported molecular sieve Ti-Z5 or by replacing the titanium-supported molecular sieve Ti-Z5 with ZSM-5 molecular sieve (other conditions were the same as in step 2 above). As can be seen from Table 1, the introduction of the catalyst improved the defluorination rate of the reaction, and the titanium-supported catalyst significantly improved the degradation effect of PFOA, demonstrating the importance of loading titanium onto ZSM-5 molecular sieve.
[0032] Table 1
[0033]
[0034] Example 2
[0035] Step 1 of this embodiment is the same as step 1 of Example 1, yielding titanium-supported molecular sieve Ti-Z5. In step 2 of this embodiment, 6 mL of 3.45 g / L PFOA aqueous solution, 0.05952 g of sodium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-Z5 were added sequentially to a round-bottom flask, and the mixture was reacted at 80 °C for 24 h to degrade PFOA. The results showed that the PFOA degradation rate was nearly 100%, and the defluorination rate was 35.17%.
[0036] Example 3
[0037] Step 1 of this embodiment is the same as step 1 of Example 1, yielding titanium-supported molecular sieve Ti-Z5. In step 2 of this embodiment, 6 mL of 3.45 g / L PFOA aqueous solution, 0.1190 g of sodium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-Z5 were added sequentially to a round-bottom flask, and the mixture was reacted at 80 °C for 24 h to degrade PFOA. The results showed that the PFOA degradation rate was nearly 100%, and the defluorination rate was 41.17%.
[0038] Example 4
[0039] Step 1 of this embodiment is the same as step 1 of Example 1, yielding titanium-supported molecular sieve Ti-Z5. In step 2 of this embodiment, 6 mL of 3.45 g / L PFOA aqueous solution, 0.2381 g of sodium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-Z5 were added sequentially to a round-bottom flask, and the mixture was reacted at 80°C for 24 h to degrade PFOA. The results showed that the PFOA degradation rate was nearly 100%, and the defluorination rate was 42.13%.
[0040] Example 5
[0041] Step 1 of this embodiment is the same as step 1 of Example 1, yielding titanium-supported molecular sieve Ti-Z5. In step 2 of this embodiment, 6 mL of 3.45 g / L PFOA aqueous solution, 0.9524 g of sodium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-Z5 were added sequentially to a round-bottom flask, and the mixture was reacted at 80 °C for 24 h to degrade PFOA. The results showed that the PFOA degradation rate was nearly 100%, and the defluorination rate was 39.48%.
[0042] Example 6
[0043] Step 1 of this embodiment is the same as step 1 of Example 1, yielding titanium-supported molecular sieve Ti-Z5. In step 2 of this embodiment, 6 mL of 3.45 g / L PFOA aqueous solution, 1.1905 g of sodium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-Z5 were added sequentially to a round-bottom flask, and the mixture was reacted at 80 °C for 24 h to degrade PFOA. The results showed that the PFOA degradation rate was nearly 100%, and the defluorination rate was 35.51%.
[0044] Example 7
[0045] Step 1 of this embodiment is the same as step 1 of Example 1, yielding titanium-supported molecular sieve Ti-Z5. In step 2 of this embodiment, 6 mL of 3.45 g / L PFOA aqueous solution, 0.59524 g of sodium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-Z5 were added sequentially to a round-bottom flask, and the mixture was reacted at 120 °C for 24 h to degrade PFOA. The results showed that the PFOA degradation rate was nearly 100%, and the defluorination rate was 30.43%.
[0046] Example 8
[0047] Step 1 of this embodiment is the same as step 1 of Example 1, yielding titanium-supported molecular sieve Ti-Z5. In step 2 of this embodiment, 6 mL of 3.45 g / L PFOA aqueous solution, 0.59524 g of sodium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-Z5 were added sequentially to a round-bottom flask, and the mixture was reacted at 80 °C for 12 h to degrade PFOA. The results showed that the PFOA degradation rate was nearly 100%, and the defluorination rate was 31.19%.
[0048] Example 9
[0049] Step 1: Add 20g of USY molecular sieve to 160mL of 0.01mol / L titanium dichlorophenoxyacetate aqueous solution, stir at room temperature for 72h, centrifuge, filter, wash the solid with ultrapure water and dry at 100℃ for 72h to obtain titanium-loaded molecular sieve Ti-A, wherein the titanium loading rate is 0.4%. Figure 5 The presence of titanium signals indicates that Ti-A synthesis was successful. Figure 6 The morphology of the USY molecular sieve is consistent with that of the USY molecular sieve, indicating that the structure of the USY molecular sieve did not change significantly during the loading of titanium. Figure 7 It can be seen that the main peaks of the USY molecular sieve did not change, indicating that the structure of the USY molecular sieve did not change significantly during the titanium loading process. Figure 8 As can be seen, Ti-A is a microporous material, and its S... BET It is 725.633m 2 g -1 The pore size is 0.3406 cc g. -1 .
