Iron-containing sludge heterogeneous Fenton catalyst based on multistage molecular self-assembly silanization modification as well as preparation method and application of iron-containing sludge heterogeneous Fenton catalyst
By using oxygen plasma pretreatment and multi-level molecular self-assembly silanization modification, the prepared heterogeneous Fenton catalyst for iron-containing sludge solved the problem of activity loss of heterogeneous Fenton catalysts under high salt conditions, and achieved efficient and stable pollutant degradation and resource recycling.
Patent Information
- Application Number
- CN202510974018.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-15
- Publication Date
- 2025-10-28
AI Technical Summary
The active components of existing heterogeneous Fenton catalysts are easily lost under high salt conditions, the mechanical strength is insufficient, and the preparation cost is high, which limits their large-scale application. In addition, the iron-containing sludge treatment method causes resource waste and environmental risks.
An iron-containing sludge heterogeneous Fenton catalyst based on multi-level molecular self-assembly silanization modification was prepared by oxygen plasma pretreatment, multi-level molecular self-assembly silanization modification and three-step thermal gradient curing process, forming an organic-inorganic hybrid protective layer with a thickness of 12-18 nm, which improves the stability and activity of the catalyst.
It efficiently degrades pollutants over a wide pH range, maintaining stability, especially in high-salt environments, with a total organic carbon removal rate of over 90%. The catalyst retains 87% efficiency even after 10 cycles of use, achieving resource recycling and improved wastewater treatment efficiency.
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Figure CN120838480A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solid waste treatment technology, specifically relating to a heterogeneous Fenton catalyst for iron-containing sludge based on multi-level molecular self-assembly silanization modification, its preparation method, and its application. Background Technology
[0002] Fenton technology has shown significant advantages in pollutant degradation, through Fe... 2+ The H2O2 system generates highly oxidizing hydroxyl radicals, which can efficiently degrade many recalcitrant organic substances, and the reaction rate is fast with simple operating conditions. However, this technology is strictly dependent on an acidic environment, and the reaction process produces a large amount of iron-containing sludge, increasing disposal costs.
[0003] Compared to traditional Fenton technology, heterogeneous Fenton, through its immobilized design, can extend the effective pH range to 3–8, significantly reducing the need for acid-base adjustments. Simultaneously, iron dissolution is improved, reducing the generation of iron sludge. However, this technology still faces challenges such as high catalyst preparation costs, insufficient mechanical strength of some support materials, and potential loss of active components during long-term operation under high-salt conditions. These factors limit its large-scale engineering application.
[0004] Iron-containing sludge is generated in large quantities during wastewater treatment processes in the steel and electroplating industries. Since its iron content is generally between 10% and 25%, it possesses significant resource utilization value. Furthermore, this sludge exhibits unique porous structure characteristics, making it an ideal raw material for catalyst carriers. Compared to traditional commercial carrier materials, the acquisition cost of iron-containing sludge is significantly lower, demonstrating a clear economic advantage.
[0005] However, current methods for treating iron-containing sludge mainly involve sanitary landfill and high-temperature incineration, which not only result in a huge waste of iron resources but also pose serious environmental risks. If iron-containing sludge could be prepared into a highly efficient heterogeneous Fenton catalyst, it would achieve both resource recycling ("waste-to-waste" treatment) and significantly improve wastewater treatment efficiency, representing a win-win solution for both environmental governance and resource recovery. Summary of the Invention
[0006] Purpose of the invention: The purpose of this invention is to address the shortcomings of existing technologies by providing a heterogeneous Fenton catalyst for iron-containing sludge based on multi-level molecular self-assembly and silanization modification, as well as its preparation method and application.
[0007] Technical solution: The objective of this invention is achieved through the following technical solution:
[0008] This invention provides a method for preparing a heterogeneous Fenton catalyst for iron-containing sludge based on multi-level molecular self-assembly and silanization modification, comprising the following steps:
[0009] (1) The iron-containing sludge raw material is pretreated with oxygen plasma with a treatment power of 50-100W and a treatment time of 10-15min;
[0010] (2) The sludge pretreated in step (1) was surface activated by an acid-alkali alternating cleaning process;
[0011] (3) The activated sludge from step (2) is immersed in a mixed silane solution consisting of γ-aminopropyltriethoxysilane APTES, octadecyltriethoxysilane ODTES and 3-glycidyl ether propyltrimethoxysilane GPTMS for reaction.