[0050] Step 2: Add 6 mL of 0.05-3.45 g / L PFOA aqueous solution, 0.2703 g of potassium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-A sequentially to a round-bottom flask. React at 80 °C for 24 h to degrade PFOA. The results show that the PFOA degradation rate is nearly 100%, and the defluorination rate is 53.70%.
[0051] Example 10
[0052] Step 1 of this embodiment is the same as step 1 of Example 9, yielding titanium-supported molecular sieve Ti-A. In step 2 of this embodiment, 6 mL of 3.45 g / L PFOA aqueous solution, 0.2703 g of potassium persulfate, and 0.15 g of titanium-supported molecular sieve Ti-A were added sequentially to a round-bottom flask, and the mixture was reacted at 80 °C for 24 h to degrade PFOA. The results showed that the PFOA degradation rate was nearly 100%, and the defluorination rate was 48.56%.
[0053] Example 11
[0054] Step 1 of this embodiment is the same as step 1 of Example 9, yielding titanium-supported molecular sieve Ti-A. In step 2 of this embodiment, 6 mL of 3.45 g / L PFOA aqueous solution, 0.1352 g of potassium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-A were added sequentially to a round-bottom flask, and the mixture was reacted at 80 °C for 24 h to degrade PFOA. The results showed that the PFOA degradation rate was nearly 100%, and the defluorination rate was 39.11%.
[0055] Example 12
[0056] Step 1 of this embodiment is the same as step 1 of Example 9, yielding titanium-supported molecular sieve Ti-A. In step 2 of this embodiment, 6 mL of 3.45 g / L PFOA aqueous solution, 0.6758 g of potassium persulfate, and 0.1 g of titanium-supported molecular sieve Ti-A were added sequentially to a round-bottom flask, and the mixture was reacted at 80°C for 24 h to degrade PFOA. The results showed that the PFOA degradation rate was nearly 100%, and the defluorination rate was 35.74%.
Claims
1. A method for the synergistic degradation of perfluorooctanoic acid (PFOA) in water using titanium-supported molecular sieves and persulfate, characterized in that... Includes the following steps: Step 1: The matrix molecular sieve is added to a titanium dichlorodicyclopentadiene aqueous solution, stirred, filtered, washed, and dried to obtain a titanium-supported molecular sieve; the concentration of the titanium dichlorodicyclopentadiene aqueous solution is 0.002–0.02 mol / L; Step 2: Add the titanium-supported molecular sieve and persulfate to an aqueous solution containing perfluorooctanoic acid (PFOA) and degrade it for 12-24 h under heating conditions of 80-120 °C; the mass ratio of persulfate to PFOA is 1-60:
1.
2. The method for the synergistic degradation of perfluorooctanoic acid in water by titanium-supported molecular sieves and persulfate according to claim 1, characterized in that: In step 1, the matrix molecular sieve is ZSM-5 molecular sieve or USY molecular sieve.
3. The method for the synergistic degradation of perfluorooctanoic acid in water by titanium-supported molecular sieves and persulfate according to claim 1, characterized in that: In step 1, the loading rate of titanium element in the titanium-loaded molecular sieve is 0.1% to 2%.
4. The method for the synergistic degradation of perfluorooctanoic acid in water by titanium-supported molecular sieves and persulfate according to claim 1, characterized in that: In step 1, the stirring time is 24–96 h.
5. The method for the synergistic degradation of perfluorooctanoic acid in water by titanium-supported molecular sieves and persulfate according to claim 1, characterized in that: In step 2, the concentration of perfluorooctanoic acid in the aqueous solution containing perfluorooctanoic acid is 1 to 5 g / L.
6. The method for the synergistic degradation of perfluorooctanoic acid in water by titanium-supported molecular sieves and persulfate according to claim 1, characterized in that: In step 2, the mass ratio of the titanium-supported molecular sieve to perfluorooctanoic acid is 0.5 to 10:
1.
7. The method for the synergistic degradation of perfluorooctanoic acid in water by titanium-supported molecular sieves and persulfate according to claim 1, characterized in that: In step 2, the persulfate is sodium persulfate or potassium persulfate.
8. The method for the synergistic degradation of perfluorooctanoic acid in water by titanium-supported molecular sieves and persulfate according to claim 1, characterized in that: In step 2, the degradation temperature is 80–100 °C.