[0012] (4) Add organotin catalyst, adjust pH, and carry out in-situ crosslinking reaction;
[0013] (5) Solidify the sludge after the in-situ crosslinking reaction in step (4) to obtain the iron-containing sludge heterogeneous Fenton catalyst.
[0014] Oxygen plasma pretreatment utilizes high-energy particle bombardment and reactive oxygen free radical action to physically etch a nanoscale rough structure onto the surface of iron-containing sludge, significantly increasing the specific surface area. Simultaneously, selective activation of the iron oxide lattice exposes more active crystal faces. This non-thermal equilibrium dry treatment, while maintaining the matrix properties, constructs an ideal anchoring interface for subsequent silanization, resulting in a significant increase in silane grafting rate, and avoiding iron loss and wastewater generation caused by traditional acid washing.
[0015] This invention employs a ternary silane system of APTES, ODTES, and GPTMS for synergistic modification, achieving complementary multiple functions. First, short-chain APTES preferentially and rapidly bonds to the iron hydroxyl groups on the sludge surface, forming a high-density anchoring layer that provides active sites for subsequent modification. Second, long-chain ODTES constructs a dense hydrophobic barrier through alkyl chain self-assembly, effectively inhibiting iron dissolution. Finally, epoxy-functionalized GPTMS acts as a cross-linking bridge; its active epoxy groups undergo ring-opening reactions with amino / hydroxyl groups, forming a three-dimensional network structure that significantly enhances the mechanical stability of the coating. This gradient assembly strategy, through molecular-level interface design, simultaneously achieves active site exposure, mass transfer channel optimization, and structural stability enhancement, enabling the catalyst to maintain high pollutant degradation efficiency over a wide pH range and under high-salt conditions.
[0016] Preferably, in step (1), the moisture content of the iron-containing sludge raw material is 70-80%, and the iron content is 10%-15%.
[0017] In a preferred embodiment of the present invention, the pretreatment is carried out in a rotating oxygen plasma device at a rotation speed of 10 to 30 rpm.
[0018] Preferably, in step (2), the acid-base alternating cleaning process involves first treating with 0.1-0.5 mol / L HCl for 30-60 min, and then treating with 0.1-0.5 mol / L NaOH for 30-60 min.
[0019] Preferably, in step (3), the molar ratio of the three silane coupling agents, γ-aminopropyltriethoxysilane APTES, octadecyltriethoxysilane ODTES, and 3-glycidyl ether oxypropyltrimethoxysilane GPTMS, is 1:(1-2):(0.3-0.5).
[0020] Preferably, in step (3), the solvent of the mixed silane solution is a mixture of ethanol and water in a volume ratio of 9:1.
[0021] Preferably, in step (3), the reaction temperature is 40-60°C and the reaction time is 4-8 hours.
[0022] Preferably, in step (4), the organotin catalyst is dibutyltin dilaurate or dimethyltin dithiolate; the amount of the organotin catalyst added is 0.1 to 0.5 wt%.
[0023] Preferably, in step (4), the pH is adjusted to 4-5; the temperature of the in-situ crosslinking reaction is 60-80°C and the time is 6-12 hours.
[0024] Preferably, in step (5), the curing adopts a three-step thermal gradient curing procedure: first, curing at 80°C for 1 hour, then heating to 120°C for 2 hours, and finally curing at 150°C for 1 hour, with a heating rate of 2 to 5°C / min.
[0025] The advantage of this invention's three-step thermal gradient curing process lies in the fact that the initial 80°C stage promotes the orderly arrangement of silane molecules and eliminates microbubbles, while the intermediate 120°C stage accelerates the cross-linking reaction to form a three-dimensional network framework, and the final 150°C stage completes densification and enhances the interfacial bonding strength. Compared with traditional single-temperature curing, this progressive curing strategy can improve the mechanical strength of the organic-inorganic hybrid layer while reducing porosity, and avoid structural stress cracking caused by sudden high-temperature changes.
[0026] The present invention also provides a heterogeneous Fenton catalyst for iron-containing sludge based on multi-level molecular self-assembly silanization modification prepared by the above preparation method.
[0027] The catalyst of this invention has the following characteristics:
[0028] (1) The catalyst surface has an organic-inorganic hybrid protective layer with a thickness of 12-18 nm;
[0029] (2) The silane layer coverage reaches over 95%;
[0030] (3) The water contact angle is 120-135°.
[0031] This invention also provides the application of the above-mentioned heterogeneous Fenton catalyst for iron-containing sludge modified by multi-level molecular self-assembly silanization in the degradation of organic matter in wastewater.
[0032] Beneficial effects:
[0033] (1) The preparation method of this invention involves a three-step thermal gradient solidification process: oxygen plasma pretreatment, self-assembly of mixed silane molecules, and synergistic crosslinking with organotin catalysts. This process directionally constructs a superhydrophobic organic-inorganic hybrid protective layer on the surface of iron-containing sludge, significantly improving the stability of the heterogeneous Fenton catalyst and the pollutant degradation efficiency.
[0034] (2) The catalyst of the present invention has stable catalytic performance in high salt environment and has a wide pH range.
[0035] (3) This invention prepares iron-containing sludge into a highly efficient heterogeneous Fenton catalyst, achieving both resource recycling through "waste-to-waste" treatment and significantly improving wastewater treatment efficiency. When 0.5–1 g of catalyst is added to a 1 L reaction system (pH 3–8, chloride ion concentration 0–20 g / L, H2O2 concentration 0.5–1 g / L, hexamethylenediamine concentration 200 mg / L), the total organic carbon removal rate is greater than 90% within 60 min. After 10 cycles of catalyst use, the TOC removal rate remains above 87%. Attached Figure Description
[0036] Figure 1 The total organic carbon removal rate is calculated by reusing the heterogeneous Fenton catalyst for iron-containing sludge 10 times. Detailed Implementation
[0037] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.
[0038] The iron-containing sludge raw material of this invention comes from the iron-containing sludge generated by the pickling process unit of a steel plant.
[0039] Before pretreatment of iron-containing sludge, the moisture content of the iron-containing sludge raw material was dehydrated to 80% using a centrifuge, and the iron content in the iron-containing sludge was determined to be 12% after digestion.
[0040] The rotating oxygen plasma equipment used in this invention is the Shanzhun brand rotating plasma low-temperature ashing instrument, model VP-T3.
[0041] Example 1
[0042] (1) Place 50g of dehydrated iron-containing sludge in a rotating oxygen plasma device for pretreatment. The rotation speed is 10rpm, the processing power is 100W, and the processing time is 1 minute.
[0043] (2) The pretreated sludge was treated with 10 mL of 0.1 mol / L HCl for 60 minutes, and then with 10 mL of 0.1 mol / L NaOH for 60 minutes.
[0044] (3) Take 1 mL of γ-aminopropyltriethoxysilane APTES, 2.2 mL of octadecyltriethoxysilane ODTES and 0.3 mL of 3-glycidyl etheroxypropyltrimethoxysilane GPTMS, and prepare a 50 mL mixed silane solution with an ethanol / water mixed solvent with a volume ratio of 9:1. Immerse the acid- and alkali-treated sludge in the solution and react at 40°C for 8 hours.
[0045] (4) Add 0.5wt% dibutyltin dilaurate to the reacted sludge, adjust the pH to 5, and carry out an in-situ crosslinking reaction at 60℃ for 12 hours.
[0046] (5) The sludge after in-situ cross-linking reaction was first solidified at 80℃ for 1 hour, then heated to 120℃ for 2 hours, and finally solidified at 150℃ for 1 hour to obtain the heterogeneous Fenton catalyst containing iron sludge. The heating rate of the three solidification stages was 2℃ / min.
[0047] Catalyst cross-sectional samples were prepared by ultrathin slicing, and the thickness of the protective layer was directly observed to be 12–18 nm under a high-resolution transmission electron microscope.
[0048] X-ray photoelectron spectroscopy analysis showed that the silane layer coverage was 96.4 ± 1.1%.
[0049] The contact angle of the catalyst with water was measured to be 128±6° using a contact angle meter.
[0050] Heterogeneous Fenton reaction experimental conditions:
[0051] 1L of simulated wastewater (wastewater composition: initial concentration of hexamethylenediamine 200mg / L, pH 8, chloride ion concentration 0g / L, H2O2 concentration 0.5g / L), with 0.5g / L of heterogeneous Fenton catalyst added to iron-containing sludge, was reacted at room temperature for 60 minutes, and the total organic carbon removal rate was 91.3%.
[0052] Example 2
[0053] (1) Place 50g of dehydrated iron-containing sludge into a rotating oxygen plasma device for pretreatment. The rotation speed is 30rpm, the processing power is 50W, and the processing time is 10 minutes.
[0054] (2) The pretreated sludge was treated with 10 mL of 0.5 mol / L HCl for 30 minutes, and then with 10 mL of 0.5 mol / L NaOH for 30 minutes;
[0055] (3) Take 1 mL of γ-aminopropyltriethoxysilane APTES, 3.3 mL of octadecyltriethoxysilane ODTES and 0.5 mL of 3-glycidyl etheroxypropyltrimethoxysilane GPTMS, and prepare a 50 mL mixed silane solution with an ethanol / water mixed solvent with a volume ratio of 9:1. Immerse the acid- and alkali-treated sludge in the solution and react at 60°C for 4 hours.
[0056] (4) Add 0.1 wt% dimethyl dithiol tin to the reacted sludge, adjust the pH to 4, and carry out an in-situ crosslinking reaction at 80°C for 6 hours.
[0057] (5) The sludge after in-situ cross-linking reaction was first solidified at 80℃ for 1 hour, then heated to 120℃ for 2 hours, and finally solidified at 150℃ for 1 hour to obtain the heterogeneous Fenton catalyst containing iron sludge. The heating rate of the three solidification stages was 5℃ / min.
[0058] Heterogeneous Fenton reaction experimental conditions:
[0059] 1L of simulated wastewater (wastewater composition: initial concentration of hexamethylenediamine 200mg / L, pH 3, chloride ion concentration 20g / L, H2O2 concentration 1g / L) was taken, and the dosage of heterogeneous Fenton catalyst containing iron sludge was 1g / L. After 60 minutes of reaction, the total organic carbon removal rate was 90.1%.
[0060] Example 3
[0061] (1) Place 50g of dehydrated iron-containing sludge into a rotating oxygen plasma device for pretreatment. The rotation speed is 20rpm, the processing power is 75W, and the processing time is 12 minutes.
[0062] (2) The pretreated sludge was treated with 10 mL of 0.3 mol / L HCl for 45 minutes, and then with 10 mL of 0.3 mol / L NaOH for 45 minutes.
[0063] (3) Take 1 mL of γ-aminopropyltriethoxysilane APTES, 2.7 mL of octadecyltriethoxysilane ODTES and 0.4 mL of 3-glycidyl etheroxypropyltrimethoxysilane GPTMS, and prepare a 50 mL mixed silane solution with a volume ratio of 9:1 ethanol / water mixed solvent. Immerse the acid- and alkali-treated sludge in the solution and react at 50 °C for 6 hours.
[0064] (4) Add 0.25wt% dibutyltin dilaurate to the reacted sludge, adjust the pH to 4, and carry out an in-situ crosslinking reaction at 70℃ for 9 hours;
[0065] (5) The sludge after in-situ cross-linking reaction was first solidified at 80℃ for 1 hour, then heated to 120℃ for 2 hours, and finally solidified at 150℃ for 1 hour to obtain the heterogeneous Fenton catalyst containing iron sludge. The heating rate of the three solidification stages was 3℃ / min.
[0066] Heterogeneous Fenton reaction experimental conditions:
[0067] 1L of simulated wastewater (wastewater composition: initial concentration of hexamethylenediamine 200mg / L, pH 5, chloride ion concentration 10g / L, H2O2 concentration 0.7g / L) was taken, and the dosage of heterogeneous Fenton catalyst containing iron sludge was 0.7g / L. After 60 minutes of reaction, the total organic carbon removal rate was 93.6%.
[0068] Example 4
[0069] To investigate the catalytic performance during catalyst recycling, the catalyst was recovered by centrifugation after the heterogeneous Fenton reaction conducted in Example 3, and the experiment was repeated. The specific steps and results are as follows:
[0070] (1) Centrifuge the heterogeneous Fenton reaction solution at 8000 rpm for 5 minutes using a high-speed centrifuge to separate the catalyst from the solution.
[0071] (2) After discarding the supernatant, transfer the catalyst in the centrifuge tube to the reaction flask and add 1L of reaction solution (simulating the composition of wastewater, wherein the initial concentration of hexamethylenediamine is 200mg / L, pH is 5, chloride ion concentration is 10g / L, and H2O2 concentration is 0.7g / L) to the reaction flask.
[0072] (3) After 60 minutes of reaction, the total organic carbon concentration in the solution before and after the reaction was measured, and the total organic carbon removal rate was calculated. The above steps were repeated 10 times, and the results of the total organic carbon removal rate are as follows: Figure 1 The total organic carbon removal rate was 90.4% when the catalyst was reused 5 times, but dropped to 87.5% when it was reused 10 times.
[0073] Comparative Example 1
[0074] A heterogeneous catalyst for iron-containing sludge was prepared following the steps in Example 3. The difference was that the iron-containing sludge was not pretreated with oxygen plasma, but instead directly subjected to acid-base treatment and subsequent operations. The prepared catalyst was used in a heterogeneous Fenton reaction experiment according to the methods in Examples 3 and 4, achieving a total organic carbon removal rate of 62.2%. After 10 reuses, the total organic carbon removal rate decreased to 60.1%.
[0075] Comparative Example 2
[0076] Following the steps in Example 3, a heterogeneous catalyst for iron-containing sludge was prepared. The difference was that only an APTES solution (1 mL APTES was prepared into a 50 mL silane solution using a 9:1 volume ratio ethanol / water mixture) was used to immerse the acid-base treated sludge, and the reaction was carried out at 60°C for 4 hours. The prepared catalyst was then used in heterogeneous Fenton reaction experiments according to the methods in Examples 3 and 4, achieving a total organic carbon removal rate of 78.4%. After 10 reuses, the total organic carbon removal rate decreased to 64%.
[0077] Comparative Example 3
[0078] A heterogeneous catalyst for iron-containing sludge was prepared following the steps in Example 3. The difference was that the sludge after the in-situ crosslinking reaction was directly solidified at 150°C for 1 hour. The prepared catalyst was used in a heterogeneous Fenton reaction experiment according to the methods in Examples 3 and 4, achieving a total organic carbon removal rate of 94.5%. After 10 reuses, the total organic carbon removal rate decreased to 66.3%.
[0079] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims
1. A method for preparing a heterogeneous Fenton catalyst for iron-containing sludge based on multi-level molecular self-assembly and silanization modification, characterized in that, Includes the following steps: (1) The iron-containing sludge raw material is pretreated with oxygen plasma with a treatment power of 50-100W and a treatment time of 10-15min; (2) The sludge pretreated in step (1) was surface activated by an acid-alkali alternating cleaning process; (3) The activated sludge from step (2) is immersed in a mixed silane solution consisting of γ-aminopropyltriethoxysilane APTES, octadecyltriethoxysilane ODTES and 3-glycidyl ether propyltrimethoxysilane GPTMS for reaction. (4) Add organotin catalyst, adjust pH, and carry out in-situ crosslinking reaction; (5) Solidify the sludge after the in-situ crosslinking reaction in step (4) to obtain the iron-containing sludge heterogeneous Fenton catalyst.
2. The preparation method according to claim 1, characterized in that, In step (1), the iron-containing sludge raw material has a moisture content of 70-80% and an iron content of 10%-15%.
3. The preparation method according to claim 1, characterized in that, In step (1), the pretreatment is carried out in a rotating oxygen plasma device at a speed of 10 to 30 rpm.
4. The preparation method according to claim 1, characterized in that, In step (2), the acid-base alternating cleaning process involves first treating with 0.1-0.5 mol / L HCl for 30-60 min, and then treating with 0.1-0.5 mol / L NaOH for 30-60 min.
5. The preparation method according to claim 1, characterized in that, In step (3), the molar ratio of the three silane coupling agents, γ-aminopropyltriethoxysilane APTES, octadecyltriethoxysilane ODTES, and 3-glycidyl etheroxypropyltrimethoxysilane GPTMS, is 1:(1~2):(0.3~0.5); the reaction temperature is 40~60℃, and the reaction time is 4~8h.
6. The preparation method according to claim 1, characterized in that, In step (4), the organotin catalyst is dibutyltin dilaurate or dimethyl dithiol tin; the amount of the organotin catalyst added is 0.1 to 0.5 wt%.
7. The preparation method according to claim 1, characterized in that, In step (4), the pH is adjusted to 4-5; the temperature of the in-situ crosslinking reaction is 60-80℃ and the time is 6-12h.
8. The preparation method according to claim 1, characterized in that, In step (5), the curing adopts a three-step thermal gradient curing procedure: first, curing at 80℃ for 1 hour, then heating to 120℃ for 2 hours, and finally curing at 150℃ for 1 hour, with a heating rate of 2 to 5℃ / min.
9. The heterogeneous Fenton catalyst for iron-containing sludge based on multi-level molecular self-assembly silanization modification prepared by the preparation method according to any one of claims 1-8.
10. The application of the iron-containing sludge heterogeneous Fenton catalyst according to claim 9 in the degradation of organic matter in wastewater.